TWIN DISC
INCORPORA TED INCORPORATED
Ser vice Manual
Power Shift Transmission Components: TD-61-1180 Transmission 8-MLW-1755-1 Torque Converter ETA28L Electronic Control
Document Number: 1019864
Document Number 1019864
April, 2000
Power Shift Transmission System Service Manual
TWIN DISC, INCORPORATED EXCLUSIVE LIMITED WARRANTY TD61-1179 / TD61-1180 TRANSMISSION SYSTEM FOR AIRPORT RESCUE FIRE FIGHTING VEHICLES A.
Twin Disc, Incorporated warrants all assembled products and parts, (except component products or parts on which written warranties issued by the respective manufacturers thereof are furnished to the original customer, as to which Twin Disc, Incorporated makes no warranty and assumes no liability) against defective materials or workmanship for a period of thirty (30) months from the date of original shipment by Twin Disc, Incorporated to the original customer, but not to exceed twenty-four (24) months of service, whichever occurs first. This is the only warranty made by Twin Disc, Incorporated and is in lieu of any and all other warranties, express or implied, including the warranties of merchantability or fitness for a particular purpose and no other warranties are implied or intended to be given by Twin Disc, Incorporated. The original customer does not rely upon any tests or inspections by Twin Disc, Incorporated or on Twin Disc, Incorporated's application engineering.
B.
The exclusive remedy provided by Twin Disc, Incorporated whether arising out of warranty within the applicable warranty period as specified, or otherwise (including tort liability), shall at the sole option of Twin Disc, Incorporated be either the repair or replacement of any Twin Disc, Incorporated part or product found by Twin Disc, Incorporated to be defective and the labor to perform that work and to remove and reinstall (or equivalent credit). In this context, labor is defined as the flat rate labor hours established by Twin Disc, Incorporated in the published Twin Disc Flat Rate Schedule, required to remove, disassemble, inspect, repair, reassemble, reinstall and test the Twin Disc, Incorporated product only. Under no circumstances, including a failure of the exclusive remedy, shall Twin Disc, Incorporated be liable for economic loss, consequential, Incidental or punitive damages. The above warranty and remedy are subject to the following terms and conditions: 1. Complete parts or products upon request must be returned transportation prepaid and also the claims submitted to Twin Disc, Incorporated within sixty (60) days after completion of the in warranty repair. 2. The warranty is void if, in the opinion of Twin Disc, Incorporated, the failure of the part or product resulted from abuse, neglect, improper maintenance or accident. 3. The warranty is void if any modifications are made to any product or part without the prior written consent of Twin Disc, Incorporated. 4. The warranty is void unless the product or part is properly transported, stored and cared for from the date of shipment to the date placed in service. 5. The warranty is void unless the product or part is properly installed and maintained within the rated capacity of the product or part with installations properly engineered and in accordance with the practices, methods and instructions approved or provided by Twin Disc, Incorporated. 6. The warranty is void unless all required replacement parts or products are of Twin Disc origin or equal, and otherwise identical with components of the original equipment. Replacement parts or products not of Twin Disc origin are not warranted by Twin Disc, Incorporated.
C.
As consideration for this warranty, the original customer and subsequent purchaser agree to indemnify and hold Twin Disc, Incorporated harmless from and against all and any loss, liability, damages or expenses for injury to persons or property, including without limitation, the original customer's and subsequent purchaser's employees and property, due to their acts or omissions or the acts or omissions of their agents, and employees in the installation, transportation, maintenance, use and operation of said equipment.
D.
Only a Twin Disc, Incorporated authorized factory representative shall have authority to assume any cost or expense in the service, repair or replacement of any part or product within the warranty period, except when such cost or expense is authorized in advance in writing by Twin Disc, Incorporated.
E.
Twin Disc, Incorporated reserves the right to improve the product through changes in design or materials without being obligated to incorporate such changes in products of prior manufacture. The original customer and subsequent purchasers will not use any such changes as evidence of insufficiency or inadequacy of prior designs or materials.
F.
If failure occurs within the warranty period, and constitutes a breach of warranty, repair or replacement parts will be furnished on a no-charge basis and these parts will be covered by the remainder of the unexpired warranty which remains in effect on the complete unit.
February 23, 2000
TDWP4013
TWIN DISC, INCORPORATED FLAT RATE HOURS ALLOWANCE (Hourly Labor Rates Must be Acceptable to Twin Disc, Incorporated) TD61-1179 / TD61-1180 TRANSMISSION SYSTEM FOR AIRPORT RESCUE FIRE FIGHTING VEHICLE POWER TRAIN INSTALLATION
Transmission , Torque Converter and Electronic Control Hour Allowed A. Removal and Reinstallation or Reset Labor from Vehicle 1. Units, Torque Converter-20 Hrs., Transmission-12 Hrs., Test-4 Hrs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Includes R&R of both units or either unit, all necessary parts and equipment. Drain and refill, clean and flush hoses and coolers, disconnect and connect hydraulic lines, linkages, and drivelines and test. 2. External Assemblies Pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Modulating Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Regulator Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Magnetic Pickup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Electronic Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wiring Harness (checking) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PTO Clutch Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lip Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 0.5 1 0.5 0.5 1 1 1
B. Repair Labor on Units TRANSMISSION 1. Unit Overhaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 (Includes pre-clean, disassemble, clean, inspect, assemble and test.) 2. Valve Assembly (Disassemble, clean, inspect, assemble and test) Modulating Valve (replace - do not open or repair) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 TORQUE CONVERTER 1. Unit Overhaul . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 (Includes pre-clean, disassemble, clean, inspect, assemble and test.) 2. Valve Assembly Modulating Valve (replace - do not open or repair) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 3. PTO Clutch Assembly with Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 (Disassemble, clean, inspect, assemble and test.)
February 23, 2000
TDWP4013
Twin Disc, Incorporated
Table of Contents
Table of Contents Introduction ............................................................9 General Information ............................................................................. 9 Replacement Parts ............................................................................... 9 Preventative Maintenance/Troubleshooting .................................... 10 Safety ................................................................................................... 11 Sources of Service Information ........................................................ 12 Warranty .............................................................................................. 12
Description and Specifications...........................13 General ................................................................................................ 13 Description .......................................................................................... 14 Sump .................................................................................................... 14 Pump .................................................................................................... 14 Regulator Valve Assembly ................................................................ 15 Range Selector Valve ......................................................................... 15 Clutch Applied Power Take Off ......................................................... 15 Special Features ................................................................................. 16 Specifications ..................................................................................... 16
Operation ..............................................................19 Basic System Description ................................................................. 19 Component Operation Summary ...................................................... 25 ETA 28-L Electronic Control Functions ............................................ 29 D.C. Power Supply .............................................................................. 32 ETA 28-L Electronic Control System Components ......................... 33 Hydraulic System ............................................................................... 38 Power Flow .......................................................................................... 40 Action of the Differential .................................................................... 42 System Operation ............................................................................... 43 Vehicle Operating Modes ................................................................... 43 Operational Problems ........................................................................ 48 Power Shift Transmission System Service Manual
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Table of Contents
Twin Disc, Incorporated
Preventative Maintenance ...................................49 General ................................................................................................ 49 Hydraulic System ............................................................................... 49 Periodic Visual Inspection ................................................................. 52 Hydraulic System Pressure Checks ................................................. 54
Troubleshooting ...................................................55 General ................................................................................................ 55 Pressure and Flow Test Kit ............................................................... 55 Troubleshooting Discussion ............................................................. 56 Diagnostic Test ................................................................................... 99
Engineering Drawings .......................................123
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Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Introduction
Introduction
General Information This publication provides the information necessary for the operation and maintenance of the Twin Disc, Incorporated equipment specified on the cover of this manual. Specific engineering details and performance characteristics can be obtained from the Product Service Department of Twin Disc, Incorporated, Racine, Wisconsin, USA. Operation and maintenance personnel responsible for this equipment should have this manual at their disposal and be familiar with its contents. Applying the information in the manual will result in consistent performance from the unit and help reduce downtime.
Special Tools Engineering drawings are included for the fabrication of special tools that should be used during disassembly and assembly of a unit. Repair of this equipment should not be attempted without special tools. Twin Disc does not manufacture these tools for general use.
Replacement Parts
Parts Lists Engineering assembly drawings and bill of materials are provided in appropriate sections of this manual to facilitate ordering spare or replacement parts.
Power Shift Transmission System Service Manual
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Introduction
Twin Disc, Incorporated
Ordering Parts
All replacement parts or products (including hoses and fittings) must be of Twin Disc origin or equal, and otherwise identical with components of the original equipment. Use of any other parts or products will void the warranty and may result in malfunction or accident, causing injury to personnel and /or serious damage to the equipment. Renewal parts and service parts kits may be obtained from any authorized Twin Disc distributor or service dealer.
Parts Shipment Furnish the complete shipping information and postal address. All parts shipments made from the factory will be FOB factory location, USA. State specifically whether the parts are to be shipped by freight, express, etc. If shipping instructions are not specified, the equipment will be shipped the best way, considering time and expense. Twin Disc, Incorporated will not be responsible for any charges incurred by this procedure. Twin Disc, Incorporated having stipulated the bill of material number on the unit’s nameplate absolves itself of any responsibility resulting from any external, internal or installation changes made in the field without the express written approval of Twin Disc. All returned parts, new or old, emanating from any of the above-stated changes will not be accepted for credit. Furthermore, any equipment which has been subjected to such changes will not be covered by a Twin Disc warranty.
Preventative Maintenance/Troubleshooting Frequent reference to the information provided in this manual regarding daily operation and limitations of this equipment will assist in obtaining troublefree operation. Schedules are provided for the recommended maintenance of the equipment and, if observed, minimum repairs (aside from normal wear) will result. In the event a malfunction does occur, a troubleshooting table is provided to help identify the problem area and lists information that will help determine the extent of the repairs necessary to get a unit back into operation.
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Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Introduction
Lifting Bolt Holes Most Twin Disc products have provisions for attaching lifting bolts. The holes provided are always of adequate size and number to safely lift the Twin Disc product.
These lifting points must not be used to lift the complete power unit. Lifting excessive loads at these points could cause failure at the lift point (or points) and result in damage or personal injury.
Select lifting eyebolts to obtain maximum thread engagement with bolt shoulder tight against housing. Bolts should be near but should not contact bottom of bolt hole.
Safety
General Safe practices must be employed by all personnel operating and servicing this unit. Twin Disc, Incorporated will not be responsible for personal injury resulting from careless use of hand tools, lifting equipment, power tools, or unaccepted maintenance/operating practices.
Important Safety Notice Because of the possible danger to person(s) or property from accidents which may result from the use of manufactured products, it is important that correct procedures be followed. Products must be used in accordance with the engineering information specified. Proper installation, maintenance, and operation procedures must be observed. Inspection should be made as necessary to assure safe operations under prevailing conditions. Proper guards and other suitable safety codes should be provided. These devices are neither provided by Twin Disc, Incorporated nor are they the responsibility of Twin Disc, Incorporated.
Power Shift Transmission System Service Manual
11
Introduction
Twin Disc, Incorporated
Sources of Service Information Each series of manuals issued by Twin Disc, Incorporated is current at the time of printing. When required, changes are made to reflect advancing technology and improvements in state-of-the-art. Individual product service bulletins are issued to provide the field with immediate notice of new service information. For the latest service information on Twin Disc products, contact any Twin Disc distributor, or contact the Product Service Department, Twin Disc, Incorporated, Racine, Wisconsin 53405-3698, USA by e-mail at
[email protected].
Warranty Equipment for which this manual was written has a limited warranty. For details of the warranty, refer to the warranty statement at the front of this manual.
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Power Shift Transmission System Service Manual
Description and Specifications
Twin Disc, Incorporated
Description and Specifications
General (Reference - Twin Disc Application # AN4010) The Twin Disc TD-61-1180 transmission is a hydraulically actuated power shift transmission, providing six speeds forward and one reverse. Used with this transmission is a Twin Disc torque converter model 8-MLW-1755-1. The transmission and torque converter are electronically controlled by a Twin Disc model ETA-28L control.
Model Identity Numbers and Letters TD-61-1180, BOM 67328 T = Transmission D = Drop box, output at different level than input 6 = Six speeds forward 1 = One speed reverse 11 = Transmission model series 80 = Basic model number (Assigned in consecutive sequence to identify specific modifications or gear ratios) 8-MLW-1755-1, BOM 67290 8 = type 8 Twin Disc torque converter M = modulated input clutch L = with lockup clutch W = with stator freewheel 175 = 17.5-inch converter circuit size 5 = specific model for application 1 = housing size to match SAE flywheel ETA-28L Electronic control BOM 40781 E = electronic T = transmission A = automatic 28L = model variation
Power Shift Transmission System Service Manual
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Description and Specifications
Twin Disc, Incorporated
Description The input section of the transmission consists of two geared-together clutch shafts. Each shaft contains two 7-inch clutch packs of the orifice type. When the clutch is engaged, output is from gear and drive rings on the clutch shafts to and through gears on the compound shaft, and then to gears on the 9-inch clutch shaft. This shaft contains two 9-inch clutch packs equipped with individual feedback dump valves. The front 9-inch clutch is an LD type clutch and the rear is an S type clutch. A spline-connected output gear on the 9-inch clutch shaft is meshed with the input gear on the inter-axle differential. The differential includes two independent output shafts connected through the inter-axle differential. The differential has a clutch that when applied, locks up the differential providing a solid drive through the differential to the outputs. The hydraulic torque converter is a single stage Type 8 design with a modulated input clutch, integral lockup clutch, and stator freewheel. The converter includes power take off mounting ports for the mounting of hydraulic pumps. The lookup clutch and modulated input clutches are hydraulically controlled in conjunction with the electronic control unit.
Sump The bottom of the transmission housing serves as the sump for all oil used in the transmission/ torque converter system. A suction strainer is installed in the sump to prevent debris from being drawn into the pump inlet.
Pump The system pump located on the rear of the torque converter is a positive displacement gear-type and is driven directly by the engine. The pump inlet draws oil through a suction strainer. Outlet from the pump is directed through a filter and regulator valve and supplies pressure for clutch apply, torque converter and lube. The pump runs at 1.28 times faster than engine speed. A scavenge pump is attached to the back of the main system pump on the converter. The scavenge pump draws oil from the bottom of the engine flywheel and converter housings and returns the oil to the transmission sump.
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Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Description and Specifications
Regulator Valve Assembly Pressure regulating valves for controlling main and lube oil pressures are contained in the regulator valve assembly on the transmission. Converter pressure is controlled by a pressure regulator at the converter outlet and the transmission lube regulator. The regulator valve on the transmission also includes a cold oil relief for protection of the converter.
Range Selector Valve Seven identical proportional valves, mounted on the rear of the transmission housing, control the application of the transmission clutches. Five of these valves are actuated by on-off electric signals, and are located in pairs in a valve body on the end of each of the top two shafts, and one on the right rear of the transmission housing. These are identified as 1, 2, 3, 4, and D. The valve identified as D controls the clutch in the transmission differential. Two valves are controlled by electronically modulated signals. This pair of valves is located at the end of the lower clutch shaft and is labeled and referred to as numbers 5 and 6. These solenoid numbers are referenced in the electronic control system drawing to aid technicians in troubleshooting the system. The lockup and modulated input clutches in the torque converter are controlled by proportional valves that are mounted on the torque converter, and are actuated by proportional electrical signals. A solenoid of a different type is used to control the torque converter mounted PTO. The control system, with associated solenoids, is powered by 12 volts dc.
Clutch Applied Power Take Off Mounted on the torque converter is a hydraulically actuated power takeoff unit which is driven by the engine. When the hydraulic clutch is disengaged the PTO output does not turn and is held stationary with a single disc brake. When the engaging solenoid is activated the hydraulic clutch engages and drives the PTO output. The PTO output is driven at engine speed x 1.28. A 12 volt dc solenoid is used to engage the clutch.
Power Shift Transmission System Service Manual
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Description and Specifications
Twin Disc, Incorporated
Special Features
Clutches Hardened steel plates and organic fiber friction plates are used on all clutches. The 7-inch clutches are of the orifice type clutch. The rear 9-inch clutch is of the S dump valve configuration. The front 9-inch clutch is of the LD dump valve configuration. The clutches are hydraulically actuated, spring-released, and oil cooled.
Bearings The 7-inch clutch shafts are supported with tapered roller bearings. The end play of the 9-inch clutch shaft is controlled by a double tapered roller bearing set, and the other end of the shaft is supported by a straight roller bearing. The output shafts and differential are supported with tapered roller bearings and ball bearings. The output end gear and ring assemblies on the clutches are supported with caged needle bearings, and located with needle thrust bearings. The input end gear and ring assemblies are supported and located by, and include, a matched set of double tapered roller bearing assemblies.
