Curso Cat d6t Stmg 1865

SERV1865 September 2008

GLOBAL SERVICE LEARNING TECHNICAL PRESENTATION

D6T TRACK-TYPE TRACTOR

Service Training Meeting Guide (STMG)

D6T TRACK-TYPE TRACTOR MEETING GUIDE

VISUALS AND SCRIPT AUDIENCE

Level II Service personnel who have knowledge of the principles of machine systems operation, diagnostic equipment, and procedures for testing and adjusting machine systems and components.

CONTENT This presentation discusses the operation of the power train, the differential steering system, the implement hydraulic system, the demand fan system, the cooling system, and the Caterpillar Monitoring System on the D6T Track-type Tractor. Also discussed is the operation of the controls in the operator compartment and the location and identification of the major components of the C9 ACERT® technology engine.

OBJECTIVES After learning the information in this presentation, the serviceman will be able to: 1. locate and identify all of the major D6T machine components; 2. locate and identify all filters, dipsticks, indicators, fill tubes, drains, and test points; 3. locate and identify the major components of the C9 ACERT® technology engine; 4. trace the flow of fuel through the C9 engine fuel delivery system; 5. trace the flow of air through the engine's air intake system; 6. trace the flow of coolant through the cooling system of the D6T ; 7. identify and explain the function/operation of each major component in the hydraulic demand fan system; 8. trace the flow of oil through the hydraulic demand fan system; 9. identify and explain the function/operation of each major component in the power train system; 10. trace the flow of oil through the power train hydraulic system and explain its operation; 11. trace the flow of oil through the steering system and explain its operation; 12. explain the function/operation of each major component in the implement hydraulic system; 13. trace the flow of oil through the implement hydraulic system; 14. locate and identify all of the major components in the Caterpillar Monitoring System.

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REFERENCES Engine Systems Operation, Testing & Adjusting (C9 Engine) . . . . . . . . . . . . . . . . . .SENR9830 Engine Troubleshooting Guide (C9 Engine) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RENR9345 Specifications (C9 Engine) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SENR9829 Systems Operation, Testing & Adjusting (Power Train) . . . . . . . . . . . . . . . . . . . . . . .KENR5124 Systems Operation, Testing & Adjusting (Hydraulic System) . . . . . . . . . . . . . . . . . .KENR5129 Operation and Maintenance Manual (OMM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SEBU8146 Schematic (Hydraulic System) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .KENR5128 Schematic (Power Train Oil System) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .KENR5125 Schematic (Electrical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .KENR5131 Systems Operation/Troubleshooting/Testing & Adjusting of D6R Series III, D6T, D7R Series II Track-Type Tractors Power Train Electronic Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RENR9867

PREREQUISITES Interactive Video Course "Fundamentals of Mobile Hydraulics" . . . . . . . . . . . . . . .TEMV9001 Interactive Video Course "Fundamentals of Electrical Systems" . . . . . . . . . . . . . . . .TEMV9002 STMG 546 "Graphic Fluid Power Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SERV1546

SUPPLEMENTARY TRAINING MATERIALS "Electronically Controlled Transmission System - Track-type Tractors (T.I.M.) . . . .SERV2639 "Caterpillar Monitoring System - Track-type Tractors" . . . . . . . . . . . . . . . . . . . . . . .SEGV2619 CD ROM version of SEGV2619 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SERV2619 Technical Instruction Module "Air Conditioning Principles and Operation" . . . . . . .SERV2580 Technical Instruction Module "Air Conditioning Service Procedures" . . . . . . . . . . . .SERV2581

Estimated Time: 8 Hours Visuals: 155 Visuals Serviceman Handouts: 4 Lab Exercises Posttest: 6 pages (and 6 answer sheets) Form: SERV1865 Date: 09/08 © 2008 Caterpillar

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TABLE OF CONTENTS INTRODUCTION ........................................................................................................................5 Undercarriage .........................................................................................................................7 OPERATOR'S COMPARTMENT ..............................................................................................11 CATERPILLAR MONITORING SYSTEM ..............................................................................23 ENGINE......................................................................................................................................36 Engine Air System ................................................................................................................64 Cooling System.....................................................................................................................66 POWER TRAIN .........................................................................................................................74 Power Train Hydraulic System.............................................................................................76 Torque Divider ......................................................................................................................81 Power Shift Transmission .....................................................................................................91 Electronic Brake Control Valve ............................................................................................98 IMPLEMENT HYDRAULIC SYSTEM..................................................................................109 Implement Pump Operation................................................................................................115 Pressure Reducing Manifold...............................................................................................127 Implement Pilot Valve operation ........................................................................................129 Implement Control Valve operation....................................................................................132 Quick-drop Valve ................................................................................................................144 Differential Steering Hydraulic System..............................................................................153

CONCLUSION.........................................................................................................................165 VISUAL LIST ..........................................................................................................................168 HANDOUTS.............................................................................................................................169 Posttest ................................................................................................................................172 Posttest Answers .................................................................................................................175

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D6T TRACK-TYPE TRACT OR

© 2008 Caterpillar

1 INTRODUCTION The D6T Track Type Tractor has been designed to meet U.S. Environmental Protection Agency (EPA) Tier III Emissions Regulations for North America and Stage III European Emissions Regulations. The D6T meets the EU sound regulations (EU Directive 2000/14/EC) for 2006. The D6T is powered by the C9 ACERT® (Advanced Combustion Emissions Reduction Technology) electronic engine equipped with the Hydraulic Electronic Unit Injection (HEUI) fuel system. This engine also utilizes the new A4 Engine Electronic Control Module (ECM) and is equipped with an Air To Air AfterCooler (ATAAC) intake air cooling system. The C9 is rated at 185 horsepower (138 kW) at 1850 rpm in the standard machine and 200 hp (149 kW) at 1850 rpm in the XL, the XW, and the LGP models. Other standard features of the D6T Track-type Tractor include: Multi Velocity Program (MVP) transmission, the SystemOne™ undercarriage system, the AutoShift and AutoKickdown power train strategies, two pump hydraulic system with a dedicated steering pump, differential steering (with Touch Shift), and under hood air conditioning for the ROPS/FOPS cab. The D6T can be ordered with an "S" blade, an "SU" blade, or with the improved VPAT (Variable Pitch Angle Tilt) blade. The machine can also be ordered with the AccuGrade Ready Option (ARO), a multi shank ripper or a PA56 winch.

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D6T SERIAL NUMBER PREFIXES WHERE BUILT

TRACTOR MODEL

E. PEORIA

GRENOBLE

PIRACICABA

SAGAMI

Standard, with SU Blade

JHB

PEZ

SMC

DHL

XL, with SU Blade

LAY

LAE

GCT

KLM

XW, with SU Blade

SKL

LBD

n/a

RAY

LGP, with SU Blade

KJL

LKJ

n/a

SNK

XL, with VPAT Blade

WFH

ZEB

n/a

n/a

XW, with VPAT Blade

DJG

RLW

n/a

n/a

LGP, with VPAT Blade

WCG

JWD

n/a

n/a

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The chart shown above illustrates the machine serial number prefixes as determined by the tractor model, the arrangement, and where the machine is assembled.

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Standard Undercarriage Arrangement

XL Undercarriage Arrangement

D6T UNDERCARRIAGE ARRANGEMENTS

XW Undercarriage Arrangement

LGP Undercarriage Arrangement

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Undercarriage The D6T machines have a standard track configuration or optional XL, XW, and LGP track configurations. The standard track configuration has six rollers. A carrier roller is available as an attachment. The XL track configuration has a longer track roller frame (seven rollers and a carrier roller) with more track toward the front of the machine. The XW track configuration also extends the track toward the front (seven rollers and a carrier roller), but has a wider track gage for better stability on slopes. The LGP arrangement has wider track, a wider track gage, and a longer track roller frame (eight rollers and a carrier roller) than the standard track configuration, extending the track both forward and to the rear. This reduces ground pressure for excellent flotation in swampy conditions.

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4 The D6T Track-type Tractor is equipped with the new SystemOne™ undercarriage as standard on all undercarriage arrangements (Std., XL, XW, and LGP). The older style undercarriage (standard for earlier D6R machines) is also available as an option. The SystemOne undercarriage system uses the following redesigned components: • track links and track pins with rotating bushings (1) • track shoes (2) • sprocket segments (3) • track idlers (4) • track rollers (5) • carrier rollers (6) • track guides (7)

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This front view of the D6T shows the standard dozer blade, blade lift cylinders and front mounted work lights.

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From the rear of the machine the drawbar, counterweight group, rear work lights, and transmission pressure taps can be seen. A ripper or winch are also available for the D6T.

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OPERATOR'S COMPARTMENT The operator's compartment for the D6T is very similar to the D6R Series III. Many of the upgrades and improvements to the operator's compartment found in the D6R III are included: • a new right hand console with electronic dozer control lever for AccuGrade Ready machines • a rocker switch to control the Multi Velocity Program (MVP) (if equipped) • improved operator visibility, both forward and backward • electro-hydraulic blade angle control for machines equipped with the VPAT blade • an electronic Implement Lockout switch

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The Cat contour seat is standard equipment, with air suspension available as an attachment. The seat provides maximum comfort and less operator fatigue. The height of the padded armrests is manually adjustable using the two knobs (1) below each armrest. The seat is angled 15° to the right in order to provide maximum visibility of implement operation. The operator can adjust the seat height using the control knob (2) under the left front of the seat. The front to rear seat position and the seat back angle can be adjusted using the control levers (3) found under the front of the seat. The seat back and the seat cushion assembly can be removed from the suspension base by removing one 8 mm bolt (4), located below the front, center of the seat.

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9 The steering control lever, or tiller (1) is located at the front of the left armrest. The steering tiller combines steering, directional changes, and gear selection into one control. Pulling UP on the parking brake switch (2) shifts the transmission to FIRST gear NEUTRAL and energizes the parking brake solenoid on the electronic brake valve, which engages the brakes. The parking brake switch also mechanically locks the tiller housing when in the UP, or ON position. The key lockout (3) locks the parking brake switch in the UP position. FORWARD, NEUTRAL, and REVERSE are controlled by rotating the tiller hand grip (4). All three positions have detents that hold the tiller in the selected position. A rotary position sensor connected to the hand grip provides a PWM signal to the Machine ECM when the handgrip is rotated. The Machine ECM then sends a corresponding current to the appropriate transmission modulating valve to ENERGIZE the solenoid. The solenoid modulating valves engage and disengage the forward and reverse clutches in the Electronic Clutch Pressure Control (ECPC) transmission. In addition, a reverse switch is installed in the tiller housing to provide an input to the Machine ECM, confirming the REVERSE position. The top yellow button (5) upshifts the transmission one gear range at a time, and the bottom yellow button (6) downshifts the transmission one gear range at a time. These switches provide an input to the Machine ECM, which then sends a corresponding current to the appropriate transmission modulating valves to ENERGIZE the solenoids in order to engage and disengage the three speed clutches in the ECPC transmission.

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Left turns are accomplished by rotating the tiller (1) toward the front. Right turns are accomplished by rotating the tiller toward the rear. When the operator releases the tiller, a centering spring returns the tiller to the center (NO STEER) position. The tiller housing shaft is connected to mechanical linkages that move the main valve stem on the steering valve. NOTE: The differential steering strategy still incorporates the standard "S-Turn" logic used in previous differential steer machines. When the parking brake is engaged, the Machine ECM monitors the parking brake switch and the ECM then ENERGIZES the secondary brake solenoid, as a back-up measure.

WARNING

With the engine running and the transmission shifted to NEUTRAL, rotating the steering tiller toward the front or the rear will cause the machine to steer. The tracks will counterrotate, resulting in the machine pivoting about its center point. To avoid personal injury and/or property damage, always ENGAGE the parking brake when not operating the machine and/or when other personnel are nearby.

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The right console contains the implement controls and switches for other machine modes and functions. These controls and switches are: • dozer control lever (1) • high/low idle switch (2) • MVP switch (if equipped) (3) • implement lockout switch (4) • ripper control handle (winch control, if so equipped) (5) • forward horn button (6)

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11 The dozer control lever (1) allows the operator to control all of the blade functions with one lever. Moving the dozer control lever forward or rearward LOWERS or RAISES the blade. Moving the dozer control lever left or right causes the blade to TILT LEFT or TILT RIGHT. If the machine is equipped with a VPAT blade, moving the thumb lever (2) to the right causes the blade to ANGLE RIGHT. Moving the thumb lever to the left will cause the blade to ANGLE LEFT. If the machine is equipped with AccuGrade®, two yellow buttons will be present on either side of the lever, at the top (as shown above). The dozer control lever will also include a trigger switch (not visible above) on the front of the lever. The left yellow button (3) allows the operator to activate the automatic blade control mode, if AccuGrade is activated. In the automatic mode, AccuGrade will make adjustments to the blade height and angle, relative to the preprogrammed "design" (or finish grade surface) desired. The right yellow button (4) disables the automatic blade control mode, allowing the operator to manually operate the blade.

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Depressing and holding the trigger switch while pressing the left yellow button decrements (or lowers) the finished design grade height by a predetermined amount. Depressing and holding the trigger switch while pressing the right yellow button increments (or raises) the finished design grade height. This increment/decrement strategy serves as a means to "offset" the preprogrammed design grade height and it will raise or lower the actual finished grade relative to the original predetermined finish grade surface. NOTE: There are four different configurations for the dozer control lever, depending on whether the machine is equipped with an S or an SU blade, or with a VPAT blade and whether the machine is ordered Accugrade Ready (ARO). These four different dozer control lever configurations are as follows: - Standard machine with the S or SU blade - the dozer control lever is a pilot operated control lever with no thumb lever, no yellow buttons, and no trigger switch. - Standard machine with the VPAT blade - the dozer control lever is a pilot operated control lever with an EH thumb lever, with no yellow buttons, and no trigger switch. - ARO machine with the S or SU blade - the dozer control lever is an electronic control lever (joystick) with no thumb lever, with two yellow buttons, and with a trigger switch. - ARO machine with the VPAT blade - the dozer control lever is an electronic control lever (joystick) with an EH thumb lever, with two yellow buttons, and with a trigger switch .

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Machines that are equipped with the optional ripper have a ripper control lever (1). Moving the ripper control lever toward the operator seat RAISES the ripper. Moving the ripper control lever away from the operator seat LOWERS the ripper. The center position is the ripper HOLD position. If the machine is equipped with a winch, the winch control lever will be located where the ripper control is. Also shown is the auxilary action light (2).

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Located to the rear of the dozer control lever are three switches for machine functions. Pressing the top of the High/Low Idle switch (1) sets the engine speed to high idle. Pressing the bottom of the High/Low Idle switch sets the engine speed to low idle. Pressing the bottom of the Implement Lockout switch (2) activates the implement lockout strategy, which disables implement movement. The implements cannot move without pilot oil. The third switch (3) controls the use of the Multi Velocity Program (MVP). MVP is an attachment to the D6T's built for the North American markets. MVP is standard equipment for all D6Ts destined for European markets.

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When MVP is selected by the operator, the Engine ECM will limit engine high idle speed during certain conditions. With MVP enabled and the transmission gear indication in the dash panel indication 1.5, 2.5, or 3.5 forward or reverse, the Engine ECM will allow a high idle speed of 2010 rpm. With the transmission gear indicator indicating 2.0 or 3.0 forward or reverse, the Engine ECM will set high idle speed to 1550 rpm. Decreasing engine high idle speed during MVP operation increases fuel economy, reduces operatiog costs and allows the operator to more closely match machine ground speed to work conditions. See the illustrations on the next page for an explanation of which high idle speed is allowed for NACD and EU. During MVP operation, the Engine ECM monitors the engine speed timing sensor and also the torque converter output speed sensor. As the difference in the rotational speed of the engine and the torque converter output shaft becomes greater (torque converter slip) the Engine ECM has the ability to allow high idle speed to reach the 2010 rpm maximum. For example the operator has enabled MVP using the rocker switch and is dozing in gear 2.0 Forward. As machine load increases and the torque converter nears its stall point, the Engine ECM will allow rpm to increase to the 2010 rpm maximum to deliver full rated engine power to the torque converter. The operator is therby not limited to the available torque of the engine at 1550 rpm but is instead able to use full engine power. As the machine load decreases and the rotational relationships of the engine and torque convereter output shaft come closer together the Engine ECM will begine to reduce high idle rpm back to the 1550 allowed during MVP. This stratgy enables the machine to be most productive regardless of operation in or out of MVP. MVP can be set to be enabled or disabled by the operator on North American destined machines only. Additionally, MVP can be locked out by the technician using Cat ET. All machines destined for european markets will have MVP enabled by default and no operator switch will be provided. MVP cannot be disabled using Cat ET on E.U. market machines. The wiper/washer controls for windows in the cab and cab doors are located overhead, above the right console. From front to rear, these controls are: • front windshield wiper/washer control (4) • left cab door wiper/washer control (5) • right cab door wiper/washer control (6) • rear cab window wiper/washer control (7)

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The charts above show the HIGH IDLE speed for each gear selection during MVP operation. The top chart is for NACD destined machines and the lower chart represents machines built for European (E.U.) markets.

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Below the dash is the service brake pedal (1) and the decelerator pedal (2). During normal operation, the machine operates at high idle. Engine rpm may be decreased to 900 rpm (200 rpm above low idle) by depressing the decelerator pedal. Intermediate engine speeds are attained in the following manner: • Set the high/low idle switch to the HIGH IDLE position • Depress the decelerator pedal to attain the desired engine speed • Press and hold the high idle (rabbit) side of the high/low idle switch for approximately five seconds • Release the switch to set the intermediate engine speed • Release the decelerator pedal The engine speed may then be reduced from this intermediate engine speed by depressing the decelerator pedal. When the decelerator pedal is released, the engine speed will return to the intermediate setting.The intermediate engine speed setting may be cancelled by pressing either the high idle (rabbit) or low idle (turtle) side of the switch again.

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The service brake pedal applies the service brakes (both left and right) proportionately to the amount of pressure applied by the operator. When the pedal is depressed a rotary switch provides a signal to the Machine ECM The Machine ECM then ENERGIZES the proportional solenoid on the electronic brake control valve, proportionately to the amount of pedal movement. When completely depressed, the solenoid is completely ENERGIZED and the brakes are fully ENGAGED. A secondary brake switch (not visible) is also connected to the shaft of the brake pedal, inside the housing (3) on the dash pedestal. Depressing the service brake pedal to approximately 75% of brake pedal travel closes the normally open secondary brake switch. When the secondary brake switch is closed, it connects the battery to the secondary brake valve solenoid and ENERGIZES the secondary brake valve solenoid. Energizing the secondary brake valve solenoid opens the secondary brake valve, which drains all the oil from the brake circuit and ensures that the spring applied brakes are fully ENGAGED.

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18 Caterpillar Monitoring System The D6T can be equipped with a Machine Security System (MSS). The MSS indicator light (1) is installed below the MSS key switch (2) on the dash. The MSS requires a key that is unique to each machine. Also on the dash are the following components: • Gear/Direction/Alert indicator module (3) • Forward Action Lamp (4) • Auto KickDown switch (5) • AutoShift switch (6) • Quad Gage module (7) • Ripper work light switch (8) • Dash, flood lights, and forward work lights switch (9) • HVAC temperature control (10) • Main display module (11) • Operator scroll switch (12) • HVAC blower fan speed switch, with four fan speeds (13) • Air-conditioning selector switch (ON/OFF) (14)

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The Main Display Module (1) contains a small ECM which performs the processing functions for the monitoring system. This module is referred to as the EMS III panel and it must be installed for the monitoring system to operate. The EMS III panel contains the monitoring system flash file. The Main Display Module is located in the lower right portion of the dash. The upper section of this module contains nine LED alert indicators and the bottom section contains an LCD display area with a digital readout. The Main Display Module receives inputs from switches, sensors, senders, and the Machine ECM (through the CAT Data Link). The software in the module uses these inputs to illuminate the LED alert indicators, which inform the operator of abnormal machine conditions. The top row of LED alert indicators in the Main Display Module are identified (left to right) as: • Air Filter Restriction • Fuel Pressure (abnormal) • Power Train Oil Filter (bypass switch activated) • Fuel Injectors Warming (injector "buzz", for cold starts) • Power Train Oil Temperature (too high - temperature sensor at power train oil pump) The second row of LED alert indicators are identified (left to right) as: • Brake System Malfunction • Transmission System Malfunction • Engine System Malfunction • Implement System Malfunction

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The digital display area of the Main Display Module provides a six digit readout for various display modes. These display modes show: • machine operational time (in HOURS) • engine speed (in rpm) • distance traveled (in MILES/KILOMETERS) • diagnostic information, or service codes (MID, CID, FMI) The operator or serviceman may press the scroll switch (2) to access the various display modes. Each press of the scroll switch will access the next display mode. When the diagnostic mode is reached, the display area shows any faults that may be present. A complete listing of all active service codes will be displayed when the diagnostic mode is reached. The Main Display Module module utilizes a pair of dedicated communication links (Display Data Link) to communicate with and drive the functions of the Gear/Direction and Alert Indicator Module and the Quad Gage Module. The Display Data Link communicates information back and forth between the Main Display Module and the Quad Gage Module and the Gear/Direction and Alert Indicator Module. The CAT Data Link is used by the Main Display Module to communicate with other electronic controls and the ECMs. The CAT Data Link is bi-directional, which allows communication with both input and output devices.

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The Quad Gage Module is installed at the upper left of the dash. The Quad Gage Module contains four analog gages which display machine conditions that are most important during machine operation. A Forward Action Lamp is also included as part of the Quad Gage Module. The machine information displayed is: • Engine Coolant Temperature (1) • Power Train/Torque Converter Oil Temperature (2) (sensed at torque converter outlet relief valve) • Hydraulic Oil Temperature (3) • Fuel Level (4) • Forward Action Lamp (5)

NOTE: The quad gage module is considered an output component.

