SENR6483-00_3412_PEEC

3412 Generator Set Engine 2WJ00001-UP(SEBP2268 - 29) - Document Structure

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Shutdown SIS

Previous Screen Product: GEN SET ENGINE Model: 3412 GEN SET ENGINE 2WJ Configuration: 3412 Generator Set Engine 2WJ00001-UP

Systems Operation 3412 GENERATOR SET ENGINES ELECTRONICALLY CONTR Media Number -SENR6483-00

Publication Date -27/01/1995

Date Updated -12/10/2001

Systems Operation

Introduction NOTE: For Specifications with illustrations, make reference to Specifications For 3412 Generator Set Engines, Form No. SENR6482. If the Specifications in Form SENR6482 are not the same as in the Systems Operation and the Testing And Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Model Views

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Top View Of Engine

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Right Side View Of Engine

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Front View Of Engine

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Rear View Of Engine

Engine Information The Caterpillar 3412 Generator Set Engine uses a microprocessor based electronic engine control to provide electronic governing, automatic fuel ratio control and torque rise shaping. Two communication data links are provided to monitor engine characteristics are provided to monitor engine characteristics and provide diagnostic information. The engine is twin series turbocharged and jacket water aftercooled with direct fuel injection. The engine has a SAE No. "0" (zero) flywheel housing and dual viscous dampers. This engine is designed for either right or left hand service and to fit within a 1220 mm (48 in) width for oil well servicefracturing rig applications. Individual injection pumps and fuel lines, one for each cylinder, meter and pump fuel under high pressure to and injection nozzle for each cylinder. New "collared washer" fuel injection lines are made from high strength steel. They incorporate a

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collared washer at the end of the fuel line to reinforce fuel line connections and increase system reliability. The 3412 Generator Set Engine has a high capacity fuel system. The plunger area for the new fuel system is increased over other 3400 Family engines. A high injection-rate camshaft, with increased stroke, is also used. This combination of increased plunger area, longer stroke and high injection rate results in a significant increase in injection pressure and volumne, with a reduction in injection duration. This yields higher power output, cleaner combustion, lower smoke levels and improved fuel economy. A full range electronic governor controls the fuel injection pump output to maintain the engine rpm, called for by the throttle position sensor. The cooling system consists of a gear driven centrifugal pump, with two thermostats which regulate the coolant temperature. A customer supplied fan drive and cooling system (radiator) is required. The engine lubricating oil, which is both cooled and filtered, is supplied by a gear driven pump. Bypass valves provide unrestricted flow of lubrication oil to the engine parts when oil viscosity is high, or if either the oil cooler or the oil filter elements should become plugged. Engine efficiency and engine performance depend on adherence to proper operation and maintenance recommendations, and the use of recommended fuels and lubrication oils. Follow the recommended Maintenance Management Schedule with emphasis on air cleaner, oil, oil filter, fuel and fuel filter maintenance found in the Operation & Maintenance Manual.

Starting The Engine The Electronic Control equipped engine may need to crank slightly longer than a mechanically governed engine, because some oil pressure is required for the electronic actuator to move the rack. The check engine light should be ON while the engine is cranking, but should GO OUT, after engine oil pressure is achieved. At temperatures below 0°C (32°F), it may be necessary to spray starting fluid into the air cleaner inlet (follow the recommended procedure in the Operation & Maintenance Manual. If the engine fails to start in 30 seconds, allow the starter motor to cool for two minutes before trying it again.

Cold Mode Operation The Electronic Control system automatically idles the engine at 900 to 1000 rpm for the correct warm up time after a cold engine start [approximately less than 5°C (40°F)]. The Electronic Control system periodically checks the engine response and will reduce the idle speed down to 600 rpm when the engine is warmed. After the engine is started and the cold mode operation is completed, the engine can be operated at low rpm and low power. The engine will reach normal operating temperature faster when operated at low rpm and low power demand than when idled at no load.

Shutoff Solenoid Override A manual shutoff solenoid override lever is located on the side of the fuel pump. The engine can be shut off by rotating the manual shutoff lever in the counterclockwise (CCW) direction. Rotating the manual

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shutoff lever in the clockwise (CW) direction disables the shutoff solenoid. If the solenoid has been disabled, the engine can be shut OFF by using the manual shutoff lever on the side of the fuel pump.

DO NOT operate the engine without the rack actuator solenoid (BTM) in place and with the fuel shutoff solenoid disabled. Excessive engine speed may result.

Customer Specified Parameters The Electronic Control system is capable of being programmed for several customer specified parameters. These parameters and a brief explanation of each are in the Operation And Maintenance Guide.

Glossary Of Electronic Control Terms Actual Rack The ECM's interpretation of the signal from the Rack Position Sensor, read as "Rack Pos" on the ECAP. Aftermarket Device A device or accessory installed by the customer after the engine is delivered. Alternating Current (AC) The direction of current flow changes (alternates) regularly and constantly. American Wire Gauge (AWG) A measure of the diameter (and therefore the current carrying ability) of electrical wire. The smaller the AWG number, the larger the wire. Before Top Center (BTC) The 180 degrees of crankshaft rotation before the piston reaches Top Center (normal direction of rotation). Boost Pressure Sensor This sensor measures inlet manifold air pressure and sends a signal to the ECM. Brushless Torque Motor (BTM) Solenoid used to move fuel rack servo spool valve, also called rack solenoid. Bypass Circuit A circuit, usually temporary, to substitute for an existing circuit, typically for test purposes. Calibration As used here, is an electronic adjustment of a sensor signal. Coolant Temperature Sensor Used to set Cold Mode and to trigger the shift out of Cold Mode during engine warmup. Code See Diagnostic Code. Data Link An electrical connection for communication with other microprocessor based devices that are compatible with the American Trucking Association and SAE Standards. The Data Link is also

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the communication medium used for programming and troubleshooting with Caterpillar service tools. Desired Rack Position ("Des Rack Pos" on ECAP) The rack setting calculated by the ECM as needed to attain or maintain the Desired RPM. Desired RPM An input to the electronic governor within the ECM, and the output signal from the engine control logic within the ECM. The engine control logic uses inputs from the Throttle Position Sensor, Engine Speed Sensor, Cold Mode, and Customer Parameters to determine "Desired RPM". Desired Timing Advance ("Des Timing Adv" on ECAP) The injection timing advance calculated by the ECM as required to meet emission and performance specifications. Diagnostic Code Sometimes referred to as a "fault code", it is an indication of an existing problem in the electronic engine control system. Direct Current The direction of current flow is consistently in one direction only. Duty Cycle Same as Pulse Width Modulation. Electrically Erasable Programmable Read Only Memory (EEPROM) A large scale integrated-circuit chip for storing digital data. It can be electronically erased and reprogrammed. Used to store electronic engine control parameters that can be changed using the ECAP. Electronic Control Analyzer and Programmer (ECAP) A Caterpillar service tool used to program and for diagnosis of a variety of electronic controls. An ECAP is needed for advanced diagnostic and programming functions not possible with a DDT. Electronic Control Module (ECM) The engine control computer that provides power to the electronic engine control electronics, monitors electronic engine control inputs and acts as a governor to control engine rpm. Electronic Control System The complete electronic system that monitors and controls engine operation under all conditions. Engine Speed Sensor A magnetic sensor that measures engine speed from the rotation of the fuel injection pump camshaft (slotted retainer). Estimated Dynamic Timing Estimated actual injection timing. Calculated internally by electronic engine control. Est Dyn Timing = Static Timing Spec + Actual Timing Advance + Port effect (.2 deg/100 rpm). The ECM's estimate of actual injection timing. Fuel/Air Ratio Control (FARC) or Fuel Ratio Control (FRC) FRC rack - a rack limit based on fuel-to-air ratio, to limit emissions during acceleration. As electronic engine control senses a higher boost pressure (more air into the cylinder) it increases the FRC rack limit (allows more fuel into cylinder). It works much like the FRC on a mechanical governor. Fuel Off and Fuel On Refers to minimum fuel and maximum fuel positions of the fuel rack. Harness The wiring bundle connecting all components of the electronic engine control system.

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Hertz (Hz) Measure of frequency in cycles per second. Inlet Air Pressure Sensor This sensor measures inlet air pressure and sends a signal to the Electronic Control Module (ECM). Jacketwater Aftercooler (JWAC) A means of cooling intake air after the turbocharger, using jacket water for cooling. The intake air is passed through an aftercooler (heat exchanger) before going to the intake manifold. Oil Pressure Sensor This sensor measures engine oil pressure and sends a signal to the ECM. Open Circuit Condition where an electrical wire or connection is broken, so that the signal or the supply voltage can no longer reach its intended destination. Parameter A programmable value which affects the characteristics or behavior of the engine. Password A group of numeric or alpha-numeric characters, designed to restrict access to parameters. The Electronic Control system requires correct passwords in order to change Customer Specified Parameters (Customer Passwords) or certain engine specifications (Factory Passwords). Passwords are also required to clear certain diagnostic codes. Personality Module or Ratings Personality Module The module connected to the ECM which contains all the instructions (software) for the ECM, logged diagnostic codes, and performance maps for a specific horsepower family. Programmable Read Only Memory (PROM) A large scale integreated-circuit chip for storing digital data. It can be programmed only at the factory. Used in the personality module to store control logic and rating information. Pulse Width Modulation (PWM) A signal consisting of variable width pulses at fixed intervals, whose "TIME ON" versus "TIME OFF" can be varied (also referred to as "duty cycle").