Specifications Normal Temperature Range: 180-220 degrees F (82-104 degrees C) Low Speed Pressures: Run at 715 rpm Main Pressure (X): 185 psi (1276 kPa) minimum at regulator. Clutch Apply Pressure (CL): 180 psi (1241 kPa) minimum at end caps and within 5 psi (34 kPa) of each other. Transmission Lube Pressure: 5-15 psi (34-103 kPa) at lube regulator (G). 2 psi (14 kPa) minimum at shaft end caps(G,1-2), (G,3-4), (G,5-6). 2-8 psi (14-55 kPa) at differential clutch when disengaged.
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Power Shift Transmission System Service Manual
Description and Specifications
Twin Disc, Incorporated
Converter outlet pressure (W): 50 to 70 psi (345-483 kPa) High Speed Pressures: Run at 2150 rpm Main Pressure (X): 228-235 psi (1572-1620 kPa) at main regulator. Clutch Apply Pressure (CL): Within 12 psi (83 kPa) of main at end caps. Transmission Lube Pressures: 35-50 psi (241-345 kPa) at lube regulator (G). 15-35 psi (103-241 kPa) at 7-inch clutch shaft end caps (G,1-2)& (G,3-4). 15-35 psi (103-241 kPa) at 9-inch clutch shaft end cap (G,5-6). 15-35 psi (103-241 kPa) at differential clutch when disengaged. Converter outlet pressure (W): 70 to 90 psi (483-621 kPa) Differential Clutch Pressure: Within 12 psi (83 kPa) of main pressure when engaged.
Engine speeds (approximate) (Freightliner 6 X 6 ARFF vehicle with Detroit Diesel Series 60, 600 hp @ 2300 rpm) Full load No load Converter stall speed
2300 rpm 2425 rpm 2083 rpm
ETA-28L CONTROL Furnished with the transmission is the ETA-28L electronic control. The control provides automatic shifting for the transmission/converter system and is necessary to coordinate the function of the vehicle, torque converter and transmission in a truck application. The control operates on 12 volts dc provided by the vehicle battery.
Power Shift Transmission System Service Manual
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Description and Specifications
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Twin Disc, Incorporated
Power Shift Transmission System Service Manual
Operation
Twin Disc, Incorporated
Operation This section covers operation of the transmission, torque converter, and the associated hydraulic and electronic control system and their relationship to the engine and vehicle. The following paragraph (prior to start-up) provides information the vehicle operator needs to know to inspect the transmission and start the engine. After each use 1.
Visually inspect the transmission, converter and drive line for security of mounting. Inspect plumbing and electrical components for security of attachment and/or leaks. Leakage must be corrected.
2.
Oil level procedure: It is best to check the oil level after the truck has been setting with the engine not running for at least 4 hours. The truck should be parked on a level surface. a.
With the engine not running, both oil level sight glasses should show full. Add oil if both glasses do not show full.
b.
Set the vehicle brakes and start the engine. With the engine at low idle, the transmission in neutral, and with cold oil (10 to 35 deg C) the oil level should be at the middle of the lower sight glass.
c.
Apply the foot brakes, shift to D6 and run the engine at 1500 RPM until the transmission oil reaches 100 deg C. Lower the engine to low idle and shift to N. The oil level should show full in the bottom sight glass and 1/2 to full in the upper sight glass.
Basic System Description This section describes the function and relationship of the following major components in your power transmission system.
!
Electronic control system (ETA-28L)
!
Engine mounted torque converter (8MLW-1755-1)
!
Converter mounted power take off (PTO)
!
Remote mounted transmission (TD61-1180)
Power Shift Transmission System Service Manual
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Operation
20 MISCELANIOUS SWITCH INPUTS POWER SOURCE
LIQUID CRYSTAL DISPLAY
SPEEDOMETER 50 40 60 70 30 80 20 90 10
RANGE SELECTOR
MODE CHANGING DIFFERENTIAL LOCK ENGINE BR AKE PTO
ACCELERATOR PEDAL POSITION POTENTIOMETER
HYDRAULIC SYSTEM FILTER DIFF. PRESS. SWITCH
ENGINE CONTROLLER
CONVERTER LOCKUP AND MODULATED CLUTCH VALVE COILS
TEMPERATURE SENSOR
PTO SOLENOID TRANSMISSION INPUT AND OUTPUT SPEED SENSORS
TRANSMISSION RANGE CLUTCH VALVE COILS
ENGINE DIFFERENTIAL LOCK SOLENOIDS
TORQUE CONVERTER WITH PTO, LOCK UP CLUTCH AND MODULATING CLUTCH
Figure 1. Control System Diagram
TRANSMISSION
Twin Disc, Incorporated
Power Shift Transmission System Service Manual
ENGINE LOAD SIGNAL
Twin Disc, Incorporated
Power Shift Transmission System Service Manual
Figure 2. Hydraulic Torque Converter
Operation
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Operation
Twin Disc, Incorporated
NOTE: Pressure test ports are SAE 7/16 - 20UNF - 2B.
Figure 3. Power Shift Transmission Engine Side
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Power Shift Transmission System Service Manual
Operation
Twin Disc, Incorporated
Figure 4. Power Shift Transmission Side View
Power Shift Transmission System Service Manual
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Operation
Twin Disc, Incorporated
NOTE: Pressure test ports are SAE 7/16 - 20UNF - 2B
PORT 1
G
MAGNETIC PICK-UP (40 TEETH) 36T PER INPUT REVOLUTION
PORT 2
G
PORT 3
X
X MAIN PRESSURE CHECK (3) PORTS MARKED "X"
PORT 4 PORT 6
X
DIFFERENTIAL CONTROL VALVE MAGNETIC PICK-UP OUTPUT SPEED 53 TEETH (OPTIONAL LOCATION)
MAGNETIC PICK-UP OUTPUT SPEED 60 TEETH
PORT 5
G LUBE PRESSURE CHECK 3 PORTS MARKED "G"
Figure 5. Power Shift Transmission Side Opposite Input
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Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Operation
Component Operation Summary
Torque Converter The torque converter is direct mounted to the engine flywheel housing, and its input member rotates with the flywheel. The transmission system oil pumps are geared to the input member, providing oil flow for transmission system operation. Two pumps are mounted in tandem. One provides oil flow for the operation of the transmission system, and the other one pumps normal torque converter drainage back to the transmission oil sump (scavenge pump). There are two internal clutches in the torque converter. One is a modulated input clutch that connects the flywheel driven member to the fluid circuit impeller. The other is the lockup clutch that connects the fluid circuit impeller to the fluid turbine or converter output shaft. Both of these clutches are controlled by the electronic controller, based on conditions. There are pressure testing ports located on the torque converter that can be used in trouble shooting certain problems. See Figure 2 in Operation.
Power Take Off (PTO) The power take off is mounted on the torque converter, and is used to connect the engine flywheel power to operate a remotely mounted pump for the vehicle.
Remote Mounted Transmission The remote mounted transmission contains several clutches that are engaged in combinations that determine the gear ratio that is used to drive the vehicle. The input shaft is directly connected to the torque converter output shaft. The transmission output shaft is directly connected to the axles of the vehicle. Electric valves are mounted on the transmission that are energized in the proper combination to engage the appropriate clutches. The transmission housing is the oil sump for the transmission system. There are several oil pressure test ports located on the transmission for use in troubleshooting certain problems. See Figure 3, 4, and 5 in Operation.
Power Shift Transmission System Service Manual
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Operation
Twin Disc, Incorporated
Electronic Control System The electronic control system coordinates functions of the vehicle, torque converter, and transmission. Various external components are used to provide inputs for the control as well as outputs for operation of the transmission/ converter system. Different operating characteristics are obtained through the positioning of various input switches to the control system. See Figure 1 in Operation. The electronic control system consists of the following components:
Cables The cables connect the components of the electronic control system to each other, and also to the sensors, valves, and switches that are located on the various components in the power transmission system.
Manual Override Switch The manual override switch (two position) is used if normal automatic operation is not possible because of certain control problems. It allows for limited operation of the vehicle for emergency or come home operation.
Never actuate the manual override, except when in neutral with the vehicle stopped, and the engine speed at idle. The use of this switch allows vehicle power in 3rd range, neutral, or reverse.
Rotary Switch The rotary switch (three position) allows selection of the drive mode, pump and roll mode, or stationary mode. The stationary mode position is used to engage the PTO, if needed, during the emergency or come home operation and is used in conjunction with the manual override switch.
Transmission Range Selector The transmission range selector is used to select the direction and maximum gear obtainable during automatic operation. There is also a neutral start switch and reverse alarm switch within the assembly.
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Power Shift Transmission System Service Manual
Operation
Twin Disc, Incorporated
Display Unit The display unit provides information to the operator about what range the transmission is in, and is also used while troubleshooting system problems. This also displays status codes that may be generated by the control box sensing abnormal conditions in the transmission system.
Control Box The control box contains the computer and eprom that has been programmed with the desired vehicle function parameters. The control box relies on information provided by several input devices, and provides signals to several outputs that result in the vehicle performing in the desired manner. The inputs are:
!
Range selector
!
Transmission input speed sensor
!
Transmission output speed sensor
!
Throttle pedal position switch
!
Engine torque signal
!
Transmission oil temperature sensor
!
Transmission filter differential pressure switch
!
Stationary PTO switch
!
Transmission differential lock switch
!
Dedicated, fused (10 amp), +12 volt battery power (through a switched relay)
!
Dedicated ground connection to the battery negative
!
Test mode connector
!
Operating mode switch
Power Shift Transmission System Service Manual
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Operation
Twin Disc, Incorporated
Based on the signals obtained from these inputs, the control box sends signals out to various devices that cause the vehicle operation. The outputs are:
!
Electrical current to the proportional solenoids used to engage the proper clutches to provide the transmission range desired NOTE: Four of these are used as on/off solenoids, and two are used as proportional solenoids.
28
!
Electrical current to the solenoid used to apply the transmission differential clutch as needed
!
Electrical current to the proportional solenoid used to apply the modulated clutch as needed
!
Electrical current to the proportional solenoid used to apply the converter lookup clutch as needed
!
Electrical current to energize the PTO solenoid as desired
!
Signals to the display unit, indicating the transmission range and direction
!
Signal to engine conversion relay
!
Pulsed signal proportional to output speed to drive a speedometer
Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Operation
ETA 28-L Electronic Control Functions The following is a description of system functions as various range selections are made. Designations shown correspond to range selections available at the range selector lever.
R--REVERSE Selected Differential lock is allowed. Torque converter lockup clutch engagement is controlled by software in the electronic controller. Reverse alarm circuit activated by closure of reverse alarm switch (switch #6).
N--NEUTRAL Selected Torque converter lockup clutch and transmission range clutches are disengaged. Selector lever must be in N to enable engine start and during power up of the electronic control system.
D6 Automatic range shifts from 2nd to 6th are permitted based on output shaft speed and throttle position. Torque converter lockup clutch is automatically applied in ranges 2nd through 6th based on turbine speed. When the differential lock is selected, automatic shifts and torque converter lockup include 1st range. The differential lock is available in range 1, 2, 3, and 4. D6 is used to select 3rd range when operating in manual override mode.
D5 Automatic range shifts and torque converter lockup clutch application are allowed in 2nd through 5th ranges based on same criteria as in D6. Differential lock is available in 1st through 4th ranges. When the differential lock is selected, automatic shifts and torque converter lockup includes 1st range.
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Twin Disc, Incorporated
D4 Automatic range changes and torque converter lockup clutch application are allowed in 2nd through 4th ranges based on same criteria as in D6. Differential lock is available in 1st through 4th ranges. When the differential lock is selected, automatic shifts and torque converter lockup includes 1st range.
D3 Automatic range changes and torque converter lockup clutch application are allowed in 2nd and 3rd ranges based on same criteria as in D6. Differential lock is available in 1st through 3rd ranges. When the differential lock is selected, automatic shifts and torque converter lockup includes 1st range.
D2 Transmission is held in 2nd range. Torque converter lockup is available based on turbine speed. Differential lock is available in 1st and 2nd ranges. When differential lock is selected, automatic shifts and torque converter lockup includes 1st range.
D1 First range only is allowed. Lockup is available with engine brake selected. Differential lock is available.
Differential Lock Switch The differential lock switch is a normally open switch that when closed signals the control to engage the inter-axle differential clutch. The differential clutch is controlled by an on/off solenoid and will not be engaged if the differential lock switch is open (not selected).
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Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Operation
Differential Clutch The function of the differential clutch is to lock the front and rear transmission output shafts together to assure equal delivery of power to front and rear axles of the vehicle. The differential clutch may be engaged in all ranges except 5th and 6th. In neutral, reverse, 1st, 2nd or 3rd, the differential clutch will be engaged when the differential lock switch is turned on. In 4th range with the differential lock switch selected, operation of the differential clutch is automatic. In this situation the differential clutch will be engaged if slip exceeding 12% is detected. Slip is monitored continuously when the clutch is off, and the clutch will remain off until slip exceeding 12% is detected. When slip conditions remain above 12% for a period of time, the clutch will cycle 20 seconds engaged followed by 2 seconds or less disengaged. The disengaged interval allows the release of any wind-up in the drive train before speeds are checked for slip. If either the turbine or the transmission speed sensors should fail, the differential clutch will respond directly to movement of the differential lock switch, but will be restricted to 3rd range or below.
Pump and Roll Switch This is used to select the vehicle pump and roll mode, and is available in all transmission ranges and can be selected at any time by rotating the switch.
Stationary Mode Switch This should only be engaged when the vehicle is stationary, the range selector is in N, and the accelerator pedal is at idle.
Stationary PTO Switch The stationary PTO switch is used to engage and disengage the PTO in the stationary and manual override modes.
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Operation
Twin Disc, Incorporated
D.C. Power Supply Input power to the electronic control is supplied by customer wiring and components. Refer to drawing number 1018316 in Engineering Drawings. The positive lead should be connected directly to the positive battery post with no other loads. The circuit protection device must not exceed time/ current characteristics of an ATO type fuse. A relay is used to turn the control power on and off. The relay is usually connected to the vehicle switch so power is supplied to the control only when the vehicle switch is in the on or run position. The system ground is through a single wire connected directly to the battery negative. There are no other connections to the battery negative or vehicle chassis . The electronic control is active when applied voltage is between 9 and 14 volts DC. NOTE: The 10 amp input power circuit protection device must not exceed the time/current characteristics of an ATO type fuse. If the installed device is larger or slower responding than specified the control could be damaged and made inoperable.
Interruption Of Power 1.
Interruption of power to the electronic control for 100 milliseconds or more will require resetting the input power to the electronic control once the input voltage has been restored above the 9 volt DC level.
2.
No outputs are enabled unless the selector lever is in N on power up. This means that after regaining power from some power fault, the selector lever must be returned to N even if the vehicle is moving. Movement of the selector out of N will not be acknowledged unless the selector lever has been in N for more than 0.25 seconds. This is to ensure that the shift is intentional.
3.
When the selector lever is moved out of N after a power interruption, the control will select and engage a range based on transmission output speed. NOTE: If the vehicle is moving, the selector lever should only be moved to engage a range in the direction the vehicle is moving. For example, if the vehicle is rolling forward move the selector lever to a forward position only. Requesting a direction change following a power interruption could cause serious damage to the transmission or drive train.
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Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Operation
ETA 28-L Electronic Control System Components
Electronic Control Monitors and controls system through four wiring harnesses. The control has no preferred mounting orientation.
Power Relay (Vehicle manufacturer supplied) Usually connected to the vehicle switch to supply power to the control only in the on or run position. Power may be removed from the control during starter engagement (thus the control is turned off and back on when the engine is started).
Range Selector Six forward positions, neutral, and reverse are available on the range selector. Range selector switches are shown in drawing number 1018316 in Engineering Drawings. The selector position communicates to the control the operator’s request for a desired operation. The control will respond when conditions are correct for a change. For example, the vehicle may be moving forward and the operator may move the selector to request R, but the control will not engage reverse until the transmission output speed (forward direction) is low enough so the power train will not be damaged. The selector must be in N when the starter is engaged (so vehicle does not lunge forward or reverse unexpectedly when the engine starts). The #7 switch in the selector closes in neutral to supply power to the start switch. If the selector is not in N, no power is supplied to the start switch, and the starter will not engage even if the operator turns or presses the start switch. Note that electrical power is supplied directly to the switch in the selector, and power goes from the neutral start switch to the start switch. The electrical power for the start switch only passes through the switch in the selector. The electronic control is not involved in the neutral start feature.
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Operation
Twin Disc, Incorporated
A neutral disconnect switch, #2 in the selector, is open when the selector is in N so the electronic control is not able to energize most of the solenoids. This provides a redundant neutral for safety - control cannot engage transmission clutches when the selector is in N. The reverse alarm is activated when the selector is placed in the R position. Power is supplied to the reverse alarm #6 switch in the selector. When the selector is in the R position, the switch closes and passes the power on to activate the reverse alarm. Note that the electronic control is not involved in operation of the reverse alarm, only the switch in the selector and the wires connected to it. This switch is also used in manual override operation to activate reverse range.