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The Gear/Direction and Alert Indicator Module are installed at the upper right of the dash. The top half of the module contains ten LED indicators which alert the operator to abnormal operating conditions. The indicators from left to right starting with the top row are: • Engine Oil Pressure (abnormal) • Alternator output at the ‘R’ Terminal (abnormal) • Intake Manifold Air Temperature (abnormal) • Fuel Level (low) • Parking Brake (ON) • AutoShift mode (1F/2R) • AutoShift mode (2F/2R) • AutoShift mode (2F/1R) • Auto Kickdown mode (active) • Implement Lockout (ON) The lower portion of the module contains an LCD display area. The left side of the display area is the tachometer section and displays a digital readout of the engine speed (rpm). The right side of the display shows a two-digit readout of the transmission gear and directional. NOTE: The AutoShift Modes are activated by pressing the AutoShift Switch. The first push of the switch activates the 1F/2R mode, the next push activates the 2F/2R mode, the third push activates the 2F/1R mode, and a fourth push will return transmission operation to NO AutoShift mode (or AutoShift OFF). The Auto KickDown switch toggles between ON and OFF.

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CATERPILLAR MONITORING SYSTEM COMPONENTS

Key Start Switch Machine ECM

J2

J1

Engine ECM

J2

J1

Product Link CAN Data Link CAT Data Link Quad Gauge Module

AccuGrade Blade Cont rol Syst em Component s ( CAN A Dat a Link)

CAN A Data Link

Data Ports

Main Display Module (EMS III) Gear / Dir. and Alert Indicator Module

Trans. Oil Filt er Bypass Swit ch

4C8195 Service Tool

Forward Action Lamp

Hydraulic Oil Temp. Sender Fuel Level Sensor

Action Alarm Alt ernat or ( R-Terminal)

ET

Rear Action Lamp

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The illustration above shows a graphical representation of the the Caterpillar Monitoring System for the D6T Track-type Tractor. The major hardware components in the monitoring system include the Main Display Module, the Quad Gage Module, the Gear/Direction and Alert Indicator Module, the Engine ECM, the Machine ECM, the Action Alarm, the Rear Action Lamp, and various switches, sensors, and senders. The illustrations on the following pages show the engine and the machine electrical systems (power train and implement). Those illustrations also identify all of the switches, the sensors, the senders, and the solenoids that are the input and the output devices in each system. Depending on how the machine is equipped, some or all of these devices may be present. Also shown in these illustrations is the means by which these components and systems communicate with each other and how the information from the input and the output devices is shared between systems. Communication of information on the standard machine occurs through the Cat Data Link and a high speed CAN (Controller Area Network) Data Link. If the machine is equipped with the Laser AccuGrade System or the GPS AccuGrade System, the D6T will also include a CAN A Data Link (shown in dashed lines) that connects these automated blade control systems to the machine electrical system. The CAN A Data Link is also used within these automated blade control systems for communication between the components within those systems.

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Power is provided by the 24V DC batteries to the Engine ECM, the Machine ECM, the Main Display Module, and the Accugrade System (if installed) when the key start switch is turned to the ON position. These major components then, in turn, supply power to the remaining components in their respective systems. The Engine ECM and the Machine ECM communicate with each other and with Cat ET through both the CAT Data Link and the CAN Data Link. Cat ET communicates through the CAN Data Link to the Engine ECM and the Machine ECM for flashing software, for performing calibrations, for viewing the status of system components, for viewing active or logged events/faults, and for clearing logged events/faults. (Events may only be cleared using a factory password.) The Cat Data Link is the only communication path by which any of these components or service tools may interface with the Main Display Module. The Main Display Module directly monitors the alternator R-terminal, the fuel level sensor, the hydraulic oil temperature sender, the transmission oil filter bypass switch, the Engine ECM, and the Machine ECM. The Main Display Module then uses the data from these sources to drive the gages, the LED indicators, and the LCD displays in the Main Display Module, the Quad Gage Module, and the Gear/Direction and Alert Indicator Module. The Main Display Module also directly controls the Action Lamps and the Action Alarm. The Forward Action Lamp, the Rear Action Lamp, and the Action Alarm are used to alert the operator or serviceman to abnormal machine conditions (faults or events) which require attention. The Main Display Module will activate the Action Lamp/Light and the Action Alarm in three different combinations, called Warning Indicators, to inform the operator or serviceman about the fault or event and the severity level of the fault or event. The three Warning Indicators Levels are identified as: • Warning Indicator Level 1: The Action Lamps will illuminate to SOLID RED. This is the least severe type of system or component fault (such as a communication failure). The fault should be analyzed and the condition corrected as soon as possible. • Warning Indicator Level 2: The Action Lamps will FLASH RED. This is a moderately severe level of system or component fault (such as overheating). The operator should change the machine operation mode immediately and have the problem analyzed by a serviceman to determine and correct the underlying cause. • Warning Indicator Level 3: The Action Lamps will FLASH RED and the Action Alarm will PULSE, alerting the operator to shut down the machine. This type of fault or event is the most severe and engine/machine damage will most likely occur if the machine continues to be operated. This level of system or component fault should be analyzed and corrected immediately. The machine should not be operated until the problem is corrected.

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Behind a cover (1) on the left side of the dash, near the floor, is a spare 175 amp alternator fuse and a fuse puller tool for the removal of the automotive style electrical fuses. The Machine ECM (2) is located under the left armrest, inside a recessed compartment in the operator platform. The Machine ECM is used to control both power train components and implement hydraulics components, when applicable. An auxiliary electrical disconnect switch (3) (if equipped) is located at the base of the left armrest.

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Other associated service points located at the machine ECM (1) are: • the 70-pin J1/P1 connector Machine ECM (2) • the 70-pin J2/P2 connector Machine ECM (3) The D6T Machine ECM code plug (4) is tied to the wiring harness leading to the J1/P1 connector, above the ECM. The Machine ECM is a multipurpose ECM. The Machine ECM has inputs from, and outputs to both the implement hydraulic components and the power train components.

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The diagnostic connector box at the left rear of the operator compartment contains two 12V DC switched power connectors (1) for powering a laptop computer, DataView, etc. Also located here is the connector (2) for the 4C-8195 Service Tool and the data port (3) for connecting a Communications Adapter and Cat Electronic Technician (ET).

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Text Reference

D6T MACHINE CONTROL ELECTRICAL SYSTEM Key Start Switch

Engine ECM

J2

J1

Machine ECM

J2

Caterpillar Monitoring System

J1

CAN Data Link CAT Data Link CAT Data Link

Engine Speed / Timing Sensors

Hydraulic Oil Pump Discharge Pressure Sensor (Attachment) Hydraulic Oil Temp. Sender

Implement Lockout Switch

Trans. Lube Temp. Sender

Trans. Oil Filter Bypass Switch

Power Train Oil Temp. Sender (Pump)

Torque Converter Oil Temp. Sender

Service Brake Pedal Position Sensor

Transmission Output Speed Sensor No. 1

Secondary Brake Switch

Transmission Output Speed Sensor No. 2

Blade Raise / Lower Position Sensor (Forward / Rearward)

Manual / Auto Blade Select Switch (Right Push-button) Auto Blade Mode Select Switch (Left Push-button)

Blade Tilt Position Sensor (Left /Right)

Blade Angle Position Sensor (Thumb Switch)

AutoShift Switch

Torque Converter Output Speed Sensor

Auto Kickdown Switch

Reverse Switch

F/N/R Position Sensor

Parking Brake Switch

Upshift Switch

Trigger Switch

EH Blade Control Lever (Attachment)

Downshift Switch Steering Control Lever

Harness Code Plug Location Code

INPUT COMPONENTS

Trans. Rev. Clutch (Solenoid No. 1)

Implement Lockout Solenoid Blade Angle Left Solenoid (Attachment)

Trans. Fwd. Clutch (Solenoid No. 2)

Blade Angle Right Solenoid (Attachment)

Trans. 3rd Gear Clutch (Solenoid No. 3)

Blade Raise Solenoid (Attachment)

Trans. 2nd Gear Clutch (Solenoid No. 4)

Blade Lower Solenoid (Attachment)

Trans. 1st Gear Clutch (Solenoid No. 5)

Blade Tilt Left Solenoid (Attachment)

Proportional Brake Solenoid Valve

Blade Tilt Right Solenoid (Attachment)

Secondary Brake Solenoid Valve

AccuGrade Boost Solenoid (Attachment)

Parking Brake Solenoid Valve

OUTPUT COMPONENTS

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The illustration above shows a graphical representation of the electrical system for the D6T Track-type Tractor power train system and implement hydraulic system. The input components for both power train and implement hydraulics provide signals to the Machine ECM, which in turn, controls the output components for both systems. The Machine ECM determines engine lug and torque curves by comparing engine speed data to the torque converter output speed data. The Machine ECM uses this information to determine when to automatically downshift the transmission for the Auto KickDown feature. Since the D5R Series III does not have an engine output speed sensor, the engine speed/timing sensors provide engine speed data to the Engine ECM, which shares that data with the Machine ECM through the CAN Data Link. Most of the implement hydraulic electrical components are only present if the AccuGrade system is installed on the machine. The implement lockout switch, the implement lockout solenoid, and the hydraulic oil temperature sender are the only electrical components in the implement hydraulic system that are standard equipment. All other electrical components of the implement hydraulic system are attachment specific. Cat ET is used to view the status of the machine electrical system components. The 4C-8195 Service Tool (clicker box) may also be used to display the status of these components through the LCD display on the Main Display Module.

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The batteries (1) are located under a hinged deck plate on the front of the left fender. Raising the deck plate and removing the forward cover (2) on the left side of the cab provides access to the electrical system fuses and circuit breakers. The main disconnect switch is located inside a compartment (3) on the front edge of the left fender.

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The main electrical disconnect switch (1) may be accessed by opening the small door on the front edge of the left fender. Also located in this compartment is the block heater receptacle (2) (if equipped). Opening the battery box lid and removing the cover on the left side of the cab provides access to the automotive style fuses (3), and the 175 amp alternator fuse (4).

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31

ENGINE The C9 ACERT® engine is used in the D6T Track-type Tractor. The engine is equipped with Hydraulic Electronic Unit Injection (HEUI) fuel injectors, and an Air To Air AfterCooler (ATAAC). The D6T may be equipped with a demand fan system, an engine driven conventional fan, or a Flexxaire engine driven fan system. The C9 engine also utilizes the A4 Engine Electronic Control Module (ECM), which is air cooled. The engine develops 185 horsepower (138 kW) at 1850 rpm in the standard machine and is rated at 200 hp (149 kW) at 1850 rpm in the XL, the XW, and the LGP models. Most of the service points for the C9 are located on the left side of the engine. The C9 ACERT technology engine meets U.S. Environmental Protection Agency (EPA) Tier III Emissions Regulations for North America and Stage IIIa European Emissions Regulations. NOTE: Engine oil and filter change intervals remain at 500 hours; however, engine load factor, sulfur levels in the fuel, oil quality, and altitude may negatively affect the extended oil change intervals. Regular engine oil samplings (S•O•S) must be performed every 250 hours to confirm oil cleanliness.

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The major service points that are accessible from the left side of the engine are: • engine oil fill tube (1) • demand fan control valve (if equipped) (2) • engine oil dipstick (3) • A4 Engine ECM (4) • starter (5) • engine oil ecology drain valve (6) • timing probe and adapter port (7) • fumes disposal and crankcase breather manifold (8) • HEUI pump (9)

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The major service points that are accessible from the right side of the engine are: • turbocharger (with mechanical wastegate) (1) • coolant sampling port (S•O•S) (2) • coolant temperature regulator (thermostat) housing (3) • alternator (4) • engine oil filter (5) • demand fan oil supply (to control valve) (6) • power train oil cooler (7)

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The coolant sight gage (1) is installed in the left side of the coolant shunt tank and is visible at the top front of the compartment. It may be accessed through the left engine compartment door. The 10 micron primary fuel filter (2) and the 4 micron secondary fuel filter (4) are located behind the shunt tank and are accessible from the left side of the engine compartment. The primary fuel filter contains a water separator (3). Water in a high pressure fuel system can cause premature failure of the fuel injectors due to corrosion and lack of lubricity. Water should be drained from the water separator daily, using the drain valve located at the bottom of the filter. Fuel is drawn from the primary fuel filter by the fuel pump (shown later) and is then sent to the secondary fuel filter (4). The secondary fuel filter removes contaminants that could damage the fuel injectors. Fuel filters should be replaced according to the guidelines in the D6T Operation and Maintenance Manual (SEBU8146) to ensure that clean fuel is always delivered to the fuel injectors. NOTE: Clogged fuel filters can degrade engine performance and restrict fuel flow, causing the fuel injectors to be starved of fuel. This condition, if ignored, can cause damage to the fuel injectors.

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The electric fuel priming pump (5) is integrated into the primary fuel filter base and is activated by switch (6). The fuel priming pump is used to fill the fuel filters after they have been replaced. The priming pump is capable of forcing the air from the entire fuel system. After the fuel filters have been replaced, activate the priming pump and then crack open the fuel line fitting at the outlet of the primary fuel filter to purge all air from the filter, the fuel line, and the priming pump. (Always place a suitable container under the primary fuel filter to collect any fuel that escapes through the fitting while purging air from the system.) Trapped air and intermittent fuel will escape through the fuel line fitting as the pump primes itself. When the fitting emits only fuel, the pump is primed and the fitting should then be retightened. At the same time, continue operating the priming pump until it is determined that all air has been forced from the entire fuel system (from the priming pump back to the fuel tank). The priming pump produces enough pressure to force fuel past the bypass valve in the fuel transfer pump and the fuel pressure regulator (check valve). NOTE: The main disconnect switch must be turned to the ON position and the key start switch (in the operator compartment) must be in the OFF position for the fuel priming pump to operate. The standard under hood work light (7) at the left rear side of the engine compartment is turned ON and OFF using the switch (8) located above the light. The air filter may be inspected and changed by removing the air filter canister cover (9) located on the left side of the engine compartment. Also visible in this illustration is the standard air conditioning condenser (10). A remote ROPS mounted air conditioning condenser is available as an attachment.

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35 The fuel transfer pump (1) is mounted to the rear of the HEUI pump (2) and is driven by the HEUI pump shaft. The gear driven HEUI pump is mounted on the back of the timing gear cover on the left side of the engine. Fuel is drawn from the primary fuel filter and water separator by the fuel transfer pump, through the pump inlet (3). The fuel transfer pump then provides fuel flow to the secondary fuel filter through a tube connected to the pump outlet (4). The fuel transfer pump contains a bypass valve that protects the fuel system components from excessive pressure. The fuel bypass valve setting is higher than the fuel pressure regulator. The HEUI pump uses engine oil as hydraulic oil for actuation of the fuel injectors. Hydraulic oil pressure replaces mechanical components for actuating the fuel injectors. This high pressure oil is controlled electronically by the injector solenoids to determine the timing and the duration of fuel injection, as well as the number of injector actuations during the compression stroke.

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The Injection Actuation Pressure (IAP) control valve connector (5) is located at the top of the HEUI pump. The IAP control valve is operated by a solenoid and changes the pump's swashplate angle to increase or decrease hydraulic oil flow. The Engine ECM controls the IAP control valve solenoid, based on numerous inputs and conditions, such as load factor, engine rpm, etc. The IAP control valve is internal to the HEUI pump. The HEUI pump can produce oil flow that creates a maximum hydraulic system pressure of approximately 28,000 kPa (4060 psi). The Engine ECM will not actuate the fuel injectors to start the engine if the pressure is below 4,000 kPa (580 psi). This hydraulic pressure is the minimum required to generate sufficient fuel pressure to exceed the nozzle Valve Opening Pressure (VOP) of approximately 18,000 kPa (2600 psi). This feature enables hydraulic oil pressure to build up faster during engine starting. The HEUI pump's internal components are not serviceable. The status of the IAP control valve solenoid may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

NOTE: For more information about the HEUI pump and the pump's specifications, refer to: • C9 Engine Specifications Manual (SENR9829) • C9 Systems Operation, Testing and Adjusting Manual (SENR9830)

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Text Reference

D6T ENGINE ELECTRICAL SYSTEM C9 ACERT

_

+ Key Start Switch Engine ECM

CAN Data Link

J2 J1

ENGINE

Pre-lube Relay (Attachment)

Starter Relay

Caterpillar Monitoring System

CAN Data Link CAT Data Link

CAT Data Link Demand Fan Speed Sensor (Attachment)

Intake Manifold Air Pressure Sensor Intake Manifold Air Temp. Sensor

Coolant Temp. Sensor

Engine Oil Pressure Sensor

Fuel Pressure Sensor

Decelerator Pedal Position Sensor

Throttle Switch

Injector No. 1 Injector No. 2 Injector No. 3 Injector No. 4 Injector No. 5

Upper Speed / Timing Sensor

Injection Actuation Pressure Sensor

Lower Speed / Timing Sensor Crank without Inject Plug Timing Calibration Probe (Connector) INPUT COMPONENTS

Injector No. 6 Injection Actuation Pressure Control Solenoid

Turbo Inlet Air Pressure Sensor

Demand Fan Pump Control Solenoid (Attachment)

Atmospheric Air Pressure Sensor

Flexxaire Fan Control Solenoid (Attachment)

Flexxaire Fan Switch (Attachment)

Ether Aid Solenoid OUTPUT COMPONENTS

36

The illustration above shows a graphical representation of the electrical system for the C9 ACERT® engine that powers the D6T Track-type Tractor. Cat ET is most easily used to view the status of the engine electrical system components. The 4C-8195 Service Tool (clicker box) may also be used to display the status of these components through the LCD display on the Main Display Module. The following list provides a few details about the component in the engine electrical system. INPUT COMPONENTS: • Throttle Switch • Decelerator Pedal Position Sensor • Lower Engine Speed/Timing Sensor • Upper Engine Speed/Timing Sensor • Engine Oil Pressure Sensor

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• Injection Actuation Pressure Sensor • Atmospheric Pressure Sensor • Turbo Inlet Pressure Sensor • Intake Manifold Air Pressure Sensor • Fuel Pressure Sensor • Intake Manifold Air Temperature Sensor • Engine Coolant Temperature Sensor • Flexxaire Fan Switch • Demand Fan Speed Sensor OUTPUT COMPONENTS: • Fuel Injectors • Injection Actuation Pressure Control Solenoid • Ether Aid Solenoid • Demand Fan Control Solenoid • Flexxaire Fan Control Solenoid

Text Reference

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The Injection Actuation Pressure (IAP) sensor (1) is installed in the left side of the cylinder head, above the fuel transfer pump. This sensor is used to determine the hydraulic (engine) oil pressure that is used to actuate the fuel injectors. The status of the Injection Actuation Pressure (IAP) sensor may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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The Upper Speed/Timing sensor (1) and the Lower Speed/Timing sensor (2) are installed in the rear of the timing gear cover, below the HEUI pump. These two sensors are "Hall Effect" type sensors that read a timing wheel in the front gear train. The sensor are installed with a clip and a bolt. The clearance (air gap) between the sensor and the timing wheel is preset and needs no adjustment. The Upper (high speed) Speed/Timing Sensor (1) measures engine speeds for normal engine operations, including governing and crankshaft position for timing purposes and cylinder identification.The Upper Speed/Timing sensor is optimized for high speed operations. The timing accuracy of the Upper Speed/Timing sensor is greater at higher speed ranges than the lower sensor and is therefore the primary sensor during normal operations. The Engine ECM shares the engine speed information with the Machine ECM for use in the AutoShift, the Auto KickDown, and other electronic power train strategies.

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The Lower Speed/Timing sensor (2) has a high output and is less accurate at high speeds than the upper sensor. The Lower Speed/Timing sensor is optimized for cranking speeds. This sensor functions as a back-up for continuous operation if the high speed sensor fails. A failure of the Upper Speed/Timing sensor will cause the Engine ECM to automatically switch to the Lower (cranking) Speed/Timing sensor. During this condition the check engine lamp will turn ON. The status of the engine speed/timing sensors may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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The intake manifold air pressure (or boost pressure) sensor (1) is installed in the top left of the cylinder head and behind the HEUI pump. The intake manifold air temperature sensor (2) is installed in the top of the intake manifold, to the left of the intake manifold air pressure sensor. Ether is injected into the intake air through the ether aid injection tube (3), which is installed on top of the intake manifold. The ether injection strategy will be discussed later in this presentation. The crank-without-inject feature (4) is located above the intake manifold air pressure sensor. The crank-without-inject feature is attached to the large wiring harness with wire ties. Removing the end plug from the "Crank-Without-Inject" connector and inserting the attached alternate plug will electronically disable the fuel injectors. No fuel will be injected into the cylinders in this mode. This allows the engine to be cranked using the starter, without the engine starting. The status of the intake manifold air pressure sensor, the intake manifold air temperature sensor, and the "Crank-Without-Inject" feature may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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40 The atmospheric pressure sensor (5) is installed in the top left of the cylinder head, behind the intake manifold air pressure sensor. The atmospheric pressure sensor measures the ambient air pressure and provides that information to the Engine ECM. The status of the atmospheric pressure sensor may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool. NOTE: The signal from the atmospheric pressure sensor is used by the Engine ECM to calculate a number of pressure measurements. The signal from the sensor is compared to the signal from the other engine pressure sensors to determine the following: • ambient (absolute) pressure is the atmospheric pressure • boost pressure is determined by comparing the atmospheric pressure (sensor) to the intake manifold pressure (sensor) • engine oil (gage) pressure is determined by comparing the atmospheric pressure (sensor) to the engine oil pressure (sensor) • air filter restriction is determined by comparing the atmospheric pressure (sensor) to the turbo inlet pressure (sensor) • fuel (gage) pressure is determined by comparing the atmospheric pressure (sensor) to the fuel pressure (sensor)

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Also, when the engine is started, the Engine ECM uses the signal from the atmospheric pressure sensor as a reference point for calibration of the other pressure sensors on the engine (if the key start switch is turned to ON for at least five seconds before the engine starts).