Example of Pulse Width Modulation

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Rated Rack Position A limit on rack position which provides the specified horsepower and torque curves. This value comes from maps programmed into the personality module at the factory. Rack Position Sensor A linear position sensor which follows movement of the rack assembly and sends an electrical signal to the ECM. Rack Solenoid (BTM) A rotary proportional solenoid [also called a Brushless Torque Motor (BTM)] used to move the fuel rack servo spool valve. Reference Voltage A regulated voltage supplied by the ECM to a sensor. The reference voltage is used by the sensor to generate a signal voltage. Sensor A device used to detect and convert a change in pressure, temperature, or mechanical movement into an electrical signal. Service Program Module (SPM) A software program on a factory programmable computer chip, designed to adapt an ECAP to a specific application. Short Circuit A condition where an electrical circuit is unintentionally connected to an undesirable point. Example: a wire which rubs against a component until it makes electrical contact. Signal A voltage or waveform used to transmit information, typically from a sensor to the ECM. Speed "burp" A sudden brief change in engine speed. Static Timing Specification Fixed number of degrees determined by design of the fuel pump camshaft (determines injection timing with no advance). Note that the value displayed is the specification for static timing, NOT an electrically measured value. Subsystem As used here, it is a part of the Electronic Control system that relates to a particular function, for instance rack subsystem. Supply Voltage A constant voltage supplied to a component to provide electrical power for its operation. It may be generated by the ECM, or it may be battery voltage supplied through the wiring harness. "T" Harness A test harness designed to permit normal circuit operation while measuring voltages, typically inserted between the two ends of a connector. Throttle Position The ECM's interpretation of the signal from the throttle position sensor. Throttle Control Sensor An electronic sensor which is connected to the throttle control and sends a Pulse Width Modulated Signal to the ECM. Total Tattletale Total number of changes to all customer specified parameters. Transducer A device that converts a mechanical signal to an electrical signal. Transducer Module A sealed unit mounted below the rack actuator housing and contains the engine Oil Pressure Sensor, Boost Pressure Sensor and protective signal conditioning circuitry.

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Electronic Control System Components

Right Side View

(1) Electronic control module (ECM). (2) Coolant level connector (P7). (3) Rack position sensor (P11). (4) Boost pressure connector (J7). (5) Engine coolant temperature sensor (P12). (6) Engine oil pressure sensor (J9).

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(7) Speed sensor (P10). (8) Atmospheric pressure sensor (J15).

View A-A

(9) Fuel shutoff solenoid (P5). (10) Fuel system rack BTM (J6). (11) ATA data link (J13). The engine electronic control system is integrally designed into the engine fuel system to electronically control fuel delivery and injection timing. The engine electronic control system uses three types of components which are input, control and output. An input component is one that sends an electrical signal to the main control module. The signal sent varies in either voltage or frequency in response to change in some specific system of the engine. The control module sees the input sensor signal as information about the condition, environment, or

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operation of the engine. A control component is that component of the system that receives the input signals. Electronic circuits inside the control evaluate the signals and supply electrical energy to the output components of the system in response to predetermined combinations of input signal values. An output component is one that is operated by a control module. It receives electrical energy from the control group and uses that energy to either: * Do work (such as move the fuel rack) and thereby take an active part in regulating or operating the engine. * Give information or warning (such as a light or an alarm will do) to the operator. These components provide the ability to electronically program the engine to improve performance, minimize fuel consumption and reduce emissions. Various sensors feed engine data to the ECM. These sensors monitor boost pressure, engine oil pressure, engine speed, fuel rack position, throttle position, and on/off ignition. The ECM processes this data and sends electronic signals to the solenoids that move the fuel rack to optimize the efficiency and performance of the engine. The electronic engine control system also has the following built-in functions: * engine overspeed * on board diagnostics A Data Link is used to communicate engine information and to communicate with Caterpillar service tools to calibrate, troubleshoot and program the electronic engine control system.

Data Link The electronic engine control system includes a Data Link intended for communication with other microprocessor based devices that are compatible with SAE Recommended Practices J1708 & J1587. The Data Link can reduce duplication of sensors by allowing controls to share information. The Data Link is used to communicate engine information to other electronic control systems and to interface with Caterpillar service tools [Electronic Control Analyzer and Programmer (ECAP)]. The engine information that is monitored and available on the Data Link include the following: * Boost Pressure * Engine Identification * Engine Speed * Oil Pressure * Rack Position * Status And Diagnostic Information * Throttle Position The Electronic Control Analyzer and Programmer (ECAP) is used to program the customer specified

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parameters. The ECAP is one method of programming the customer specified parameters that are selected by a customer. The tool plugs into the Data Link Connector to communicate with the ECM. The ECAP can be also be used to display real time values of all information available on the Data Link for diagnosing engine problems.

System Diagnostic Codes

For a complete explanation of the Diagnostic Codes, see 3412 Generator Set Engine, Electronic Troubleshooting Guide, Form No. SENR6477.

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Electronic Control Module (ECM) And Personality Module

ECM And Personality Module (1) Electronic Control Module (ECM). (2) Fuel Outlet. (3) Fuel Inlet. (4) Personality Module.

The 3412 Generator Set Engine use a microprocessor based Electronic Control Module (ECM) which is isolation mounted on the top of the aftercooler housing. The ECM (1) and Personality Module (4) are cooled by fuel as it circulates through a manifold between two circuit boards in the control module. The fuel enters the control module, from the fuel transfer pump, at fuel inlet (3), and exits the control module at fuel outlet (2). All inputs and outputs to the control module are designed to tolerate short circuits to battery voltage without damage to the control. Resistance to radio frequency and electro-magnetic interference are designed into the electronic engine control system. The system has passed tests for interference caused by two-way radios and switching noise. The ECM power supply provides electrical power to all engine mounted sensors and actuators. Reverse voltage polarity protection and resistance to vessel power system voltage "swings" or "surges" (due to sudden alternator load, etc.) have been designed into the ECM. In addition to acting as a power supply, the ECM also monitors all sensor inputs and provides the correct outputs to ensure desired engine operation.

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The ECM contains memory to store and identify a selected factory engine rating. This memory also contains a personality module identification code to deter unauthorized tampering or switching of personality modules and other pertinent manufacturing information. The wiring harness provides communication or signal paths to the various sensors (boost sensor, throttle control sensor), the Data Link Connector, and the engine connectors. The Personality Module, is attached to the ECM, and provides the instructions necessary for the ECM to perform its function. The Personality Module contains all the engine performance and certification information such as, fuel ratio and rated rack control maps for a particular ratings group that utilizes common engine components. The ECM is programmed to run diagnostic tests on all inputs and outputs to partition a fault to a specific circuit (example, Throttle Position Sensor or the harness connecting it to the ECM). Once a fault is detected, it can be displayed on a diagnostic lamp or the Diagnostic Code can be read using a service tool (ECAP). A multimeter can be used to check or troubleshoot most problems. The ECM also will log or record most diagnostic codes generated during engine operation. These logged or intermittent codes can be read by the ECAP.

Throttle Control Sensor A Throttle Control Sensor is used to interface with the throttle. The Throttle Control Sensor output is a constant frequency Pulse Width Modulation (PWM) signal rather than an analog voltage (refer to Pulse Width Modulation in glossary). The PWM signals overcomes the serious errors that can result from analog signals when pin to pin leakage or contamination occurs in the wiring harness and/or connectors. The engine returns to Low Idle if the PWM signal is invalid due to a broken or shorted wire.

Fuel Rack Controls

Cross Section View Of Rack Housing (1) Shutoff solenoid. (2) Rack solenoid (BTM). (3) Fuel rack servo.

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Cross Section View Of Rack Position Sensor (4) Fuel rack. (5) Rack position sensor. (6) Manual shutoff. Shutoff override shaft and lever assembly.

Cross Section View Of Engine Speed Sensor (7) Flywheel starter ring gear. (8) Engine speed sensor.

Engine oil pressure is used to move the fuel rack. An electronically actuated rack solenoid (BTM) (2) controls a double acting hydraulic servo. The servo directs engine oil pressure to either side of a piston connected to the fuel rack which moves the piston and fuel rack.