Differential Lock Switch When the differential lock switch is closed it signals the control of the operators request to turn on the differential lock clutch in the transmission (locks the front and rear output shafts of the transmission together). The control will turn the differential clutch solenoid on when conditions are appropriate. If the control has reverse, 1st, 2nd, or 3rd range engaged, it turns on the differential clutch solenoid. If the control has 4th range engaged, the differential will be turned on only if a significant difference exists between the expected and actual output speed (control knows transmission input speed and gear ratio) indicating that the front or rear wheels are “spinning”. The control will not turn the differential solenoid on if it has 5th or 6th range engaged.
Work Mode Switch When the work mode switch is selected and other vehicle conditions are met, the electronic control converts vehicle operation to the work mode.
Diagnostics Test Switch and Connector Normally closed push button switch used during diagnostic tests and an integral plug that is used to enter diagnostics test mode.
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Operation
Speed Sensors Voltage signal is generated as each tooth of a gear moves past the sensor. This results in an ac voltage signal with a frequency determined by the frequency of a tooth passing the sensor. The control knows how many teeth are on the gear under the sensor and converts the frequency of pulses to determine gear/shaft RPM. Turbine speed sensor measures torque converter output speed (equals transmission input speed). The sensor is mounted on the upper part of the transmission. The output speed sensor measures output speed of one of the output shafts on the transmission. The control uses the input and output speed information when determining appropriate transmission range, engagement of the lockup clutch, etc. Resistance of the sensors is approximately 1100 ohms. The control does not measure the voltage of the speed sensor signals, it only uses the frequency of the pulses. The amplitude (voltage) of the signal is determined by the velocity of the gear tooth as it passes the sensor and the gap between the gear tooth and the end of the sensor. The sensor must be close to the gear to generate a signal that is large enough to reach the control where the frequency is measured. Measuring the voltage of the speed sensor signal would only be useful for verifying that the sensor is generating a signal. The control checks resistance of speed sensor circuits frequently. If value is found to be out of range, a status code is shown on the display to alert the operator. This could indicate a fault in a wire to the sensor or in the sensor itself. The control also knows what range is engaged and the transmission ratio. It alerts the operator if it does not receive a frequency signal from one of the sensors when it expects to see one. For example, the control will show a status code if it sees signal indicating output speed, a range is engaged, and it sees no signal from the turbine/transmission input speed sensor.
Accelerator Potentiometer Potentiometer linked to the accelerator pedal mechanism which provides the control a voltage signal varying from 0.5 volts dc (at the sensor) at idle position to 3.6 volts dc (at the sensor) at full throttle position (control will alert operator with a status code if voltage is out of this range). Throttle position tells the control if the operator is trying to accelerate (pedal is partially depressed) or if the throttle pedal is released indicating coasting or deceleration. Shifts may be made at different points or may be quicker (harsher) or slower (softer) depending on a variety of inputs the control is monitoring.
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Operation
Twin Disc, Incorporated
Display The liquid crystal display (LCD) is usually installed on the vehicle dash. It indicates the transmission range that the control has engaged. It is also used to inform the operator if the control has detected a fault in one of the external circuits, and is used during the diagnostics test to communicate with the operator.
Solenoid and Electric Modulating Valves Solenoids (S1, S2, S3, S4, and SD), and electric modulating valves (M5, M6, ML, MI) are used for controlling high pressure oil being directed to engage clutches. They are all identical cartridge valves that are capable of being used as proportional modulating valves. S1, S2, S3, S4, and SD are controlled with an on/off signal. These pressures are either full on or full off. M5, M6, ML, MI are controlled with a signal type that can control pressure full off, full on, or at intermediate levels as needed for proper vehicle shifting and control. Resistance of these solenoids ranges approximately between 5 and 11 ohms depending on temperature. The electric modulating valves (M5, M6, ML, MI) are used to control the engagement of a particular clutch. The control is able to turn these valves on from 0 to 100 percent. The oil flow/pressure supplied to the clutch pack can be more precisely controlled with these valves. This is especially important when the control changes transmission ranges - turning some clutches off and others on. Solenoid SP is strictly an on/off solenoid, capable of full off or full on only. The resistance of this solenoid is approximately 10 ohms. The on/off solenoids are not polarity sensitive - current in either direction will energize them. The control knows the appropriate resistance of each of the valves and the wires to/from the valve and checks the external circuits continuously. If it detects a value that is out of range, it shows a status code on the display to alert the operator to check the circuit and the valve. This will alert the operator if a wire is cut or plug comes unplugged, etc.
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Power Shift Transmission System Service Manual
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Operation
Filter Sensor Detects pressure across the oil filter (inlet pressure vs. outlet pressure). When pressure reaches a high level (filter starting to plug) the control will alert operator with a status code.
Output Signal to Speedometer A pulsed output signal with a frequency equal to output speed sensor frequency divided by 4 is provided by the control. Based on the 60 teeth on the output shaft sprocket, the signal provides 15 pulses per output shaft revolution.
Oil Temperature Sensor This sensor is located in the transmission clutch oil supply circuit. It is used to modify shift profiles to compensate for the affects of temperature. The sensor is a variable resistance element that provides an analog signal to the control. The sensor excitation is 8.6 volts via a 3K resistor.
Engine Conversion Relay A set of normally open relay contacts close when the controller is in pump or stationary mode. The customer supplied engine speed control sets the engine speed for PTO operation when these contacts are closed. The contacts are rated for a nominal one amp noninductive load and are isolated from other controller circuitry.
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Operation
Twin Disc, Incorporated
Hydraulic System See hydraulic system schematic and piping diagram in the drawing section of this manual. The hydraulic system provides oil at correct pressures and flows for operation and lubrication of the transmission and torque converter. A cascading-type system is used, wherein the demand for pressure and flow for transmission functions are supplied in sequence from a single pump. Regulator valves control and maintain the necessary pressures for each function. As the demand for pressure and flow are met for one area of the system, oil is cascaded to meet the demands of the next area. Hydraulic system components and their functions are as follows:
Transmission Sump The sump is located in the bottom of the transmission housing and serves as a reservoir for all oil used in the system. Oil level is checked with two sight glasses on the side of the transmission. Please refer to Preventative Maintenance for oil level check and filling procedures. A suction screen installed in the reservoir prevents debris from being drawn into the pump inlet. This screen is not serviceable from the outside.
Pump The pump is a positive displacement gear-type, rated at 32 gpm (121 L/min) for the front element and 15.6 gpm (59 L/min) for the rear element at 2100 rpm engine speed.
Main Pressure Regulator Valve The main pressure regulator valve maintains main system pressures for application of clutches. Please refer to Description and Specifications for designed pressure limits. Main system pressure, opposed by preset spring tension on the back side of the regulator piston, causes the valve to open and cascade excess oil into the torque converter circuit, thereby maintaining system pressure at the desired value. As main pressure is building up, oil passes through an orifice into lube to provide for lubrication during start-up.
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Power Shift Transmission System Service Manual
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Operation
Cold Oil Relief A spring and ball located in the main regulator valve sense pressure at the outlet port. Excessive pressure causes the ball to open and bypass oil to the lube circuit which protects the converter.
Converter Regulator Valve The torque converter circuit oil pressure is regulated by the converter regulator valve that is located in the converter housing of the torque converter. This regulates the converter circuit outlet pressure to the desired level, and the oil is then discharged through the oil cooler and into the lube oil circuit of the transmission.
Lube Regulator Valve The lube regulator valve maintains lube system pressure at the desired level. Please refer to Description and Specifications for pressure limits. Lube is provided for lubrication of bearings and splines, and for lubricating and cooling clutches. The maximum lube pressure is limited by cascading the excess oil to the transmission sump.
Transmission Range Actuating Valves Two proportional cartridge valves are housed in each of three valve bodies that are also the clutch shaft end caps or collectors. When a range is selected, the valve solenoids for that range are energized, permitting regulated main pressure to apply the desired clutch packs. When another range is selected, the solenoids for the new range are energized, and the solenoids for the previous range are de-energized, allowing the passage of clutch apply oil to the sump, thus releasing the clutch. Two of these valves are supplied with signals that are capable of controlling the pressures at intermediate levels to aid in shift profiles, and four are used as on/off solenoids.
Converter Lockup Clutch and Modulated Input Clutch Valve Two proportional cartridge valves are mounted in the converter regulator valve body to supply pressure to the lockup clutch and to the converter input clutch. Main pressure is supplied to this valve from the main pressure regulator on the transmission.
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Operation
Twin Disc, Incorporated
Differential Clutch Apply Valve A proportional cartridge valve is located on the front of the transmission housing, and is used by the control system to apply the differential clutch when the operator has selected this option, and the control senses the proper conditions.
PTO Actuation Valve An on/off solenoid is located on the PTO clutch rate of rise valve located on the PTO at the right rear of the torque converter. This solenoid supplies oil to the pilot spool and rate of rise portion of the valve, resulting in a controlled pressure rise to the clutch. The PTO solenoid is energized by the control system or the operator, depending on the conditions that exist.
Power Flow The torque converter driving ring bolts directly onto the engine flywheel. The internal teeth of the driving ring mesh with the gear teeth on the rotating housing. The rotating housing provides input power to the input clutch. The output of this clutch is connected to the impeller wheel of the torque converter. Power flow system components and their functions are as follows:
Converter Drive When in converter drive, with the input clutch engaged, converter fluid is moved by the impeller blades and directed against the turbine wheel blades, driving the turbine wheel assembly. Since the turbine wheel assembly is spline connected to the output shaft, the output shaft is driven. After the fluid passes through the turbine wheel blades, it is redirected to the impeller wheel blades by the stator blades. When output torque requirements exceed input torque, the freewheel unit on the stator is locked up. However, when output torque requirements are equal to, or less than, input torque, the stator freewheels. Disengaging the input clutch disconnects the impeller from the engine. The pumps and power take off will still run at engine speed.
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Power Shift Transmission System Service Manual
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Operation
Lockup Clutch Drive The lockup clutch is controlled automatically through the electronic control system. When the lockup clutch is engaged, power is transmitted from the rotating housing, through the steel driving plates which are spline connected to the rotating housing, and to the friction clutch plates by clamping action of the engaged clutch. The friction clutch plates are spline connected to the turbine hub. The turbine hub is spline connected to the output shaft. Thus, the lockup clutch provides direct mechanical drive.
Freewheel Function When the lockup clutch is engaged, the freewheel assembly allows the stator to freewheel. This improves the unit efficiency. The freewheel assembly locks the stator to the stator carrier during converter operation. This allows the torque converter to multiply engine torque.
Transmission Power flow is from the engine through the torque converter output shaft to the input yoke on the front of the transmission input shaft. The three driver gears, one on the rear of each of the two 7-inch clutch shafts and one on the rear of the 9-inch clutch shaft, are connected to their shafts. The gears on the two 7-inch clutch shafts are connected by a tapered interference fit, and the gear on the 9-inch clutch shaft is connected by a spline. Whenever the engine is running the input (7-inch clutch) shaft and its driver gear will turn engine direction. The driven 7-inch clutch shaft is rotated by its interference fit driven gear, which meshes with the input shaft driver gear, causing the gear and shaft to rotate in anti-engine direction. If the transmission is in neutral, the power flow stops at this point. In order to have power to the wheels, one 7-inch clutch and one 9-inch clutch must be engaged.
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Operation
Twin Disc, Incorporated
Action of the Differential In all ranges, input to the differential is through the driving gear on the 9-inch clutch shaft to the driven gear bolted to the outside diameter of the differential housing. The differential housing is bolted to the planet carrier. All output torque from the range clutches passes through these driven gears turning the differential housing and planet carrier. Within the differential are one sun gear, one ring gear, a planet carrier, and a set of planet gears. There are two output shafts. The sun gear is spline-connected to the rear output shaft. The ring gear is spline-connected via the clutch spider and the differential housing to the front output shaft.
Operation When the planet carrier rotates, the front and rear output shafts are rotated by the planet gear driving the sun and ring gears. If the rear output shaft meets some resistance, the planet gears will rotate inside of the ring gear. The sun gear, planet gears, and front output shaft will continue to rotate. If the front shaft is stopped and the rear shaft is free, the planet gears walk around the sun gear. The ring gear, planet gears and output shaft continue to rotate. This principle can be applied when either shaft must rotate slower than the other. When the differential clutch is applied, the differential is locked and turns en masse with both output shafts turning at the same speed as the differential housing. This clutch is applied when the proportional cartridge valve is energized by the control system when the differential lock switch is closed and specific conditions are met. See drawing number 1018205 in Engineering Drawings.
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Twin Disc, Incorporated
System Operation Start Up 1.
Selector lever must be in N. This closes the neutral start switch #2 in the selector, which supplies power to the Start switch.
2.
Activate the start switch to supply electrical power to the starter circuit. A relay is normally used to remove electrical power from the control during starter engagement.
3.
When the operator releases the start switch, the switch returns to the on or run position. The power relay will energize and again supply electrical power to the ETA-28L electronic control.
Vehicle Operating Modes The are five modes of operation: Drive mode, pump and roll mode, stationary mode, manual override mode, and diagnostic mode.
Normal Operation in Drive Mode Power is supplied to the control box when the vehicle switch is turned on. The control box does a self test sequence, and upon passing this, looks at the various input signals. If the range selector is in N, the operator is allowed to start the engine. The control box continuously monitors the various inputs, and outputs to prevent improper operation of the transmission system.
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Operation
Twin Disc, Incorporated
When the operator selects a maximum forward drive range (D1 through D6), the control box monitors the transmission output speed to select the appropriate transmission clutches to engage. If the vehicle is stopped, and the transmission input speed is below a preset speed condition, the transmission will go into 2nd range. Note that if the differential lock switch has been selected, the transmission will go into 1st range. The transmission will then upshift and downshift automatically, between the maximum gear selected and 2nd based on the transmission input and output speeds, throttle position, and engine torque signal level, and the converter lockup clutch will be applied to obtain direct drive through the torque converter. If the differential lock switch has been selected, the transmission will upshift and downshift automatically between the maximum gear selected and 1st. The control box monitors the throttle pedal position, and will not allow automatic upshifts if the pedal is not applied. The display shows the letter D and the corresponding range that the transmission is in while in forward, and the letter R1 when in reverse. Movement of the range selector lever from a forward range to N and back to a forward range (i.e. D6 to N to D6) while the vehicle remains in motion will cause the transmission to be engaged in a range corresponding with output shaft speed. Subsequent automatic upshifts or downshifts will be made based on selector lever position, output shaft speed and throttle position. If the operator moves the transmission range selector into N while the vehicle is moving forward, the transmission will shift into neutral, and the control box will monitor the transmission output speed. If the selector is moved back into a forward range, the control box will calculate the appropriate gear range, and shift to it regardless of the maximum forward range selected. If the operator moves the selector to the reverse direction while still moving forward, the transmission will remain in neutral until the transmission output speed slows to a predetermined speed to prevent damage to the transmission. The differential lock may be applied in all ranges except 5th and 6th. In 1st, 2nd, 3rd, neutral, and reverse, the differential lock clutch will engage immediately upon closure of the differential lock switch. Clutch operation in 4th range is automatic. When 4th range is engaged and the differential lock switch is closed, the clutch will engage when 12% slip is detected. The power take off (PTO) is never allowed to engage in the drive mode.
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Operation
Examples of Operation Basic: Vehicle is on a paved road. Differential lock is not selected. Operator starts truck. Selector is placed in reverse. Control looks at all of the inputs and decides it is appropriate to engage reverse range in the transmission. Control energizes one solenoid valve and one modulating valve to engage two clutch packs in the transmission. See drawing number 1018316 in Engineering Drawings. Appropriate valves for reverse are #4 and #5. Two clutch packs must be engaged in the transmission to transmit power to the wheels. Operator releases vehicle brakes. Operator depresses accelerator, engine provides power to the torque converter, output of torque converter provides power to the transmission, output shaft provides power to the driveshafts to move the vehicle in reverse direction. The vehicle speed will respond to the operator moving the accelerator pedal or activating the brakes. Operator stops the vehicle using vehicle brakes. Operator moves selector to the D6 position. Control looks at inputs, and energizes two valves to engage 2nd range. (1st range used in certain conditions only - differential lock selected or selector placed in D1 position). Control will respond to changes in the inputs. Operator depresses accelerator pedal - power is provided to wheels. When vehicle speed (transmission output speed) reaches an appropriate point, the control will engage 3rd range. As the vehicle continues to accelerate (operator still pressing accelerator), control will engage higher ranges as they become appropriate. With the selector in the D6 position, the control may engage ranges up to 6th range. Converter lockup clutch may also be engaged in all of the ranges when conditions are appropriate. Converter lockup clutch connects the converter output directly to the engine through the clutch pack, bypassing the use of the torque converter circuit to transmit engine power directly to the transmission. This is an efficient operating condition and the transmission input RPM will equal engine RPM. Control will continue to respond to changes in inputs. If control has 6th range engaged and the truck approaches a hill, the vehicle may slow down. Control will engage 5th if output speed reaches appropriate point. If operator stops pressing the accelerator and presses the brakes, the control will select appropriate transmission range as the output speed decreases, all the way down to 2nd range if the vehicle slows that much. If operator presses the accelerator, the control will continue to select the appropriate transmission range as the speed changes. If the vehicle is rolling when the operator depresses the accelerator, the control sees that the operator is trying to accelerate (pedal depressed), and it may decide it is appropriate to select a lower range to provide quicker acceleration.