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The ether aid bottle (1) and the ether control solenoid (2) are mounted on a bracket at the left rear of the engine compartment. When the ether control solenoid is energized, ether is injected into the intake manifold to aid in starting the engine in cold weather. The Engine ECM controls ether injection by monitoring the intake air temperature and the coolant temperature sensors. If the temperature of the engine coolant or the intake air is less than 0° C (32° F), and the engine speed is greater than 35 rpm, but less than 700 rpm (low idle speed), then ether injection will be activated. Once the engine starts and the low idle speed is reached, the Engine ECM then looks to the ether injection map (contained in the engine software) to determine how long and how often to provide ether injection. This strategy helps meet emissions regulations by eliminating white smoke when the engine is first started. The status of the ether control solenoid may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool. NOTE: There is no inlet air heater used in the C9 ACERT® engine for the D6T.

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The air cooled A4 Engine ECM (1) is located at the left rear of the engine, above the starter (2). The Engine ECM and its software (flash file) are the main components of the electronic engine control system. The ECM controls engine performance by determining fuel injection timing, limiting fuel, and also functions as the governor. The Engine ECM receives signals from all the sensors and controls the engine through the output components, such as the IAP control valve and the fuel injector solenoids. The Engine ECM also receives commands from the Machine ECM for various machine strategies, such as the Controlled Throttle Shifting strategy used during transmission shifts. The Engine ECM has the ability to communicate through the CAT Data Link with a Personal Computer (PC) using the Cat Electronic Technician (ET). The Engine ECM also communicates through the Controller Area Network (CAN) Data Link with the Machine ECM. The J1/P1 connector (3) for the Engine ECM is a 70 pin connector and it connects the engine wiring harness to the ECM. The J2/P2 connector (4) is a 120 pin connector and it connects the Engine ECM to the machine wiring harness. The timing probe cable connector (5),(not visible in the illustration above), is fastened to the J2/P2 wiring harness, above the Engine ECM.

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The engine oil pressure sensor (1) is located ahead of the Engine ECM. The difference in pressure between the atmospheric pressure (sensor) and the engine oil pressure (sensor) is the engine oil (gage) pressure. An engine oil pressure test port (2) is located above the engine oil pressure sensor. Engine oil pressure varies with engine speed. Oil pressure can be read as absolute pressure or as gage pressure using Cat ET Low oil pressure threshold calculations are programmed into the Engine ECM. As long as oil pressure stays above these thresholds, the ECM reads adequate oil pressure. If engine oil pressure decreases below these thresholds, the following occurs: • An event is generated and logged in the permanent ECM memory. • A Level 3 Warning (alert indicator, action lamp, and alarm) is generated by the Caterpillar Monitoring System. The status of the engine oil pressure sensor may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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The crankcase breather (3) is mounted to the left side of the engine block, forward of the Engine ECM. Fumes are directed from the valve cover to the breather through the large molded rubber hose (4). The fumes are vented at the left front of the tractor, beneath the radiator, through the flexible rubber hose (5).

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The turbo inlet pressure sensor (1) is installed in the tube at the outlet of the air filter canister. Turbo inlet air pressure sensor readings are used to determine air filter restriction. The Engine ECM compares the signal from the turbo inlet air pressure sensor to the signal from the atmospheric air pressure sensor and calculates the difference. If the pressure differential is too high, it will cause the engine to derate. The engine coolant temperature sensor (2) is installed in the top of the cylinder head and is located at the front center of the engine, immediately forward of the valve cover. It is a two-wire, resistive type (passive) temperature sensor. The status of the turbo inlet pressure sensor and the engine coolant temperature sensor may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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46 The coolant (S•O•S) sampling port (1) is installed in the steel tube that directs water from the the temperature regulator (thermostat) housing (2) to the radiator. It is located at the right front of the engine and is accessible through the right side engine compartment door. The jacket water pump (3) is also located at the right front of the engine, below the regulator housing. The bypass tube (4) connects the regulator housing to the jacket water pump. A single regulator is contained in the housing. When the coolant is cold the regulator is closed and the coolant is diverted from the cylinder head back to the jacket water pump through the bypass tube. When the coolant warms sufficiently, the regulator opens and the coolant is then directed to the radiator before returning to the jacket water pump. The jacket water pump forces coolant through the engine oil cooler and the power train oil cooler before it enters the engine block and cylinder head. NOTE: Coolant samples should be taken only when the engine is at operating temperature and the coolant is circulating through the entire system. Always use a clean, lint-free towel to clean the test port prior to taking a fluid sample and replace the protective cap after a fluid sample has been taken. This will prevent damage to the test port and reduce the chance of introducing contamination into future fluid samples.

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The turbocharger (1) on the C9 ACERT® engine uses a standard mechanical wastegate (2). The wastegate acts as a bypass valve for exhaust gasses to the turbine, which limits turbocharger rpm thereby limiting boost pressure. The wastegate is operated by a pressure line (3) that connects the compressor side of the turbocharger to the piston mechanism of the wastegate. When the intake air (boost) pressure reaches the actuation pressure of the wastegate, the piston forces the linkage down, opening the wastegate. When the wastegate opens it allows some of the exhaust gasses to bypass the turbine side of the turbocharger limiting boost pressure, which in turn, limits the maximum engine cylinder pressure. The turbocharger bearings are lubricated with cooled engine oil. The engine oil is directed to the bearings through the hard steel tube (lube line) (4).

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48 The alternator (1) is mounted at the lower right front of the engine and is accessible through the right side engine compartment door. The engine oil filter (2) is located to the rear of the alternator. The engine oil cooler (6) is an oil-to-water type cooler and is internal to the engine block. It is located behind the engine oil filter. The engine oil sampling (S•O•S) port (3) is installed in the side of the engine block, to the rear of the engine oil filter. The sampling port is positioned upstream of the flow of oil to the filter. Also shown above is the engine oil supply line (4) to the demand fan control manifold and the turbocharger lube oil supply line (5). Below and to the rear of the engine oil cooler is the oil-to-water type power train oil cooler (7), which is in series to the engine oil cooler. NOTE: Engine oil samples should be taken only when the engine is at operating temperature and the engine oil is circulating through the entire system. Always clean the test port prior to taking an oil sample and replace the protective cap after an oil sample has been taken. This will prevent damage to the test port and reduce the chance of contaminating future oil samples.

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The fuel pressure regulator (1) is located at the rear of the cylinder head. It is an in-line check valve that is upstream of the fuel line hose fitting (2) that returns unburned fuel to the fuel tank. The fuel pressure regulator maintains a fuel system pressure between 455 and 579kPa (6684psi). The fuel pressure sensor (3) is installed in a "Tee" fitting, upstream from the fuel pressure regulator. The status of the fuel pressure sensor may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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An engine prelube system is available as an attachment for the D6T Track-type Tractor. The engine prelube pump (1) is driven by an electric motor (2). (The prelube pump is no longer driven by the starter motor.) The engine prelube pump is mounted to the lower right side of the engine, toward the front, as shown above. The engine prelube pump draws engine oil through a hose (3) that connects to a fitting at the engine oil drain valve. The engine oil drain valve is located at the bottom left side of the engine oil pan. A bracket (4) mounted to the inside of the right frame rail anchors the hose (5) that delivers the oil from the prelube pump to the engine block. This hose connects to a fitting at the engine oil cooler. The prelube timer and relay (6) is mounted to a bracket at the upper rear of the engine compartment. The engine prelube system ensures there is sufficient oil pressure,30 kPa (4.4 psi), throughout the engine oil system before allowing the starter to crank the engine. This prelube system helps prevent premature wear of critical engine components.

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The serviceman can override the engine prelube system by turning the key start switch to the START position, then cycling the key start switch to the OFF position and back to the START position again within one second. This will allow the starter to engage without cycling the engine prelube pump. NOTE: Can not be used on machines equipped with VPAT.

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3

51

The Quick-Evac Oil Change system for engine oil and power train oil is available as an attachment for the D6T. This system allows the oil from either system to be quickly drained and refilled through the same connections. The quick-disconnect couplings for this system are located at the front left side of the engine compartment opening, near the top, and may be accessed by opening the left side engine compartment door. The outer coupling (1) is for engine oil and it is connected to a hose (2) that runs to a fitting on the oil pan drain (3).

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C9 ACERT

Text Reference

ENGINE FUEL DELIVERY SYSTEM

Electric Fuel Priming Pump

Fuel Tank Secondary Fuel Filter

Primary Fuel Filter Fuel Pressure Regulator Fuel Gallery

HEUI Pump

Fuel Transfer Pump

52

Fuel System Fuel is drawn from the fuel tank through the 10 micron primary fuel filter and water separator by a gear-type fuel transfer pump. The fuel transfer pump is mounted to the rear of the HEUI pump. The fuel transfer pump then produces the flow that pushes the fuel through the 2 micron secondary fuel filter. The fuel then flows through a fuel line where it enters the front of the cylinder head. The fuel flows into the fuel gallery (inside the cylinder head), where it is made available to each of the six HEUI fuel injectors. Any excess fuel not injected leaves the rear of the cylinder head and is directed to the fuel pressure regulator. The fuel pressure regulator is an in-line check valve. The fuel pressure regulator maintains a fuel system pressure of approximately 518 kPa (75 psi) between the fuel transfer pump and the fuel pressure regulator. From the fuel pressure regulator, the excess fuel flow returns to the fuel tank. The ratio of fuel used for combustion and fuel returned to tank is approximately 3:1 (i.e. four times the volume required for combustion is supplied to the system for combustion and for injector cooling and lubrication purposes).

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AIR INTAKE AND EXHAUST SYSTEM

Intake Air Manifold

Exhaust Manifold Exhaust Valve

Text Reference

Intake Valve

Air To Air AfterCooler

Turbocharger Turbine Side

Air Inlet From Air Filter

Exhaust Outlet

Compressor Side Pressure Line

Wastegate

53

Engine Air System Intake air is drawn into the engine air precleaner by the vacuum created by the compressor wheel in the turbocharger. The precleaner removes the large particles from the intake air and ejects them through the exhaust stack. The intake air is then drawn through the air cleaner where the fine contaminants are removed by the filter element. The clean intake air is then drawn into the air inlet of the turbocharger. The turbocharger compresses the intake air and forces it out of the compressor outlet The compressed intake air then enters the inlet to the Air To Air AfterCooler (ATAAC). As the intake air passes through the ATAAC core, the air is cooled and becomes more dense. The intake air then exits the ATAAC through the ATAAC outlet. The compressed, cooled intake air is then directed to the intake air manifold through the intake air tube. From the intake manifold, the intake air enters the cylinder head. The cooler, more dense air enters the cylinders through the intake valves in the cylinder head. As the pistons rise, they compress the air. The compressed air then becomes super-heated. When fuel is injected in the hot air, combustion occurs. The combustion of the fuel/air mixture forces the pistons down, transferring the energy to the crankshaft.

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Text Reference

As the pistons rise during the exhaust stroke, the exhaust gasses flow out of the exhaust valves in the cylinder head, and enter the exhaust manifold. The exhaust manifold directs the exhaust gasses into the inlet of the turbine side of the turbocharger. These hot, high-pressure gasses are used to power the turbine wheel as they pass through the turbocharger. The turbine wheel is connected to the compressor wheel by a shaft. As the turbine rotates, so does the compressor wheel. The exhaust gasses then exit the turbocharger through the exhaust outlet, which directs the gasses to the muffler and the exhaust stack. The turbocharger on the C9 ACERT® technology engine uses a standard mechanical wastegate. The wastegate acts as a bypass valve for exhaust gasses to the turbine. The wastegate is operated by a pressure line that connects the compressor side of the turbocharger to the piston mechanism of the wastegate. When the intake air (boost) pressure reaches the actuation pressure of the wastegate, a linkage connected to the piston opens the wastegate. When the wastegate opens, it allows some of the exhaust gasses to bypass the turbine side of the turbocharger. The wastegate limits boost pressure, which in turn, limits the maximum engine cylinder pressure.

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Text Reference

D6T COOLING SYSTEM

ENGINE AT OPERATING TEMPERATURE Fill Tube and Cap Vent Line Shunt Tank

> 92 C

Bypass Tube

Hottest C9 ACERT

87 C

< 81 C

Thermostat Housing

Engine Jacket Water Pump

Increasing Coolant Temperature Coldest Power Train Oil Cooler

ATAAC (Right Side)

Hydraulic Oil Cooler

Cab Heater

Engine Oil Cooler

AMOCS Radiator

54

Cooling System Shown above is a schematic of the cooling system for the D6T Track-type Tractor. The C9 uses an Air To Air AfterCooler (ATAAC) to cool the intake air. The ATAAC is mounted vertically in the radiator guard (not pictured). It is in line with, and to the right of the AMOCS radiator cores. The hydraulic oil cooler is an oil-to-air type cooler and it is mounted vertically, behind the AMOCS cores at the right side of the radiator guard. The AMOCS radiator in the D6T contains six cores and are the standard "two-pass" design. The D6T is equipped with a standard belt driven fan. An optional FlexxAire Fan or a demand fan may be ordered, and both are controlled by the Engine ECM. The fan is mounted to the front of the engine and it is positioned behind the radiator. This arrangement draws air in through the sides of the engine compartment, through the hydraulic oil cooler, the radiator cores and the ATAAC core, and then the air exits the front of the tractor. Coolant flows from the jacket water pump, through the engine oil cooler and then the power train oil cooler, where it enters a manifold that directs the coolant into the engine block. Coolant flows through the engine block and then into the cylinder head.

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Text Reference

From the cylinder head, the coolant flows to the temperature regulator housing. From the regulator housing, the coolant either flows directly to the water pump through the bypass tube or to the radiator, depending on the temperature of the coolant. The coolant flows directly to the water pump through the bypass tube when the engine is cold. The regulator housing for the C9 engine contains a single temperature regulator. Opening temperature for the regulator is 81° - 84° C (178° - 183° F). The regulator should be fully open at 92° C (198° F). When the regulator opens, the coolant enters the radiator inlet, at the bottom right of the radiator. The coolant is cooled the first time as it flows upward through the front side of the AMOCS radiator cores and a second time as it flows down the back side of the cores. The coolant then exits the radiator and returns to the jacket water pump. Coolant is added to the system through the radiator cap and filler tube on top of the shunt tank. The radiator cap is accessible by opening a spring-hinged door, on top of the radiator guard. A coolant sight glass is installed in the left side of the shunt tank and can be viewed by opening the left side engine compartment door. The air vent lines remove air from the cooling system during operation and while the system is being filled. The shunt tank is a reservoir which retains the expansion volume of the coolant as the coolant temperature increases. The level of the coolant in the shunt tank will rise as the coolant temperature increases and will fall as the temperature of the coolant decreases. A drain valve below the radiator is used to drain coolant from the radiator cores, the engine oil cooler, the power train oil cooler, and the cab heater circuit.

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Text Reference

55

The front of the radiator core and the cooler cores can be accessed by opening the hinged guards on the radiator support of the D6T. Also seen here are the horns on the upper right.

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Text Reference

2

1

4

3

56

The six AMOCS radiator cores (1) are positioned on the left side of the radiator guard. The ATAAC core (2) is located on the right side of the radiator guard. Coolant from the regulator housing enters the bottom tank of the radiator through inlet (3), at the lower right side of the tank. Cooled coolant exits the radiator through outlet (4) at the lower left side of the tank and returns to the jacket water pump. The cooling system drain valve (not visible above), is located at the bottom left of the radiator.

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Text Reference

1

57

2

3

58

Access to the radiator cap and fill tube (1) is provided by lifting the lockable spring-hinged door on top of the radiator guard. It is easily accessible by standing on the left track. The coolant shunt tank (2) is positioned above the radiator. A sight glass (3) is installed in the left side of the shunt tank and is visible by opening the left side engine compartment door. Coolant should always be visible in the sight glass, regardless of the temperature of the coolant. Coolant needs to be added to the system if it not visible in the sight glass.

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Text Reference

D6T DEMAND FAN CONTROL MAXIMUM FAN SPEED

MINIMUM FAN SPEED

High Pressure to Fan Clutch

To Drain

High Pressure To Fan Clutch

High Pressure Supply

To Drain

High Pressure Supply

To Clutch Lube Port

To Clutch Lube Port

59

Demand Fan System If the machine is equipped with a demand fan, the demand fan control valve manifold is mounted to a bracket forward of the muffler. The demand fan is optional on the D6T Tracktype Tractor. The fan is a hydraulic component that uses engine oil as hydraulic fluid and it is controlled by the Engine ECM. The Engine ECM constantly monitors the engine intake air temperature sensor and the engine coolant temperature sensor as inputs for controlling the fan. The highest temperature of these two inputs (relative to the percentage of its individual temperature map) is the controlling temperature for fan operation. A fan speed sensor provides feedback information to the Engine ECM. The Engine ECM monitors the temperature inputs and considering the fan speed sensor, the Engine ECM provides a current to the (proportional) fan control solenoid. To attain minimum fan speed, the Engine ECM sends approximately 1.8 amps of current to the fan control solenoid, resulting in approximately 15 kPa (2 psi) oil pressure to the fan clutch, as shown in the left side of Illustration No. 51. At minimum fan speed, almost all of the oil is sent to the fan clutch lube port. Maximum current is sent to the solenoid to produce minimum fan speed. This strategy ensures that if communication with the demand fan solenoid is lost, the fan will default to maximum fan speed.

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Text Reference

To reach maximum controlled fan speed, the Engine ECM sends approximately 0.2 amps of current to the fan control solenoid, resulting in approximately 413 kPa (60 psi) oil pressure to the fan clutch. At maximum fan speed, almost all of the oil is sent to the fan clutch to pressurize the clutch. Full engagement pressure for the fan clutch occurs at approximately 275 kPa (40 psi). Fan system pressure may be tested using the pressure test port, on top of the fan control valve manifold. The status of the demand fan control solenoid may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool. NOTE: Always refer to the service information in the service manual SENR9830 or SIS Web for the latest testing and adjusting specifications and procedures.

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5

Text Reference

6

4 7 60

3

2 1

10

9

61

8

The demand fan control valve manifold is mounted to a bracket in front of the muffler. Engine oil is used as hydraulic fluid to operate the fan clutch. Engine oil supply is through the right hose (3). The steel tube (2) that branches off the supply line is for internal component lubrication when the fan clutch is not engaged. High pressure supply from the manifold to the fan clutch is through the upper steel tube (4). Clutch control pressure may be tested using the pressure test port (5) on top of the manifold. The proportional fan control solenoid (6) is ENERGIZED by the Engine ECM to DISENGAGE the fan clutch. As the solenoid is DE-ENERGIZED, the fan speed increases. The hose (7) is the manifold drain line. The demand fan clutch (8) is supplied with high pressure oil through the right steel tube (9). Fan speed data is monitored by the Engine ECM using a speed sensor. The cable from the sensor (10) is visible in the above illustration.

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Text Reference

D6T POWER TRAIN COMPONENT LOCATION

Torque Converter Outlet Relief Valve

C9 ACERT

Engine

Power Train Oil Cooler Torque Divider

Machine ECM

Power Train Oil Pump

Torque Converter Inlet Relief Valve

Remote Power Train Pressure Ports (M and N)

Lube Distribution Manifold

Power Train Oil Fill Tube and Dipstick

Electronic Brake Valve

Power Train Oil Filter

Steering Differential

Bevel and Transfer Gears Final Drive

Service Brakes Transmission Charge Circuit Accumulator

Transmission Hydraulic Control

Transmission

62

POWER TRAIN Shown above is an illustration that identifies the relative location of all of the major power train components for the D6T Track-type Tractor. Numerous upgrades implemented in the power train of the D6R Series III machine are continued. The newest upgrade to the powertrain in the D6T is the Multi Velocity Program (MVP).

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Text Reference

1

63

Caterpillar’s new Multi Velocity Program (MVP) allows the operator to choose from a variety of machine speeds to ensure the optimal speed for any application. When the attachment MVP is installed an enabled on a machine, the ECM will operate the ECPC transmission in 5 forward speeds and 5 reverse speeds in place of the default 3 forward and 3 reverse speeds. The D6T is equipped with a new switch (1) in the right-hand console to allow the operator to choose between the three or five speed configuration. The switch is located between the throttle rocker switch and the implement lockout switch. NOTE: For machines with the European (EU) configuration, the ECM will activate the MVP function at machine start up and will continue to operate in the MVP mode at all times during operation of the machine. For machines with the standard configuration, the ECM will activate the MVP function based on the status of the multi-velocity program enable switch that is installed in the cab. The operator will determine when the MVP function will be enabled or disabled by using the switch.

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Text Reference

D6T POWER TRAIN SCHEMATIC FIRST GEAR FORWARD

Left Lube Pressure (LB 1)

Left Brake Pressure Lube Distribution Manifold

Flywheel Lube Pressure (L 2 )

T. C. Inlet Pressure (M ) Torque Converter Outlet Relief Valve

Transmission and Bevel Gear Lube

Main Relief Pressure (P)

Torque Converter Inlet Relief Valve

Brake Pressure (B 1 )

Clutch 4 Proportional Valves (2nd)

Clutch 3 (3rd)

Clutch 5 (1st)

Clutch 2 (FWD)

Clutch 1 (REV)

PTO Temp. Sender

Electronic Brake Valve

Hydraulic Pump

T. C. Outlet Pressure (N ) C9 ACERT Engine

Vent Line Accumulator Trans. Lube Pressure (L1)

T. C. Temp. Sender

Transmission Diff. Steer Lube

Trans. Lube Temp. Sender

Torque Converter Charging Section "A" Scavenge Section "C" Right Brake Pressure

Right Lube Pressure (LB 2 )

Torque Converter

Flywheel Lube

Power Train Oil Cooler

Transmission Charging Section "B"

S O S

Transmission Charge Filter and Bypass

64

Power Train Hydraulic System The illustration above shows the power train hydraulic system for the D6T Track-type Tractor. There are three distinct hydraulic circuits within the power train hydraulic system: the transmission charging circuit, the torque converter charging circuit, and the scavenge oil circuit. The three-section fixed displacement power train oil pump is installed at the right front of the main case. The pump is driven by a drive shaft connected to a drive hub at the right rear of the flywheel housing. The torque converter charging section "A" of the power train oil pump supplies oil flow to the torque converter. The torque converter inlet relief valve is installed between the pump and the torque converter and limits the maximum pressure to the torque converter. The torque converter outlet relief valve maintains a minimum pressure inside the torque converter. Oil that exits the torque converter through the torque converter outlet relief valve is directed to the oil-to-water type power train oil cooler, where the oil is cooled by engine coolant. Oil that exits the power train oil cooler is then sent to the lube distribution manifold, where it provides lubrication for the brakes, the transmission, and the bevel gears. This lube oil is directed from the lube distribution manifold to these components through steel tubes inside the main case.