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The servo group is a gerotor-type oil pump. It increases the pressure of the engine oil supplied to the governor. The increased oil pressure allows better regulation of engine speed during rapid application or removal of heavy loads on the engine. Rack solenoid (BTM) (2) is installed in the side of the rack actuator housing on the fuel injection pump and is controlled by the electronic control module. The lever of rack solenoid (BTM) is engaged in a collar on the rack servo valve. Rack solenoid (BTM) is spring loaded toward the "Fuel Off" position and must receive a positive voltage to move in the "Fuel On" direction. Rack position sensor (5) is located inside the rack actuator housing and is attached to the fuel rack by a magnet. The rack position sensor is a linear potentiometer used for accurate feedback information for the electronic control module. In addition to the rack position data, the electronic control module receives data from other sensors located in the rack actuator housing. The engine speed sensor (8) is triggered (signaled) by radial slots on the flywheel. Oil pressure, inlet air pressure, and the boost pressure sensors are mounted on the engine and connected to the ECM. The electronic control module will limit engine speed and power output of the engine if low oil pressure occurs. The control module adjusts the quantity of fuel or the timings of fuel delivered to the engine when a change in boost and/or inlet air pressure is detected. The electronic control module operates an energized to run shutoff solenoid (1). If rack solenoid (BTM) (2) is unable to move the fuel rack to the "Fuel Off" position, the shutoff solenoid will apply an additional force on the fuel rack to move the rack to the "Fuel Off" position. A manual shutoff (6) (shutoff override shaft and lever assembly) is provided. The manual shutoff control shaft is spring loaded to a neutral position. If the shutoff solenoid fails to energize, solenoid override may be used to move the shutoff lever away from the fuel rack servo (3). This will allow rack solenoid (BTM) to move the fuel rack even though the shutoff solenoid is not energized. The manual shutoff may be used to shut down the engine with the shutoff solenoid energized and power is maintained to the electronic control module. This method of shut down is used in some troubleshooting procedures. The mechanical fuel ratio control, torque control group, and various adjustment screws have been eliminated. The electronic control module performs all of these functions. The control module adjusts engine power and torque rise to compensate for operating the engine with plugged air cleaners, or to limit smoke. The amount of fuel needed by the engine to maintain a desired rpm is determined by the electronic control module. With the engine running at a desired speed, the engine speed will decrease when an additional load is applied. The signal from engine speed sensor (8) to the electronic control module changes. The control module receives this signal and other data, processes all the data, and sends a positive voltage to rack solenoid (BTM). Rack solenoid (BTM) moves the valve in fuel rack servo (3) and the fuel rack moves in the "Fuel On" direction. The increase in fuel to the engine will increase engine speed. This action will continue until the engine is again running at the desired speed or until the rack position has increased up to a rack position limit. With the engine running at a desired speed, the engine speed will increase when the load is decreased. The control module receives the changed signal from the engine speed sensor (8). The electronic control

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module reduces the electrical signal to rack solenoid (BTM). Rack solenoid (BTM) moves the valve in fuel rack servo (3), and the fuel rack moves in the "Fuel Off" direction. The decrease in fuel to the engine will decrease engine speed. This action will continue until the engine is again running at the desired speed. With the electronic engine control system, when the engine is cranked to start there is no need to use the throttle control. The electronic control module will automatically provide the engine with the correct amount of fuel to start the engine. Since some oil pressure is required for the fuel rack servo to move the fuel rack, electronically controlled engines may require a slightly longer cranking time to start.

Governor Servo

Rack Movement Toward "Full Fuel" (1) Piston. (2) Cylinder. (3) Sleeve. (4) Valve. (5) Fuel rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

When the rack solenoid (BTM) is energized, it moves valve (4) to the left. The valve opens oil outlet (B) and closes oil passage (D). Pressure oil from oil inlet (A) pushes piston (1) and fuel rack (5) to the left. Oil behind the piston goes through oil passage (C), along valve (4) and out oil outlet (B).

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No Rack Movement (Constant Engine Speed) (1) Piston. (2) Cylinder. (3) Sleeve. (4) Valve. (5) Fuel Rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

When the desired engine speed is reached, the rack solenoid (BTM) holds valve (4) in a fixed position. Piston (1) moves to the left until both oil outlet (B) and oil passage (D) are blocked by valve (4). Oil is trapped in the chamber behind piston (1) and creates a hydraulic lock which stops piston and fuel rack movement.

Rack Movement Toward "Fuel Off" (1) Piston. (2) Cylinder. (3) Sleeve. (4) Valve. (5) Fuel rack. (A) Oil inlet. (B) Oil outlet. (C) Oil passage. (D) Oil passage.

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When the rack solenoid (BTM) is de-energized, spring force in the solenoid moves valve (4) to the right. The valve closes oil outlet (B) and opens oil passage (D). Pressure oil from oil inlet (A) is now on both sides of piston (1). The area of the piston is greater on the left side than on the right side of the piston. The force of the oil is also greater on the left side of the piston and moves the piston and fuel rack (5) to the right.

Fuel System Fuel Flow

Fuel System Schematic (1) Secondary fuel filter base. (2) Fuel injection pump housing. (3) Pressure regulating valve. (4) Fuel injection line. (5) Fuel

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injection nozzle. (6) Fuel return line. (7) Electronic control module (ECM). (8) Fuel transfer pump. (9) Fuel priming pump. (10) Primary fuel filter. (11) Fuel tank.

As the engine is cranked and started, fuel transfer pump (8) pulls fuel from fuel tank (11) through primary fuel filter (10). NOTE: When the engine has reached its normal operating temperature, inlet fuel temperature to transfer pump must not exceed 65°C (149°F). Fuel temperatures above 65°C (149°F) reduce the life of the electronics in the ECM and the transfer pump check valves. High fuel temperatures also reduce engine power output. If the engine is equipped with auxiliary fuel heaters, make sure the fuel heaters are turned off in warm weather operating conditions. From fuel transfer pump (8) the fuel is pushed through electronic control module (7) to keep the electric circuits cool. The cooling plate for the control module is a one piece die cast aluminum housing. Manifolds on top and bottom of the control module route fuel from the transfer pump through the cooling plate. The fuel exits the electronic control module and flows through the secondary fuel filter to the fuel manifolds in fuel injection pump housing (2). The fuel manifolds supply fuel for each fuel injection pump. Some of the fuel in the manifolds is constantly sent through a pressure regulating valve that connects the manifold to fuel return line (6). The pressure regulating valve controls the pressure in the manifolds and the amount of fuel that goes back to the fuel tank (11). The constant flow of fuel back to the tank removes air from the system. Individual fuel injection lines carry fuel from the fuel injection pumps to each cylinder. One section of line connects between the fuel injection pump and an adapter on the valve cover base. Another section of line on the inside of the valve cover base connects between the adapter and the fuel injection nozzle. The fuel transfer pump (8) is installed opposite the rotary servo pump on the end of the fuel injection pump. The fuel transfer pump has a pressure relief valve and a bypass valve. The pressure relief valve controls the maximum pressure of the fuel to the fuel injection pump housing. When the pressure gets too high, the relief valve open and directs the fuel back to the inlet side of the transfer pump. The bypass valve allows the fuel to go around the transfer pump gears when fuel priming pump is used. When there is air on the inlet side of the system, the fuel priming pump is used, before the engine is started, to fill the low pressure side of the fuel system from the fuel tank. When the priming pump is used, movement of fuel through the low pressure side of the system removes air from the lines and components back into the fuel tank. There is no bleed orifice or valve installed on the fuel injection pump housing to vent air from the high pressure part of the fuel system. Air trapped in the fuel injection lines can be vented by loosening all of the fuel injection line nuts where they connect to the adapters in the valve cover base. Move the governor lever to the low idle position. Crank the engine with the starter motor until fuel (without air) comes from the fuel line connections. Tighten the fuel line nuts. This procedure is necessary because the fuel priming pump will not create enough pressure to push fuel through the reverse flow check valves located in the fuel injection pump bonnets. The injection pumps are in time with the engine and send fuel to the injection nozzles under high pressure. When the fuel pressure at the injection nozzle is high enough the nozzle opens and sends fuel into the combustion chamber.

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Fuel Injection Pump

Cross Section Of The Fuel Injection Pump Housing (Typical Example) (1) Fuel manifold. (2) Inlet passage. (3) Pressure relief passage. (4) Check valve. (5) Pump plunger. (6) Spring. (7) Gear. (8) Fuel rack (left). (9) Lifter assembly. (10) Camshaft.

The rotation of the lobes on the camshaft (10) cause lifter assembly (9) and pump plunger (5) to move up and down. The stroke of each pump plunger is always the same. The force of springs (6) hold lifters against the cams of the camshaft. The pump housing is a "V" shape (similar to the engine cylinder block), with six pumps on each side. When the pump plunger is down, fuel from fuel manifold (1) goes through inlet passage (2) and fills the chamber above pump plunger (5). As the plunger moves up it closes the inlet passage. The pressure of the fuel in the chamber above the plunger increases until it is high enough to cause check valve (4) to open. Fuel under high pressure flows out of the check valve, through the fuel line to the injection nozzle, until the inlet passage opens into pressure relief passage (3) in the plunger. The pressure in the chamber decreases and the check valve closes. The longer inlet passage (2) is closed, the larger the amount of fuel which will be forced through check valve (4). The period for which the inlet passage is closed is controlled by pressure relief passage (3). The design of the passage makes it possible to change the inlet passage closed time by rotation of the

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plunger. When the governor moves fuel racks (8), they move a gear (7) that is fastened to plunger assembly (5). This causes a rotation of the plungers.