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Operation
Twin Disc, Incorporated
NOTE: Operator interface consists of having the selector in a forward position, pressing/releasing the accelerator pedal, using vehicle brakes as needed. The control will automatically select and engage appropriate transmission ranges and engage the lockup clutch when conditions are appropriate.
Normal Operation in Pump and Roll The pump and roll mode is available in all transmission ranges, and can be selected at any time. In this mode, the PTO clutch is engaged, and vehicle’s engine speed is controlled independent of the throttle pedal. The vehicle speed and tractive effort is controlled by the throttle pedal that is now controlling the converter input modulated clutch, which is allowed to slip as necessary to control the vehicle speed. The vehicle speed is controllable from a stopped condition, up through a considerable speed, depending on the transmission range selected and throttle pedal position. The converter lockup clutch is not applied in the pump and roll mode. The display shows the letter P and the corresponding range that the transmission is in. Drive mode is available at any time while operating in the pump and roll mode. When the drive mode is selected, the control box monitors the vehicle output speed, and if it is above a predetermined level, engine speed control is immediately given back to the throttle pedal, and the transmission shifted into the appropriate range for the vehicle speed. If the vehicle output speed is below this level, engine control is immediately given back to the throttle pedal, the display shows blank, and the transmission held in neutral for a short period of time before shifting into the appropriate gear range based on the output speed. As soon as the transmission is shifted into a gear, the display will again show D and the corresponding range.
Normal Operation in Stationary Mode Stationary mode should only be selected when the vehicle is stopped, and the engine idling with the transmission in neutral. Electrical power is removed from the transmission, except power will be supplied to the stationary PTO switch. The power take off will then be controlled on or off by this switch. The throttle pedal will not control anything in this mode, and the engine speed will be controlled by external means.
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Operation
Manual Override Mode Manual override mode allows limited operation of the transmission in neutral, 3rd and reverse when difficulties with the controller occur. In manual override mode, the controller is unpowered, the accelerator pedal controls engine speed, and the modulated converter clutch is fully engaged. To engage manual override: stop the vehicle, place the selector in N, and rotate the override switch to the manual override position. To move the vehicle forward, wait until the engine speed is at idle, then move the range selector to D6. To move the vehicle backward, wait until the engine speed is at idle, then move the range selector to R. To limit vehicle speed, apply vehicle brakes. To increase vehicle speed, depress the accelerator pedal. Moving the range selector to N, disengages the transmission clutches. To engage the PTO, move the mode selector switch to the pump position. Both vehicle speed and PTO speed are controlled by the vehicle accelerator pedal position.
Operating the engine at high speed with the vehicle brakes applied, stalls the torque converter and generates considerable heat in the transmission hydraulic circuit. If greater PTO (pump) speed is needed, place the selector in N while applying vehicle brakes and use the vehicle accelerator pedal to increase engine speed and pump flow. To disengage manual override and return to normal controller operation, stop the vehicle, place the selector in N, allow the engine speed to return to idle, rotate the manual override mode switch to the normal operating position and repower the controller.
No direction change inhibit occurs in manual override mode. Selected ranges will be engaged immediately, regardless of engine speed or vehicle direction of travel.
Selector changes should only be performed with the engine at idle and the vehicle stopped. Failure to do so could cause harsh transmission engagement or engagement in a direction opposite of vehicle travel, either of which could cause injury to personnel or damage to equipment.
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Operation
Twin Disc, Incorporated
Diagnostics Mode Diagnostics mode is available for controller system tests, and for ease in certain troubleshooting procedures. These tests verify operation of the controller, integrity and function of the external circuits, and provide a means to energize clutches individually. Nine separate tests can be individually selected and performed with the switch assembly and two character display. Please refer to Troubleshooting for the correct troubleshooting procedures. This mode is entered by separating the two sections of the flat connector located in cable J1 and reconnecting them such that an electrical path is completed through the connector. Electrical power must be removed from, and re-applied to the control to enter this mode.
Operational Problems If the normal operation of the vehicle is not occurring. Please refer to Troubleshooting for the correct troubleshooting procedures. A clear understanding of the normal operation of the vehicle systems is essential to understand and troubleshoot any problems.
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Preventative Maintenance
Preventative Maintenance
General
Lubrication Lubrication for the TD-61-1180 transmission and the 8-MLW-1755-1 torque converter is accomplished by a full pressure system utilizing oil in the transmission sump. The transmission sump is the reservoir for all oil used in the hydraulic and lubrication systems. No lubrication is required beyond a daily check of the transmission oil level with the sight gauge.
Transmission/Converter Overhaul Interval A complete overhaul of the transmission and converter should be accomplished at the same time as a scheduled engine overhaul. This is to minimize down time. Parts indicating wear, or damage should be replaced at this time.
Hydraulic System
Checking Oil Level The oil level in the transmission must be checked after each use. Procedure for checking oil is as follows: 1.
Visually inspect the transmission, converter and drive line for security of mounting. Inspect plumbing and electrical components for security of attachment and/or leaks. Leakage must be corrected.
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Preventative Maintenance
2.
Twin Disc, Incorporated
Oil level procedure: It is best to check the oil level after the truck has been setting with the engine not running for at least 4 hours. The truck should be parked on a level surface. a.
With the engine not running, both oil level sight glasses should show full. Add oil if both glasses do not show full.
b.
Set the vehicle brakes and start the engine. With the engine at low idle, the transmission in neutral, and with cold oil (10 to 35 deg C) the oil level should be at the middle of the lower sight glass.
c.
Apply the foot brakes, shift to D6 and run the engine at 1500 RPM until the transmission oil reaches 100 deg C. Lower the engine to low idle and shift to N. The oil level should show full in the bottom sight glass and 1/2 to full in the upper sight glass.
Adding Oil The oil fill plug is located on the rear face of the transmission. Refer to Figure 3 in Operation. Add or remove oil as needed to set proper level.
Do not operate the transmission with oil levels above or below the recommended settings. Either condition can result in overheating or loss of power and damage to the equipment. When following this oil check procedure be sure the vehicle parking brakes are on. The vehicle wheels should also be blocked or the truck parked up against an immovable object.
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Preventative Maintenance
Oil/Filter Change Interval Change the transmission oil after every 1200 hours of operation. Change the oil filter after each 300 hours of operation or sooner if the filter pressure indicator shows FP in the display. Note: The FP code is triggered by a switch that senses pressure drop across the filter. As the filter fills with contamination the pressure drop increases. A filter may show an FP code under cold oil conditions at high engine speeds even though the filter is still usable. With oil temperature between 0 and 35 deg C at low idle engine speed and with oil at 80 to 100 deg C at any engine speed the FP code should not appear. If it does come on under these conditions, the oil filter must be changed as soon as possible. When changing the oil in the transmission system drain the transmission sump and the engine flywheel housing. Change the oil filter. When installing new units or newly rebuilt units it may be necessary to replace the oil filter after a few hours of operation. Monitor the filter pressure indicator for the FP code.
Recommended Oil
Oil Classification Use specified engine oil viscosity grade that meets one of the API service classification: CF, CF-2, CG-4, or CH-4 per SAE J138a and the requirements of Caterpillar TO-2 and Allison C4 specifications or the requirements of MILL-2104E.
Oil Viscosity The approved viscosity for this application is SAE 10W. Some multi-viscosity oils (SAE 15W40) have also been approved in this transmission. Contact Twin Disc for approval.
Filter Requirement A filter is to be installed between the main pump outlet and pressure regulating valve. Provision is made for the filter and it is shown on the hydraulic schematic. The Twin Disc part number for replacement filter elements is 1016502.
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The Twin Disc filter or equivalent must be used to assure transmission warranty consideration.
Periodic Visual Inspection Periodically, inspect all transmission and converter mounting points for security and/or damage. Re-torque any loose mounting bolts and replace any damaged parts. Check the drive line fasteners at the converter and transmission yokes. Check all electrical wiring components (switches, magnetic pickups, etc.) and connections for security, chafing and/or other damage. Tighten loose connections and replace any damaged parts. Reroute or otherwise secure wiring to prevent chafing damage.
Control Cables and Wiring Inspect and care for control cables and harnesses as follows:
52
1.
The connector end of the control cable or harness must be secured to its own support six inches back from each connector. The cable or harness must be secured at 18-inch intervals to its own frame supports between the cable or harness ends.
2.
Keep cable or harness away from hot surfaces, moving parts and oil locations.
3.
Attach cable or harness to machine, making the connector the highest point of the cable. If not possible, install cable or harness with drip loop.
4.
Protect cable or harness with grommet, loom or flex guard at any rub point, particularly when passing a sheet metal hole.
5.
Locate cable or harness away from potential hazards. For example: a screw cutting through the jacket and shorting a conductor to the chassis, welding, drilling, etc.
6.
Prevent the cable from becoming a step or hand rail.
Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Preventative Maintenance
7.
When mating connectors, make sure they will mate properly. Coat pins and sockets only with dielectric compound to seal out moisture and corrosive substances (Twin Disc part number MA890 or Dow 4 Compound.) Locate and use the connector orientation key.
8.
Circular connectors must be hand tightened.
9.
Cable or harness bend radius must not be less than twenty times the cable diameter.
10.
Avoid twisting or winding cable along its axis during installation or removal.
11.
Whenever mating connectors, always inspect each for damage or defects. For example: bent pins, pushed-back sockets, broken keys, etc.
12.
Check that sure-seal connectors have clip/clamps in place.
13.
Check the cable or harness tie downs. Keep cable securely fastened to machine frame.
14.
Check the condition of the cable or harness at any rub point and wherever the cable passes through a sheet metal hole.
15.
Check cable or harness for cracks, effects of vibration, abrasion, brittleness or abuse.
Hydraulic Lines, Flexible Hoses and Connectors Inspect all hydraulic lines, hoses, etc. for damage, sponginess, loose connections, chafing, etc. Correct leaks and replace damaged parts. Lines, hoses, etc. which show evidence of chafing should be replaced, rerouted, and/or otherwise protected to prevent further damage.
Externally Mounted Components Periodically inspect split lines between housing halves and between externally mounted components such as valves and covers for leakage or damage. Repair leaks and/or replace damaged parts as required.
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Twin Disc, Incorporated
Preventative Maintenance
Hydraulic System Pressure Checks At the time of each transmission oil change the main and lube pressure of the transmission should be checked. See Figures 2, 3, 4, and 5 in Operation for pressure test point locations. Prior to making pressure checks, ensure that the transmission is filled with oil of the correct type.
Pressures should be measured with gages or instrumentation that allows the technician to be at a safe distance from the vehicle tires. Gages must be installed while the engine is not running. Pressure checks are made with the engine running, the transmission in neutral, and the vehicle parking brakes on. No one must be allowed in front of, nor behind the vehicle nor near the vehicle tires. Check main and lube system pressures as follows:
54
1.
Select desired check point and install 0-300 psi (0-2000 kPa) pressure gauge to check main and clutch apply pressures, and 0-100 psi (0800 kPa) pressure gauge for lube system.
2.
Apply the vehicle parking brakes and start the engine. Shift to D6 and bring the engine up to 1500 rpm. Allow the transmission oil to heat to 80 to 100 deg C.
3.
Refer to pressure requirements in Description and Specifications.
Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Troubleshooting
Troubleshooting General This section of the maintenance manual has been prepared to assist maintenance personnel in troubleshooting the power shift transmission and control. When troubleshooting the equipment, always remember to consider the entire power package of the vehicle. Interaction between the transmission, the engine, and the vehicle functions are all part of the troubleshooting process. It is suggested that you take some time to understand the operational characteristics of the transmission power system to more accurately diagnose the problem at hand. See Figures 1, 2, 3, 4, and 5 in Operation.
Pressure and Flow Test Kit A portable pressure and flow test kit NU 2451 is available and contains the necessary equipment to accurately test and troubleshoot the hydraulic system of this Twin Disc unit. The kit contains pressure gauges, hoses, adapters, and flow meters. Contact the Twin Disc Service Department, Racine Wisconsin for specific information concerning this test kit. One principle of troubleshooting is to start with the simple and move to the more difficult. Check the simple items first. Run the simple test first. Then move to the more difficult.
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Troubleshooting Discussion The troubleshooting discussion includes the following topics: !
Problems that do not produce a status code in the display
!
Problems that do produce a status code in the display
!
Pressure testing for troubleshooting
!
Recommended testing following field service repairs This should be performed after the installation of any major components such as transmission or torque converter.
Problems that Show No Status Codes in the Display See the troubleshooting flow charts, Figures 6 through 13, in Troubleshooting.
1.
Display is blank with the vehicle ignition in the on position Possible causes:
No dc Power to Control Verify that the proper dc voltage (12 volts) is supplied to the transmission control. Check the circuit breaker, relay or fuse in the electrical power supply to the transmission control box. Repair or replace the fuse, relay, or circuit breaker.
Loose Cables If proper voltage is being supplied to the control but the display is blank, check the cable connections between the display and the transmission control unit. Tighten all loose connections.
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Failed Control If the cable connections are tight but the display is still blank, either the display or the control box are defective. If the vehicle will still drive as it should, then the control unit is functioning properly. Replace the display unit. If the display is blank and the vehicle will not move, replace the control unit.
2.
Vehicle will not move in forward or reverse when the shift lever is moved out of N NOTE: If the display is blank, follow the procedures in Step 1 above. NOTE: If the display shows N when the shift lever is in the N position, and shows either R or D2 when the selector is moved out of the N position, then the display and control unit are functioning properly. Possible causes
Low Transmission Oil Level With the engine not running the oil level should be above the top sight level gauge. Start the engine and with the transmission in neutral, the engine at low idle and the vehicle brakes locked, watch the transmission oil level. The oil level should drop to the normal operating range within 10 to 15 seconds. If the oil level is low, add oil to bring to proper operating level. If vehicle now drives properly, low oil level was the cause of malfunction. If oil level is high and does not drop when the engine is running, either the oil level was set over full or the main pump is not supplying oil.
Failed Main Pump Since the vehicle will not move, it is possible that the pump is not supplying oil. Check main pressure with a pressure gage at the transmission main pressure test port “X”. At low idle, while in neutral, main pressure should be 170 to 190 psi. If main pressure is at or near 0 psi, the pump is not supplying oil to the transmission. Power Shift Transmission System Service Manual
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Pump Suction Leak Check for leaks in the suction hose between the pump inlet and the transmission. Suction leaks can be difficult to find. They may not leak oil out but they may allow air into the pump causing the pump to loose the ability to pump oil. Look for loose hose clamps, loose hydraulic fittings, or worn spots in the suction hose. If no pump suction leaks are found, remove and replace the main transmission pump mounted on the torque converter.
Failed Clutch Solenoid If there is partial or full pressure on a clutch that is not selected even when the opposite clutch on the same shaft is not selected, then remove and inspect the selector valve assembly. Check for a valve spool that may be stuck in the “engaged” position. If the solenoid is good, remove the shaft end cover and check for damaged or worn seal rings near the end of the shaft.
Failed Clutch Pack
DO NOT GET UNDER THE VEHICLE FOR THIS TEST! If the oil level is correct but the vehicle will not move, start the engine and while at low idle and with all vehicle brakes on, shift out of N into D6, and then R. With the vehicle operator still in the cab, an assistant should stand off to the side of the vehicle in a position where the drive shaft between the converter and transmission can be seen. Use a mirror under the vehicle if necessary.