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Text Reference

The transmission charging section "B" of the power train oil pump provides oil flow to the transmission charge circuit, through the 6 micron transmission charge filter. The transmission main relief valve is situated downstream from the transmission hydraulic control and the brakes. The main relief valve maintains a common top pressure for operation of the transmission modulating valves and the brakes. An accumulator, located beneath the fuel tank, is incorporated in the transmission charge circuit. The accumulator helps maintain a constant transmission charge circuit pressure during clutch engagements. Power train oil that spills past the transmission main relief valve mixes with and supplements the lube oil from the lube distribution manifold. The common top pressure power train strategy eliminates the need to perform transmission clutch engagement pressure calibrations. (Clutch fill calibrations and brake touch-up calibrations are still required.) The transmission clutch pistons and the brake pistons have been redesigned so they all operate at the same (common top) pressure. When the transmission main relief valve is properly adjusted, all of the pressures for operation of the transmission clutches and for the operation of the brakes are also properly adjusted. The scavenge section "C" of the power train oil pump draws oil from the transmission case, the bevel and transfer gear case, and the torque divider housing through screened ports. (Flywheel lube oil from the flywheel housing drains into the torque divider case.) This scavenge oil is used to lubricate the steering differential gear set and the oil then drains back into the main sump. Pressure test ports for the transmission main relief pressure (P) and for the transmission lube pressure (L1) are easily accessible from the rear of the machine. Remote pressure test ports for the torque converter outlet pressure (N) and the torque converter inlet pressure (M) are located inside the compartment on the front of the right fender. The power train breather is remotely mounted beside these two pressure test ports. The flywheel lube pressure test port (L2) is located below the floor plate in the operator compartment. NOTE: Refer to the Hydraulic Schematic Color Code chart at the end of this presentation to interpret the meaning of each color/pattern in the power train schematic and subsequent illustrations.

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Text Reference

3 2 4

5 1

6

7

65

The screened main suction manifold (1) for the power train oil pump is located at the right front of the main case, near the bottom. The three-section gear-type power train oil pump (2) is mounted to the front of the main case, at the upper right. The electronic brake valve (3) is located on top of the main case, to the left of center. The steering motor (yet to be installed) is located at the upper left of the main case (4). The steering motor provides the input to the steering differential. The fitting (5) connects the vent line from the main case to the torque divider case. A "tee" in the vent line is used to connect a remote line that leads to the power train breather. The breather is located in the forward compartment on the front of the right fender. The torque converter inlet relief valve and the lube distribution manifold are both incorporated into one housing (6). These two components are mounted to the left front of the main case, near the bottom. The transmission (not installed) is located inside the transmission case, which is installed inside the main case. The transmission input shaft extends forward through the large bore (7) in the front of the main case. The drive shaft from the torque divider connects to the transmission input shaft.

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Text Reference

4

3

5

2

1

66

The power train oil pump draws oil for the torque converter charging circuit and for the transmission charging circuit from a screened suction manifold that connects to the pump at the pump inlet (1). The torque converter charging section "A" (2) of the power train oil pump supplies approximately 145 L/min. (38.3 US gal./min.) of oil to the torque converter circuit for operation of the torque converter and for lubrication purposes. The transmission charging section "B" (3) of the power train oil pump supplies approximately 54 L/min. (14.3 US gal./min.) of oil to the transmission and brakes circuit. The transmission and torque converter scavenge section "C" (4) of the power train oil pump draws approximately 125 L/min. (33 US gal./min.) from the torque divider case, and the transmission case. The scavenge oil is used for lubrication of the steering differential. The power train oil temperature sender (5) provides main sump oil temperature information to the Machine ECM. This is the temperature sender that is considered when performing power train calibrations, such as brake touch-ups and transmission clutch fill calibrations.

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Text Reference

The status of the power train oil temperature sender may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool. NOTE: All power train oil flow rates are calculated at the rated engine speed .

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Text Reference

9 8 7 1

6

2

3 5 4

67

Torque Divider The D6T Track-type Tractor uses a torque divider (1) to transfer engine power to the transmission. The torque divider is similar to those used on other Caterpillar Track-type Tractors. The torque divider provides both a hydraulic and a mechanical connection from the engine to the transmission. The torque converter provides the hydraulic connection, while the planetary gear set provides the mechanical connection. During operation, the planetary gear set and the torque converter work together to provide an increase in torque as the load on the machine increases. The torque converter output speed sensor (8) is installed above the torque divider output shaft (6) and senses the speed of the output shaft. The Machine ECM monitors the signal from this sensor and uses it, along with the signal from the engine speed/timing sensors to determine engine lug and shifting points for several electronic power train control strategies. Torque converter charge oil from the torque converter inlet relief valve enters the torque converter through the torque converter inlet port (3), at the right side of the torque divider housing.

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Text Reference

A small amount of torque converter charge oil is used to lubricate the flywheel and the pump drive gears. This flywheel lube oil is directed to the flywheel housing through the small hose (2) at the right side of the torque converter inlet port (3). The torque converter outlet relief valve (7) is located on the left side of the torque divider housing. The scavenge section of the power train oil pump draws oil from torque divider housing through the port (5) at the bottom center of the housing. The torque converter scavenge screen (not visible) is located just inside the port. Flywheel lube oil drains into the torque divider housing and is returned to the main sump by the scavenge section, also. The ecology drain for the torque divider housing is located at the bottom, right rear of the torque divider housing (4) (not installed in this illustration). The upper hose (not shown here) connects the vent line the torque divider case to the main case. A "tee" in the vent line is used to connect a remote line that leads to the power train breather. The breather is located in the forward compartment on the front of the right fender. The vent line and breather is used to maintain atmospheric pressure inside the main case and the torque divider case so that the cases do not develop positive or negative pressures as the power train oil and components warm or cool. Also shown is the drive hub (9) for the power train oil pump drive shaft. The status of the torque converter output speed sensor may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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Text Reference

TORQUE DIVIDER Engine Flywheel

Housing Outlet Passage

Planet Gears

Sun Gear

Output Shaft

Stator Planet Carrier Inlet Passage

Ring Gear

Impeller

Turbine

68 The illustration above shows a typical torque divider. The impeller, the rotating housing (shown in red), and the sun gear (shown in brown) are mechanically connected. The engine flywheel (shown in gray) is splined to the rotating housing and the sun gear. The turbine and the ring gear (shown in blue) are connected with splines. The planet carrier (brown) and output shaft (shown in blue) are connected with splines, also. The sun gear and the impeller always rotate at engine speed. As the impeller rotates, it directs oil against the turbine blades, causing the turbine to rotate. Turbine rotation causes the ring gear to rotate. During NO LOAD conditions, the planet gears and the planet carrier (shown in brown) rotate as a unit, with the planet gears stationary on their shafts. As the operator loads the machine, the output shaft slows down. A decrease in output shaft speed causes the rpm of the planetary carrier to decrease. Decreasing the planetary carrier rotation causes the relative motion between the sun gear and the planet carrier to cause the planet gears to rotate. Rotating the planet gears decreases the rpm of the ring gear and the turbine. At this point, the torque splits with the torque converter multiplying the torque hydraulically, and the planetary gear set multiplying the torque mechanically.

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Text Reference

An extremely heavy load can stall the machine. If the machine stalls, the output shaft and the planetary carrier will not rotate. This condition causes the ring gear and turbine to slowly rotate in the opposite direction of engine rotation. Rotating the ring gear and turbine in the opposite direction provides maximum torque multiplication. During load conditions, the torque converter provides 70% of the output and the planetary gear set provides the remaining 30% of the output. The size of the planetary gears establishes the torque split between the hydraulic torque and mechanical torque.

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Text Reference

3

2 1

7 4

5 6

69

The torque converter inlet relief valve (1) and the lube distribution manifold (2) are both contained in one housing. Oil from the torque converter charging section of the power train oil pump is supplied to the torque converter inlet relief valve through the upper hose (3). The torque converter inlet relief valve is installed in the housing. Excess oil flows past the inlet relief valve into the main sump through a port in the front of the case, and behind the housing. Oil flow to the torque converter inlet is through the hose on the right (4). Cooled oil from the power train oil cooler is directed to the lube distribution manifold through the hose on the left (6). The smaller hose (7) is the line leading to the remote pressure test port for torque converter inlet pressure (M). This remote pressure test port is located inside the front compartment on the right fender. Torque converter inlet relief pressure may also be tested at the pressure test port (5) on the housing.

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Text Reference

D6T TORQUE CONVERTER INLET RELIEF VALVE Housing

Pressure Test To Torque Converter Inlet Port (M)

Torque Converter Charging Pump Supply

Torque Converter Inlet Relief Valve Retaining Ring

Front of Main Case

To Main Sump

Bottom of Main Case

70 The torque converter inlet relief valve protects the components in the torque converter by limiting the maximum oil pressure to the torque converter during pressure spikes in the system and when the engine is started and the oil is cold. The torque converter inlet relief valve is a cartridge type check valve that is installed into the lower center port in the back of the dual purpose housing that also contains the power train lube distribution manifold. The torque converter inlet relief valve is held in place by a retaining ring. Oil from the torque converter charge section of the power train oil pump is directed through a hose to the inlet passage of the housing that contains the torque converter inlet relief valve. The dual purpose manifold is installed on the left front of the main case and directs the torque converter oil to the torque converter inlet relief valve through an internal passage in the manifold. The manifold also directs the torque converter oil to the torque converter through a hose connected to the front of the manifold. Torque converter charge pressure acts against the top of the poppet in the inlet relief valve. When the pressure acting against the top of the poppet overcomes the force of the spring, the poppet opens (down) and dumps the excess oil back into the main case through a port, limiting the pressure in the torque converter circuit. The torque converter inlet relief valve is not adjustable.

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Text Reference

1

2

3

4

71

The torque converter outlet relief valve (1) is installed at the left rear of the torque divider housing. Torque converter oil exiting the torque converter enters the torque converter outlet relief valve from the back side of the valve body. The torque converter oil then exits the outlet relief valve and is directed to the power train oil cooler through the steel tube (4). After the oil passes through the oil cooler, it is directed to the lube distribution manifold. The torque converter oil temperature sender (3) is installed in the torque converter outlet relief valve. It senses the temperature of the oil exiting the torque converter and provides a signal to the Machine ECM. The Caterpillar Monitoring System monitors this temperature signal from the Machine ECM and uses it to operate the (analog) torque converter oil temperature gage in the quad gage module. The fitting (2) on the rear of the valve body connects a small hose which transmits torque converter outlet relief pressure (N) to the remote power train pressure test port, located in the forward compartment on the right fender. The status of the torque converter oil temperature sender may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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Text Reference

TORQUE CONVERTER OUTLET RELIEF VALVE

Inlet Passage from Torque Converter Spool Shim Outlet Passage to Power Train Oil Cooler Spring

72

The torque converter outlet relief valve maintains a constant minimum pressure inside the torque converter. Oil from the torque converter enters the torque converter outlet relief valve through the inlet passage. The pressure of the oil acts against the top of the spool. When the pressure of the torque converter oil becomes greater than the force of the spring, the spool shifts down. Torque converter oil then flows through the holes around the circumference of the spool to the outlet passage. The outlet passage directs the hot torque converter oil to the power train oil cooler. The torque converter outlet relief valve may be adjusted by adding or removing shims between the spring and the spool.

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6

Text Reference

7

1 5

4 3

2

73

The power train oil cooler (1) is an oil-to-water type oil cooler. It is located on the right side of the engine. Hot oil from the torque converter outlet relief valve flows through the upper steel tube (4) and enters the power train oil cooler at the cooler inlet (5). The oil is cooled as it flows through tubes that are surrounded by engine coolant. The cooled power train oil then exits the power train oil cooler through outlet (2), where it flows through the lower steel tube (3), through a hose to the power train lube distribution manifold. Engine coolant flows from the water pump and then through the engine oil cooler (7). After cooling the engine oil, the coolant then flows into the back of the power train oil cooler through a passage in the engine block to the coolant inlet not visible above). The coolant flows from front to rear through the power train oil cooler, then exits the cooler through the large "L" shaped manifold (6), where it enters the engine block through a passage (not visible) behind the manifold. NOTE: The coolant flows from front to rear through the cooler and the power train oil flows from the rear to the front of the cooler.

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Text Reference

D6T LUBE DISTRIBUTION MANIFOLD From Power Train Oil Cooler Housing

Orifices

Front of Main Case

To Left Brake

To Right Brake To Transmission and Bevel Gears

Bottom of Main Case

74

The lube distribution manifold is contained in the dual purpose manifold that also contains the torque converter inlet relief valve. This dual purpose manifold is installed on the left front of the main case. The lube distribution manifold directs cooled oil from the power train oil cooler to both the left and the right brake housing and to the transmission and the bevel gears through steel tubes inside the main case. The back of the manifold (housing) contains three ports for distributing the lube oil. The left port and the right port contain orifice inserts that control the flow of oil to the brakes. A small diameter (orificed) passage directs lube oil for the transmission and the bevel gears through the center port.

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Text Reference

POWER SHIFT TRANSMISSION Ring Gears

Ring Gears

Input Sun Gears

Input Shaft

Output Shaft Planetary Carrier

Output Sun Gears

1

2

3

4

5

75

Power Shift Transmission This illustration shows a sectional view of a typical transmission group like that used in the D6T Track-type Tractor. The planetary group has two directional and three speed clutches which are numbered in sequence (1 through 5) from the rear of the transmission to the front. Clutches No. 1 and No. 2 are the reverse and forward directional clutches. Clutches No. 3, No. 4, and No. 5 are the third, second, and first speed clutches. The No. 5 clutch is a rotating clutch. In this sectional view of the transmission, the input shaft and input sun gears are shown in red. The output shaft and output sun gears are blue. The ring gears are shown in green. The planetary carrier is brown. The planet gears and shafts are shown in brown. The clutch discs, the clutch plates, the pistons, the springs and the bearings are shown in yellow. The stationary clutch housings are shown in gray. The input sun gears are splined to the input shaft and drive the directional gear trains. The output shaft is driven by output sun gears No. 3 and No. 4 and rotating clutch No. 5. When the No. 2, No. 3, or No. 4 clutches are engaged, their respective ring gears are held stationary. The No. 1 planetary carrier is held when the No. 1 clutch is engaged. When engaged, the No. 5 rotating clutch locks the output components (for FIRST gear) to the output shaft.

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Text Reference

2

1

3

9

8

7

6

5

4

76

Located at the rear of the machine, on top of the the transmission case are the following service points: • transmission main relief pressure test port (P) (1) • transmission lube pressure test port (L1) (2) • transmission lube temperature sender (3) Pressure test ports for each of the five transmission clutches are installed in the transmission inspection cover. These pressure test ports are: • transmission clutch No. 1 (reverse clutch) (4) • transmission clutch No. 2 (forward clutch) (5) •transmission clutch No. 3 (speed 3) (6) • transmission clutch No. 5 (speed 1) (7) • transmission clutch No. 4 (speed 2) (8)

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Text Reference

Also shown above is the transmission charge circuit accumulator (9), which is mounted beneath the fuel tank. The accumulator has been added to the power train hydraulic system with the elimination of the priority valve. This accumulator is pre-charged to approximately 1724 kPa (250 psi). The accumulator is used to ensure there is sufficient transmission charge circuit pressure for short periods of time, such as when the transmission clutches are filling (shifts) or at other times when the pressure in the transmission charging circuit may drop (cold oil, low idle, etc.). The status of the transmission lube temperature sender may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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Text Reference

4

1

3 2

77 This illustration shows a typical ECPC power shift transmission hydraulic control manifold, with main relief valve, and solenoid controlled transmission modulating valves. The transmission main relief valve (2) may be accessed by removing the transmission inspection cover, which is located at the top of the main transmission cover. The transmission main relief valve is installed in the transmission hydraulic control manifold (1). The transmission main relief valve may be adjusted by using the adjustment screw and locknut (3), at the right of the transmission hydraulic control manifold. Each of the transmission clutch modulating valves (4) on the D6T have a plug installed in the pressure test port at the top of the valve body. Individual clutch pressures may be tested by connecting a hose and pressure gage to the test port on the corresponding transmission modulating valve.

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Text Reference

TRANSMISSION MODULATING VALVE SOLENOID DE-ENERGIZED Ball

Orifice

Edge Filter

Valve Spool

Passage Spring

Hole Solenoid

Pin

Supply Oil from Pump

To Clutch

SOLENOID ENERGIZED Ball

Orifice

Edge Filter

Valve Spool

Passage Spring

Hole Solenoid

Pin To Clutch

Supply Oil from Pump

78

The transmission clutches are hydraulically engaged and spring released. When a clutch is not engaged, its clutch modulating valve solenoid is DE-ENERGIZED, as shown in the top illustration. When DE-ENERGIZED, the solenoid pin is retracted, allowing the ball to be unseated from the orifice. Pump supply oil enters the cross-drilled hole in the valve spool and flows through the center of the spool, past the edge filter and then flows freely to the drain passage. The spring at the right end of the valve spool keeps the spool shifted to the left. Pump supply oil is blocked by the valve spool. The passage to the clutch piston is open to drain. With no pressure to the clutch piston, the springs in the clutch keep the clutch DISENGAGED. When the operator selects a speed or directional shift, the Machine ECM sends a PWM signal to the correct transmission modulating valve solenoid and it is ENERGIZED, as shown in the bottom illustration. As current is applied to the solenoid, the solenoid pin extends to the right and moves the ball closer to the orifice. The ball restricts the amount of oil allowed to flow to drain through the orifice. This restriction causes the pressure to increase at the left end of the valve spool. As the pressure at the left end of the valve spool increases, the spool shifts to the right against the spring, closing off the passage from the clutch to the drain. At the same time, the movement of the valve spool to the right opens the passage from the pump supply to the clutch. This movement causes the clutch pressure to increase. The clutch becomes ENGAGED when clutch engagement pressure is reached.

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Text Reference

As the valve spool moves to the right, supply oil to the clutch also flows through the drilled passage in the valve spool that connects the clutch passage to the right end of the valve spool. As the pressure to the clutch increases, the same pressure is felt at the right end of the valve spool. This pressure adds to the spring force, which balances the pressures and forces. This results in a more smooth and controlled clutch engagement, or clutch modulation. De-energizing the solenoid decreases the force of the pin against the ball. This decreased force allows the pressure at the left end of the valve spool to unseat the ball, de-pressurizing the chamber at the left end of the spool. With lower pressure at the left end of the spool, the valve spool shifts to the left due to the spring force plus the supply oil pressure to the clutch. This reduces the pressure to the clutch by closing off the supply passage and opening up the drain passage. When the pressure to the clutch falls below the clutch engagement pressure, the clutch will be released by spring force. When the transmission is in NEUTRAL, the transmission modulating valve that controls engagement of the No. 3 clutch allows flow to the clutch. The other modulating valves stop flow to their clutches, thereby allowing the clutches to be released by spring force. Since neither the No. 1 nor the No. 2 directional clutches are engaged, no power is transmitted to the output shaft of the transmission. When the transmission is in FIRST SPEED FORWARD, the modulating valves that control flow to the No. 2 and the No. 5 clutches receive a signal from the Machine ECM. These signals energize the solenoids which send flow to engage the clutches. The status of both of all five transmission modulating valve solenoids may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C8195 service tool. NOTE: Clutch Engagement Pressure Calibrations are no longer necessary due to the common top pressure strategy. However, Transmission Clutch Fill Calibrations must be performed when any of the following repair procedures have been performed: • Transmission modulating valve and/or solenoid is replaced, • Transmission is serviced or replaced, • Machine ECM is replaced, and/or • Machine ECM is re-flashed. Automated Transmission Clutch Fill Calibrations may be easily performed using Cat ET.

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Text Reference

TRANSMISSION MAIN RELIEF VALVE Adjustment Screw

Spring

Spool

Slug Chamber

Slug

Locknut From Transmission Charging Section of PTO Pump

To Transmission and Bevel Gear Lube Circuit

To Transmission Hydraulic Cont rol and Accumulat or

79

The transmission main relief valve is located in the transmission hydraulic control manifold. The manifold is on top of the transmission planetary group. The transmission main relief valve maintains the "common top pressure" from the transmission charging section of the power train oil pump. This oil is used to operate the brakes and the transmission clutches. Oil to the main relief valve is supplied by the transmission charging section of the power train oil pump. An accumulator is incorporated into the transmission charge circuit to ensure there is sufficient transmission charge circuit pressure for short periods of time, such as when the transmission clutches are filling (shifts) or at other times when the pressure in the transmission charging circuit may drop (cold oil, low idle, etc.). Oil from the power train oil pump flows through the transmission charge filter and then to the electronic brake control valve, the accumulator, and the transmission modulating valves. The transmission main relief valve is downstream from the accumulator, the electronic brake control valve, and the transmission modulating valves. The excess oil that flows over the main relief valve combines with the oil from the lube distribution manifold to supplement lubrication of the brakes, the transmission, the steering differential, and the bevel gears.