7000 Series Fuel Injection Nozzles The fuel injection nozzle is installed in an adapter in the cylinder head and is extended into the combustion chamber. The fuel injection pump sends fuel with high pressure to the fuel injection nozzle where the fuel is made into a fine spray for good combustion.

Fuel Injection Nozzle (1) Carbon dam. (2) Seal. (3) Passage. (4) Filter screen. (5) Inlet passage. (6) Orifice. (7) Valve. (8) Diameter. (9) Spring.

Seal (2) goes against the nozzle adapter and prevents leakage of compression from the cylinder. Carbon dam (1) keeps carbon out of the bore in the nozzle adapter. Fuel with high pressure from the fuel injection pump goes into inlet passage (5). Fuel then goes through filter screen (4) and into passage (3) to the area below diameter (8) of valve (7). When the pressure of the fuel that pushes against diameter (8) becomes greater than the force of spring (9), valve (7) lifts up. This occurs when the fuel pressure goes above the Valve Opening Pressure of the fuel injection nozzle. When valve (7) lifts, the tip of the valve comes off of the nozzle seat and the fuel will go through the six small orifices (6) into the combustion chamber. The injection of fuel continues until the pressure of fuel against diameter (8) becomes less than the force of spring (9). With less pressure against diameter (8), spring (9) pushes valve (7) against the nozzle seat and stops the flow of fuel to the combustion chamber. NOTE: The fuel injection nozzle can not be disassembled and no adjustments can be made.

Fixed Timing Unit For Use With A Series Turbocharger Application (4P3369)

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The fixed timing unit is installed on the front of the camshaft for the fuel injection pump and is gear driven through the timing gears. No adjustments can be made to this timing unit.

Automatic Timing Advance Unit For Use With A Twin Turbocharger Application (7E0524)

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Automatic Timing Advance Unit (1) Flange. (2) Weight. (3) Springs. (4) Slide. (5) Drive gear. (6) Camshaft.

The automatic timing advance unit is installed on the front of the camshaft (6) for the fuel injection pump and is gear driven through the timing gears. The drive gear (5) for the fuel injection pump is connected to camshaft (6) through a system of weights (2), springs (3), slides (4) and flange (1). Each one of the two slides (4) is held on drive gear (5) by a pin. The two weights (2) can move in guides inside flange (1) and over slides (4), but the notch for the slide in each weight is at an angle with the guides for the weight in the flange. As centrifugal force (rotation) moves the weights away from the center, against springs (3), the guides in the flange and the slides on the gear make the flange turn a small amount in relation to the gear. Since the flange is connected to the camshaft for the fuel injection pump, the fuel injection timing is also changed. No adjustment can be made in this timing advance unit.

Air Inlet And Exhaust System For Twin Turbocharger Arrangement

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Air Inlet System And Exhaust System (1) Exhaust manifold. (2) Aftercooler. (3) Engine cylinder. (4) Air inlet. (5) Turbocharger compressor wheel. (6) Turbocharger turbine wheel. (7) Exhaust outlet.

The components of the air inlet and exhaust system control the quality and the amount of air available for combustion. There is an air cleaner, turbocharger and exhaust manifold on each side of the engine. A common aftercooler is located between the cylinder heads and toward the rear of the engine. The inlet manifold is a series of passages inside the cylinder block which connect the aftercooler to the inlet ports (passages) in the cylinder heads. A single camshaft, in the cylinder block, controls the movement of the valve system components. Air flow is the same on both sides of the engine. Outside air enters the system through the air cleaners. Air is pulled through the turbocharger air inlet (4), compressed and heated by the turbocharger compressor wheel (5). The compressed air is then directed through a pipe assembly to the aftercooler (2). The aftercooler (2) lowers the temperature of the compressed air before it enters the inlet manifold. This cooled compressed air passes through the inlt manifold and fills the inlet ports in the cylinder heads. Air flow from the inlet port into the cylinder is controlled by the intake valves. There are two intake and two exhaust valves for each cylinder. Intake valves open when the piston moves down on the inlet stroke. When the intake valves open, cooled compressed air from the inlet port is pulled into the cylinder. The intake valves close and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. When the piston is near the top of the compression stroke, fuel is injected into the cylinder. The fuel mixes with the air and combustion starts. The force of combustion pushes the piston down on the power stroke. When the piston moves up again, it is on the exhaust stroke. The exhaust valves open, and the exhaust gases are pushed through the exhaust port into the exhaust manifold. After the piston makes the exhaust stroke, the exhaust valves close and the cycle (inlet, compression, power, exhaust) starts again. Exhaust gases from exhaust manifold (1) enter the turbine side of the turbocharger and cause the turbocharger turbine wheel (6) to turn. The turbine wheel is connected to the shaft which drives the

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compressor wheel. Exhaust gases from the turbocharger pass through the exhaust outlet (7).

For Series Turbocharger Arrangement

Air Inlet System And Exhaust System. (1) Exhaust manifold. (2) Aftercooler. (3) High pressure turbocharger air inlet. (4) High pressure turbocharger compressor wheel. (5) High pressure turbocharger turbine wheel. (6) High pressure turbocharger exhaust outlet. (7) Low pressure turbocharger air inlet. (8) Low pressure turbocharger compressor wheel. (9) Low pressure turbocharger turbine wheel. (10) Low pressure turbocharger exhaust outlet.

The components of the air inlet and exhaust system control the quality and the amount of air available for combustion. There is an air cleaner, two turbochargers and exhaust manifold on each side of the engine. A common aftercooler is located between the cylinder heads and toward the rear of the engine. The inlet manifold is a series of passages inside the cylinder block which connect the aftercooler to the inlet ports (passages) in the cylinder heads. A single camshaft, in the cylinder block, controls the movement of the valve system components. Air flow is the same on both sides of the engine. Outside air enters the system through the air cleaners. Air is pulled through the low pressure turbocharger air inlet (7), compressed and heated by the compressor wheel (8) of the low pressure turbocharger. The compressed air is then directed through pipe assembly to the high pressure turbocharger air inlet (3) of the high pressure turbocharger. After additional compression by the high pressure turbocharger compressor wheel (4) the air is forced into the aftercooler (2). The aftercooler (2) lowers the temperature of the compressed air before it enters the inlet manifold. This cooled compressed air passes through the inlet manifold and fills the inlet ports in the

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cylinder heads. Air flow from the inlet port into the cylinder is controlled by the intake valves. There are two intake and two exhaust valves for each cylinder. Intake valves open when the piston moves down on the inlet stroke. When the intake valves open, cooled compressed air from the inlet port is pulled into the cylinder. The intake valves close and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. When the piston is near the top of the compression stroke, fuel is injected into the cylinder. The fuel mixes with the air and combustion starts. The force of combustion pushes the piston down on the power stroke. When the piston moves up again, it is on the exhaust stroke. The exhaust valves open, and the exhaust gases are pushed through the exhaust port into the exhaust manifold. After the piston makes the exhaust stroke, the exhaust valves close and the cycle (inlet, compression, power, exhaust) starts again. Exhaust gases from exhaust manifold (1) enter turbine side of the high pressure turbocharger and cause the turbine wheel (5) to turn. The compressed gases from the high pressure turbocharger enter the turbine side of the low pressure turbocharger turbine wheel (9). The turbine wheels are connected to the shafts which drives the compressor wheels. Exhaust gases from the low pressure turbocharger pass through the low pressure turbocharger exhaust outlet (10).

Aftercooler

Aftercooler.

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(1) Aftercooler. (2) Pipe.

The aftercooler (1) cools the air coming out of the turbochargers before it goes into the inlet manifold. The aftercooler is located toward the rear of the engine between the cylinder heads. Coolant from the water pump flows into the aftercooler. It flows through the core assembly, then out of the aftercooler through a different pipe into the rear of the cylinder block. Inlet air from the compressor side of the turbochargers flows into the aftercooler through a pipe (2) on each side of the aftercooler housing. This lowers the temperature of the air to approximately 93°C (200°F). The cooler air goes out the bottom of the aftercooler into the inlet manifold. The purpose of this is to make the air going into the combustion chambers more dense. The more dense the air is, the more fuel the engine can burn efficiently. This gives the engine more power.

Turbocharger

Turbocharger. (1) Turbocharger (low pressure). (2) Turbocharger (high pressure). (3) Exhaust pipe.

There are two turbochargers (1) and (2) installed on each side of the engine. The first turbocharger (high pressure) on each side is connected to the exhaust manifold. Exhaust gases from the turbine side of first turbocharger are routed to the turbine side of the second turbocharger (low pressure). The exhaust are then expelled through exhaust pipe (3). The compressor side of the first turbocharger is connected to the

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compressor side of the second turbocharger by pipe assembly. The compressed air is then forced into the aftercooler housing.