When the range selector is in the N position the drive shaft between the converter and the transmission should be rotating. If the drive shaft is not rotating when in the N position, the transmission is lockedup internally or the torque converter is not transmitting power. When the range selector is shifted out of N the drive shaft should come to a stop quickly. If the drive shaft stops but the vehicle does not move, the transmission may be locked-up internally. If the drive shaft does not come to a stop when shifted out of N, one or more of the transmission clutches are not engaged properly. Further testing is required to identify the problem. 58
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Install pressure test fittings at each clutch pressure test port. See the test port locations in Operation. Go into the test modes T7 and T8. With the engine running, verify that the pressure at each clutch is at full pressure when selected and at zero pressure when not selected. On the transmission the solenoid valves 1,2,3, and 4 (S1,S2,S3,S4), are used as on/off valves and T7 is used to test these. Proportional valves 5 and 6 (M5,M6) on the transmission and the proportional valves on the torque converter (MI,ML) are tested with T8 for a check of pressure versus percent of full current. If there is partial pressure on a clutch that is not selected only when the opposite clutch on the same shaft is selected, remove the shaft end cover and check for damaged or worn seal rings on the shaft. For this reason, it is important to observe pressure on the clutch when the opposite clutch on the same shaft is engaged. If no problems are found during the clutch pressure test, it is likely that a clutch pack has failed. Dark or burnt smelling oil is an indication of a failed clutch. A clutch pack may be seized, causing the clutch to be locked up. Or, the clutch pack may be worn out causing it to slip. The transmission must be removed to repair either condition.
Locked Axle or Brakes If no problems are detected during the clutch pressure tests, remove the front and rear output drive shafts from the transmission to verify that the vehicle brakes and/or axles are not the cause of the problem. With the transmission output drive shafts removed the transmission input shaft should spin regardless of shift selector position. The transmission output flanges should spin when the selector is not in N.
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3.
Vehicle only moves in forward Possible causes:
Failed Reverse Solenoid Valve If the display indicates R but the vehicle will not move in reverse, run test T7 and check pressure to the reverse clutch pack. If no reverse clutch pressure when engaged, then inspect, repair or replace the reverse clutch solenoid.
Failed Reverse Clutch If reverse clutch pressure is good when engaged but the transmission input drive shaft does not stop rotating when R is selected, then the reverse clutch pack is slipping internally. Dark or burnt oil is confirmation of clutch damage. Remove the transmission to repair. If reverse clutch pressure is good when engaged and the drive shaft into the transmission does stop when R is selected, but the vehicle does not move, it is possible that the opposite clutch on the same shaft is seized causing the transmission to stall. Remove the transmission to repair.
4.
Vehicle only moves in reverse Possible causes:
Failed 2nd/5th Range Solenoid Valve If the display indicates D2 but the vehicle will not move in forward, run test T7 and check pressure to the 2nd and 5th range clutch pack. If no pressure when engaged, then inspect, repair or replace the clutch solenoid.
Failed 2nd/5th Range Clutch If the 2nd/5th clutch pressure is good when engaged but the drive shaft into the transmission does not stop when D6 is selected, then the 2nd/5th clutch pack is slipping internally. Dark or burnt oil is confirmation of clutch damage. Remove the transmission for repair. If the 2nd/5th clutch pressure is good when engaged and the drive shaft into the transmission does stop when D6 is selected, but the vehicle does not move, it is possible that the opposite clutch on the same shaft is seized causing the transmission to stall. Remove the transmission to repair. 60
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As additional troubleshooting methods, try other selector positions or operating modes. This process of elimination will help to identify a failed clutch pack.
Select D1 Rather Than D6 On the Selector. D6 starts the truck moving in 2nd range but D1 starts the truck moving in 1st range. If the truck will drive in 1st but not 2nd range, then the low range 9" clutch is good and the 2nd/5th range clutch is likely bad. If the truck will not move in 1st, 2nd, or reverse, the low range 9" pack is failed. Check pressure on the low range 9" pack.
Go Into Test Mode T9 and Select D6 On the Selector. This puts the transmission in 5th range. If the vehicle drives in 5th but not reverse, 1st or 2nd, then it is likely that the low range 9" pack has failed. Check pressure on the low range 9" pack.
Do not drive the vehicle more than a few feet in test mode T8.
Connect the manual override mode and select D6 or R. This will put the transmission in either 3rd forward or reverse. This will determine if the low range 9", reverse or 3rd range packs are good.
5.
Vehicle will not upshift into the upper ranges Possible Causes:
Low Engine Power With the selector in N and the vehicle brakes on, fully press the throttle pedal. Maximum engine speed should agree with manufactures noload engine specification. With the transmission in test mode and T9 selected, apply the vehicle parking brakes and the foot brakes. Shift the selector to D6 (transmission will be in 5th range) and fully depress the throttle pedal. The loaded engine speed (loaded against the torque converter) should agree with engine application specifications. If the engine speeds do not agree with engine specifications it is possible that the engine is not performing as expected.
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Poor Engine Flywheel Scavenge Another possibility is that the engine flywheel housing is running with too much residual oil. The lube oil and normal leakage from the torque converter must be removed (scavenged) from the flywheel housing and returned to the transmission sump. This is done with the scavenge pump mounted on the torque converter. If the oil is not completely scavenged from the flywheel housing, the excess oil will cause drag on the engine. This will create both heat and loss of power. Poor flywheel housing scavenging can be detected by looking for heat discolored paint on the torque converter housing or on the transmission at the scavenge oil return port area. Or, after running the engine at low idle for a few minutes, shut the engine off, set the parking brakes on and feel the transmission housing in the area of the scavenge oil return port. If this area is much hotter than the other areas of the transmission, the scavenge return system is not working properly. Inspect and clean the strainer screen at the inlet side of the scavenge pump. Disconnect the hose at the outlet side of the scavenge pump and direct it to a bucket. Start the engine and observe if oil is coming from the pump. Initially the hose should run full until the oil from the flywheel housing is evacuated. While the hose is running full, catch the oil in a 2 liter or ½ gallon container and measure the time to fill the container. At 700 RPM, the pump should deliver 19.9 liter/minute (5.25Gal/ minute) or fill the container in about 6 seconds. When the flywheel housing is evacuated, the hose should flow a mixture of air and oil. If the pump outlet is below the expected value, check for damaged or loose hose or fittings in the suction side of the scavenge pump. Also, check the drain port at the bottom of the engine flywheel housing for obstructions. Replace the scavenge pump if necessary.
Failed Converter If the pump continues to deliver a solid stream of oil and the pump is delivering as expected , it is likely that the leakage from the torque converter is greater than normal and the scavenge pump can not keep up. The torque converter must be removed for repair. Raise engine rpm to approximately 1000 rpm and run for several minutes. Repeat the oil flow measurement at this engine rpm. A solid oil stream at this rpm supports the decision to remove the torque converter because of excessive leakage.
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6.
Converter/transmission does not go into converter lockup Repeat the engine performance and flywheel housing scavenge checks as in step 5. Other possible causes:
Lockup Clutch Solenoid With the engine running at low idle go into test T8, and select ML to verify that the converter lockup clutch pressure is following the pressure versus current %. Observe main pressure at the same time. Follow the instructions as outlined in the electronic test mode section. If lockup clutch pressure is low but main pressure remains normal, replace the proportional valve on the converter.
Lockup Clutch If lockup pressure is low and main pressure drops significantly as lockup is applied, then an internal leak in the lockup clutch apply section is likely. The converter must be removed for repair.
7.
Shifts harsh into certain ranges Possible causes:
Improper Main Pressure
Improper Speed Signal
Throttle Position Sensor Out of Adjustment
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Worn Clutch Pack Check for dark or burnt smelling oil.
Defective Temperature Sensor Go into test mode and select T4 to verify proper display voltage from the throttle position sensor and the temperature sensor. Adjust the throttle sensor if necessary. Replace the temperature sensor if necessary.
Slow Response from Solenoid Valve Select T7 and T8 to verify full pressure to each clutch pack and proper pressure versus % current for clutches M5, M6, MI, and ML. Watch main pressure at the same time. If main pressure drops and stays low when a clutch is engaged, there is an internal leak to the clutch. Remove shaft end cover and inspect piston rings. If main pressure drops only for a split second and then recovers to full, but the clutch pressure is still low, check or replace clutch solenoid valves.
8.
Transmission and/or torque converter oil runs hot Possible causes:
Too Much Oil in Transmission Adjust the transmission oil to the proper fill level.
Poor Scavenge from Engine Flywheel Follow engine flywheel scavenge checks as outlined in step 5.
Low Oil Flow Through the Converter and Cooler Measure transmission main and lube pressures and converter outlet pressure. Low pressure, especially low lube pressure is an indication of low oil flow through the torque converter. Replace the transmission main pump on the torque converter.
Cooler Not Working Properly Check vehicle cooling system.
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9.
Vehicle is poor in performance, lacks power Possible causes:
Poor Engine Flywheel Scavenge Run flywheel scavenge checks and engine performance checks as outlined in step 5.
Engine Not Performing Properly Too Much Oil in Transmission Adjust transmission oil level.
Low Converter Outlet Pressure Measure converter outlet pressure. With the transmission in neutral and the vehicle parking brakes applied, measure converter outlet pressure at low engine idle speed and at 2100 RPM. Converter outlet pressure should be 50 to 70 psi (345 to 483 kPa) at low idle and 70 to 90 psi (483 to 621 kPa) at 2100 RPM. Values will vary somewhat with oil temperature. Pressure well below specification will produce poor converter performance. Check the converter pressure regulator for a broken spring or stuck spool. Check the transmission lube pressure as well. Low lube pressure is an indication of low transmission main pump flow. Replace the main pump.
10.
Transmission system loses oil Possible causes:
Leaks in Hoses and Fittings Check all hoses and fittings for leaks. Repair as needed.
Seal Leak Between Engine and Torque Converter Check the engine oil. If the transmission continues to lose oil and the engine gains oil, it is likely that the engine crankshaft oil seal at the rear of the engine is leaking. The converter must be removed from the truck and the engine crankshaft oil seal replaced. Power Shift Transmission System Service Manual
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11.
Inter-axle differential action not present Possible causes:
Differential Seized Remove the output shaft driveline from either end of the transmission with the engine off. The transmission output yoke should be free to turn when a torque of 50 lb. ft. is applied. If it will not turn, the differential has internal damage such as the clutch. Remove the transmission to repair. If the differential is free to turn, but does not turn when the engine is running, clutch may be applied due to a faulty solenoid valve.
12.
Inter-axle differential not locking up when selected Possible causes:
No Pressure to Differential Clutch, Failed Differential Clutch Pack Disconnect the output shaft driveline from one of the ends of the transmission. Completely remove the input driveline between the torque converter and transmission. With engine running, the vehicle brakes applied, and the differential clutch applied in test mode T7, measure pressure in differential test port as shown in Figures 3 and 4 in Operation. With correct pressure, the transmission output yoke should not be able to be rotated when torque is applied. If the yoke can be rotated while the differential clutch is pressurized, remove the transmission to repair.
13.
No vehicle ground speed in work mode Possible causes:
Converter Modulated Clutch Pressure Incorrect It may be necessary to monitor the clutch apply pressure to Clutch 5 and Clutch 6 to ascertain release of Clutch 6 when throttle is applied while in the work mode. Refer to Pressure Test of System in Troubleshooting.
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Twin Disc, Incorporated
Modulated Clutch Failed Run test T8, as identified in Troubleshooting, to determine if the problem is caused by the solenoid or due to an internal mechanical failure within the torque converter.
Internal Braking Action of Transmission Not Releasing. 14.
Vibrations in vehicle Possible causes:
Unbalanced or Bent Drive Shafts Inspect input and output drive shafts of the transmission. Look for bad universal joint assemblies. Verify that the drive shafts are phased properly (universal joint yokes at each end of the center section must be parallel with each other). Inspect cross and bearing journals for brinelling or other damage. With the selector in the N position, run the engine speed up slowly. If there is vibration present in the speed range, the source is likely the drive shaft between the torque converter and transmission. Repair or replace the drive line.
Tire Damage
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IGNITION SWITCH ON, DISPLAY IS BLANK Possible causes: No D.C. power to control, loose cables, failed control
IS FUSE OR CIRCUIT BREAKER CLOSED?
No
REPLACE FUSE OR RESET BREAKER
Yes
12 VOLTS PIN F TO G ON CABLE P3 AT CONTROL BOX?
No
CHECK POWER RELAY
Yes
ARE CABLES CONNECTED AND TIGHT
No
CONNECT AND TIGHTEN
Yes
DOES VEHICLE DRIVE
No
REPLACE CONTROL BOX
Yes
REPLACE DISPLAY UNIT
Figure 6. Troubleshooting Flowchart
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Twin Disc, Incorporated
ENGINE RUNNING, VEHICLE WILL NOT MOVE IN FWD OR REV DISPLAY SHOWS D OR R Possible causes: low oil level, failed main pump, pump suction leak, failed clutch solenoid, failed clutch pack, locked axle or brakes
ARE BRAKES APPLIED?
Yes
RELEASE BRAKES
No
ADD OIL FOLLOWING FILL PROCEDURE
No
WITH ENGINE OFF, IS OIL LEVEL ABOVE TOP SIGHT GAUGE? Yes
ENGINE AT IDLE, IS OIL LEVEL ABOVE BOTTOM OF LOWER SIGHT GAUGE?
ADD OIL FOLLOWING FILL PROCEDURE
No
Yes
CHECK MAIN PRESSURE PORT X.
ENGINE AT IDLE, IS OIL LEVEL ABOVE TOP OF UPPER SIGHT GAUGE?
170 TO 190
BELOW 170 PSI
CHECK FOR OIL PUMP SUCTION LEAKS (See
REMOVE OIL TO PROPER LEVEL
No
Trouble Shooting Discussion) Yes
REPAIR SUCTION LEAKS
REPLACE OIL PUMP
TRANSMISSION IN NEUTRAL, IS DRIVESHAFT TURNING Yes
ENGINE OFF, DOES TRANSMISSION INPUT DRIVESHAFT TURN EASILY
No
Yes
No Yes
RUN PRESSURE TEST TO DIAGNOSE
TRANSMISSION IS DAMAGED INTERNALLY AND MUST BE REMOVED
Figure 7.
PUT SELECTOR IN RANGE, IS DRIVESHAFT TURNING No
TRANSMISSION IS HYDRAULICLY LOCKED UP, RUN PRESSURE TEST TO DIAGNOSE
Troubleshooting Flowchart
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VEHICLE MOVES IN FORWARD BUT NOT REVERSE Possible Causes: Failed reverse clutch, failed reverse solenoid
DOES DISPLAY INDICATE
R?
No
DIAGNOSE SELECTOR
Yes
ENGINE AT IDLE, DOES TRANSMISSION DRIVESHAFT STOP IN REVERSE?
Yes
RUN PRESSURE TEST EXTRA CLUTCH MAY BE APPLIED
MAIN - NORMAL REVERSE - ZERO
REPAIR OR REPLACE REVERSE SOLENOID VALVE
No
RUN TEST T7 AND CHECK MAIN AND REVERSE PRESSURE
MAIN - NORMAL REVERSE - LOW MAIN - NORMAL REVERSE - NORMAL
SWAP REVERSE SOLENOID WITH # 2 SOLENOID
IF ALL PRESSURES ARE NORMAL, REVERSE CLUTCH IS SLIPPING - REMOVE TRANSMISSION
NO CHANGE
REMOVE AND REPAIR TRANSMISSION
Figure 8. Troubleshooting Flowchart
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VEHICLE MOVES IN REVERSE BUT NOT FORWARD
DOES DISPLAY INDICATE
D2?