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Text Reference

4 5 3

2

1

80

Electronic Brake Control Valve The electronic brake control valve (1) is installed on top of the main case, below the operator's seat. The brake control valve may be accessed by removing the operator seat, the seat pedestal, and the rear floor plate in the operator compartment. The brake valve body contains a proportional solenoid valve (2). The proportional solenoid valve is controlled by the Machine ECM, which receives a signal from the PWM rotary position sensor that is connected to the service brake pedal. The proportional solenoid is ENERGIZED when the brakes are released. Depressing the service brake pedal DECREASES the amount of current that the ECM sends to the proportional solenoid and DE-ENERGIZES it to apply the brakes. The secondary brake valve is controlled by an ON/OFF solenoid (3). The secondary brake valve solenoid is ENERGIZED by connecting it to the battery when the secondary brake switch is activated. The secondary brake switch is a normally open limit switch that is operated by the service brake pedal. The switch is closed when the service brake pedal nears the end of travel.

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Text Reference

An ON/OFF solenoid also controls the parking brake valve (4). The parking brake valve solenoid is ENERGIZED by connecting it to the battery when the operator activates (pulls UP) the parking brake switch. Brake pressure at the brake control valve (B1) may be tested at the brake pressure test port (5). The status of all three brake solenoids, the PWM brake pedal position sensor, the secondary brake switch, and the parking brake switch may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

NOTE: The following information outlines the state of the three brake valve solenoids in the three possible conditions: Service Brakes Released • Proportional brake valve solenoid - ENERGIZED • Parking Brake valve solenoid • DE-ENERGIZED • Secondary brake valve solenoid - DE-ENERGIZED Service Brakes Applied (full) • Proportional brake valve solenoid - DE-ENERGIZED • Parking Brake valve solenoid - DE-ENERGIZED • Secondary brake valve solenoid - ENERGIZED Parking Brake Applied • Proportional brake valve solenoid - DE-ENERGIZED • Parking Brake valve solenoid - ENERGIZED • Secondary brake valve solenoid - ENERGIZED Also note that the secondary brake valve solenoid is ENERGIZED, along with the parking brake valve solenoid when the parking brake is set to ON. This is a new back-up strategy and is a recent change for this type of brake control valve. The machine ECM "sees" the parking brake switch condition(ON) and the ECM then sends a current to the secondary brake valve solenoid to ENERGIZE it as a back-up to the parking brake valve solenoid.

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Text Reference

D6T ELECTRONIC BRAKE CONTROL VALVE ENGINE ON / BRAKES RELEASED

Parking Brake Solenoid Valve and Secondary Brake Solenoid Valve

Parking / Secondary Brake Valve

Parking / Secondary Brake Valve Pilot Chamber

Accumulator Piston Reducing Spool

Pilot Valve

Pressure Feedback Chamber

Orifice

Accumulator Chamber Proportional Solenoid Valve

Pilot Pressure Chamber

Slot Holes Shutoff Spool

To Brakes

Supply Oil from Pump

Shutoff Valve

81 The proportional solenoid valve for the service brakes on the D6T is controlled by the Machine ECM. The solenoid valve is ENERGIZED to release the brakes. The Machine ECM determines the amount of current to send to the solenoid by the amount of the signal received from the PWM rotary position sensor attached to the service brake pedal. When the proportional solenoid is ENERGIZED, the pilot valve is closed, allowing no oil to drain to tank. With the pilot valve closed, pump supply oil can then pressurize the pilot pressure chambers at the proportional solenoid valve, at the parking brake valve and the secondary brake valve, and in the accumulator chamber. As the accumulator chamber pressure increases, the reducing spool moves to the right against the spring. When the reducing spool moves to the right, it closes off the drain passage and, at the same time, the passage to the brakes is opened to the pump supply oil. Pressure then builds in the pressure feedback chamber and the passage to the brakes. As the pressure increases, the spring applied brakes are released. When the operator depresses the service brake pedal, the PWM sensor attached to the service brake pedal sends a signal to the Machine ECM. The Machine ECM then decreases the current to the proportional solenoid at a rate that is directly proportional to the movement of the pedal. As the solenoid is DE-ENERGIZED, the pilot valve opens and allows the pump supply oil in the pilot pressure chamber to drain to tank. This reduces the pressure in the pilot pressure chamber at the solenoid valve. The accumulator chamber and the parking/secondary brake valve pilot chamber are also reduced by draining through the holes in the shutoff spool.

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Text Reference

As the pilot pressure at the left end of the shutoff spool decreases, the pilot pressure at the right end of the shutoff spool moves the spool to the left, against the spring. When the spool moves all the way to the left, the holes in the spool are opened to drain, due to the slots that are machined in the shutoff valve. The pressures in the accumulator chamber and the parking/secondary brake valve pilot chamber are now allowed to drain through the holes in the spool. As the pilot pressure decreases, the spring begins to move the shutoff spool back to the right. As the shutoff spool moves back to the right, the holes in the spool are covered again by the right end of the shutoff valve. This reduces the rate of reduction in pilot pressure, allowing the brakes to be slowly applied. The pilot oil can then only escape by flowing between the outer diameter of the shutoff spool and the inner diameter of the shutoff valve, and then through the holes in the shutoff spool. As the pilot pressure slowly decreases, the spring moves the shutoff spool further to the right until the holes in the spool are uncovered again at the right end of the shutoff valve. The remainder of the pilot pressure then completely drains to thetank through the shutoff spool. As the pilot pressure decreases, the combined force of the reducing spool spring and the pressure in the feedback chamber moves the reducing spool to the left. The accumulator piston acts as a cushion and aids in preventing the reducing spool from moving too rapidly. As the reducing spool moves to the left, the pump oil supply passage to the reducing spool is closed off. At the same time, the tank passage to the reducing spool is opened, allowing the pressure oil in the brakes to drain to tank. As the pressure to the brakes decreases, the Belville springs begin to engage the brakes. If the operator depresses the service brake pedal completely, the secondary brake switch is activated. The secondary brake switch makes a direct connection between the battery and the secondary brake valve solenoid, which ENERGIZES the secondary brake solenoid. When the parking brake switch is set to the ON position, the parking brake valve solenoid is connected directly to the battery, which ENERGIZES the parking brake solenoid. The Machine ECM constantly monitors the parking brake switch. When the parking brake switch is activated, the ECM also sends a current to ENERGIZE the secondary brake solenoid. Energizing either of the solenoids for the parking brake valve or the secondary brake valve completely drains all pilot pressure oil, resulting in all of the oil being drained from the brakes. The brakes are then fully engaged. NOTE: There are no longer any check valves installed in the brake valve body passage between the reducing spools and the secondary or parking brake valves. These check valves serve no purpose in differential steer machines. These check valves are present, however, in brake valves used on Finger Tip Control machines. They serve to isolate the left brake and right brake passages from each other, for steering purposes.

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Text Reference

BRAKE CONTROL VALVE SERVICE BRAKES RELEASED Proportional Brake Solenoid

Pressure Reducing Spool (Left Brake)

Parking Brake Solenoid

To Right Brake

To Left Brake

Pressure Reducing Spool (Right Brake)

Pump Supply

Secondary Brake Solenoid

82

When the operator releases the service brake pedal, the PWM rotary position sensor (connected to the service brake pedal) sends a signal to the Machine ECM. The Machine ECM then increases the current to the (proportional) brake solenoid. The amount of current sent to the solenoid is directly proportional to the position of the service brake pedal. The increased current ENERGIZES the solenoid, which closes the poppet in the solenoid valve and closes off the flow of pump supply oil to drain. The result is increased pilot pressure to both pressure reducing spools. This increased pressure moves the reducing spools downward. As the spools move downward, the flow of supply oil is shut off to the drain passages and the supply oil then flows into the brake passages and out to the brakes. This increased pressure releases the brakes against the brake (Belleville) springs.

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Text Reference

BRAKE CONTROL VALVE SERVICE BRAKES ENGAGED

Proportional Brake Solenoid

Pressure Reducing Spool ( Left Brake)

Parking Brake Solenoid

To Right Brake

To Left Brake

Pressure Reducing Spool (Right Brake)

Pump Supply

Secondary Brake Solenoid

83

When the operator depresses the service brake pedal, the PWM rotary position sensor (connected to the service brake pedal) sends a signal to the Machine ECM. The Machine ECM then decreases the current to the proportional (service) brake solenoid. The amount of current sent to the solenoid is directly proportional to the position of the service brake pedal. The decreased current DE-ENERGIZES the solenoid, which opens the poppet in the solenoid valve and opens the flow of pump supply oil to drain. The result is decreased pilot pressure to both pressure reducing spools. This decreased pressure allows the springs below the reducing spools to move the reducing spools upward. As the spools move upward, the passage from the brakes is connected to the drain passage, which decreases the pressure to the brakes. This decreased pressure allows the brake (Belville) springs to begin engaging the brakes. When the operator completely depresses the service brake pedal, the secondary brake switch is activated. The secondary brake switch directly connects the battery to the secondary brake solenoid. The ENERGIZED secondary brake solenoid valve completely dumps the pilot pressure to the tank, which causes the reducing spools to move upward. As the spools move upward, the passages from the brakes are connected to the drain passages, which decreases the pressure to the brakes and the brakes are fully engaged.

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Text Reference

BRAKE CONTROL VALVE PARKING BRAKES ENGAGED

Proportional Brake Solenoid

Pressure Reducing Spool (Left Brake)

Parking Brake Solenoid

To Right Brake

To Left Brake

Pressure Reducing Spool (Right Brake)

Pump Supply

Secondary Brake Solenoid

84

When the operator pulls the parking brake switch UP (ON), the switch is activated. The parking brake switch directly connects the parking brake solenoid to the battery and the solenoid is ENERGIZED. The secondary brake solenoid is also ENERGIZED by the Machine ECM as a backup measure. The parking brake valve and the secondary brake valve completely dump the pilot pressure to tank, which causes the reducing spools to instantly move upward. As the spools move upward, the passages from the brakes are connected to the drain passages, which decreases the pressure to the brakes. This decreased pressure allows the brake (Belleville) springs to fully engage the brakes.

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Text Reference

1

85

5

2

86 4

3

The combination power train oil fill tube and dipstick (1) may be accessed through the top door of the forward compartment on the right fender. The dipstick is integrated into the fill tube cap. The power train oil filter (3) may be accessed by opening the front door of the forward compartment on the right fender. This spin-on type canister contains a replaceable 6 micron filter element. The filter is in-line between the transmission charging section of the power train oil pump and it filters the oil in the transmission charging circuit before the oil flows to the transmission and the brakes. Small orifices in the transmission modulating valve and in the electronic brake control valve require the oil to be free of contaminants in order to operate properly. Power train oil cleanliness is critical to the life of these components.

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Text Reference

The power train oil filter base contains a filter bypass switch (2). This is a normally open switch that is held closed by the filter bypass valve spool. When the difference in pressure between the filter inlet and the filter outlet becomes great enough (approximately 50 psi), the bypass valve will open, which allows the switch to open. The switch is monitored by the Caterpillar Monitoring System and alerts the operator to the filter bypass condition when the open circuit is detected. The power train oil filter base also contains the power train oil sampling (S•O•S) port (5) and a pressure test port (4) for the transmission charging circuit. The pressure test port is situated downstream from the filter. The S•O•S port is situated upstream, or before the filter. Power train oil samples should be taken when the power train oil is at operating temperature and the oil has had sufficient time to circulate through the entire system. By doing so, the oil sample will be a true reflection of the cleanliness of all the oil in the system. Always use a clean, lint-free towel to clean the test port prior to taking a fluid sample. Always replace the protective cap after a fluid sample has been taken. Doing so will prevent damage to the test port and lessen the likelihood of introducing contamination into subsequent fluid samples. The status of power train oil filter bypass switch may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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Text Reference

1

2 3

87

Also located in the forward compartment on the right fender and inboard from the power train oil filter canister are the following service points: • remote power train breather (1) • remote pressure test port for torque converter inlet pressure (M) (2) • remote pressure test port for torque converter outlet pressure (N) (3)

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Text Reference

2

1

88

4

5 89 3

Brake pressure for the left brake may be tested at the left final drive housing by removing the plug (1) and installing a pressure test tap. Brake lube pressure (LB1) for the left brake may be tested at the rear port (2). The test ports for right brake pressure and right brake lube pressure (LB2) are reversed on the right final drive The service brake pedal (3) is connected to a rotary position sensor (4). The rotary position sensor sends a PWM signal to the Machine ECM which controls the proportional solenoid for the service brakes. The secondary brake switch is mounted inside the housing at the base of the dash pedestal. The status of service brake pedal position sensor and the secondary brake switch (5) may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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Text Reference

D6T STEERING AND IMPLEMENT HYDRAULICS COMPONENT LOCATION Blade Lift Cylinders Quick-drop Valve Implement Pump

Hydraulic Oil Cooler

AccuGrade EH Pilot Manifold

Machine ECM

Blade Angle EH Pilot Manifold

Steering Pilot Valve

Pressure Reducing Manifold

Steering Motor

Case Drain Filter

Implement Control Valve Stack

Implement Return Filter

Hydraulic Oil S O S Port

Hydraulic Tank

90

IMPLEMENT HYDRAULIC SYSTEM The implement hydraulic systems for the D6T contain the following major components: • a load sensing, pressure compensated, variable displacement piston type hydraulic pump • pilot operated implement control valves and differential steering control • a fixed displacement steering motor • electro-hydraulic implement control for all blade functions on AccuGrade ready machines (ripper/winch controls remain pilot operated in all cases) • a new A4 Machine ECM used for implement hydraulic functions and system monitoring • hydraulic oil filters for both case drain oil and for implement return oil • an oil-to-air hydraulic oil cooler mounted behind the radiator cores • an electronic implement lockout control

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Text Reference

The standard implement hydraulic system for the D6T machine has changed from the D6R Series III machine. Pilot operated controls are used for all blade functions, for ripper (or winch) operation. An EH blade angle control (thumb rocker switch) and an EH manifold with two proportional solenoids for blade angle control are added if the machine is equipped with a VPAT blade. The differential steering system is similar to the D6R Series III machine except it doesn’t use a counterbalance valve. An Electro-Hydraulic (EH) dozer control lever (joystick) and an EH pilot manifold with four proportional solenoids for blade lift and blade tilt functions, as well as an ON/OFF (AccuGrade Boost) solenoid are added on machines that are equipped with AccuGrade. The EH dozer control lever also contains a thumb rocker blade angle control and the associated (second) EH pilot manifold with the blade angle solenoids if the AccuGrade machine is equipped with a VPAT blade. There are four versions of the implement hydraulic system. These four distinct versions of the hydraulic system are: • implement hydraulic system with an "S" or "SU" blade (pilot operated controls and pilot operated implement control valves) • implement hydraulic system with a VPAT blade (pilot operated controls and pilot operated implement control valves with EH blade angle control) • AccuGrade® ready implement hydraulic system with "S" or "SU" blade (pilot operated controls and pilot operated implement control valves for the ripper/winch and EH blade control for all blade functions) • AccuGrade® ready implement hydraulic system with a VPAT blade (pilot operated controls and pilot operated implement control valves for the ripper/winch and EH blade control for all blade functions)

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Text Reference

3 4

2

5

1

91

The hydraulic oil tank (1) is located on top of the right fender. The hydraulic oil tank serves as the reservoir that provides oil for the operation of the implements and the steering. Components of the hydraulic oil tank and associated service points are identified in the illustration above: • implement case drain oil filter (2) • vacuum breaker (3) • hydraulic oil fill tube (4) • fluid level sight glass (5) An ecology drain valve is located on the bottom of the tank (not visible, above) and may be easily accessed through an opening on the underside of the right fender. NOTE: The vacuum breaker on the hydraulic oil tank should always be used to equalize the pressure inside the hydraulic oil tank with the atmospheric pressure before removing the cap from the filler tube. Doing so will prevent scalding injuries due to hot hydraulic oil being expelled through the filler tube when the cap is removed.

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Text Reference

3

2

4 1

92

The implement hydraulic pump on the D6T is a load sensing, pressure compensated, variable displacement piston type pump. The pump (1) is mounted to the rear of the flywheel housing, at the upper left corner. The implement hydraulic pump draws oil from the hydraulic oil tank and provides high pressure oil flow to the implement valve stack. The pump also provides oil flow to the pressure reducing manifold, which in turn, provides pilot pressure oil to the pilot operated implement controls. High pressure supply oil to the implement valve stack is directed through a hose that connects to the pump discharge port. High pressure supply oil to the pressure reducing manifold is directed through a hose that connects to an "L" fitting that is installed in the side of the pump discharge port. Other components identified are the : • pump pressure and flow compensator valve (2) • fitting for the load sensing signal line (from the signal resolver network) (3) • fitting for the case drain line (4)

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Text Reference

A "tee" fitting replaces the "L" fitting at the pump discharge port on AccuGrade® Ready machines. A pump discharge pressure sensor is installed on one side of the "tee" fitting. The fitting on the opposite side of the "tee" connects to the supply line to the pressure reducing manifold. The pump discharge pressure sensor is only present on machines that are equipped with AccuGrade®. This pressure sensor is a necessary component to perform the calibrations of the four proportional solenoid controlled pilot valves on the EH pilot manifold. The solenoid controlled pilot valves are used for blade lift and blade tilt control functions and they will be discussed later in this presentation. The status of the pump discharge pressure sensor may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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Text Reference

PUMP AND COMPENSATOR OPERATION ENGINE OFF

Pump Output Cutoff Spring

Margin Spring

Large Actuator Swashplate

Case Drain Passage

Load Sensing Signal

Drive Shaft Flow Compensator Spool Pressure Compensator Spool

Signal Passage to Actuator Piston

Small Act uat or and Bias Spring Piston and Barrel Assembly

93

Implement Pump Operation When the engine is OFF, the bias spring holds the swashplate at maximum angle. When the engine is started, the pump drive shaft begins to rotate. Since the bias spring holds the swashplate at maximum angle, oil is drawn into the barrel by the outward movement of the pistons as the piston and barrel assembly rotates. As the piston and barrel assembly rotate the oil is forced out into the system when the piston is forced into the barrel by the angle of the swashplate. Oil flow is blocked by the closed-center implement control valves and pressure begins to build as the oil flows out into the system. If no implements are moved, the compensator valve will cause the swashplate to move toward minimum angle, maintaining a system pressure called LOW PRESSURE STANDBY.

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Text Reference

PUMP AND COMPENSATOR OPERATION LOW PRESSURE STANDBY Pump Output Cutoff Spring

Margin Spring

Large Actuator Swashplate

Case Drain Passage

Load Sensing Signal

Drive Shaft Flow Compensator Spool Pressure Compensator Spool

Small Actuator and Bias Spring Piston and Barrel Assembly

Signal Passage to Large Actuator

94

When no flow is required by the implements, no signal pressure is generated. System pressure (red and white stripes) generated by the pump is called LOW PRESSURE STANDBY. The pump produces enough flow to compensate for system leakage and maintain sufficient pressure to provide instantaneous implement response when an implement is actuated. At machine start-up, the bias spring holds the swashplate at maximum angle. As the pump produces flow, system pressure begins to increase because the flow is blocked at the implement control valves. This pressure is felt under both the flow compensator spool and the pressure compensator spool. The flow compensator spool moves up against the low spring force and permits pump discharge oil, at system pressure, to go to the large actuator piston in the pump. As the pressure acting on the large actuator piston increases, the large actuator piston overcomes the force of the bias spring and the pressure in the small actuator piston. The increasing pressure in the large actuator moves the swashplate to a reduced angle. The large actuator piston moves to the right until a balance is reached between the pressure in the large actuator and the pressure in the small actuator plus the force of the bias spring. At this minimum angle, the pump will produce just enough flow to make up for system leakage. The system pressure at this time is called LOW PRESSURE STANDBY and it is set to approximately 3240 kPa (470 psi).

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Text Reference

Low pressure standby is higher than margin pressure. This characteristic is due to a higher back pressure created by the oil which is blocked at the closed-center valves when all the valves are in HOLD. Pump supply oil pushes the margin spool up and further compresses the margin spring. A small amount of pump supply oil then goes to the large actuator piston.

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Text Reference

\PUMP AND COMPENSATOR OPERATION UPSTROKING

Pump Output Cutoff Spring

Margin Spring

Large Reduced Actuator Pressure Swashplate

Case Drain Passage

Load Sensing Signal

Drive Shaft Flow Compensator Spool Pressure Compensator Spool

Small Actuator and Bias Spring Piston and Barrel Assembly

Signal Passage to Large Actuator

95

When an implement is moved, a load sensing signal is sent to the pump compensator valve. This signal causes the force (margin spring plus signal pressure) at the top of the flow compensator spool to become higher than the supply pressure at the bottom of the spool. The spool then moves down which blocks oil to the large actuator piston and opens a passage from the large actuator to the case drain. Pressure at the large actuator piston is reduced or eliminated, which allows the bias spring to move the swashplate to an increased angle. The pump will now produce more flow. This condition is called UPSTROKING. The following conditions can result in upstroking the pump: 1. An implement control valve is activated when the system is at low pressure standby. 2. The implement control valve spool is moved further for additional flow. 3. An additional circuit is activated. 4. Engine rpm decreases. In this case, pump speed decreases which causes a decrease in flow and pump supply pressure. The pump must then upstroke to maintain the same system flow requirements.

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Text Reference

INSTRUCTOR NOTE: Signal pressure does not necessarily need to increase for the pump to upstroke. For example, if one implement is activated and is operating at 13790 kPa (2000 psi), the system supply pressure is 16065 kPa (2330 psi) due to the maximum signal pressure of 13790 kPa (2000 psi) plus the margin spring force of 2275 kPa (330 psi). If the operator activates another implement at an initial operating pressure of 6900 kPa (1000 psi), the maximum signal pressure is still 13790 kPa (2000 psi), but the supply pressure decreases momentarily to provide the increased flow now needed at the implements. The force at the top of the flow compensator spool (now higher than the force at the bottom of the flow compensator spool) pushes the spool down and allows oil in the pump control to drain to tank. The swashplate angle increases and the pump provides more flow.