Turbocharger (4) Air inlet. (5) Compressor wheel. (6) Turbine wheel. (7) Exhaust outlet. (8) Compressor housing. (9) Oil inlet port. (10) Thrust collar. (11) Thrust bearing. (12) Turbine housing. (13) Spacer. (14) Air outlet. (15) Oil outlet port. (16) Bearing. (17) Lubrication passage. (18) Bearing. (19) Exhaust inlet.

The exhaust gases go through the blades of turbine wheel (6). This causes the turbine wheel and compressor wheel (5) to turn, which causes a compression of the inlet air. When the load on the engine is increased, more fuel is put into the engine. This makes more exhaust gases and will cause the turbine and compressor wheels of the turbocharger to turn faster. As the turbocharger turns faster, it gives more inlet air and makes it possible for the engine to burn more fuel and will give the engine more power. Maximum rpm of the turbocharger is controlled by the rack setting, the high idle speed setting and the height above sea level at which the engine is operated.

NOTICE If the high idle rpm or the rack setting is higher than given in the Fuel Setting And Related Information Fiche (for the height above sea level at which the engine is operated), there can be damage to engine or turbocharger parts. Damage will result when increased heat and/or friction, due to the higher engine output, goes beyond the engine cooling and lubrication systems abilities.

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Bearings (16 and 18) for the turbocharger use engine oil under pressure for lubrication. The oil comes in through the oil inlet port (9) and goes through lubrication passage (17) in the center section for lubrication of the bearings. Oil from the turbocharger goes out through the oil outlet port (15) in the bottom of the center section and goes back to the engine lubrication system. The fuel rack adjustment is done at the factory for a specific engine application. The governor housing is sealed to prevent changes in the adjustment of the rack and the high idle speed setting.

Valve System Components The valve system components control the flow of inlet air and exhaust gases into and out of the cylinders during engine operation. The crankshaft gear drives the camshaft gear. The camshaft gear must be timed to the crankshaft gear to get the correct relation between piston and valve movement. The camshaft has two cams for each cylinder. One cam controls the exhaust valves, the other controls the intake valves.

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Valve System Components (1) Intake bridge. (2) Rocker arms. (3) Push rods. (4) Rotocoil. (5) Valve spring. (6) Valve guide. (7) Intake valves. (8) Lifter. (9) Camshaft.

As the camshaft turns, the lobes of camshaft (9) cause lifters (8) to go up and down. This movement makes push rods (3) move rocker arms (2). Movement of the rocker arms makes intake bridges (1) move up and down on dowels mounted in the cylinder head. The bridges let one rocker arm open and close two valves (intake or exhaust). There are two intake and two exhaust valves for each cylinder. Rotocoils (4) cause the valves to turn while the engine is running. The rotation of the valves keeps the deposit of carbon on the valves to a minimum and gives the valves longer service life. Valve springs (5) cause the valves to close when the lifters move down.

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Valve System Components (1) Intake bridge. (2) Intake rocker arm. (7) Intake valves. (10) Exhaust rocker arm. (11) Exhaust bridge. (12) Exhaust valves.

Lubrication System

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Engine Oil Flow During Normal Operation (1) Oil passage to rocker arm shaft. (2) Oil passage to idler gear in flywheel housing. (3) Oil passage to gear bearings in flywheel housing. (4) Oil passage to fuel injection pump housing and governor. (5) Rocker arm shaft. (6) Valve lifter bore lubrication passages. (7) Camshaft bearings. (8) Piston cooling tubes. (9) Oil passage to timing gear housing. (10) Oil passage to idler gear shaft. (11) Oil manifold. (12) Main bearings. (13) Oil supply line to turbocharger. (14) Oil supply line to manifold in cylinder block. (15) Filter bypass valve. (16) Cooler bypass valve. (17) Turbocharger. (18) Engine oil cooler. (19) Oil return line from turbocharger. (20) Oil filters. (21) Oil pan. (22) Oil pump.

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Oil Flow Through The Oil Cooler, Oil Filters And The Engine

Oil Lines And Filters (15) Filter bypass valve. (16) Cooler bypass valve. (20) Oil filters. (23) Bypass valve body.

When the engine is in operation and the temperature of the oil is normal, oil pump (22) sends oil through bypass valve body (23), engine oil cooler (18) and oil filters (20) to oil manifold (11). From oil manifold (11) in right side of the cylinder block, oil is sent to the left oil manifold through drilled passages in the cylinder block that connect main bearings (12) and camshaft bearings (7). Oil goes through drilled holes in the crankshaft to give lubrication to the connecting rod bearings. A small amount of oil is sent through piston cooling tubes (8) to make the pistons cooler. Oil goes through grooves in the bores for the front and rear camshaft bearings and then into the valve lifter bore lubrication passages (6). Oil is sent through the oil passage to rocker arm shaft (1), to rocker arm shafts (5) on both cylinder heads. Holes in rocker arm shafts (5) let the oil give lubrication to the valve system components in the cylinder head. The fuel injection pump and governor gets oil from a passage in the cylinder block. There is a small gear pump between the injection pump housing and the governor. This pump sends oil under pressure to the fuel injection pump and governor. The idler gear bores get oil from an oil passage to the idler gear shaft (10), oil then goes through the shaft for the bearings of the idler gears installed on the front and rear of the cylinder block.

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The idler gear bearings get oil under pressure through an oil passage to to idler gear in flywheel housing (2). The driven gear bearings get oil under pressure through an oil passage to gear bearings in flywheel housing (4). Pressure oil is sent to the turbocharger bearings through an oil supply line to turbocharger (13). The oil goes out of turbocharger (17) back to oil pan (21) through oil return line from turbocharger (19). There is a bypass valve in the oil pump. This bypass valve controls the maximum pressure of the oil from the oil pump. The oil pump can put more oil into the system than is needed. When there is more oil than needed, the oil pressure goes up and the bypass valve will open. This allows the oil that is not needed to go back to the inlet oil passage of the oil pump. After the oil for lubrication has done its work, it goes back to the engine oil pan. When the engine is cold (starting condition), the filter bypass valve (15) and cooler bypass valve (16) open because cold oil with high viscosity causes a restriction to the oil flow through engine oil cooler (18) and oil filters (20). With the bypass valves open, oil flows directly from the oil pump to oil manifold (11). This will give immediate lubrication to all components until the engine becomes warm. When the oil gets warm, the pressure difference in the filter bypass valve (15) and cooler bypass valve (16) decreases and the bypass valves close. Now there is a normal flow through oil cooler (18) and oil filters (20). The bypass valves will also open when there is a restriction in the oil cooler or oil filter. This action does not let an oil cooler or oil filter with a restriction prevent the lubrication of the engine.

Cooling System This engine has a pressure type cooling system. A pressure type cooling system gives two advantages. The first advantage is that the cooling system can have safe operation at a temperature that is higher than the normal boiling (steam) point of water. The second advantage is that this type system prevents cavitation (the sudden making of low pressure bubbles in liquids by mechanical forces) in the water pump. With this type system, it is more difficult for an air or steam pocket to be made in the cooling system.

Radiator Cooled System

Cooling System Components (1) Turbocharger. (2) Aftercooler. (3) Temperature regulator housings. (4) Outlet to radiator. (6) Outlet bonnet of oil cooler.

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(7) Engine oil cooler. (8) Line to aftercooler. (9) Inlet bonnet of oil cooler. (10) Water pump. (11) Water pump inlet (from radiator bottom). (12) Radiator bypass lines.

In normal operation (engine warm), water pump (10) sends coolant through engine oil cooler (7) and then into the cylinder block. Coolant moves through the cylinder block to both cylinder heads, and then goes to the temperature regulator housings (3). The temperature regulators are open and most of the coolant goes through the outlet to radiator (4). The coolant is made cooler as it moves through the radiator. When the coolant gets to the bottom of the radiator, it goes to water pump inlet (11).

Example Of Radiator Cooled System (1) Turbochargers. (2) Aftercooler. (3) Temperature regulator housings. (4) Outlet to radiator. (5) Radiator. (6) Outlet bonnet of oil cooler. (7) Engine oil cooler. (8) Line to aftercooler. (9) Inlet bonnet of oil cooler. (10) Water pump. (11) Water pump inlet (from radiator bottom). (12) Radiator bypass lines.

NOTE: The water temperature regulator is an important part of the cooling system. It divides coolant flow between radiator (5) and radiator bypass lines (12) as necessary to maintain the correct temperature. If the water temperature regulator is not installed in the system, there is no mechanical control, and most of the coolant will take the path of least resistance through the bypass. This will cause the engine to overheat in hot weather. In cold weather, even the small amount of coolant that goes through the radiator is too much, and the engine will not get to normal operation temperatures. When the engine is cold, the water temperature regulator is closed, and the coolant is stopped from going to the radiator. The coolant goes from the temperature regulator housings (3) back to the water pump (10) through radiator bypass lines (12).