No
DIAGNOSE SELECTOR
Yes
RUN PRESSURE TEST EXTRA CLUTCH MAY BE APPLIED
Yes
ENGINE AT IDLE, DOES TRANSMISSION DRIVESHAFT STOP IN D2? No
SELECT D1 AND NOTE IF TRANSMISSION DRIVESHAFT STOPS
RUN TEST T7 AND CHECK MAIN AND 2-5 CLUTCH PRESSURE
MAIN - NORMAL REVERSE - ZERO
REPAIR OR REPLACE # 2-5 CLUTCH SOLENOID VALVE
MAIN - NORMAL REVERSE - LOW
MAIN - NORMAL REVERSE - NORMAL
IF ALL PRESSURES ARE NORMAL, REVERSE CLUTCH IS SLIPPING - REMOVE TRANSMISSION
SWAP # 2-5 CLUTCH SOLENOID WITH REVERSE SOLENOID NO CHANGE
REMOVE AND REPAIR TRANSMISSION
Figure 9. Troubleshooting Flowchart
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VEHICLE WILL NOT UPSHIFT INTO UPPER RANGES CONVERTER DOES NOT GO INTO LOCK-UP POOR VEHICLE PERFORMANCE, LACKS POWER Possible causes: Low engine power, poor engine flywheel scavenge, Improper oil level, Converter Input or Lock-up clutch or solenoid, improper pressures
CHECK OIL LEVEL
SELECTOR IN NEUTRAL, BRAKES ON, OPEN THROTTLE FULLY. ENGINE RPM MATCHES NO LOAD SPECIFICATION ( A P P R O X I M A T E L Y 2 4 2 5 R P M )
No
INVESTIGATE CAUSE OF ENGINE MALFUNCTION
Yes
RUN DIAGNOSTIC TEST ON LOCK-UP CLUTCH AND SOLENOID T8
Yes
BRAKES ON, SELECT TEST MODE T9, SHIFT TO D6, FULLY DEPRESS THROTTLE. ENGINE RPM SHOULD AGREE WITH ENGINE STALL TORQUE SPECIFICATION (EXPECT 2000 TO 2150 RPM) No
PRESSURE TEST CONVERTER AND INPUT CLUTCH (MODULATED CLUTCH) >180 PSI; T8
RUN DIAGNOSTIC TEST ON INPUT CLUTCH AND SOLENOID
No
Yes
PERFORM CONVERTER SCAVENGE PUMP TEST
SERVICE ENGINE
Fail
IDENTIFY AND CORRECT PROBLEM WITH TORQUE CONVERTER
Pass
Lock-up pressure low Main pressure normal
MEASURE LOCKUP AND MAIN PRESSURE IN TEST MODE T8
REPLACE PROPORTIONAL VALVE ON CONVERTER
Lock-up pressure low Main pressure drops when lock-up clutch is applied
Test Mode T8, 95%, move selector N to D6, Both pressures normal no evidence of slight engine lug down when lock-up is applied
LOCK-UP CLUTCH IS FAILED, REMOVE AND REPAIR CONVERTER
INTERNAL LEAKAGE, REMOVE AND REPAIR CONVERTER
Figure 10. Troubleshooting Flowchart 72
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Twin Disc, Incorporated
HARSH SHIFTING INTO SOME RANGES Possible causes: Worn clutch pack, slow solenoid valve, improper pressure, improper speed signal, throttle position sensor out of adjustment, defective temperature sensor
RUN TEST MODE T4 AND VERIFY INTEGRITY OF TEMPERATURE SENSOR AND THROTTLE SENSOR ADJUSTMENT
CHECK FOR DARK OR BURNED SMELLING OIL
PERFORM PRESSURE TEST
Figure 11.
Troubleshooting Flowchart
Power Shift Transmission System Service Manual
73
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TRANSMISSION / TORQUE CONVERTER RUNS HOT Possible causes: Too much oil in transmission, poor scavenge from engine flywheel, low oil flow thru converter and cooler, cooler not working properly
ADJUST TRANSMISSION OIL TO PROPER LEVEL
PERFORM PRESSURE TEST
PERFORM TORQUE CONVERTER SCAVENGE TEST
INSPECT AND REPAIR VEHICLE COOLING SYSTEM
Figure 12. Troubleshooting Flowchart
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Power Shift Transmission System Service Manual
Troubleshooting
Twin Disc, Incorporated
TORQUE CONVERTER SCAVENGE PUMP TEST Possible causes: Excessive Torque Converter leakage, obstructed pump inlet, suction leak
ENGINE OFF, DISCONNECT SCAVENGE PUMP HOSE FROM TRANSMISSION. DIRECT TOWARD BUCKET
IDLE ENGINE AT 1000 RPM AND MEASURE OIL FLOW RATE BY MEASURMENT AND TIME. NOTE FLOW RATE.
OIL FLOW REMAINS STEADY AT PUMP RATED CAPACITY
AFTER A SHORT TIME, OIL FLOW SHOULD INCLUDE SOME AIR, AND MEASURED FLOW RATE SHOULD SLOW
(APPROXIMATELY 7.4 GPM @ 1000 RPM)
Low Flow but converter getting hot
CONVERTER LEAKAGE EXCESSIVE, REMOVE AND REPAIR CONVERTER
CLEAN PUMP INLET SCREEN AND EXAMINE DEBRIS FOR POSSIBLE ORIGIN
CHECK FOR PUMP SUCTION LEAKS
REPLACE PUMP
Figure 13.
Troubleshooting Flowchart
Power Shift Transmission System Service Manual
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Troubleshooting
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Problems that Show Status Codes in the Display The purpose of this section is to help troubleshoot the ETA-28L control system. This section is divided into component groups and/or specific status codes. Turn to the part covering the problem area for specific troubleshooting information. The diagnostics test in Troubleshooting may be used to perform the initial tests. A volt-ohm multi-meter will be required to complete the troubleshooting.
NOTE: Problems are usually caused by wiring faults or other parts of the system rather than the control itself. Voltage and resistance measurements will be required throughout the troubleshooting section. When making resistance measurements, the power to the control must be off. DO NOT use a test light to check for voltage. Control damage can result.
Status Code Definitions
General The control system is designed to maintain safe operation in all modes of operation. The system also runs special software routines in conjunction with the main program to check system integrity. For example, if a range is engaged, a test routine checks that the correct solenoids are turned on and that all others are off. If not, the system reacts by going to neutral. At the instant such faults are detected the operator is notified by a status code on the display. Only status codes that are listed on the following page should be displayed. If unusual codes are displayed, use diagnostics Test 1 in Troubleshooting to check the operation of the display.
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Code
Definition
PP LN I2 I3
Low input voltage to controller Neutral not seen on power up RAM error Check sum error
T2 T4
Invalid switch combination detected from range selector Accelerator pedal position sensor or Transmission oil temperature sensor signal out of range
TA TX 1A
No turbine speed sensor signal Turbine Speed sensor circuit open or shorted No output speed sensor signal
1X
Output speed sensor circuit open or shorted
S1 S2 S3 S4
Transmission solenoid 1 Transmission solenoid 2 Transmission solenoid 3 Transmission solenoid 4
M5 M6
Transmission solenoid 5 Transmission solenoid 6
ML MI
Converter lockup solenoid Converter modulating clutch solenoid
SP SD
PTO clutch solenoid Transmission differential lock solenoid
FP
Hydraulic system filter differential pressure switch circuit open Bad torque (load) signal from engine (signal out of range)
BT
If a malfunction occurs that puts the transmission into neutral, a status code appears and the operator must apply the brakes to slow the vehicle.
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1.
Engine cranking problems Vehicle engine cranking system and power supply is discussed here, as the transmission control system contains a neutral start switch and vehicle circuitry supplies input power to the transmission control.
Engine Won’t Crank (Selector in N) Disconnect the harness at the range selector. With vehicle switch in the run position, measure voltage being supplied to the neutral start switch. Voltage between pins N and F of the harness should be 12 volts dc.
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A.
If less than 12 volts is measured, check vehicle wiring diagram for neutral start switch power source. Electrical power must be supplied to the switch before the starter can be activated.
B.
If 12 volts is measured, measure resistance of the neutral start switch. With the selector in N, resistance between sockets K and N of the selector should be less than 10 ohms. a.
If resistance is larger than 10 ohms, either the neutral start switch or the wires to it are the cause of the fault; range selector will need to be replaced or repaired.
b.
If resistance is less than 10 ohms, check vehicle wiring diagram for vehicle start circuit. Typically, power from the neutral start switch continues to the start switch on the dash, and then the starter relay. Verify that power is being supplied to the starter relay itself when the start switch is activated.
Power Shift Transmission System Service Manual
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Engine Cranks with Selector In Gear Disconnect the harness at the range selector. Measure resistance between sockets K and N of the selector. There should be no connection between the two sockets when the selector is not in N. Resistance should be less than 10 ohms when the selector is in N. A.
If a connection is found when the selector is not in N, the neutral start switch or the wires to it are the cause of the fault. The range selector will need to be repaired or replaced.
B.
If there is no connection when the selector is not in N, check the vehicle wiring diagram for the start circuit. Continue troubleshooting by looking for a possible short in the wiring after the neutral start switch that would supply electrical power to the start switch on the dash or to the starter circuit.
Display Faults Possible display faults include segments that don’t come on, stay on when they should not, or a blank display. Common causes of these faults include control not seeing any power, display not receiving signal from control, or a faulty display. It should be noted that display problems are usually caused by wiring faults rather than a faulty display or control. Possible solutions: A.
Make sure J3 connector is properly connected to the control.
B.
With the input power on, measure the voltage across positive socket F and negative socket G at the P3 wiring harness. The meter should read 9-14 volts dc. If it doesn’t, check the following: a. b. c. d. e. f. g. h.
Wiring from the switch to the power relay. Power relay. Wiring from the power relay to ground. Wiring from the battery to the 10 amp fuse. 10 amp fuse. Wiring from the 10 amp fuse to the power relay. Wiring from the power relay to socket F of the P3 wiring harness connector. Battery ground to socket G of the P3 wiring harness connector.
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C.
Measure the voltage across positive pin M and negative socket L at the J1 connector on the control. If 9-14 volts dc is measured at the P3 wiring harness but not at the J1 control connector: a.
Bad connection between the P3 wiring harness and the control.
b.
Replace the electronic control.
NOTE: The 10 amp input power circuit protection device must not exceed the time/current characteristics of an ATO type fuse. If the installed device is larger than specified it is possible that the control could be damaged and made inoperable.
D.
E.
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If 9-14 volts dc is measured at the P3 wiring harness and the J1 control connector: a.
Bad connection between the P1 wiring harness and the electronic control.
b.
Bad connection between the P1 wiring harness and the display.
c.
The P1 wiring harness is defective.
d.
Replace the display.
If some of the display segments do not light up as required or light up when not required: a.
The P1 wiring harness is defective.
b.
Replace the display.
c.
Replace the control.
Power Shift Transmission System Service Manual
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PP Status Code This status code indicates that the supply voltage for the control has dropped and stayed below 9 volts dc for more than 0.1 second. The 9 volts dc is necessary to sustain the outputs. The electronic control will go to computer neutral. Manual override is not allowed. The voltage levels are not sufficient to sustain the outputs. NOTE: Voltage dropping below 9 volts dc for longer than 0.1 seconds followed by restoration of voltage above 9 volts dc will cause the electronic control to repower (act as if the power was turned off, then on). If the selector is in a D position, or R, an LN code will appear. Possible causes: A.
The code may appear briefly when electrical power is removed from the control during activation of the starter or when the run switch is turned off. This is a normal response to input power dropping off.
B.
Battery voltage low. Power is supplied to the control through sockets F (positive) and G (negative) of the P3 wiring harness. Disconnect the P3 harness form the control and measure voltage between these sockets with the vehicle run switch on. Voltage should be greater than 9 volts dc. Other loads on the battery may reduce the amount ofpower that is available to the control during vehicle operation.
C.
Loose or poor connection between the control and the power source or ground. Poor connection may briefly remove power or limit the amount of current being supplied to the electronic control.
D.
Charging system of the vehicle not functioning properly, resulting in low supply voltage during operation.
E.
Run relay contacts are not disconnecting during the start cycle.
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2.
T4 status code If the accelerator pedal position sensor signal, or temperature signal is out of range, the T4 status code will be displayed until the fault is corrected and the controller is repowered.
Accelerator Pedal An out of range accelerator pedal signal results in the following: Drive Mode: Range changes are made from a fixed load zone (P5). Work Mode: The modulating clutch is disengaged and the transmission brake is not applied.
Accelerator Pedal Potentiometer Use diagnostics test 4 to check the accelerator potentiometer signal voltage to the control. The display should show 1.5 ± 0.5 (pedal at idle) and 3.5 ± 0.1 at full throttle. (Actual voltage at the potentiometer wiper is approximately 1.8 times the reading on the display in Test 4.) A.
B.
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If the display shows 0.0 through the entire accelerator pedal travel: a.
The wire from P2 socket G to pin B at the potentiometer connection is open or shorted to the chassis.
b.
Poor connection between P2 and the control or from the harness to the potentiometer.
c.
The potentiometer is defective.
If the display shows some constant value through the entire accelerator pedal travel: a.
The wire from P2 socket G to pin B at the potentiometer connector is shorted to a power source.
b.
The potentiometer is defective.
Power Shift Transmission System Service Manual
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C.
If a variable voltage is read, but it doesn’t coincide with the voltages listed above: a.
Refer to accelerator potentiometer calibration on the previous page.
b.
The potentiometer is defective.
8.6 Volts dc is Supplied to the Potentiometer. This can be verified by placing voltmeter leads on pin A (positive) and pin C (negative) of the cable that connects to the potentiometer. A.
B.
If the voltage read is zero (0) volts: a.
The wire from P2 socket E to pin A at the potentiometer connector is open or shorted to the chassis.
b.
The wire from P2 socket H to pin C at the potentiometer connector is open.
c.
Replace the control.
If voltage read is not approximately 8.6 volts dc: a.
Low supply voltage to the control.
b.
Bad connection between P2 harness and the control.
c.
Bad connections in the wiring harness.
d.
Replace the control.
Transmission Oil Temperature Signal A T4 status code will be displayed if the signal from the temperature sensor is out of range. An unacceptable temperature sensor signal will cause range changes from a fixed setting. Refer to test T4 in Troubleshooting.
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3.
Speed sensor problems This section deals with status codes associated with turbine and output speed sensor circuits.
TA Status Code: Turbine Speed Signal Absent This status code indicates that there is a fault with the turbine speed sensor SIGNAL. The TA code indicates the electronic control is not sensing a signal from the turbine speed sensor when conditions indicate it should be. The vehicle will continue to shift through all of the ranges. The status code will be displayed and torque converter lockup clutch engagement will be inhibited. The differential lock clutch will be limited to use in R, N, 1st, 2nd, and 3rd. The display will alternately flash TA and the transmission range. The status code will clear when the signal is present. Possible causes: Turbine speed sensor out of adjustment or damaged. Sensor is at the upper part of the transmission. A.
Remove the turbine speed sensor.
B.
Thoroughly clean the turbine speed sensor or replace if damaged.
C.
Align the gear seen through the turbine speed sensor hole so the gear tooth is in the middle of the hole.
D.
Screw the turbine speed sensor into the hole until it just contacts the gear tooth.
E.
Back out the turbine speed sensor 1/4 turn. *
F.
Use jam nut to lock the turbine speed sensor in place (50 inlbs, 5.7 Nm).
Refer to Test 5 in Troubleshooting. *
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Turbine and Output Speed Sensor. 1/4 a turn gap corresponds to approximately .016 in. air gap between the speed pickup tip and the top of the gear tooth.
Power Shift Transmission System Service Manual
Troubleshooting
Twin Disc, Incorporated
1A Status Code: Speed Sensor #1 Signal Absent This status code indicates that there is a fault with the output speed sensor signal. The code indicates the controller is not sensing a signal from the output speed sensor when conditions indicate it should be. The turbine speed sensor will be used to determine the proper shift points for all shifts including lockup. Shifts from neutral to forward will engage the highest transmission range, then shift based on the turbine speed sensor signal. Shifts from neutral to reverse will be inhibited above a predetermined turbine speed. The differential lock clutch would then be limited to use in R, N, 1st, 2nd, and 3rd. After the fault is corrected, the controller must be repowered to clear the code. Possible causes: A.
Output speed sensor out of adjustment or damaged. Transmission output speed sensor is at the rear output shaft. a.
Remove the speed sensor.
b.
Thoroughly clean the sensor or replace if damaged.
c.
Align the gear seen through the transmission sensor hole so the gear tooth is in the middle of the hole.
d.
Screw sensor into the hole until it just bottoms out on the gear tooth.
e.
Back out the sensor 1/4 turn. *
f.
Use jam nut to lock the sensor in place (50 in-lbs, 5.7 Nm).
B.
Mechanical fault in the transmission. Pulses from the OUTPUT speed pickup may be much less than expected if a transmission clutch is slipping, speed pickup gear is not turning as fast as the shaft or is not directly under the sensor. Verify transmission operation, noting certain ranges where the code occurs, etc.
*
Turbine and Output Speed Sensor. 1/4 a turn gap corresponds to approximately .016 in. air gap between the speed pickup tip and the top of the gear tooth.
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TX Status Code: Turbine Speed Fault The TX code indicates the controller is sensing a short or an open in the turbine speed sensor or circuit. The status code will be displayed and the output speed sensor will be used to determine the engagement of the torque converter lockup clutch. The differential lock clutch will be limited to use in R, N, 1st, 2nd, and 3rd. After the fault is corrected, the controller must be repowered to clear the status code. Note the differences from the TA status code. An intermittent status code may be caused by an intermittent or a temperature sensitive fault in the sensor or the wires between the control and the sensor. Look for any trends in occurrence of the status code. Try to check sensor and harnesses immediately after an intermittent code occurs. Use diagnostic test 5, to further identify fault.
Possible solutions: A.
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If the “+” symbol appears indicating an open circuit: a.
Check the speed sensor for an internal open across the terminals. A proper value measure using an ohmmeter should be 1000 to 1300 ohms.
b.
Unplug J4 harness from the control. Resistance between sockets L and T of the harness should be approximately equal to sensor resistance measured above (sensor must be plugged into harness). If open circuit is measured - poor connection or fault in harnesses between the control and the sensor.
c.
Unplug J4 harness from the control. There should be no connection between socket L and the chassis, the harness end, or to any of the other sockets except T (value measured above). If a connection is found, a fault exists in the harness between the control and the sensor.