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Text Reference

PUMP AND COMPENSATOR OPERATION CONSTANT FLOW

Pump Output Cutoff Spring

Margin Spring

Large Reduced Actuator Pressure Swashplate

Case Drain Passage

Load Sensing Signal

Drive Shaft Flow Compensator Spool Pressure Compensator Spool

Small Actuator and Bias Spring Piston and Barrel Assembly

Signal Passage to Large Actuator

96

As pump flow increases, pump supply pressure also increases. When the pump supply pressure (red) equals the sum of the work port (signal) pressure plus the force of the margin spring, the flow compensator spool moves to a metering position and the system becomes stabilized. This condition is called CONSTANT FLOW. The difference between the signal pressure and the pump supply pressure is the value of the force of the margin spring, which is approximately 2275 kPa (330 psi). If no other implements are activated during the movement of an implement (such as DOZER RAISE), and if no external forces influence the movement of the implement, then the pump will maintain the CONSTANT FLOW condition until the movement of that implement has stopped.

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Text Reference

PUMP AND COMPENSATOR OPERATION DESTROKING

Pump Output Cutoff Spring

Margin Spring

Large Increased Actuator Pressure Swashplate

Case Drain Passage

Load Sensing Signal

Drive Shaft Flow Compensator Spool Pressure Compensator Spool

Small Actuator and Bias Spring Piston and Barrel Assembly

Signal Passage to Large Actuator

97

When less flow is needed, the pump is destroked. The pump destrokes when the pressure at the bottom of the flow compensator spool becomes higher than combined signal pressure and spring force at the top. The flow compensator spool then moves up and allows more flow to the large actuator piston. Pressure in the large actuator piston then overcomes the combined force of the small actuator piston and force of the bias spring and moves the swashplate to a reduced angle. The pump will now produce less flow. This condition is called DESTROKING The following conditions can result in destroking the pump: 1. All implement control valves are moved to the HOLD position. The pump returns to low pressure standby. 2. The implement control valve directional stem is moved to reduce flow. 3. An additional circuit is deactivated. 4. Engine rpm increases. In this case, pump speed increases causing an increase in flow. The pump destrokes to maintain the same system flow requirements.

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Text Reference

As pump flow decreases, pump supply pressure also decreases. When the pump supply pressure (red) decreases and becomes the sum of load pressure plus margin pressure, the flow compensator spool moves to a metering position and the system stabilizes. NOTE: Always refer to the service information in the service manual KENR5129 or SIS Web for the latest testing and adjusting specifications and procedures. INSTRUCTOR NOTE: Signal pressure does not necessarily have to decrease for the pump to destroke. For example, if two implements are activated, with one operating at 13800 kPa (2000 psi) and the other operating at 6900 kPa (1000 psi), the system supply pressure is 16075 kPa (2330 psi) due to the highest signal pressure of 13800 kPa (2000 psi) plus the margin spring force of 2275 kPa (330 psi). If the operator returns the implement that is operating at 6900 kPa (1000 psi) to HOLD, the signal pressure is still 13800 kPa (2000 psi), but the supply pressure will increase momentarily, due to the reduced flow requirement for the single implement operation. The higher pump flow rate will produce a higher pump supply pressure, which will push the flow compensator spool up and allow more oil to flow to the pump's large actuator. This action causes the pump to DESTROKE to produce only the flow that is now required for the single implement, but system pressure remains the same. When the pump DESTROKES to produce the lesser flow requirements, the pump will then go to the CONSTANT FLOW state that is required by the single implement operation.

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Text Reference

PUMP AND COMPENSATOR OPERATION HIGH PRESSURE STALL

Cutoff Spring

Margin Spring

Pump Output Large Increased Actuator Pressure Swashplate

Case Drain Passage

Load Sensing Signal

Drive Shaft Flow Compensator Spool Pressure Compensator Spool

Small Actuator and Bias Spring Piston and Barrel Assembly

Signal Passage to Large Actuator

98

The pressure compensator (or cutoff) spool is in parallel with the flow compensator (or margin) spool. The pressure compensator limits the maximum system pressure at any given pump displacement. The spool is held down during normal operation by the pressure compensator spring. During stall or when system pressure is at maximum, signal pressure is equal to pump supply pressure. The combination of the signal pressure and the margin spring forces the flow compensator spool down. This movement of the flow compensator spool normally opens a passage in the pump compensator valve for the oil in the large actuator piston to drain and causes the pump to upstroke. However, if the supply pressure is high enough, the pressure compensator spool is forced up against its spring. This upward movement of the pressure compensator spool blocks the oil in the large actuator piston from going to the drain passage. Instead, the supply oil is now directed to the large actuator piston. The increase in pressure allows the large actuator piston to overcome the combined force of the small actuator piston and bias spring destroking the pump. The pump is now in a minimum flow condition and pump supply (system) pressure is at maximum. This condition is maintained for a single implement in a stall condition and is called HIGH PRESSURE STALL (or sometimes called High Pressure Cutoff).

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Text Reference

This hydraulic system also incorporates a main relief valve-located in the inlet manifold. The main relief valve is set higher to limit pressure spikes in the system. The main relief valve must be removed from the machine to be adjusted properly. The main relief valve should be adjusted according to the specifications and procedures found in KENR5129 Specifications Systems Operation, Testing and Adjusting or on SIS or SIS Web. When operating two or more implements, and with one implement in stall, the pump will produce flow to meet the needs of the other implements operating at a lower work port pressure.

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Text Reference

D6T PRESSURE REDUCING MANIFOLD HA

Implement Pump Supply

Screen Pressure Reducing Valve

To Tank Accumulator Check Valve

SOS CPG Accumulator Implement Lockout Valve

Pilot Relief Valve CP

Pilot Supply 99

Pressure Reducing Manifold The pressure reducing manifold supplies pilot pressure oil to the steering pilot valve and to the pilot operated implement controls (or to the solenoid controlled pilot valves, on ARO machines equipped with EH control of the blade functions). Supply oil from the implement hydraulic pump flows through a screen as it enters the manifold. The oil then flows to the pressure reducing valve. The pressure reducing valve is infinitely variable, and meters the oil to provide pilot pressure oil of approximately 3275 kPa (475 psi). This oil is now pilot oil. The pilot oil then flows through the accumulator check valve, which is installed upstream of the hydraulic accumulator. The check valve prevents backflow in the pilot system, in case of low pilot pressure conditions. The check valve also prevents the hydraulic accumulator from discharging when the machine is shut down. The oil then flows to the hydraulic accumulator and the pilot relief valve. The pilot relief valve limits the pressure in the pilot oil system past the pressure reducing valve to protect the accumulator. The pilot relief valve opens to dissipate excess pressure in the event of pressure spikes in the pilot oil system.

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Text Reference

The hydraulic accumulator stores energy (pilot pressure) for approximately 1-2 minutes after the engine is stopped, allowing the implements to be lowered using the implement controls in a dead engine situation. The pilot oil then flows to the solenoid operated implement lockout valve. The implement lockout valve is controlled by the implement lockout switch, which is located on the right console in the operator compartment. The implement lockout valve is operated using an ON/OFF solenoid. When the implement lockout switch is set to the UNLOCKED position, the implement lockout solenoid is ENERGIZED and the implements may be operated using the implement control levers. When the implement lockout switch is set to the LOCKED position, the implement lockout solenoid is DE-ENERGIZED and the pilot supply oil is blocked. The implements can not be operated using the implement controls when the implement lockout switch is in the LOCKED position. When the implement lockout valve is in the UNLOCKED condition, the pilot supply oil exits the pilot manifold at the outlet. The pilot supply oil is then directed to the pilot operated implement controls (or to the solenoid controlled pilot valves, on ARO machines equipped with EH control of the blade functions). The status of the implement lockout switch and the implement lockout solenoid may be viewed using Cat ET, or through the LCD display on the Main Display Module in the dash, using the 4C-8195 service tool.

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3

Text Reference

1 5

4

6

1

2

100

Pressure Reducing Manifold The pressure reducing manifold (1) is located inside the forward compartment on the right fender and is situated outboard from the power train oil filter. Service points are: • pilot relief valve (2) • pressure reducing valve (3) • implement pump discharge pressure test port (HA) (4) • accumulator (5) • pilot supply pressure test port (CP) (6) Note: not visible in this picture are the : • hydraulic oil sampling port (S•O•S) • accumulator pressure test port (CPG) • accumulator check valve (near, or left side of the implement lockout solenoid) • implement lockout solenoid (ENERGIZED in the UNLOCKED condition)

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Text Reference

D6T IMPLEMENT HYDRAULIC SYSTEM S-BLADE, RIPPER, NON ARO (PILOT CONTROL)

Ripper Lift Cylinder

HOLD

Steering Charge Pump Supply

Steering Motor Case Drain

Blade Lift Cylinder

Implement Pump

HA

Main Relief Valve

Pressure Reducing Manifold

HB

Blade Lift Cylinder

Quick-drop Valve SOS Accumulator Pressure (CPG)

Tilt Vacuum Breaker

Blade Tilt Cylinder Left

Angle

Pilot Supply (CP)

Dual Tilt Option

Right

Single Tilt Option Winch Ripper Control Pilot Valve

Lower

Dozer Control Pilot Valve

Raise Float Pilot Boost

101

Implement Hydraulic System Operation (Pilot Control) This color schematic shows the components and conditions in the implement hydraulic system with the engine running, all of the implements in HOLD, and the implement pump at LOW PRESSURE STANDBY. Oil is drawn from the hydraulic oil tank by the load sensing, variable displacement, piston-type implement pump. High pressure supply oil is sent to the closedcenter implement control valves by the pump. Return oil from the implement control valves and the case drain oil from the pumps and motors is returned to the hydraulic oil tank. High pressure supply oil from the implement pump is also sent to the pressure reducing manifold which produces and supplies pilot pressure oil to the pilot valves. When the operator moves a pilot operated implement control oil is sent to the implement control valve to move the valve spool, allowing oil to flow to the implement cylinder(s). The implement movement is proportional to the amount of implement control movement. (The farther the implement control is moved, the faster the implement will move.)

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Text Reference

As the implement control valve spool moves due to pilot oil pressure, the pilot oil at the opposite end of the control valve spool is returned back to the tank. Pilot return oil from the implement control valves enters the pilot valve body through the control ports also. The pilot return oil flows past the pilot valve spool and is directed through internal passages in the pilot valve body to a common pilot return oil passage the pilot oil returns to the tank. The control lever assembly and the control plate determines the amount of movement of the pilot valve spools. When the control lever is moved, the lever assembly rotates and the control plate pushes down on the upper plunger. The upper plunger and the centering spring move the pilot valve spools down to close off the tank passages and open the pilot supply passages to the control ports. When the control lever is in the HOLD position, the centering springs, the pressure control return springs, and bias springs keep the pilot spools and the lever assembly in the HOLD position. When in the HOLD position, pilot supply oil is blocked by each of the four pilot valve spools and each implement control valve end is open to the tank (through the pilot lines and the control ports). Each pilot valve spool has a cross-drilled hole in the spool that intersects with an axial passage through the center of the spool that is open at the bottom. An orifice is installed in the axial passage at the the bottom of the pilot valve spool. Tank pressure oil is allowed to move through the cross-drilled hole, the axial passage, and the orifice so that a hydraulic lock cannot prevent the free movement of the pilot valve spool. The orifice at the bottom of the pilot valve spool also helps stabilize and dampen the movement of the spool. The dozer control lever is equipped with a magnetic coil assembly that is positioned around the upper portion of the BLADE LOWER pilot valve. A cupped washer is attached to the bottom of the control plate, and it is positioned above the coil. When the dozer control lever is moved forward to approximately 90 percent of lever travel, the washer contacts the magnetic coil. This is the FLOAT position for the dozer blade. The magnetic coil is always ENERGIZED and the coil will hold the washer to maintain the FLOAT position until the dozer control lever is moved back toward the RAISE position. The dozer control lever also has a float detent attached to the underside of the control plate above the BLADE RAISE pilot valve spool. A detent plate is attached to the top of the valve body. The detent is spring biased outward so that the point of the detent moves freely within the cutout in the detent plate. When the dozer control lever is moved to approximately 85 percent of forward lever movement (BLADE LOWER), the chisel point of the detent contacts the lip at the top of the detent plate. The lip provides the operator with a bit of "feel" to indicate that the QUICK-DROP position is close. When the dozer control lever is moved further so that the detent point moves past the lip, the QUICK-DROP function is activated. The detent also indicates the relative location of the FLOAT position, which is only a few degrees of lever movement past the lip.

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Text Reference

2

102 1

3 7

4 103 6 5

The dozer control pilot valve (1) is located at the front of the right console and is mounted to the top of the console. The dozer control lever (2) operates the pilot valve. The ripper control pilot valve (3) is located at the rear of the right console and is mounted to a bracket beneath the console. The following lines are visible in the illustration above: • ripper raise pilot line (to RAISE end of ripper control valve) (4) • pilot valve drain line (to tank) (5) • ripper lower pilot line (to LOWER end of ripper control valve) (6) • pilot supply line (from pressure reducing manifold) (7)

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Text Reference

D6R DOZER CONTROL PILOT VALVE BLADE HOLD

Float Detent Plate

Lever Assembly

Float Detent and Spring

Control Plate

Upper Plunger Washer

Centering Spring Ball

Magnetic Float Coil

Retainer Pressure Control Return Spring

Blade Lower Spool

Hole Blade Raise Spool

Control Port To / From Lower End of Blade Lift Control Valve

Control Port To / From Raise End of Blade Lift Control Valve

Pilot Supply from Pressure Reducing Manifold

Orifice Bias Spring

Pilot Drain to Tank

104

Implement Pilot Valve Operation The standard implement hydraulic system for the D6T Track-type Tractor uses pilot operated implement control valves. The illustration above shows a cross-sectional view of the pilot valve that is used for dozer blade functions. Only the blade raise and the blade lower pilot valve spools are shown, for clarity. The dozer control pilot valve also contains pilot valve spools for the blade tilt left and the blade tilt right functions. Pilot valves are also used for operation of the ripper or the winch, if the machine is equipped with either of these attachments. The pilot valves for the ripper and the winch operate similarly to the dozer control pilot valve. Pilot valves for blade control are used only on non-ARO machines. Pilot supply oil from the pressure reducing manifold enters the pilot valve at the pilot supply inlet. Pilot supply oil is made available to all four pilot valve spools through internal passages in the pilot valve body. The four pilot valve spools direct pilot oil to their respective control ports when they are actuated. Four pilot lines connect the four control ports to the respective ends of the implement control valves. The flow of pilot (pressure) oil to any implement control valve spool is proportionate to the amount of movement of the implement control lever. The pilot pressure sent to the end of any implement control valve spool determines the amount of its movement. The amount of movement of the implement control valve spool determines the flow rate of high pressure pump supply oil that is sent to the implement cylinders.

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Text Reference

5

4

3 1

2

105

Implement Control Valve Operation The implement control valve stack is located below the right console in the operator compartment. The valve stack is mounted to a bracket on the inside the right fender. The control valve stack may be accessed by removing the operator seat and pedestal and then removing the sound panel and metal access cover beneath the right armrest. The implement control valve stack consists of the inlet manifold (1), the blade lift control valve (2), the blade tilt control valve (3), the blade angle control valve (4) and the end cover (5). The implement control valves are all parallel to each other. The blade angle control valve is only present on machines equipped with the VPAT blade. The ripper/winch control valve will only be present if the machine is equipped with those attachments. The EH pilot manifold for blade lift and tilt functions is mounted to the outboard side of the valve stack bracket, if the machine is equipped with AccuGrade®.

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Text Reference

The implement hydraulic system main relief valve (not shown) is installed in the inlet manifold (1) of the valve stack. The main relief valve is set off machine using the 1U9358 Test Block manifold. The main relief valve setting is approximately 3000 kPa (435 psi) higher than the high pressure cutoff setting of the pressure compensator valve on the implement pump. NOTE: Machines equipped with Accugrade® Ready Option (ARO) will have a separate pilot electro-hydraulic maniifold and implement control joystick.

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Text Reference

D6T BLADE LIFT CONTROL VALVE BLADE HOLD

Tank Passage

Pilot Supply

Rod End

Head End

Makeup Valve

Tank Passage Signal Chamber

Main Valve Spool

Pilot Supply

Tilt Control Valve

Resolver

Tank Passage

Pump Compensator

Load Check Valve Pump Supply

106

The blade lift control valve is a closed-center, pilot operated valve that is controlled with pilot oil from the dozer control pilot valve. The blade lift control valve has four positions: RAISE, HOLD, LOWER, and FLOAT. Centering springs keep the spool in the HOLD position when the control valve is not in use. The illustration above shows the blade lift control valve in the HOLD condition. When the operator starts the machine, the implement pump sends high pressure supply oil through the inlet manifold to the load check valve to the main valve spool. With the main valve spool in the HOLD position, oil cannot flow to the cylinders and oil pressure will begin to increase in the hydraulic system. Components of the implement control valves are: Load Check Valve: The Load Check Valve prevents reverse implement flow when the operator moves a valve from HOLD and system pressure is lower than the cylinder, or work port pressure. Without the load check valve, the implement would drift down slightly (droop) before moving as commanded. The load check valve will open to allow supply oil to flow through the control valve when the system pressure is higher than the work port pressure.

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Text Reference

Resolver: Also called a double check valve, the resolver compares the signal between the control valves and sends the highest resolved work port pressure to the implement pump compensator. Although this illustration shows the resolver and signal lines as external components, the resolver is internal to the control valve and the signal lines are internally drilled passages. Main Valve Spool: The Main Valve Spool controls oil flow to the implement cylinders and return oil from the implement cylinders back to the tank. The spool contains three cross-drilled holes that connect to an axial drilled passage through the center of the spool. The two crossdrilled holes on the left hand side of the spool sense work port pressure in the head and rod ends of the cylinders. The work port pressures are transmitted to the pilot chamber through the cross-drilled hole.on the right hand side of the spool. Makeup Valve: The Makeup Valve opens to allow tank pressure oil to fill voids in the head ends of the cylinders during times when cylinder supply pressure decreases below the tank pressure. Orifice: The Orifice provides smoother implement operation by delaying the rate at which the signal pressure in the flow control spool spring cavity decreases when the operator changes implement directions. NOTE: A dozer valve without a flow compensator valve is only fitted on the following machine arrangements; S-Blade & Ripper, S-Blade & ARO, & Ripper, VPAT Blade, & Ripper, VPAT Blade & ARO, & Ripper. A dozer control valve with a flow compensator will be fitted to the following machine arrangements; S-Blade & winch, S-Blade & ARO, & winch, VPAT Blade & winch, VPAT Blade & ARO & winch.

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Text Reference

D6T IMPLEMENT HYDRAULIC SYSTEM WITH VPAT BLADE, ARO, RIPPER (EH OVER PILOT) HOLD

Steering Charge Pump

Steering Motor Case Drain

Blade Lift Cylinder

Ripper Lift Cylinder Implement Pump Main Relief Valve HB Lift

Quick-drop Valve

HA Pressure Reducing Manifold

Accumulator Pressure (CPG)

Blade Lift Cylinder

C2

C1

Blade Tilt Cylinder

Tilt

SOS

C3

Vacuum Breaker

C4

Left Blade Angle Cylinders Right

Angle

C4

C3

C2

Implement EH Manifold

C1

Pilot Supply (CP)

Ripper

Ripper Control Pilot Valve

Raise

Blade Angle EH Manifold

Lower Lower

Machine ECM J1

EH Implement Joystick

J2

Angle Left

Raise Float Pilot Boost

Angle Right

107

Implement Hydraulic System Operation (Electro-Hydraulic Control, ARO) Machines that are equipped with AccuGrade use an electrohydraulic control group to operate the bulldozer. This color schematic shows the components and conditions in the implement hydraulic system solenoid valves for a standard blade or seven solenoid valves for a VPAT blade. The electrohydraulic control group consists of the following components: With the engine running, all of the implements in HOLD, and the implement pump at LOW PRESSURE STANDBY oil is drawn from the hydraulic oil tank by the load sensing, variable displacement, piston-type implement pump. High pressure supply oil is sent to the closedcenter implement control valves by the pump. Return oil from the implement control valves and the case drain oil from the pumps and motors is returned to the hydraulic oil tank. High pressure supply oil from the implement pump is also sent to the pressure reducing manifold. The electrohydraulic control allows the Machine ECM to move the blade when AccuGrade is active.

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Text Reference

When the implement controls are in HOLD position, the solenoids are de-energized and pilot oil is blocked. Oil in the passages to the main control valve are connected to the tank through the pilot manifold. When an implement control is activated, the solenoid for that circuit is energized forcing a spool in the pilot manifold to shift. This shift allows pilot oil to travel from the pilot manifold to the end of the main control spool. The main spool shifts and the implement moves in the direction selected by the operator. The solenoids are proportional. The movement of the valve spool will be in proportion to the amount of movement of the implement control lever.

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Text Reference

D6T BLADE LIFT CONTROL VALVE WITH VPAT BLADE, ARO AND WINCH BLADE HOLD

Tank Passage Pilot Supply from EH Manifold

Rod End

Head End

Makeup Valve

Tank Passage Signal Chamber

Main Valve Spool

Pilot Supply from EH Manifold Tilt Control Valve

Resolver

Tank Passage

Pump Compensator

Load Check Valve Pump Supply

Flow Control Valve

Load Sense Relief Valve

108

The above illustration shows the components of the dozer lift valve when the machine is configured with VPAT Blade, ARO, and winch. A flow control spool and load sense relief valve are installed in this situation.