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On engines, part of the coolant flows to the engine oil cooler and part of the coolant flows through line (8) to the aftercooler. From the aftercooler, the coolant flows through the block, through the heads and back to the regulators.

Coolant Conditioner Some conditions of operation have been found to cause pitting (small holes in the metal surface) from corrosion or cavitation erosion (wear caused by air bubbles in the coolant) on the outer surface of the cylinder liners and the inner surface of the cylinder block next to the liners. The addition of a corrosion inhibitor (a chemical that gives a reduction of pitting) can keep this type of damage to a minimum. The "spin-on" coolant conditioner element, similar to the fuel filter and oil filter elements, fastens to a base that is mounted on the front of the engine. Coolant flows from the water pump through the base and element back to the block. There is a constant flow of coolant through the element when valves are in the OPEN position. The element has a specific amount of inhibitor for acceptable cooling system protection. As coolant flows through the element, the corrosion inhibitor, which is a dry material, dissolves (goes into solution) and mixes to the correct concentration. Two basic types of elements are used for the cooling system, and they are called the "PRECHARGE" and the "MAINTENANCE" elements. Each type of element has a specific use and must be used correctly to get the necessary concentration for cooling system protection. The elements also contain a filter and should be left in the system so coolant flows through it after the conditioner material is dissolved. The "PRECHARGE" element has more than the normal amount of inhibitor, and is used when a system is first filled with new coolant (unless Dowtherm 209 Antifreeze is used). This element has to add enough inhibitor to bring the complete cooling system up to the correct concentration. The "MAINTENANCE" elements have a normal amount of inhibitor and are installed at the first change interval and provide enough inhibitor to keep the corrosion protection at an acceptable level. After the first change period, only "MAINTENANCE" elements are installed at specified intervals to give protection to the cooling system. Liquid supplemental coolant additive is also available which must be added in the proper amount to the antifreeze/water mixture. Refer to "Cooling System Specifications" in the Operation and Maintenance Manual.

NOTICE Do not use Dowtherm 209 Full-Fill in a cooling system that has a coolant conditioner. These two systems are not compatible (corrosion inhibitor is reduced) when used together.

Basic Block Cylinder Block, Liners And Heads

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The cylinders in the left side of the block make an angle of 65 degrees with the cylinders in the right side of the block. The main bearing caps are fastened to the block with two bolts per cap. The cylinder liners can be removed for replacement. The top surface of the block is the seat for the cylinder liner flange. Engine coolant flows around the liners to keep them cool. Three O-ring seals around the bottom of the liner make a seal between the liner and the block. A filler band at the top of each liner forms a seal between the liner and the cylinder block. The engine has a single, cast head on each side. Four vertical valves (two intake and two exhaust), controlled by a pushrod valve system, are used per each cylinder. The opening for the fuel nozzles in each cylinder is located between the four valves. Series ports (passages) are used for both intake and exhaust valves. A steel spacer plate is used between the cylinder head and block. A thin gasket is used between the plate and the block to seal water and oil. A thick metal gasket is used between the plate and the head to seal combustion gases, water and oil. The size of the pushrod openings through the head permits the removal of the valve lifters with the head installed. Valve guides without shoulders are pressed into the cylinder head.

Pistons, Rings And Connecting Rods

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Piston Assembly (1) Crown assembly. (2) Skirt assembly. (3) Piston pin. (4) Retainer ring.

The piston assembly is of a two piece articulated design. The crown assembly is held in position in the piston skirt by a piston pin. The piston pins are held in place by two snap rings that fit in the grooves in the pin bore of the pistons. The connecting rod has a taper on the pin bore end. The aluminum pistons have three rings; two compression rings and one oil ring. All rings are located above the piston pin bore. The compression rings are of the KEYSTONE type, which has a tapered shape. The action of these rings in the piston groove, which is also tapered, helps prevent ring seizure caused by too many carbon deposits. The oil control ring is of the standard (conventional) type. The seat for the rings is an iron band that is cast into the piston. Oil returns to the crankcase through holes in the oil ring groove. Piston cooling tubes, located on the cylinder block main webs, direct oil to cool and give lubrication to the piston pins and cylinder walls.

Crankshaft The crankshaft changes the combustion forces in the cylinder into usable rotating torque which powers the machine. Vibration, caused by combustion impacts along the crankshaft, is kept small by a vibration

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damper on the front of the crankshaft. There is a gear at the front of the crankshaft to drive the timing gears and the oil pump. Seals and wear sleeves are used at both ends of the crankshaft for easy replacement and a reduction of maintenance cost. Pressure oil is supplied to all bearing surfaces through drilled holes in the crankshaft. The crankshaft is supported by seven main bearings. A thrust plate at either side of the center main bearing controls the end play of the crankshaft.

Camshaft The engine has a single camshaft that is driven at the front end. It is supported by seven bearings. As the camshaft turns, each cam (lobe) (through the action of valve systems components) moves a roller follower, which in turn moves a push rod and two valves (either exhaust or intake) for each cylinder. The camshaft gear must be timed to the crankshaft gear. The relation of the cam (lobes) to the camshaft gear cause the valves in each cylinder to open and close at the correct time. A gear on the rear of the camshaft is used to drive the balance gear and any accessory equipment mounted on the rear of the engine.

Vibration Damper The twisting of the crankshaft, due to the regular power impacts along its length, is called twisting (torsional) vibration. A viscous (fluid type) vibration damper is installed on the front end of the crankshaft. It is used for reduction of torsional vibrations and stops the vibration from building up to amounts that cause damage.

Electrical System The 3412 Generator Set Engines use a wide variety of electronic input devices. These components require an operating voltage, and often times a reference voltage as well. The electronic control modules on these engines are not sensitive to the common external sources of noise, but electro-mechanical buzzers can cause disruptions in the power supply. If electro-mechanical buzzers are used anywhere on the engine, it is desirable to have the entire electronic control system (control group, throttle position sensor, and check engine lamp) powered directly from the battery system through a dedicated relay, and not through a common power bus with other key switch activated devices.

Electronic Control Module Power Circuit The design of the electronic circuits inside the Electronic Control Module (ECM) are such that the ordinary switch input circuits to the ECM have a tolerance for resistance and shorts between wires. These tolerances are as follows: 1. The Electronic Engine Control System will tolerate resistance in any ordinary switch up to 2.5 Ohms without malfunctioning. 2. The Electronic Engine Control System will tolerate shorts between wires in any ordinary switch input down to 5,000 Ohms without malfunctioning.

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NOTICE The +24 Volt wire in the data link harness of the ECM is provided to power the Electronic Engine Control System service tools only. No other devices should be powered by this wire. The ECM was not designed to carry high current loads and is not short circuit protected.

The ECM draws a maximum of 6.5 Amps at 24 Volts from the electrical system under steady state conditions. The ECM will draw a maximum of 9 Amps on engine start-up. However, the Electronic Engine Control System will function with less than 24 Volts. A minimum of 8 Volts is required while cranking, and 24 Volts when the engine is running. Power enters the ECM through the positive BATTERY wire, and exits through the negative BATTERY wire. Negative BATTERY must be within 0.5 Volt of -Battery. The Electronic Engine Control System is protected against power surges on the 24 Volt power supply due to alternator load dumps, etc. and for jump starting with voltages up to 32 Volts.

Engine Speed Input Circuit Engine speed is sensed by an electronic engine speed sensor. It is similar to electro-magnetic pickups with which you may already be familiar; that is, the signal is generated by placing the sensor near a rotating component, but it is different in that it requires an operating voltage. The engine speed sensor is provided an operating voltage of 8.0 ± 0.4 Volts by the ECM. The output of the engine speed sensor is a voltage pulse whose frequency is dependent on the speed of the engine. The frequency of the pulse is interpreted by the ECM as engine speed. Typically the frequency of this signal is 10 to 50 Hz (Hertz) while cranking, and approximately 120 Hz at low idle.

Fuel Rack Input Circuit The engine fuel rack signal is obtained from an electronic linear position sensor which follows the movement of the rack assembly. This sensor requires an operating voltage of 8.0 ± 0.4 Volts, and a reference voltage of 5.0 ± 0.25 Volts. These voltages are provided by the ECM. The output of the rack position sensor is a voltage between 0.3 and 5.25 Volts. This voltage is dependent upon the position of the rack position sensor, and is interpreted by the ECM as rack position.

Engine Coolant Temperature Circuit Engine coolant temperature is obtained from an electronic sensor. It is mounted on the engine and its data is sent to the ECM via the engine wiring harness. This sensor requires an operating voltage of 8V ± 0.4V and operates at a temperature range between 40 to 120°C (104 to 248°F). The output of the coolant temperature sensor is a voltage between 0.5V and 4.5V at the previously stated input range. This voltage is dependent upon the engine coolant temperature, and is interpreted by the ECM as the coolant temperature.