Power Shift Transmission System Service Manual
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d.
Measure resistance between J4 pin T and J3 pin G into the control itself. Resistance should be close to 0 ohms. If open circuit is found, internal ground fuse in the control may be blown. Voltage may have been supplied to the control through socket T of the harness. The control must be replaced if the internal ground fuse is damaged.
Verify that no voltage is being supplied to the sensor ground before installing another control (voltage will damage the replacement control also). B.
If the “-” symbol appears indicating a short circuit: a.
Measure resistance between the pins of the sensor pigtail. Proper value should be 1000 to 1300 ohms. Small value would indicate an internal short in the sensor or the pigtail.
b.
Unplug J4 harness from the control. Resistance between sockets L and T of the harness should be approximately equal to sensor resistance measured above (sensor must be plugged into harness). If small value is measured - fault in harnesses between the control and the sensor.
c.
Unplug J4 harness from the control. There should be no connection between socket L and the chassis, to the harness end, or to any of the other sockets except T (value measured above). If a connection is found, a fault exists in the harness between the control and the sensor.
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1X Status Code: Speed Sensor #1 Fault This status code indicates a short or an open in the transmission output speed sensor or in the cable to the sensor. The vehicle will continue to shift through all of the gears, including the converter lockup. The display will alternately flash 1X and the transmission gear. Use diagnostics Test 5, in Troubleshooting, to check the rear transmission speed sensor. Possible solutions: A.
If the “+” symbol appears indicating an open circuit: a.
Check the speed sensor for an internal open across the terminals. A proper value measure using an ohmmeter should be 1000 to 1300 ohms.
b.
Unplug J4 harness from the control. Resistance between sockets M and S of the harness should be approximately equal to sensor resistance measured above (sensor must be plugged into harness). If open circuit is measured - poor connection or fault in harnesses between the control and the sensor.
c.
Unplug J4 harness from the control. There should be no connection between socket M and the chassis, to the harness end, or to any of the other sockets except “S” (value measured above). If a connection is found, a fault exists in the harness between the control and the sensor.
d.
Measure resistance between J4 pin S and J3 pin G into the control itself. Resistance should be close to 0 ohms. If open circuit is found, internal ground fuse in the control may be blown. Voltage may have been supplied to the control through socket T of the harness. The control must be replaced if the internal ground fuse is damaged.
Verify that no voltage is being supplied to the sensor ground before installing another control (voltage will damage the replacement control also).
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B.
If the “-” symbol appears indicating a short circuit: a.
Measure resistance between the pins of the sensor pigtail. Proper value should be 1000 to 1300 ohms. Small value would indicate an internal short in the sensor or the pigtail.
b.
Unplug J4 harness from the control. Resistance between sockets M and S of the harness should be approximately equal to sensor resistance measured above (sensor must be plugged into harness). If small value is measured - fault in harnesses between the control and the sensor.
c.
Unplug J4 harness from the control. There should be no connection between socket M and the chassis, to the harness end, or to any of the other sockets except S (value measured above). If a connection is found, a fault exists in the harness between the control and the sensor.
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4.
Input switch problems This section deals with status codes associated with input switching devices. Separate switching devices are used to control the operation of the vehicle. These devices are the range selector, differential lock switch, pump and roll mode switch, and filter sensor switch. As discussed below, each device activates various contacts in different positions. The key to troubleshooting the switching systems is to know which contacts are to be closed or open at the various switch positions. Two status codes are available to indicate switching faults:
LN Status Code: Looking for Neutral The control is not seeing the neutral disconnect contacts open at power up. This status code indicates that the selector lever is in forward or reverse during power up. The LN status code will be displayed and the electronic control will remain in computer neutral. This status code may be cleared by moving the selector lever to the N position. Also see note under PP code in Troubleshooting.
T2 Status Code: Range Selector Switches This status code indicates the control has sensed an incorrect combination of switch closures from the range selector. A range will be maintained based on the last valid combination of selector switch closures. The status code will flash alternately with the range engaged until a proper combination of range selector switch closures is seen by the control. Another indication of a switch malfunction would be the inability to obtain various modes of operation although no status codes are displayed. Diagnostics test 2 and 3 can be used to test the opening and closing of individual contacts along with actually measuring resistance of a switch with an ohmmeter. A closed switch has approximately 0 OHMS of resistance. An open switch has resistance too large to be measured.
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Range Selector Perform diagnostics Test 2 to verify selector lever position as seen by the control.
Table 1. Range Selector Contacts
Switch
M eter Placement Points ( at Selector
M eter Placement Points at Cable P3
Selector Positions with Switch Closed
1.
A to E
S to C
Rev, D5, D6, D1
2.
G to H
E to H
Rev, D5, D6, D5, D4, D3, D2, D1
3.
B to E
N to C
Rev, D5, D4, D3
4.
P to E
L to C
Rev, D3, D2, D1
5.
Not Used
Not Used
Not Used
6.
L to M
At Range Selector
Reverse (Rev. Alarm & M anual O verride)
7.
K to N
At Range Selector
Neutral ( Pow er to Start Sw itch only in Ne utral)
8.
J to M
At Range Selector
D6 (f or M anual O verride Fw d.)
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A.
B.
C.
If a switch measures open on the ohm meter when the chart indicates it should read closed: a.
The switch is electrically opened, or
b.
The switch wiring is opened between the control and the switch.
c.
Check all the connectors for proper attachment.
If the switch measures closed on the ohmmeter when the chart indicates it should read open: a.
The switch is electrically shorted, or
b.
The switch wiring is shorted together.
The mechanical actuation of the switches could be faulty.
Individual Switches These switches are: differential lock switch, pump and roll mode switch, and the transmission oil filter differential pressure switch. The switches can be tested by placing an ohmmeter across the connections and opening and closing the switch. A.
If the switch measures open on the ohmmeter when the chart indicates it should read closed: a. b. c.
B.
If the switch measures closed on the ohmmeter when the chart indicates it should read open: a. b.
C.
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The switch is electrically opened, or The switch wiring is opened between the control and the switch. Check all the connectors for proper attachment.
The switch is electrically shorted, or The switch wiring is shorted together.
The mechanical actuation of the switches could be faulty.
Power Shift Transmission System Service Manual
Troubleshooting
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5.
S_ or M_ status codes: Solenoid or modulating solenoid fault
S1, S2, S3, S4, M5, and M6 This status code indicates there is a short or an open in the applicable solenoid circuit. The S or M will be located on the left digit of the display and a number in the right digit of the display will correspond to transmission solenoids 1, 2, 3, 4 and low range, high range electric modulating valves 5 and 6. Upon identification of a short or an open in one of these solenoid circuits, the corresponding code is displayed and computer neutral is maintained. No more computer controlled shifts are allowed. Manual override may not function if the S3(Fwd), S3(Rev), MI, or M5 solenoids are not able to be energized due to an electrical fault. Manual override may not function if one of the other solenoids is shorted to a power source or one of these solenoids, causing an extra clutch to be engaged. Possible transmission lockup could occur from two clutches being engaged and trying to drive the output at different speeds. After the fault is fixed, the control must be repowered to clear these codes.
SD Status Code: Solenoid Differential Lock This status code indicates a fault in the differential lock solenoid circuit. Vehicle operation will continue, but differential lock is unavailable. After the fault is fixed, repower the control to clear the status code.
SP Status Code: Solenoid PTO This status code indicates a fault in the PTO solenoid circuit. The PTO solenoid will not be activated. Vehicle operation in drive mode will continue uninterrupted. The pump and roll mode will not function properly since there will be no engagement of the PTO. After the fault is fixed, repower the control to clear the status code.
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ML Status Code: Modulated Lockup Clutch Solenoid This status code indicates a fault in the electric modulating valve circuit for the lockup clutch in the torque converter: A.
If the lockup electric modulating valve or circuit is shorted to the chassis or is internally shorted, control will continue vehicle operation using alternate shift tables with lockup clutch engagement not allowed.
B.
If the lockup modulating valve or circuit is open or shorted to an electrical power source, the control disengages the solenoids and computer neutral is maintained. This is done because a short to an electrical power source could cause the lockup clutch to be engaged at all times, possibly causing damage to the lockup clutch or stalling the engine.
After the fault is fixed, the control must be repowered to clear the status code.
MI Status Code: Modulated Input Clutch Solenoid This status code indicates a fault in the electric modulating valve circuit for the input clutch in the torque converter: A.
If the input clutch electric modulating valve or circuit is shorted to positive power and unable to disengage, normal operation can continue while in the drive mode and no status code will be displayed. When the work mode is entered, the status code will be displayed and computer neutral will be implemented
B.
If the modulating valve or circuit is internally shorted or shorted to the vehicle chassis while in any operating mode, the control disengages the solenoids and computer neutral is maintained.
C.
If the input clutch modulating valve or circuit is open, vehicle operation will continue, but the clutch will not be engaged. Some vehicle movement can occur due to normal viscous drag within the torque converter, but the vehicle will not accelerate.
After the fault is fixed, the control must be repowered to clear the status code.
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Table 2. Transmission Solenoid Listing
Diagnostic Display Code
Solenoid Energized
Integrity Code
Connector
Contacts
Approximate Resistance Ohms
S1
1
S1
P4
X and E
5 to 11
S2
2
S2
P4
W and E
5 to 11
S3
3
S3
P4
Y and E
5 to 11
S4
4
S4
P4
U and E
5 to 11
SP
PTO
SP
P4
K and E
10
M5
5, HIGH
M5
P4
D and J
5 to 11
M6
6, LOW
M6
P4
P and Q
5 to 11
SD
Differential Lock
SD
P4
R and E
5 to 11
ML
Modulated Lockup CL
ML
P4
B and Z
5 to 11
MI
Modulated Input CL
MI
P4
C and V
5 to 11
An intermittent status code may be caused by an intermittent or a temperature sensitive fault in the valve or the wires between the control and the valve. Look for any trends in occurrence of the status code, such as only when transmission oil is cold or hot. Try to check valve and harnesses immediately after an intermittent code occurs. If several solenoid status codes occur at the same time, verify that the #2 switch in the range selector is closing properly. The switch must close to indicate the operator has moved the selector out of N before the solenoids may be engaged. For safety reasons, the control cannot energize any solenoids if the selector is in N. If the #2 switch or the cables to it have high resistance, the solenoid circuits will all be affected, and several status codes may occur.
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Possible Solutions for Solenoid Status Codes: Unplug the pigtail of the indicated valve and measure the resistance of the solenoid valve itself. Expected resistance values are listed in the chart. Place ohmmeter leads on the two sockets corresponding to the solenoid in question. See Table 2 in Troubleshooting. A proper ohmmeter reading for the solenoid is shown in the chart. Also verify that the solenoid leads are not shorted to the chassis by measuring resistance between the connector and the transmission housing, there should be no connection.
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A.
If an incorrect resistance is measured at the valve pigtail, the fault is in the pigtail wires or in the internal coil of the valve. Valve may need to be replaced.
B.
If correct resistance is measured into the valve and there is no connection to the chassis, reconnect the harness to the valve. a.
Unplug the J4 cable from the electronic control.
b.
Measure the resistance between the contacts shown. Resistance value should be the same as measured at the valve itself. If the resistance is very high, there is a fault in one of the harnesses from the control to the valve or there is a poor connection in one of the cable connections.
c.
If the resistance measured is very low, the two wires going to the valve are shorted together in the harnesses between the control and the valve.
Power Shift Transmission System Service Manual
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Twin Disc, Incorporated
d.
If the correct resistance is measured between the connections shown, check for connections between the solenoid wires and other wires in the harness or connections to the chassis. Place the ohmmeter on the first contact shown in the chart for the valve indicated. Measure the resistance to each of the other contacts in the P4 harness and also to the chassis. Modulating valve (status codes with an M followed 5, 6, L, or I ) circuits should have no connection to any other connections or to the chassis. If a connection is found to another contact or to the chassis, there is a fault in one of the harnesses or connectors. On/Off solenoid (status codes with an S followed by the solenoid number) circuits all connect to a common ground contact (E). A resistance value approximately double the value measured for the solenoid itself will be measured to the first contact listed for each of the other on/off solenoids. There should be no connection to any of the modulated valve contacts or to the chassis. If a connection is found, there is a fault in one of the harnesses or connectors between the control and the valve itself.
6.
Internal control problems This section deals with status codes associated with internal circuitry in the control box.
I2 or I3 Status Code These status codes are caused by an internal problem in the control. They indicate an internal defect in the control circuitry. The status code will be displayed and the control will maintain computer neutral. No further computer controlled shifts are allowed. The control should be replaced. Manual override mode is possible.
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CONTROL SYSTEM STATUS CODES PP, LN, I2, I3, T2, T4, TA, TX, 1A, 1X, S1, S2, S3, S4, M5, M6, ML, MI, SP, SD, FP, BT PP
LN
I2
I3
FP
IN GEAR WHEN POWER APPLIED
INTERNAL RAM ERROR
INTERNAL EPROM ERROR
OIL FILTER PRESSURE DROP HIGH
CAN CAUSE
INPUT POWER HAS DROPPED BELOW 9 VOLTS FOR MORE THAN 0.1 SECONDS
NEUTRAL TO CLEAR REPLACE CONTROL OVERRIDE ALLOWED
-
LOW BATTERY VOLTAGE LOOSE CONNECTION BAD GROUND BAD POWER RELAY CONTACTS
- COLD OIL - PLUGGED FILTER - OPEN LEAD
CODE ALTERNATES WITH NORMAL DISPLAY. CIRCUIT MUST BE OPEN >37 SECONDS TO DISPLAY, AND REMAIN CLOSED >5 SECONDS TO CLEAR OPERATION IS NOT AFFECTED
BT
T2
T4
TA
ENGINE LOAD SIGNAL BAD SHIFT COMFORT OR FEEL AFFECTED
RANGE SELECTOR SWITCH COMBINATION INVALID OPERATION CONTINUED FOLLOWING LAST RECOGNIZED SELECTION
ACCELERATOR PEDAL OUT OF RANGE OR OIL TEMP SENSOR CIRCUIT DRIVE MODE - SHIFT FEEL AFFECTED WORK MODE - NO MOD CLUTCH ACTION
TURBINE SPEED SIGNAL MISSING LOCK-UP NOT ALLOWED DIFFERENTIAL LOCK RESTRICTED TO BELOW 4TH RANGE
- SHORTED WIRE - OPEN WIRE -ENGINE PROBLEM
SELF CLEARING
- OPEN WIRE - SHORTED WIRE - BAD SWITCH >>PERFORM T2 TEST>PERFORM T4 TEST>PERFORM T5 TEST>PERFORM T5 TEST 1/4 turn) - SENSOR DEFECTIVE - INTERNAL PROBLEM >>PERFORM T5 TEST 1/4 turn) - SENSOR DEFECTIVE - INTERNAL PROBLEM
- OPEN WIRE - SHORTED WIRE - BAD SENSOR --- R = 1000 TO 1300 OHMS -SAME FOR J4 PIN M TO S. AT CONTROL -- J4 PIN S TO J3 PIN G = 0. IF OPEN, INTERNAL FUSE BAD MUST REPOWER TO CLEAR
SELF CLEARING
S1 S3 SD
S2 S4 SP
M5 MI
M6 ML
DESIGNATED SOLENOID SHORTED OR OPEN COMPUTER NEUTRAL NO SHIFTS ALLOWED PERFORM T6 TEST OPEN SOLENOID SHORTED SOLENOID OPEN WIRE SHORTED WIRE SEE TROUBLESHOOTING TABLE # 2 FOR CABLE PINS TO TEST MUST REPOWER TO CLEAR
Figure 14. Control System Status Codes Flowchart 98
Power Shift Transmission System Service Manual
Troubleshooting
Twin Disc, Incorporated
Diagnostic Test
General See Figure 15 in Troubleshooting. A test routine is included within the control to aid in troubleshooting the external components of the control system. It is also helpful in calibrating the foot pedal system and troubleshooting the transmission and torque converter. Electrical power must be removed from the control (turn off power switch) before entering the diagnostics test mode. The diagnostics test mode is entered by connecting two wires in the test mode cable by means of a connector. The diagnostics test connector is located in the Twin Disc J1 cable. Consult the manufacturer’s vehicle manual for the specific locations.
Entering the Diagnostics Test Mode The procedure for entering the test mode is: 1.
Turn the control system electrical power off.
2.
Place the test connector plug in test mode position. The plug is in the J1 harness of the control, one wire comes into each half of the plug. Unplug the connector, and realign the pin and socket so the two wires will be connected when the halves are plugged together (this completes the circuit). This can be done by only connecting one pin and one socket of the two plug halves.
3.