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Text Reference

D6T BLADE LIFT CONTROL VALVE BLADE RAISE

Tank Passage

Pilot Supply

Rod End

Head End

Makeup Valve

Tank Passage Signal Chamber

Main Valve Spool

Pilot Supply

Tilt Control Valve

Resolver

Tank Passage

Pump Compensator

Load Check Valve Pump Supply

109

When the dozer pilot control lever is moved to the RAISE position, pilot oil is directed to the right end of the blade lift control valve spool. The main spool shifts to the left and the implement hydraulic pump oil flows past the load check valve, main control spool and out to the rod end of the blade lift cylinders causing the blade to raise. Oil from the passes through the quick drop valve before it reaches the blade lift cylinders. Oil from the head end of the blade lift cylinders passes through the quick drop valve and then enters the main control valve. The oil flows past the main control spool and returns to the hydraulic oil tank. Work port pressure in the cylinder rod end also flows into the cross-drilled passage in the middle of the main spool. This signal oil is directed to the signal resolver passage. If this is the highest pressure in the signal resolver network the signal resolver ball shifts to the right and the signal pressure is sent to the pump compensator valve. The pump then UPSTROKES to meet the flow demand in proportion to the signal pressure.

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Text Reference

BULLDOZER TILT CONTROL VALVE WITHOUT VPAT BLADE HOLD

Tank Passage

Pilot Supply

Rod End

Head End

Tank Passage Signal Chamber

Main Valve Spool

Pilot Supply

Tilt Control Valve

Resolver

Tank Passage

Pump Compensator

Load Check Valve Pump Supply

Flow Control Spool

110

The illustration above shows the blade tilt control valve in the HOLD position. In this position the flow from the hydraulic pump enters the control valve at the supply port. Initially, the flow control valve is held to the left by the spring. When the system flow comes into the valve it passes the flow control valve and is stopped by the main spool. the pressure builds and moves the flow control valve to the right metering the flow to the main spool. The load check valve is also in the closed position while the control is in HOLD. NOTE: All tilt control valves are fitted with flow compensator valves. Line relief and make-up valves will be fitted to both workports when the machine is configured with VPAT blade.

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Text Reference

BULLDOZER TILT CONTROL VALVE WITHOUT VPAT BLADE TILT LEFT

Tank Passage

Pilot Supply

Head End

Rod End

Tank Passage Signal Chamber

Main Valve Spool

Pilot Supply

Lift Control Valve

Resolver

Tank Passage Load Check Valve Pump Supply

Flow Control Spool

Angle or Ripper Valve

111

When the operator moves the dozer control lever from HOLD to TILT LEFT, the dozer control pilot valve directs pilot oil to right end of the blade tilt control valve, which shifts the main valve spool to the left into the TILT LEFT position. Oil from the implement hydraulic pump flows past the load check valve and then past the main control spool to the rod end of the tilt cylinder which causes the blade to tilt left. As the blade tilts left, oil from the head end of the tilt cylinder returns through the head end passage and flows past the main spool and the returns to the hydraulic oil tank. Work port pressure in the cylinder rod end also flows into the cross-drilled passage in the middle of the main spool. This signal oil is directed to the signal resolver passage. If this is the highest pressure in the signal resolver network the signal resolver ball shifts to the right and the signal pressure is sent to the pump compensator valve. The pump then UPSTROKES to meet the flow demand in proportion to the signal pressure.

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Text Reference

BULLDOZER ANGLE CONTROL VALVE HOLD

Tank Passage

EH Pilot Manifold

Rod End

Head End

Makeup Valve

Tank Passage Signal Chamber

Main Valve Spool

EH Pilot Manifold

Tilt Control Valve

Resolver

Tank Passage Load Check Valve

Pump Compensator

Pump Supply

Flow Control Spool

Load Sense Relief Valve

112

The illustration above shows the BLADE ANGLE control valve in the HOLD position. In this position the flow from the implement hydraulic pump enters the control valve at the supply port. Initially, the flow control valve is held to the left by the spring. When the system flow enters the valve it passes the flow control valve and is stopped by the main spool. The pressure in the passage increases and moves the flow control valve to the right metering the flow to the main spool. The load check valve is also in the closed position while the control is in HOLD. Oil from both rod end and head end of the cylinders is blocked by the main control valve spool. Both the rod and head ends of the blade angle cylinder are protected by a combination makeup valve and line relief. NOTE: All angle control valves are fitted with flow compensator valves and are supplied pilot oil from a pilot EH manifold.

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Text Reference

BULLDOZER ANGLE CONTROL VALVE ANGLE RIGHT

Tank Passage

EH Pilot Manifold

Rod End

Head End

Makeup Valve

Tank Passage Signal Chamber

Main Valve Spool

EH Pilot Manifold

Tilt Control Valve

Resolver

Tank Passage Load Check Valve

Pump Compensator

Pump Supply

Flow Control Spool

Load Sense Relief Valve

113

When the operator moves the BLADE ANGLE pilot control valve for ANGLE RIGHT pilot oil is directed to the right end of the main control valve spool. The oil from the implement pump flows from the supply port past the load check valve, the main spool, and then to the head end of the left angle cylinder and to the rod end of the right angle cylinder. Oil from the opposite ends of the cylinders returns to the control valve past the main control spool and then returns to the hydraulic oil tank. Work port pressure in the cylinder rod end also flows into the cross-drilled passage in the middle of the main spool. This signal oil is directed to the signal resolver passage. If this is the highest pressure in the signal resolver network the signal resolver ball shifts to the right and the signal pressure is sent to the pump compensator valve. The pump then UPSTROKES to meet the flow demand in proportion to the signal pressure.

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Text Reference

RIPPER LIFT CONTROL VALVE HOLD

Tank Passage

Pilot Supply

Rod End

Head End

Makeup Valve

Tank Passage Signal Chamber

Main Valve Spool

Pilot Supply

Tilt Control Valve

Resolver

Tank Passage

Pump Compensator

Load Check Valve Pump Supply

114

When the machine is equipped with a ripper, the control valve will be the fourth valve in the valve stack. The control valve is spring centered and has three positions, HOLD, RAISE, and LOWER. When the control is in the HOLD position, implement pump supply oil flows into the inlet of the valve, past the load check valve and is stopped by the closed center control valve spool. This supply passage is a common passage to all the control valves in the stack. In HOLD, the pump will maintain a pressure of 3000 kPa (435 psi) in the common passage. NOTE: A dozer valve without a flow compensator valve is only fitted on the following machine arrangements; S-Blade & Ripper, S-Blade & ARO, & Ripper, VPAT Blade, & Ripper, VPAT Blade & ARO, & Ripper. A dozer control valve with a flow compensator will be fitted to the following machine arrangements; S-Blade & winch, S-Blade & ARO, & winch, VPAT Blade & winch, VPAT Blade & ARO & winch.

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Text Reference

RIPPER LIFT CONTROL VALVE RAISE

Tank Passage

Pilot Supply

Rod End

Head End

Makeup Valve

Tank Passage Signal Chamber

Main Valve Spool

Pilot Supply

Tilt Control Valve

Resolver

Tank Passage

Pump Compensator

Load Check Valve Pump Supply

117

When the operator moves the pilot control valve to RIPPER RAISE, position pilot oil is directed to the left end of the main control valve for the ripper. The main spool moves to the right and the implement pump oil flows from the supply port past the main control spool out the port to the head end of the ripper cylinder. Oil from the rod end of the cylinder returns through the rod end port of the control valve, past the main control spool and then returns to the hydraulic oil tank. Work port pressure in the cylinder head end also flows into the cross-drilled passage in the middle of the main spool. This signal oil is directed to the signal resolver passage. If this is the highest pressure in the signal resolver network the signal resolver ball shifts to the right and the signal pressure is sent to the pump compensator valve. The pump then UPSTROKES to meet the flow demand in proportion to the signal pressure.

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Text Reference

D6T SIGNAL RESOLVER NETWORK RIPPER LIFT CONTROL VALVE ACTIVATED

From From Ripper Bulldozer Lift Control Angle Control Valve Valve

From Bulldozer Tilt Control Valve

From Bulldozer Lift Control Valve

To Pump Compensator

Float Boost Signal

116

The resolver network consists of a resolver (ball check valve) in each implement control valve. Each resolver compares the signal pressure from the previous control valve to the pressure from the current control valve. The resolver valve shifts to allow the highest work port pressure to flow to the implement hydraulic pump pump compensator valve. In the illustration above the ripper control valve has been activated. The resolver for the ripper compares it’s signal pressure to that coming from the float boost. The ripper signal is higher because the ripper control has been activated. The signal from the ripper then travels to the reolvers for the bulldozer angle, bulldozer tilt, and bulldozer lift circuits. In this case the ripper circuit has the highest signal pressure because none of the other implements have been activated. This signal goes to the pump compensator to control implement pump output. When all the implements are in HOLD, the pressure in the resolver network is equal to tank pressure. The pump compensator will keep the pump in the LOW PRESSURE STANDBY position until an implement is activated.

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Text Reference

1

117

Quick Drop Valve The single quick-drop valve (1) is mounted on top of the radiator guard, in the center of the guard and is covered with a metal enclosure. This valve provides the quick drop function for both lift cylinders.

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Text Reference

QUICK-DROP VALVE

To Rod End To Blade Lift Control Valve

Blade Lift Cylinders To Head End Quick-drop Valve

118

Shown in the illustration above is a schematic for the single quick-drop valve. The valve is mounted on top of the engine hood at the front of the machine. In the schematic, components in the quick-drop valve are shown with the blade on the ground. The variable orifice sleeve is the essential component in the valve and functions to create the pressure necessary to move the valve spool and direct rod end oil to the head end in the QUICK-DROP mode. The piston bypass valves that are contained in the blade lift cylinder pistons allow high pressure oil to pass from either the rod end or the head end of the cylinders. The bypass valves serve to soften the end-of-stroke for the cylinders. The bypass valves also allow high pressure oil to pass from either rod end or head end when one cylinder reaches end-of-stroke before the other cylinder reaches end-of-stroke. This situation could be caused by the blade being tilted during a BLADE RAISE or a BLADE LOWER function.

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Text Reference

QUICK-DROP VALVE DOZER LOWER

To Right Cylinder Head End

To Left Cylinder Head End

From Left Cylinder Rod End

From Right Cylinder Rod End Passage to Plunger End

Plunger

Valve Spool

Cover

Cover

Orifice Sleeve To / From Lift Control Valve

Passage to Spool End

119

Shown in this illustration are the components of the single quick-drop valve: the orifice sleeve, the plunger, the valve spool, the right and left covers, and the spring. As shown in the previous illustration, the valve components are shown with the dozer blade on the ground. Both the orifice sleeve and the plunger can float in the valve and their positions in HOLD depend on the previous action of the lift control valve: RAISE, LOWER, or FLOAT.

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Text Reference

QUICK-DROP VALVE DOZER RAISE

From Right Cylinder Head End

From Left Cylinder Head End

To Right Cylinder Rod End

To Left Cylinder Rod End

Passage to Plunger End Plunger

Valve Spool

Cover Cover Orifice Sleeve To / From Lift Control Valve

Passage to Spool End

120

When the main control valve spool in the blade lift control valve is moved to the RAISE position, high pressure supply oil enters the quick-drop valve through the passage at the lower left and moves the orifice sleeve to the right. The oil then flows out to the rod ends of the lift cylinders. Return oil from the head ends of the lift cylinders enters the quick-drop valve through the upper passages and flows past the valve spool to the blade lift control valve. At the same time, return oil pressure also enters the passage to the plunger end inside the valve spool and this pressure is felt on the right end of the plunger. However, the blade RAISE pressure felt on the left end of the plunger is higher than the return oil pressure and keeps the plunger shifted to the right. Blade RAISE pressure also enters the passage to the right end of the spool. Since the same pressure is felt on the left end of the spool, the spring keeps the spool shifted to the right. NOTE: The orifice sleeve floats on the valve spool and is kept on the spool by a retaining ring.

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Text Reference

QUICK-DROP VALVE DOZER LOWER

To Right Cylinder Head End

To Left Cylinder Head End

From Left Cylinder Rod End

From Right Cylinder Rod End Passage to Plunger End

Plunger

Valve Spool

Cover

Cover

Orifice Sleeve To / From Lift Control Valve

Passage to Spool End

121

As the operator moves the dozer control lever forward to LOWER the blade (but not to within 3° - 4° of the FLOAT detent), return oil from the rod ends of the lift cylinders enters the quick-drop valve through the middle passages. The return oil flows past the orifice sleeve to the control valve and moves the orifice sleeve to the left against the retaining ring. This oil flow creates a pressure differential across the orifice sleeve. High pressure supply oil (red) from the blade lift control valve enters the quick-drop valve through the lower middle passage and flows past the valve spool to the head ends of the lift cylinders. Supply oil pressure also enters the passage to the right plunger end and is felt on the right end of the plunger. The return oil pressure (red/white hatch) on the right end of the plunger is higher and keeps the plunger shifted to the left. Rod end return oil pressure (red and white stripe) enters the passage to the right end of the spool. This pressure is also felt on the major diameter at the left end of the spool just to the right of the orifice sleeve. In addition, return oil pressure, after the pressure drop across the orifice sleeve, is felt on the minor diameter at the left end of the spool. The net result is that the spool is kept to the right because of the spring and return oil pressure. The major diameters of the spool (the effective area at the right end and the effective area just to the right of the orifice sleeve) cancel each other. The pressure on the right end of the spool is not high enough to overcome the spring and return oil pressure on the minor diameter at the left end of the spool.

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Text Reference

QUICK-DROP VALVE QUICK-DROP

To Right Cylinder Head End

To Left Cylinder Head End

From Right Cylinder Rod End

From Left Cylinder Rod End

Passage to Plunger End Plunger

Valve Spool

Cover Cover Orifice Sleeve To / From Lift Control Valve

Passage to Spool End

122

When the dozer blade is rapidly lowered to the ground (the blade control lever has been moved to a forward position that is within 3° - 4° of the FLOAT detent), the quick-drop valve operates in the QUICK-DROP mode. The increased lever travel results in higher cylinder rod end flow and a higher pressure drop across the orifice sleeve. The only difference from the dozer LOWER position is that the pressure drop across the orifice sleeve that is felt on the minor diameter of the right end of the spool overcomes the resistance of the spring, and the spool starts to move. The minimum flow that causes the necessary pressure drop across the orifice sleeve to begin spool movement is referred to as the "trigger point" and occurs at a point just before the float detent of maximum lever travel. When the spool starts to move, the effective area of the orifice sleeve decreases and the pressure drop increases to shift the spool even further. The result is that the spool shifts completely to the left. This movement connects the rod end of the lift cylinders to the head end of the lift cylinders across the slots in the spool. This connection provides even less resistance and the downward blade velocity and flow from the rod ends increases. This connection also provides a "filling" function of the head ends of the cylinders to minimize the pause time. Some of the oil from the rod ends still flows across the orifice sleeve causing a pressure drop to keep the spool shifted.

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Text Reference

QUICK-DROP VALVE

DOZER LOWER WITH DOWN PRESSURE

To Right Cylinder Head End

To Left Cylinder Head End

From Left Cylinder Rod End

From Right Cylinder Rod End Passage to Plunger End

Plunger

Valve Spool

Cover Cover Orifice Sleeve To/From Lift Control Valve

Passage to Spool End

123

When the blade contacts the ground and stops, flow from the rod ends of the lift cylinders also stops. With no pressure drop across the orifice, the spring shifts the spool back to the right. After the pump fills the head ends of the cylinders (pause time) and the head end cylinder pressure starts to increase, the blade begins to move down. Supply oil pressure (red) enters the passage to the right end of the plunger. Return oil pressure (red and white stripes) from the rod end of the lift cylinders is felt on the left end of the plunger. This pressure is lower than the oil pressure (red and white stripes) on the right end of the plunger, and the plunger moves to the left. The pressure drop across the orifice sleeve that is felt on the minor diameter of the right end of the spool works to move the spool to the left. However, this movement is resisted by the spring and the supply oil pressure (red and white stripes) acting on the plunger. Therefore, the spool stays shifted to the right.

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Text Reference

D6T DIFFERENTIAL STEER TRACK-TYPE TRACTOR STEERING SYSTEM

Hydraulic Oil Cooler

Cooler Bypass Valve Cold Oil Relief Valve Steering Pilot Valve

Steering Pump

Steering Charge Circuit Filter and Pressure Tap

Hydraulic Oil Tank Case Drain Filter

Steering Motor

124

Differential Steering System The components of the steering system include the hydraulic oil cooler, cooler bypass valve, cold oil relief valve, steering pump, hydraulic tank, case drain filter, steering motor, steering circuit filter and pressure tap, and the steering pilot valve. The steering and implements systems share the common tank and suction line. The case drain lines from both systems also join together and share the same case drain filter and inlet port to the tank. The steering system is made up of two hydraulic circuits. There is a high pressure closed loop system that provides oil for the steering of the machine. There is also a low pressure charge circuit that provides control and makeup oil for the high pressure loop.

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Text Reference

1 2

3

125

The steering pump on the D6T is an axial piston pump with overcenter capability. The pump output is controlled by the steering pilot valve. The pilot valve is attached to the bottom of the steering tiller. The pump displacement varies proportionally to the range of the pilot pressure. The pilot pressure range is 600 to 1800 kPa (87 to 261 psi). The flow from the steering pump controls the speed and direction of the steering motor. The steering pump is mounted on the upper right of the torque convertor housing. It also contains the charge pump relief valve, the pressure compensator valve, and the crossover relief and makeup valves. The charge relief valve (1) maintains the oil pressure in the charge circuit after the oil has been filtered and cooled. The pressure compensator valve limits the maximum pressure in both sides of the steering loop. The crossover relief and makeup valves (3) protect the system from pressure spikes and also provide makeup oil to the low pressure side of the steering loop when needed. The pump control valve (2) controls the direction and volume of oil flow through the high pressure loop by moving the swashplate in the steering pump.

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Text Reference

D6T STEERING HYDRAULIC SYSTEM (VPAT) MA

HD

Charge Pump

Supply from Tank X2

Steering Pump

X1

Steering Charge Filter SOS

H

Steering Motor

Steering Pilot Valve

Charge Relief

HC

MB P.O.R Valve

Cross Over Relief

Right

Left

Y2

Y1

Tank J Hydraulic Oil Cooler

Cold Oil Relief Valve Return To Tank

Cooler Bypass And Relief Valve

126

The illustration above shows the steering system with the engine running and the steering in HOLD position. The steering charge pump oil flows through the hydraulic oil cooler and the steering charge filter. It then flows to the crossover relief and makeup valves and provides charge pressure for the steering loop. When the operator selects the direction of a turn the steering pilot valve directs the oil to the steering motor in proportion to the movement of the control lever. This oil flow will drive the steering motor turning the tractor.

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Text Reference

1

2

127

The steering motor (1) is a fixed displacement bent axis motor with a self-contained flushing valve. Oil flow through the motor can be in either direction. A change in the direction of the oil flow changes the rotation of the barrel, pistons and shaft. This change in rotation does not change the output torque from the shaft of the motor. The case drain port (2) is also identified above.

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Text Reference

Lever

STEERING PILOT VALVE NO TURN

Left Steer Plunger

Right Steer Plunger

Centering Spring Metering Spring Stem

Stem From Steering Charge Pump

Pump Control Valve

128

The steering pilot control valve on the D6T is located in the left operator’s console. The pilot valve is controlled manually by the operator and controls the displacement and direction of the steering pump. The pilot valve has two pressure reducing valves which control the displacement of the steering pump. One valve is the STEER RIGHT condition and the other is for STEER LEFT. When the lever is in the NO TURN (centered) position, return spring force keeps the pilot valve assemblies in the centered position and pilot oil is blocked by both pilot stems. The pilot oil ports at the bottom of the valve assemblies are open to drain and no pilot oil is sent to the steering pump.

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Text Reference Lever

STEERING PILOT VALVE LEFT TURN

Left Steer Plunger

Right Steer Plunger

Centering Spring Metering Spring Stem

Steering Charge Pump

Pump Control Valve

129

The illustration above shows the steering pilot control valve in the LEFT TURN position. When the operator moves the lever to the right (as shown), the cam follower linkage depresses the left port plunger and regulating spring. The increased force on the regulating spring pushes the left pilot stem down and opens a passage through the pilot stem from the pilot pressure supply passage to the left pilot (signal) port. The pilot stem meters the pilot oil from the supply passage to the pilot port. This metering controls the signal pressure to the steering pump. The pressure of this signal is determined by the force of the regulating spring, which depends on the distance the plunger is depressed.

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Text Reference

DIFFERENTIAL STEER COMPONENTS Hydraulic Motor Input

Transmission Input

To Right Final Drive

To Left Final Drive

Steer Planetary

Drive Planetary

Equalizing Planetary

130

Differential steer tractors are not equipped with steering clutches but have a steering differential, a hydraulic pump, a hydraulic steering motor, and steering controls. (The hydraulic components will be discussed in the Implement Hydraulic section of this presentation.) The steering differential has two power inputs: a speed and direction (FORWARD and REVERSE) input from the transmission and a steering input (LEFT and RIGHT) from the hydraulic motor. The steering differential uses the hydraulic motor power input to increase the speed of one track and equally decrease the speed of the other track. The resulting difference in track speed causes the tractor to turn. The steering differential consists of the steer planetary, the drive planetary, and the equalizing planetary. Color codes in this illustration designate the various components. The drive pinion, the bevel gear shaft, and the drive planetary carrier are shown in red. The bevel gear shaft is splined to the drive planetary carrier. During turns, the hydraulic motor pinion drives the steer planetary ring gear.

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Text Reference

The hydraulic motor pinion and steer planetary ring gear are shown in orange. The center shaft connects the sun gears for all three planetaries. The sun gears and the center shaft are shown in blue. The planet gears for all three planetaries are shown in yellow. The left and right outer axle shafts are splined to the steer planetary and the equalizing planetary respectively. Also, the steer planetary carrier is directly connected to the drive planetary ring gear. These components are shown in green. The equalizing planetary ring gear is bolted to the right brake housing and is always stationary. The equalizing planetary is shown in gray.