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Inlet Air Pressure Input Circuit The inlet air pressure sensor is located on the engine. Inlet air pressure, taken before the turbocharger and after the air cleaner, is routed to this sensor. It requires a reference voltage of 5.0 ± 0.25 Volts. The output of the inlet air pressure sensor is a DC voltage between 1.0 and 5.0 Volts. This voltage is dependent upon the pressure felt by the inlet air pressure sensor, and is interpreted by the ECM as inlet air pressure (absolute).

Boost Pressure Input Circuit The boost pressure sensor is mounted in the air inlet manifold. The same operating and reference voltages provided to the inlet air pressure sensor are provided to this sensor. The output of the boost pressure sensor is a DC voltage of .35 to 4.6 Volts. This voltage is dependent upon the pressure felt by the boost pressure sensor, and is interpreted by the ECM as engine boost pressure (gauge).

Engine Oil Pressure Input Circuit The engine oil pressure sensor is also located in the engine oil lines. Engine oil pressure from the fuel injection pump is routed to this sensor. This sensor requires an operating voltage of 5 Volts. The output of the oil pressure sensor is a DC voltage of .35 to 4.6 Volts. This voltage is dependent upon engine oil pressure and is interpreted by the ECM as oil pressure. The engine oil pressure sensor is designed to measure oil pressure between 0 and 690 kPa (100 psi). Engine oil pressures greater than 690 kPa (100 psi) are read as 690 kPa (100 psi). This limited oil pressure reading range provides more accurate low oil pressure readings (where oil pressure readings are most important) than a sensor capable of reading the maximum engine oil pressure.

Throttle Control Input Circuit Throttle position is obtained from an electronic sensor. An operating voltage of 24 Volts is provided to the sensor by the electrical system. The output of the throttle position sensor is a constant frequency pulsed voltage of 0 to 5.25 Volts. The pulse width, not the frequency, of the signal is dependent upon the position of the throttle position sensor and is interpreted by the ECM as throttle position. Output pulse width is from 10 to 90% and is rescaled by the ECM as a throttle position of 0 to 100%.

Shutoff Solenoid Output Circuit The shutoff solenoid is an output component of the Electronic Engine Control System that must be energized for the engine to run. The output of the ECM module to the shutoff solenoid is a pulsed voltage that can reach up to 6 Volts

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for about one-half second after the power switch(es) is turned ON for the purpose of pulling in the solenoid, and then drops off to approximately 1 Volt to hold the solenoid in. The Electronic Engine Control System is designed to continue operation of the engine with as many faults as possible. There are five conditions which will deenergize the shutoff solenoid and shut down the engine. These are as follows: 1. Loss of electrical power to the Electronic Engine Control System control module. 2. A defective shutoff solenoid. 3. An engine speed signal of 2500 RPM or greater. 4. Loss of both engine speed signals (main and backup). 5. Defective relay or switch in the engine overspeed switch box.

Fuel Rack Output Circuit Movement of the engine fuel rack is accomplished by the electronic engine control system with a rotary solenoid [Brushless Torque Motor (BTM)]. A rotary solenoid (BTM) is a device whose movement is proportional to the electrical current flowing through it. The ECM provides a pulsed voltage of 0.0 to 3.6 Volts to the rotary solenoid (BTM). The rotary solenoid (rack solenoid) moves the engine fuel rack through the movement of the governor servo spool valve and hydraulic pressure. The electronic engine control system has a built-in operational test for the rack solenoid (BTM). This test is accomplished as follows: 1. Remove the rack solenoid (BTM) from its housing. 2. Position it so that the arm of the solenoid is free to move. 3. Turn the power switch(es) ON. The expected results of this test are that after about five seconds the solenoid arm will sweep to the full ON position, remain there a few seconds, and then sweep back to the OFF position. Sweep time will be about five seconds in both directions.

Check Engine Light Output Circuit The data link harness provides information about the electronic engine control system to the check engine light. The light is ON when the power switch(es) is ON and the engine is not running to verify that the lamp is working, and should go out when the engine has been started and correct engine oil pressure is reached. If the light does not go out shortly after starting the engine it is an indication of either low oil pressure, or an electronic engine control system fault has been detected.

Electronic Speed Switch

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The Overspeed Protection System is designed with controls built into a single unit to monitor several functions at the same time. The functions that are monitored are:

Engine Overspeed This is an adjustable engine speed setting (normally 127% of rated speed) that prevents the engine from running at a speed that could cause damage. An overspeed condition will cause relay SR1 to open and de-energize the shutoff solenoid. The deenergizing of the shutoff solenoid will cut the fuel to the engine causing the engine to shutdown.

Crank Termination This is an adjustable engine speed setting that signals the starting motor that the engine is firing and cranking must be terminated. When the speed setting is reached, a switch will open to start the engine hour meter. The Overspeed Protection System consists of: Electronic Speed Switch (ESS) Relay (SR1) Terminal Block

Engine Electrical System The engine electrical system has two circuits: the charging circuit, and the low amperage circuit. Some of the electrical system components are used in more than one circuit. The battery (batteries), disconnect switch, circuit breaker, ammeter, cables and wires from the battery are all common in each of the

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circuits. The charging circuit is in operation when the engine is running. An alternator makes electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output to keep the battery at full charge.

NOTICE The disconnect switch, if so equipped, must be in the ON position to let the electrical system function. There will be damage to some of the charging circuit components if the engine is running with the disconnect switch in the OFF position.

The low amperage circuit and the charging circuit are both connected through the ammeter.

Charging System Components NOTICE Never operate the alternator without the battery in the circuit. Making or breaking an alternator connection with heavy load on the circuit can cause damage to the regulator.

3T6352, 5N5692 and 7G7889 Alternators

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3T6352, 5N5692 and 7G7889 Alternator Shown. (1) Regulator. (2) Roller bearing. (3) Stator winding. (4) Ball bearing. (5) Rectifier bridge. (6) Field winding. (7) Rotor assembly. (8) Fan.

The alternator is driven by V-belts from the crankshaft pulley. This alternator is a three phase, selfrectifying charging unit, and the regulator is part of the alternator. This alternator design has no need for slip rings or brushes, and the only part that has movement is the rotor assembly. All conductors that carry current are stationary. The conductors are: the field winding, stator windings, six rectifying diodes, and the regulator circuit components. The rotor assembly has many magnetic poles like fingers with air space between each opposite pole. The poles have residual magnetism (like permanent magnets) that produce a small amount of magnet-like lines of force (magnetic field) between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced in the stator windings from the small magnetic lines of force made by the residual magnetism of the poles. This AC current is changed to direct current (DC) when it passes through the diodes of the rectifier bridge. Most of this current goes to charge the battery and to supply the low amperage circuit, and the remainder is sent to the field windings. The DC current flow through the field windings (wires around an iron core) now increases the strength of the magnetic lines of force. These stronger lines of force now increase the amount of AC current produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator. The voltage regulator is a solid state (transistor, stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output.

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7N9720 Alternator The alternator is driven by V-belts from the crankshaft pulley. This alternator is a three phase, selfrectifying charging unit. The regulator is part of the alternator.

7N9720 Alternator Shown. (1) Fan. (2) Stator winding. (3) Field winding. (4) Regulator. (5) Ball bearing. (6) Roller bearing. (7) Rotor. (8) Rectifier assembly.

This alternator design has no need for slip rings or brushes, and the only part that has movement is the rotor assembly. All conductors that carry current are stationary. The conductors are: the field winding, stator windings, six rectifying diodes, and the regulator circuit components. The rotor assembly has many magnetic poles like fingers with air space between each opposite pole. The poles have residual magnetism (like permanent magnets) that produce a small amount of magnet-like lines of force (magnetic field) between the poles. As the rotor assembly begins to turn between the field winding and the stator windings, a small amount of alternating current (AC) is produced in the stator windings from the small magnetic lines of force made by the residual magnetism of the poles. This AC current is changed to direct current (DC) when it passes through the diodes of the rectifier bridge. Most of this current goes to charge the battery and to supply the low amperage circuit, and the remainder is sent to the field windings. The DC current flow through the field windings (wires around an iron core) now increases the strength of the magnetic lines of force. These stronger lines of force now increase the amount of AC current produced in the stator windings. The increased speed of the rotor assembly also increases the current and voltage output of the alternator. The voltage regulator is a solid state (transistor, stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the

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field windings) for the alternator to make the needed voltage output.

9G4574 Alternator The alternator is driven by V-belts from the crankshaft pulley. The alternator has three-phase, full-wave rectified output. It is brushless. The rotor and bearings are the only moving parts. The regulator is part of the alternator.

9G4574 Alternator Shown. (1) Fan. (2) Front frame assembly. (3) Stator assembly. (4) Rotor assembly. (5) Field winding (coil assembly). (6) Regulator assembly. (7) Condenser (suppression capacitor). (8) Rectifier assembly. (9) Rear frame assembly.

When the engine is started and the rotor turns inside the stator windings, three-phase alternating current (AC) and rapidly rising voltage is generated. A small amount of alternating current (AC) is changed (rectified) to pulsating direct current (DC) by the exciter diodes on the rectifier assembly. Output current from these diodes adds to the initial current which flows through the rotor field windings from residual magnetism. This will make the rotor a stronger magnet and cause the alternator to become activated automatically. As rotor speed, current and voltages increase, the rotor field current increases enough until the alternator becomes fully activated. The main battery charging current is charged (rectified) from AC to DC by the other positive and

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negative diodes in the rectifier and pack (main output diodes) which operate in a full wave linkage rectifier circuit. Alternator output is controlled by a regulator, which is inside the alternator rear frame.

6T1395 Alternator

6T1395 Alternator (1) Slip rings. (2) Fan. (3) Stator assembly. (4) Rotor assembly. (5) Brush and holder assembly.

The alternator is a three phase, self-rectifying charging unit that is driven by V-belts. The only part of the alternator that has movement is the rotor assembly. Rotor assembly (4) is held in position by a ball bearing at each end of the rotor shaft. The alternator is made up of a front frame at the drive end, rotor assembly (4), stator assembly (3), rectifier assembly, brushes and holder assembly (5), slip rings (1) and rear end frame. Fan (2) provides heat removal by the movement of air through the alternator. Rotor assembly (4) has field windings (wires around an iron core) that make magnetic lines of force when direct current (DC) flows through them. As the rotor assembly turns, the magnetic lines of force

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are broken by stator assembly (3). This makes alternating current (AC) in the stator. The rectifier assembly has diodes that change the alternating current (AC) from the stator to direct current (DC). Most of the DC current goes to charge the battery and make a supply for the low amperage circuit. The remainder of the DC current is sent to the field windings through the brushes.

3T6353 Alternator Regulator

3T6353 Regulator

The voltage regulator is an electronic switch. It feels the voltage in the system and gives the necessary field current (current to the field windings of the alternator) for the alternator to make the needed voltage. The voltage regulator controls the field current to the alternator by switching on and off many times a second.

9G7567 Alternator Regulator

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9G7567 Regulator

The voltage regulator is an electronic switch. It feels the voltage in the system and gives the necessary field current (current to the field windings of the alternator) for the alternator to make the needed voltage. The voltage regulator controls the field current to the alternator by switching on and off many times a second.

7T2798 Alternator Regulator

7T2798 Regulator

The regulator is fastened to the alternator by two different methods. One method fastens the regulator to the top, rear of alternator. With the other method the regulator is fastened separately by use of a wire and a connector that goes into the alternator.

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The voltage regulator is a solid state (transistor, no moving parts) electronic switch. It feels the voltage in the system and gives the necessary field current (current to the field windings of the alternator) for the alternator to make the needed voltage. The voltage regulator controls the field current to the alternator by switching on and off many times a second. There is no voltage adjustment for this regulator.

6T9445 Alternator Regulator

6T9445 Regulator

The voltage regulator is not fastened to the alternator, but is mounted separately and is connected to the alternator with wires. The regulator is solid state (transistor, stationary parts) electronic switch. It feels the voltage in the system and switches on and off many times a second to control the field current (DC current to the field windings) for the alternator to make the needed voltage output. There is a voltage adjustment for this regulator to change the alternator output.

Starting System Components Solenoid A solenoid is a magnetic switch that does two basic operations. a. Closes the high current starter motor circuit with a low current start switch circuit. b. Engages the starter motor pinion with the ring gear.

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Typical Solenoid Schematic

The solenoid switch is made of an electromagnet (one or two sets of windings) around a hollow cylinder. There is a plunger (core) with a spring load inside the cylinder that can move forward and backward. When the start switch is closed and electricity is sent through the windings, a magnetic field is made that pulls the plunger forward in the cylinder. This moves the shift lever (connected to the rear of the plunger) to engage the pinion drive gear with the ring gear. The front end of the plunger then makes contact across the battery and motor terminals of the solenoid, and the starter motor begins to turn the flywheel of the engine. When the start switch is opened, current no longer flows through the windings. The spring now pushes the plunger back to the original position, and at the same time, moves the pinion gear away from the flywheel. When two sets of windings in the solenoid are used, they are called the hold-in windings and the pull-in windings. Both have the same number of turns around the cylinder, but the pull-in windings uses a larger diameter wire to produce a greater magnetic field. When the start switch is closed, part of the current flows from the battery through the hold-in windings, and the rest flows through the pull-in windings to motor terminal, then through the motor to ground. When the solenoid is fully activated (connection across battery and motor terminal is complete), current is shut off through the pull-in windings. Now only the smaller hold-in windings are in operation for the extended period of time it takes to start the engine. The solenoid will now take less current from the battery, and heat made by the solenoid will be kept at an acceptable level.

Starter Motor The starter motor is used to turn the engine flywheel fast enough to get the engine to start running. The starter motor has a solenoid. When the start switch is activated, the solenoid will move the starter pinion to engage it with the ring gear on the flywheel of the engine. The starter pinion will engage with the ring gear before the electric contacts in the solenoid close the circuit between the battery and the starter motor. When the circuit between the battery and the starter motor is complete, the pinion will turn the engine flywheel. A clutch gives protection for the starter motor so that the engine cannot turn the

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starter motor too fast. When the start switch is released, the starter pinion will move away from the ring gear.

Starter Motor Cross Section (1) Field. (2) Solenoid. (3) Clutch. (4) Pinion. (5) Commutator. (6) Brush assembly. (7) Armature.

Other Components Circuit Breaker The circuit breaker is a switch that opens the battery circuit if the current in the electrical system goes higher than the rating of the circuit breaker. A heat activated metal disc with a contact point makes complete the electric circuit through the circuit breaker. If the current in the electrical system gets too high, it causes the metal disc to get hot. This heat causes a distortion of the metal disc which opens the contacts and breaks the circuit. A circuit breaker that is open can be reset (an adjustment to make the circuit complete again) after it becomes cool. Push the reset button to close the contacts and reset the circuit breaker.

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Circuit Breaker Schematic (1) Reset button. (2) Disc in open position. (3) Contacts. (4) Disc. (5) Battery circuit terminals.

Air Starting System The air starting motor is used to turn the engine flywheel fast enough to get the engine running.

Air Starting System (1) Starter control valve. (2) Oiler. (3) Relay valve. (4) Air starting motor.

The air starting motor is on the right side of the engine. Normally the air for the starting motor is from a storage tank which is filled by an air compressor installed on the left front of the engine. The air storage tank holds 297 liter (10.5 cu. ft.) of air at 1720 kPa (250 psi) when filled. For engines which do not have heavy loads when starting, the regulator setting is approximately 690 kPa (100 psi). This setting gives a good relationship between cranking speeds fast enough for easy starting and the length of time the air starting motor can turn the engine before the air supply is gone. If the engine has a heavy load which cannot be disconnected during starting, the setting of the air

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pressure regulating valve needs to be high in order to get high enough speed for easy starting. The air consumption is directly related to speed, the air pressure is related to the effort necessary to turn the engine flywheel. The setting of the air pressure regulator can be up to 1030 kPa (150 psi) if necessary to get the correct cranking speed for a heavily loaded engine. With the correct setting, the air starting motor can turn the heavily loaded engine as fast and as long as it can turn a lightly loaded engine. Other air supplies can be used if they have the correct pressure and volume. For good life of the air starting motor, the supply should be free of dirt and water. The maximum pressure for use in the air starting motor is 1030 kPa (150 psi). Higher pressures can cause problems. The 1L5011 Regulating and Pressure Reducing Valve Group has the correct characteristics for use with the air starting motor. Most other types of regulators do not have the correct characteristics. Do not use a different style of valve in its place.

Air Starting Motor (5) Air inlet. (6) Rotor. (7) Vanes. (8) Pinion. (9) Gears. (10) Piston. (11) Pinion spring.

The air from the supply goes to relay valve (3). The starter control valve (1) is connected to the line before the relay valve (3). The flow of air is stopped by the relay valve (3) until the starter control valve (1) is activated. Then air from the starter control valve (1) goes to the piston (10) behind the pinion (8) for the starter. The air pressure on the piston (10) puts the pinion spring (11) in compression and puts the pinion (8) in engagement with the flywheel gear. When the pinion is in engagement, air can go out through another line to the relay valve (3). The air activates the relay valve (3) which opens the supply line to the air starting motor. The flow of air goes through the oiler (2) where it picks up lubrication oil for the air starting motor. The air with lubrication oil goes into the air motor. The pressure of the air pushes against the vanes (7) in the rotor (6). This turns the rotor which is connected by gears (9) to the starter pinion (8) which turns

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the engine flywheel. When the engine starts running the flywheel will start to turn faster than the starter pinion (8). The pinion (8) retracts under this condition. This prevents damage to the motor, pinion (8) or flywheel gear. When the starter control valve (1) is released, the air pressure and flow to the piston (10) behind the starter pinion (8) is stopped, the pinion spring (11) retracts the pinion (8). The relay valve (3) stops the flow of air to the air starting motor.

Copyright 1993 - 2007 Caterpillar Inc. All Rights Reserved. Private Network For SIS Licensees.

Mon Nov 5 16:10:36 EST 2007

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