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Text Reference

DIFFERENTIAL STEER COMPONENTS STRAIGHT LINE OPERATION

Hydraulic Motor Input

Transmission Input

To Right Final Drive

To Left Final Drive

Steer Planetary

Drive Planetary

Equalizing Planetary

131

This illustration shows the power flow through the differential steer system during straight line operation (FORWARD or REVERSE). In this condition, the hydraulic steering motor does not turn. Since the hydraulic steering motor does not turn, the steering pinion and steer planetary ring gear are stationary (shown in gray) and the transmission provides all of the power flow through the system. The transmission sends power through the transfer gears, pinion, bevel gear, and bevel gear shaft to the drive planetary carrier. At this point, the power divides causing a torque split. Most of the torque goes through the drive planetary ring gear to the steer planetary carrier. From the steer planetary carrier, the resulting power reaches the left final drive through the left outer axle. The remaining torque from the drive planetary carrier is transmitted to the equalizing planetary sun gear through the drive planetary sun gear and the center axle. The equalizing planetary planet gears multiply the torque in the sun gear and send the resulting power through the right outer axle to the right final drive. The effect of this operation is that the left and right outer axles rotate in the same direction with the same power magnitude and the machine, therefore, tracks in a straight line.

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Text Reference

DIFFERENTIAL STEER COMPONENTS LEFT TURN / FORWARD

Hydraulic Motor Input

Transmission Input

To Right Final Drive

To Left Final Drive

Steer Planetary

Drive Planetary

Equalizing Planetary

132

During a turn, both the transmission and the hydraulic motor provide inputs to the differential steer system with the transmission supplying most of the power to the system. The transmission input power is transmitted to the outer axles in the same manner as during straight line operation. The hydraulic motor input determines the turn direction and turn radius. The rpm of the hydraulic motor controls the turn radius (the higher the rpm, the greater the turn radius) and the direction of rotation establishes the turn direction. During a LEFT TURN in the FORWARD direction, the hydraulic motor sends power through the steering planetary ring gear and planet gears to the sun gear. The input from the hydraulic motor has two effects on the system: 1. The first effect is that the speed of all three sun gears and the speed of the center axle increases, causing the speed of the right outer axle to increase. 2. The second effect is that the relative motion of the sun gear and planet gears in the steer and the drive planetaries cause the drive planetary ring gear, the steer planetary carrier, and the left outer axle to slow down. (This relative motion is due to the fact that the drive planetary carrier is turning at a constant rpm.) The speed decrease of the left outer axle is equal to the speed increase of the right outer axle.

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Text Reference

To make a RIGHT TURN, the direction of the hydraulic motor is opposite of the direction for a LEFT TURN. The motor now applies power to the steering planetary carrier causing an increase in the speed of the steering planetary carrier, the drive planetary ring gear, and the left outer axle. Simultaneously, all three sun gears, the center axle, and the right outer axle slow down. The speed decrease of the right outer axle is equal to the speed increase of the left outer axle. NOTE: During normal operation, this system does not provide a "pivot turn" capability. When the transmission is in NEUTRAL and is suppling no power to the steering differential, the tractor will pivot about its center point when the steering lever is moved. This is caused by the steering motor being the only rotational input into the steering differential and then to the axles.

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Text Reference

133

CONCLUSION This presentation has discussed locations of components and the systems operation of the engine, the cooling system, the power train, the steering and implement hydraulic system, the electrical system, and the Caterpillar Monitoring System for the D6T Track-type Tractor. When used in conjunction with the Service Manual and the reference information listed at the beginning of this presentation, the information in this package will help the serviceman analyze problems in any of the major systems of the D6T Track-type Tractor. Pictured above is a special configuration D6T for the logging industry.

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Text Reference

HYDRAULIC SCHEMATIC COLOR CODE This illustration identifies the meanings of the colors used in the hydraulic schematics, the power train schematics, and the cross-sectional views shown throughout this presentation.

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1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43.

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Visual List

VISUAL LIST D6T right side view 44. Turbocharger inlet pressure sensor Serial number prefixes 45. Engine coolant temperature sensor Undercarriage arrangements 46. SOS sampling port (cooling system) SystemOneTM 47. C9 wastegate turbocharger D6T front view 48. Engine right side front D6T rear view 49. Fuel pressure regulator Operator’s compartment 50. Engine prelube system Seat 51. Quick-Evac-Oil Change system Steering control lever 52. C9 Fuel delivery system Right console controls 53. C9 Air intake and exhaust system Implement control lever 54. D6T Cooling system Ripper control lever 55. Front view of radiator Rt. console function switches 56. AMOCS/ATAAC cores Wiper control switches 57. Radiator cap MVP High Idle Speeds for NACD Market 58. Coolant shunt tank Machines 59. D6T Demand fan control MVP High Idle Speeds for E.U. Market 60. Demand fan control valve manifold Machines 61. Demand fan clutch Service brake pedal 62. D6T Power Train components Dash panel 63. MVP control switch Main display module 64. Power Train hydraulic system Quad gage module 65. Bare frame front view Alert indicator module 66. Power train oil pump Monitoring system components 67. Torque divider 175 amp fuse 68. Torque divider sectional view Machine ECM 69. Torque convertor inlet relief view Machine ECM service points 70. Torque convertor inlet relief sectional Diagnostic box 71. Torque convertor outlet relief view Machine control electrical system 72. Torque convertor outlet relief sectional Battery box 73. Power Train oil cooler Machine electrical disconnect 74. D6T PT lube distribution manifold Fuse panel access 75. ECPC transmission sectional view Engine left side view 76. ECPC test ports view Engine left side service points 77. ECPC hydraulic control manifold Engine right side 78. Transmission modulating valve Engine compartment left side 79. Transmission main relief valve HEUI fuel pump and transfer pump 80. Electronic brake control valve view Engine electrical system 81. Electronic brake valve sectional view IAP sensor 82. Brake control valve-service brakes released Upper and lower speed/timing sensors 83. Brake control valve-service brakes applied Intake manifold pressure sensor 84. Brake control valve-parking brake applied Atmospheric pressure sensor 85. Power train fill and dipstick Ether aid 86. Power train oil filter Engine ECM 87. PT breather, convertor test ports Engine oil pressure sensor

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88. 89. 90. 91. 92. 93. 94. 95. 96. 97. 98. 99. 100. 101. 102. 103. 104. 105. 106. 107. 108. 109. 110. 111. 112. 113. 114. 115. 116. 117. 118. 119. 120. 121. 122. 123.

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Visual List

VISUAL LIST Brake pressure test ports left side 124. Differential steer track-type tractor-steer Service brake pedal and rotary sensor system Implement Hydraulic system 125. Steering pump view Hydraulic tank 126. Steering hyd. system VPAT Implement hydraulic pump 127. Differential steer motor Implement pump-engine off 128. Steering pilot control valve-no turn Implement pump-low pressure standby 129. Steering pilot control valve-left turn Implement pump-upstroking 130. Differential steer components Implement pump-constant flow 131. Differential steer components-straight line Implement pump-destroking operation Implement pump-high pressure stall 132. Differential steer-left turn/forward D6T pressure reducing manifold 133. Conclusion Pressure reducing manifold view Implement hyd. pilot control Implement pilot control valve Ripper control valve Implement pilot valve sectional view Implement control valve stack Blade lift control valve-hold Implement hyd. sys. with VPAT Blade, ARO, Ripper-hold Blade lift control valve with VPAT and ARO-blade hold Blade tilt control tilt left-blade raise Bulldozer tilt control valve without VPAThold Bulldozer tilt control valve without VPATtilt left Bulldozer angle control valve-hold Bulldozer angle control valve-angle right Ripper lift control valve-hold Ripper lift control valve-raise D6T signal network Quick drop valve Quick drop valve schematics Quick drop valve-hold Quick drop valve-blade raise Quick drop valve-blade lower Quick drop valve-quick drop Quick drop valve lower w/downpressure

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Handout No. 1

Engine System Components Identification Directions: Use this sheet to take notes during the engine presentation. During the lab exercise, use this sheet as a checklist for locating/identifying the system's major components. Engine Components ____ Primary and Secondary fuel filters

____ Intake manifold air temperature sensor

____ Electric fuel priming pump and switch

____ Injection actuation pressure sensor

____ HEUI pump

____ Fuel pressure regulator

____ Fuel transfer pump

____ Fuel pressure sensor

____ Engine oil fill tube and dipstick

____ Turbo inlet pressure sensor

____ Engine oil filter

____ "Crank-without-Inject" connector/plug

____ Engine oil S•O•S test port

____ Upper/Lower speed/timing sensors

____ Engine oil pressure test port

____ Starter

____ Engine oil pressure sensor

____ Coolant temperature sensor

____ Engine prelube motor and pump

____ Timing calibration probe connector

____ Air filter

____ Timing calibration probe/adapter port

____ Turbocharger and wastegate

____ Auxiliary start receptacle

____ AMOCS radiator and shunt tank

____ Fumes disposal/crankcase breather

____ Engine coolant S•O•S test port ____ Main electrical disconnect switch ____ A4 Engine ECM ____ Alternator ____ Ether injection control solenoid ____ Intake manifold air pressure sensor ____ Atmospheric air pressure sensor

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Handout No. 2

Cooling System and Fan System Components Identification Directions: Use this sheet to take notes during the cooling/fan systems presentation. During the lab exercise, use this sheet as a checklist for locating/identifying the system's major components. Cooling System Components

Fan System Components (If equipped)

____ Engine oil cooler

____ Demand fan control manifold

____ Power train oil cooler

____ Demand fan control solenoid

____ Jacket water pump

____ Demand fan oil pressure test port

____ AMOCS radiator cores

____ Demand fan speed sensor

____ Coolant temperature regulator housing

____ Flexxaire fan

____ Coolant shunt tank

____ Flexxaire fan switch

____ Coolant fill tube and cap ____ Coolant level sight glass ____ Cooling system drain valve

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Handout No. 3

Power Train Components Identification Directions: Use this sheet to take notes during the power train presentation. During a lab exercise, use this sheet as a checklist when locating/identifying the system's major components. Power Train Components

Power Train Pressure Test Ports

____ Machine ECM

____ Torque converter outlet relief pressure test port (N)

____ Power train oil fill tube and dipstick ____ Power train lube distribution manifold

____ Torque converter inlet relief (supply) pressure test port (M)

____ Torque converter inlet relief valve

____ Transmission lube pressure (L1)

____ Torque converter outlet relief valve

____ Flywheel lube pressure (L2)

____ Torque converter outlet temp. sender

____ Transmission main relief pressure test port (P)

____ Power train oil filter ____ Power train oil filter bypass switch

____ Transmission clutch pressure test ports (5)

____ Power train oil pump

____ Power train oil S•O•S port

____ Power train oil temp. sender (pump)

____ Right brake lube pressure test port (LB2)

____ Transmission circuit accumulator

____ Right brake pressure test ports (final drive)

____ Torque converter output speed sensor ____ Left brake lube pressure test port (LB1) ____ Electronic brake control valve ____ Left brake pressure test ports (final drive) ____ Proportional brake valve solenoid ____ Brake pressure test port (B1, brake valve) ____ Secondary brake valve solenoid ____ Parking brake valve solenoid ____ Service brake pedal position sensor ____ Parking brake switch ____ Transmission lube temperature sender ____ Power train breather

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Handout No. 4

Steering and Implement Hydraulic System Components Identification Directions: Use this sheet to take notes during the hydraulic system presentation. During a lab exercise, use this sheet as a checklist when locating/identifying the system's major components. Steering/Implement Hydraulic Components Steering/Implement Hydraulic Test Ports ____ Hydraulic oil tank

____ Steering Pump

____ Hydraulic oil fill tube and sight glass

____ Pump discharge pressure test port (HA)

____ Hydraulic oil filters (2)

____ Pilot supply pressure test port (CP)

____ Implement pump

____ Accumulator pressure test port (CPG)

____ Pump pressure sensor (if equipped)

____ Hydraulic oil S•O•S (fluid sampling) port

____ Pressure reducing manifold

____ Left steer loop pressure test port (MA)

____ EH pilot manifold(s) (if equipped)

____ Right steer loop pressure test port (MB)

____ Implement lockout solenoid valve ____ Blade lift control valve ____ Ripper lift control valve (if equipped) ____ Blade angle control valve (if equipped) ____ Steering pilot control valve ____ Hydraulic system main relief valve ____ Dozer pilot valve (or EH joystick) ____ Ripper pilot valve (or winch-if equipped) ____ Quick-drop valve ____ Machine ECM ____ Hydraulic oil cooler and bypass valve ____ Hydraulic oil temperature sensor ____ Steering motor

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Handout No. 5A Posttest

MACHINE SYSTEMS POSTTEST Using any of the provided classroom materials, demonstrate your knowledge of the various machine systems by circling the BEST ANSWER for each of following questions. The C9 ACERT® Engine 1. The atmospheric pressure sensor is used: A. to calculate boost pressure and air filter restriction B. to determine ambient air pressure and as a reference for all other engine pressure sensors C. to calculate gage pressures for engine oil and fuel D. all of the above answers (A, B, and C) E. answers A and C 2. The intake manifold air pressure sensor is used to: A. calculate boost pressure B. calculate air filter restriction C. determine ATAAC restriction D. answers A and B 3. The turbo inlet air pressure sensor is used to: A. calculate boost pressure B. calculate air filter restriction C. determine turbocharger failure D. answers A and B 4. The fuel transfer pump: A. draws fuel from the secondary fuel filter B. draws fuel from the primary fuel filter C. maintains fuel system pressure D. provides fuel flow through the entire fuel system E. answers A, C, and D F. answers B and D 5. The fuel pressure regulator: A. maintains fuel system pressure B. is positioned between the fuel injectors and the fuel tank C. is positioned between the fuel injectors and the fuel transfer pump D. answers A and B E. answers A and C 6. The upper and lower speed/timing sensors: A. provide engine speed information to the Engine ECM B. provide engine speed information to the Machine ECM C. are used to calculate shifting points for the Auto KickDown shifting strategy D. answers A, B, and C E. answers A and B

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Handout No. 5B Posttest

MACHINE SYSTEMS POSTTEST (continued) Using any of the provided classroom materials, demonstrate your knowledge of the various machine systems by circling the BEST ANSWER for each of following questions. The Power Train System 11. The Torque Converter Inlet Relief Valve: A. limits the maximum oil pressure to the torque converter B. limits the maximum oil pressure in the torque converter C. protects the components in the torque converter when the oil is cold D. answers A and C E. answers B and C 12. The Torque Converter Outlet Relief Valve: A. ensures a constant oil pressure to the torque converter B. maintains a constant maximum oil pressure in the torque converter C. maintains a constant minimum oil pressure in the torque converter D. limits the maximum temperature inside the torque converter E. answers C and D 13. The Transmission Main Relief Valve maintains a minimum oil pressure: A. for operation of the transmission B. for operation of the torque converter C. for operation of the brakes D. all of the above answers E. answers A and C 14. The brakes are: A. spring applied and hydraulically released B. hydraulically applied and spring released C. hydraulically applied and hydraulically released D. none of the above answers 15. When the service brakes are FULLY ENGAGED: A. the proportional brake solenoid valve is DE-ENERGIZED and the secondary brake solenoid valve is ENERGIZED B. the proportional brake solenoid valve is ENERGIZED and the secondary brake solenoid valve is DE-ENERGIZED C. the proportional brake solenoid valve is DE-ENERGIZED and the secondary brake solenoid valve is DE-ENERGIZED D. the proportional brake solenoid valve is ENERGIZED and the secondary brake solenoid valve is ENERGIZED E. none of the above answers

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Handout No. 5C Posttest

MACHINE SYSTEMS POSTTEST (continued) Matching - Using any of the provided classroom materials, demonstrate your knowledge of the steering and implement hydraulic system by matching the letter of the BEST ANSWER at the right to each of the implement system components listed at the left. Implement Hydraulic System ____ Hydraulic oil tank ____ Pilot manifold ____ Implement pilot valve ____ Pump compensator valve ____ Implement lockout solenoid valve ____ Float pilot boost line ____ Implement control valve ____ Main relief valve ____ Solenoid controlled pilot valve ____ Quick-drop valve ____ Machine ECM ____ Accugrade Boost solenoid valve

A. Directs the flow of high pressure pump supply oil to the implement cylinders. B. Directs pilot pressure oil to move the main implement control valve spool, in proportion to the movement of the implement control lever. C. ENERGIZED by the Machine ECM at all times when an automated blade control device is turned ON. D. ENERGIZED by the Machine ECM to direct pilot pressure oil to move the main implement control valve spool, in proportion to the movement of the implement control lever. E. Receives signals from implement control lever sensors and sends corresponding currents to the appropriate solenoid controlled pilot valves. F. Blocks the flow of pilot pressure oil to the implement pilot valves when DE-ENERGIZED. G. Directs rod-end oil from the blade lift cylinders into the head-ends when the blade falls rapidly to the ground. H. Serves as a reservoir for the hydraulic oil. I. Contains the pressure reducing valve and the accumulator and provides pilot pressure oil to the pilot valves. J. Controls margin pressure and limits maximum pump pressure. K. Is set higher than the pump cutoff setting and protects the hydraulic system from excess pressures. L. Directs pilot pressure oil into the signal resolver network, causing the implement pump to upstroke.

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Handout No. 5A Posttest Answers

MACHINE SYSTEMS POSTTEST ANSWERS Using any of the provided classroom materials, demonstrate your knowledge of the various machine systems by circling the BEST ANSWER for each of following questions. The C9 ACERT® Engine 1. The atmospheric pressure sensor is used: A. to calculate boost pressure and air filter restriction B. to determine ambient air pressure and as a reference for all other engine pressure sensors C. to calculate gage pressures for engine oil and fuel D. answers A, B, and C E. answers A and C 2. The intake manifold air pressure sensor is used to: A. calculate boost pressure B. calculate air filter restriction C. determine ATAAC restriction D. answers A and B 3. The turbo inlet air pressure sensor is used to: A. calculate boost pressure B. calculate air filter restriction C. determine turbocharger failure D. answers A and B 4. The fuel transfer pump: A. draws fuel from the secondary fuel filter B. draws fuel from the primary fuel filter C. maintains fuel system pressure D. provides fuel flow through the entire fuel system E. answers A, C, and D F. answers B and D 5. The fuel pressure regulator: A. maintains fuel system pressure B. is positioned between the fuel injectors and the fuel tank C. is positioned between the fuel injectors and the fuel transfer pump D. answers A and B E. answers A and C 6. The upper and lower speed/timing sensors: A. provide engine speed information to the Engine ECM B. provide engine speed information to the Machine ECM C. are used to calculate shifting points for the Auto KickDown shifting strategy D. answers A, B, and C E. answers A and B

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Handout No. 5B Posttest Answers

MACHINE SYSTEMS POSTTEST (continued) Using any of the provided classroom materials, demonstrate your knowledge of the various machine systems by circling the BEST ANSWER for each of following questions.

The Power Train System 11. The Torque Converter Inlet Relief Valve: A. limits the maximum oil pressure to the torque converter B. limits the maximum oil pressure in the torque converter C. protects the components in the torque converter when the oil is cold D. answers A and C E. answers B and C 12. The Torque Converter Outlet Relief Valve: A. ensures a constant oil pressure to the torque converter B. maintains a constant maximum oil pressure in the torque converter C. maintains a constant minimum oil pressure in the torque converter D. limits the maximum temperature inside the torque converter E. answers C and D 13. The Transmission Main Relief Valve maintains a minimum oil pressure: A. for operation of the transmission B. for operation of the torque converter C. for operation of the brakes D. all of the above answers E. answers A and C 14. The brakes are: A. spring applied and hydraulically released B. hydraulically applied and spring released C. hydraulically applied and hydraulically released D. none of the above answers 15. When the service brakes are FULLY ENGAGED: A. the proportional brake solenoid valve is DE-ENERGIZED and the secondary brake solenoid valve is ENERGIZED B. the proportional brake solenoid valve is ENERGIZED and the secondary brake solenoid valve is DE-ENERGIZED C. the proportional brake solenoid valve is DE-ENERGIZED and the secondary brake solenoid valve is DE-ENERGIZED D. the proportional brake solenoid valve is ENERGIZED and the secondary brake solenoid valve is ENERGIZED E. none of the above answers

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Handout No. 5C Posttest Answers

MACHINE SYSTEMS POSTTEST (continued) Matching - Using any of the provided classroom materials, demonstrate your knowledge of the steering and implement hydraulic system by matching the letter of the BEST ANSWER at the right to each of the implement system components listed at the left. Implement Hydraulic System _H__ Hydraulic oil tank _I__ Pilot manifold _B__ Implement pilot valve _J__ Pump compensator valve _F__ Implement lockout solenoid valve _L__ Float pilot boost line _A__ Implement control valve _K__ Main relief valve _D__ Solenoid controlled pilot valve _G__ Quick-drop valve _E__ Machine ECM _C__ Accugrade Boost solenoid valve

A. Directs the flow of high pressure pump supply oil to the implement cylinders. B. Directs pilot pressure oil to move the main implement control valve spool, in proportion to the movement of the implement control lever. C. ENERGIZED by the Machine ECM at all times when an automated blade control device is turned ON. D. ENERGIZED by the Machine ECM to direct pilot pressure oil to move the main implement control valve spool, in proportion to the movement of the implement control lever. E. Receives signals from implement control lever sensors and sends corresponding currents to the appropriate solenoid controlled pilot valves. F. Blocks the flow of pilot pressure oil to the implement pilot valves when DE-ENERGIZED. G. Directs rod-end oil from the blade lift cylinders into the head-ends when the blade falls rapidly to the ground. H. Serves as a reservoir for the hydraulic oil. I. Contains the pressure reducing valve and the accumulator and provides pilot pressure oil to the pilot valves. J. Controls margin pressure and limits maximum pump pressure. K. Is set higher than the pump cutoff setting and protects the hydraulic system from excess pressures. L. Directs pilot pressure oil into the signal resolver network, causing the implement pump to upstroke.