If test 7, 8, or 9 will be performed with the engine running, the engine will need to be started. This is necessary to provide system hydraulic pressure. Note that the power to the control is interrupted when the key switch is moved to the start position, so the test mode cycle is reinitiated. As a safety precaution, it is suggested that the output shafts may be disconnected from the transmission or the vehicle parking brakes engaged to keep the vehicle from moving in tests 7 and 8.
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4.
Turn the system power “On”. A check of the EPROM will be performed at power up and a code will be displayed that indicates the software program that is loaded in the chip. The software identification code is four characters long. Two characters are displayed at a time on the two character display. If there is an internal fault, the status code I2 or I3 is displayed. If there are no internal faults, Test 1 will be entered to test the display. Display will show 2 digits (for example F6) (pause)
Display will show 2 digits (for example 27)
(pause)
Display will show T1, indicating the first test is being started.
Test 1. Display Test On power-up into the diagnostics test, the display test will be entered automatically. The purpose of this test is to verify the function of the display, as it is used as a readout device in all of the following tests. T1 for test 1 is first displayed. After 2 seconds, the display will indicate the following sequence at 0.5 second intervals: “XX”, “++”, “0.0”, “**”. This sequence will continue repeating until the test is exited. To exit test 1, momentarily depress the diagnostics test push button. The control will return to the main menu, described below.
Main Menu The main menu is a list of all the diagnostics tests in symbolic form. To enter the main menu from the display test (Test 1) depress the diagnostics test push button. The display will begin to cycle from T2 through T9 and then start again at T2. To select the desired test, wait until the symbol for the desired test appears in the display and then momentarily depress the diagnostics test push button. The desired test will now be entered. Refer to the section covering the selected diagnostics test for information on how to exit to the main menu. Once in the main menu, a new diagnostics test can be entered.
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Test 2. Range Selector Test To enter the range selector test, momentarily depress the diagnostics test push button when T2 is indicated in the display. During this test, the display will indicate the position of the range selector lever as seen by the control. The following positions can be tested: !
R
!
N
!
6
!
5
!
4
!
3
!
2
!
1
If the selector lever is between positions or a switch is defective such that it will not close during activation a “ — “ code will appear. To exit Test 2, momentarily depress the diagnostics test push button. The electronic control will return to the main menu.
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Test 3. Input Switch Test To enter the input switch test, momentarily depress the diagnostics test push button when T3 is indicated in the display. During this test, the status of the pump and roll mode, differential lock, filter pressure, and stationary PTO switches will be indicated on the display, followed by XX to allow exiting of the test loop. The test will start out by cycling through the selections within T3.
T3 Sub Menu Selections !
P = Pump and roll mode switch
!
D = Differential lock switch
!
F = Filter sensor switch
!
W = Stationary PTO switch
!
XX = Return to main menu
Any of the five choices can be selected by momentarily depressing the diagnostics test push button when the desired choice is indicated on the display. Once a choice is made within T3 for a switch, the display will indicate the status of that switch as follows.
102
!
PX Pump and roll mode (PTO) not selected (switch open)
!
PS Pump and roll mode (PTO) selected (switch closed)
!
DX Differential lock not selected (switch open)
!
DS Differential lock selected (switch closed)
!
FX Filter differential pressure switch (switch open)
!
FS Filter differential pressure switch (switch closed)
!
WX Stationary PTO not selected (switch open)
!
WS Stationary PTO selected (switch closed)
Power Shift Transmission System Service Manual
Troubleshooting
Twin Disc, Incorporated
The control will continue to display the status of the switch until the diagnostics test push button is momentarily depressed which will cause the control to go back to the sub menu listing the four selections. A new switch may be selected by momentarily depressing the diagnostics test push button when the choice is displayed. To exit test 3, momentarily depress the diagnostics test push button when the XX appears in the sub menu display. The electronic control will return to the main menu.
Test 4. Accelerator Pedal and Temperature Sensor Test To enter this test, momentarily depress the diagnostics test push button when T4 is displayed. During this test, the display indicates a value, relative to the voltage received by the controller, from the accelerator pedal position potentiometer, and temperature sensors. The test will start out by cycling through the selections within T4. The T4 Sub Menu Selections are as follows. !
T = Accelerator pedal (throttle) potentiometer
!
S = Temperature sensor
!
XX = Return to Main Menu
Any of the choices can be selected by momentarily depressing the diagnostics test push button when the desired choice is displayed. The display range is 0.0 to 4.0 volts. Normal accelerator pedal and values are 1.0 to 3.5 volts. When the accelerator pedal is at the idle position, the display must read 1.0 ± 0.5. When the accelerator is fully depressed (full throttle position), the display must read 3.5 ± 0.1 volts. The temperature sensor should read about 2.1 at 70 deg F and will read 3.7 if out of range (320 deg F). NOTE: The resistance of the temperature sensor should be between 800 and 1800 ohms, and should measure approximately 1000 ohms at 77 deg F. To exit test 4 and return to the main menu, momentarily depress the diagnostics test push button when the XX appears in the sub menu display.
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Test 5. Speed Sensor Integrity Test To enter the speed sensor integrity test, momentarily depress the diagnostics test push button when T5 is indicated in the display. The control will cycle through the selections available in T5. To choose which speed sensor is to be checked, momentarily depress the diagnostics test push button when the correct speed sensor symbol is displayed.
T5 Sub Menu Selections: !
T = Turbine speed sensor
!
1 = Number 1 output speed sensor (transmission rear)
!
XX = Return to main menu
Once a speed sensor is chosen, the condition of the speed sensor will be displayed. Both segments of the display will be used. The left segment will indicate the condition of the speed sensor. The right segment will indicate which speed sensor is being tested. The possible conditions of the speed sensors are as follows. !
+1
= an open in the output #1 speed sensor or circuit
!
+T
= an open in the turbine speed sensor or circuit
!
-1
= a short in the output #1 speed sensor or circuit
!
-T
= a short in the turbine speed sensor or circuit
!
TT
= a valid turbine speed sensor impedance
!
11
= a valid output #1 speed sensor impedance
The electronic control will continue to display the status of the speed sensor until the diagnostics test push button is momentarily depressed which will cause the electronic control to go back to the sub menu listing the three selections. A new speed sensor may be selected by momentarily depressing the diagnostics test push button when the correct symbol is displayed. To exit the sub menu and return to the main menu, momentarily depress the diagnostic test push button when XX appears in the display. The electronic control will return to the main menu.
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Test 6. Solenoid Integrity Test To enter the solenoid integrity test, momentarily depress the diagnostics test push button when T6 is indicated in the display. During this test, all solenoids will be briefly energized one at a time in a continuous, rapid sequence. The control will test the integrity of each of the solenoid circuits. The selector must be moved out of N to allow the solenoids to be energized. (The display will show N if the selector is not moved out of the N position.) When all solenoids have the proper impedance, the display will show oK. If a fault is found in a solenoid circuit, it will be indicated on the display. Solenoid number with a fault will be indicated in the right digit of the display. The left digit of the display will indicate the following !
“-”
circuit is open or shorted to a positive power source
!
“+”
circuit is internally shorted or shorted to the chassis
Table 3. Solenoid Chart
Right Display Character
Solenoid
1
1
2
2
3
3
4
4
5
5
6
6
P
P TO
L
Co n ve rte r lo ckup clu tch
M
Co nve rte r mo d ula ting clutch
D
T ra nsmissio n d iffe re ntia l lo ck
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To return to the main menu, move the selector lever to N and momentarily depress the diagnostics test push button. The electronic control will return to the main menu. NOTE: Tests 7 and 8 may be used to verify torque converter and transmission clutch engagement. The engine must be running to perform the hydraulic tests. If the engine was not running when the test mode was entered, the control will have to be repowered into the diagnostics test mode (Turn the control off, start the engine, turn the control on with the J1 plug in test mode). As a safety precaution it is suggested that the output shafts be disconnected from the transmission or the vehicle parking brakes engaged to keep the vehicle from moving during tests 7 and 8. Pressure gauges will be required to verify that each clutch is engaging to its proper value. Connect the pressure gauges to the pressure ports indicated. The correct pressures are given in Description and Specifications. The display shows the identifier of the solenoid or electric modulating valve currently energized.
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Test 7. Solenoid Powered Test To enter the solenoid powered test, momentarily depress the diagnostics test push button when T7 is indicated in the display. The selector lever must be moved out of N with the engine running to allow the solenoids to be energized. Pressure gauges should be connected to transmission ports indicated. During this test, the control will cycle through a sub menu of solenoids.
T7 Sub Menu Selections: !
S1 = Transmission solenoid 1
!
S2 = Transmission solenoid 2
!
S3 = Transmission solenoid 3
!
S4 = Transmission solenoid 4
!
SP = PTO solenoid
!
SD = Transmission differential lock solenoid
!
R1 = Engine conversion relay (select pump and roll)
!
XX = Exit to main menu
To select any solenoid, momentarily depress the diagnostics test push button when the desired solenoid symbol is in the display. Once selected, the desired solenoid will be energized. The electronic control will continue to display the symbol for the energized solenoid until the diagnostics test push button is momentarily depressed which will cause the electronic control to go back to the sub menu listing the choices. A new solenoid may be selected by momentarily depressing the diagnostics test push button when the desired symbol is in the display. To exit the sub menu and return to the main menu, move the selector lever to N and momentarily depress the diagnostics test push button when the XX appears in the display.
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Test 8. Modulated Solenoid Powered Test To enter the modulated solenoid powered test, momentarily depress the diagnostics test push button when T8 is indicated in the display. The selector lever must be moved out of the N position with the engine running to allow the electric modulating valve to be energized. See note in Test 6. During this test, the electronic control will cycle through a sub menu of the electric modulating valves.
T8 Sub Menu Selections: !
M5 = Modulated solenoid, 5 (ranges 1,2,3 and rev)
!
M6 = Modulated solenoid, 6 (ranges 4,5, &6)
!
ML = Modulated solenoid, lockup clutch
!
MI = Modulated solenoid, input clutch
!
XX = Exit to main menu
To select any electric modulating valve, momentarily depress the diagnostics test push button when the desired electric modulating valve symbol is in the display. The selected modulating valve will be energized. Depressing the diagnostics test push button a second time and holding it down will cause the electric modulating valve current to increase in 5% increments until the diagnostics test push button is released. Table 4 in Troubleshooting lists the expected clutch pressures. To reinstate the stepping of the current level, depress the diagnostics test push button and hold until the next desired level is achieved. This can be repeated as often as desired until the display shows 95 which indicates full current has been achieved. After this point, XX will appear in the display. To return to the sub menu, momentarily depress the diagnostics test push button. To exit the sub menu and return to the main menu, move the selector lever to N and depress the diagnostics test push button when the XX appears in the display. The electronic control will return to the main menu.
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ETA-28L Electric Modulating Valves Table 4 shows expected pressure values for the electric modulating valves tested in diagnostics test 8. Note that the oil temperature is between 100 deg F and 180 deg F, and the system main pressure is 250 psi or less, and SAE 10W oil is used. If the main pressure is lower, the pressure will be limited to that value, but pressures below main should not be affected much at any given setting. The important things to consider when testing a valve are that there should not be any pressure at zero current, and full pressure when 95 is displayed. A plot of pressure vs. current should result in a reasonably smooth line from minimum current to maximum current.
NOTE: The value shown in the display indicates the percent of full current sent to the electric modulating valve. The range of values will be from 0 - 95 percent in 5 percent increments.
Table 4. Proportional Valve Pressure Chart
Current % of full 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95
Pressure Valve M and L min 0 0 0 0 0 0 0 3 10 30 52 74 93 112 135 155 177 195 215 223
coil end down max 0 0 0 0 0 0 0 12 31 50 71 92 112 132 152 172 192 210 225 230
Power Shift Transmission System Service Manual
Pressure Valve 5 and 6 min 0 0 0 0 0 0 0 8 25 46 69 90 109 130 150 172 192 212 227 227
(c oil end up) max 0 0 0 0 0 0 15 29 46 70 90 110 129 148 170 189 210 226 230 230
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Test 9. Stall Check Test 9 may be used to verify proper operation of the torque converter. The engine must be running to perform the stall check. If the output shafts were disconnected to perform other tests, they must be reconnected. If the engine was not running before entering the test mode, the control will have to be repowered into the diagnostics test mode (Turn power off, start engine, turn power on with the J1 plug in test mode). Test 9 should be entered with the selector lever in N. The vehicle brakes must be applied in this test.
During the operation of test 9, it is necessary to have all personnel and any obstacles clear of the vehicle. If vehicle brake failure occurs, the transmission will accelerate in 5th range. Operation can be stopped by any of the following. !
Selecting N
!
Turning the vehicle power off
!
Depressing the diagnostics test push button
To enter the stall test, momentarily depress the diagnostic test push button when T9 is indicated in the display. Depress the selection button when the desired sub menu selection is displayed.
T9 Sub Menu Selections: !
5
5th gear will be engaged when range selector is in D
!
XX
Return to main menu
Selection of 5th allows the engine to be loaded. Engine speed is manually controlled by the foot throttle. High amounts of energy will be transferred to the transmission oil during this test. This test should only be performed for short periods of time to allow the oil temperature to diminish. Failure to allow the oil to sufficiently cool may cause system damage. To exit test 9, move the selector lever to N and momentarily depress the diagnostics test push button. The electronic control will return to the main menu.
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Exiting the Test Mode 1.
Turn system power off.
2.
Return plug connection to normal position (no connection between yellow and green wires).
3.
Turn system power on.
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112
CONTROL SYSTEM DIAGNOSTICS START DIAGNOSTICS BY TURNING POWER OFF, AND CONNECTING PLUG IN J1 HARNESS TO CONNECT WIRES TURN POWER ON, AND THE DIAGNOSTICS DOES AN INTERNAL TEST. IF PASSED, IT WILL THEN DISPLAY T1, FOLLOWED BY THE
START TEST
. D I S P L A Y T E S T C H A R A C T E R S . (XX, ++, . , ** ) P R E S S TEST M E A N S T O D E P R E S S T H E TEST B U T T O N O N T H E V E H I C L E EXIT DIAGNOSTICS BY TURNING POWER OFF, AND RECONNECTING PLUG IN J1 HARNESS TO OPEN CIRCUIT POSITION XX
T1 DISPLAY
T2 RANGE SELECTOR
(EPROM CHECKSUM WILL DISPLAY ONCE )
T3 INPUT SWITCH P, D, F, W, XX PRESS TEST TO SELECT DESIRED SWITCH
PRESS TEST TO ENTER AND EXIT
XX
XX
T4 ACCELERATOR TEMPERATURE T, S, XX PRESS TEST TO ENTER
T5 SPEED SENSOR T, 1, XX
T6 SOLENOID INTEGRITY TEST
PRESS TEST TO ENTER OR EXIT
SELECT NEUTRAL PRESS TEST TO EXIT
1
**
WORK MODE (PTO) PX - N O T S E L E C T E D PS - S E L E C T E D
CONTROL AND DISPLAY GOOD PRESS TEST TO EXIT
DIFFERENTIAL LOCK DX - N O T S E L E C T E D DS - S E L E C T E D
XX, ++, . ,
FILTER DELTA PRESSURE FX - OPEN FS - C L O S E D STATIONARY PTO WX - NOT SELECTED WS - S E L E C T E D MOVE SELECTOR TO ALL LOCATIONS
TURBINE SENSOR TT : GOOD +T : OPEN -T : S H O R T E D PRESS TEST TO EXIT OUTPUT SENSOR 11 : G O O D +1 : O P E N -1: S H O R T E D PRESS TEST TO EXIT
MOVE SELECTOR OUT OF NEUTRAL
"-" A N D S O L 1,2,3,4,5,6,P, L, M, O R D INDICATES OPEN SOLENOID
W
GOOD SELECTOR
TEMP SENSOR 70 F (21C) = 2.1 0.8 TO 3.7 F O R -40F TO 320F (-40C TO 160C)
T9 CONVERTER STALL TEST
T
"+" A N D S O L 1,2,3,4,5,6,P, L, M, O R D INDICATES SHORTED SOLENOID
T
"R,N,6,5 ,4,3,2,1"
CONTROL DEFECTIVE BAD WIRES OR SWITCH IN SELECTOR
F
ADJUST THROTTLE IDLE: 1.0+0.5 FULL: 3.5+0.1
I2 O R I3
"--" IN DETENT
D
T8 MODULATED VALVE
S
oK INDICATES ALL SOLENOIDS ARE GOOD
APPLY BRAKES, ENGINE IDLE, SHIFT FROM NEUTRAL
APPLY BRAKES, ENGINE IDLE, SHIFT FROM NEUTRAL
XX PRESS TEST TO ENERGIZE WHEN DISPLAYED M5, M6, ML, MI, XX
XX
PRESS TEST T O ENERGIZE WHEN DISPLAYED S1, S2, S3, S4, SP, SD, R1, XX
XX
XX
RECORD MAIN AND CLUTCH PRESSURE PRESS TEST TO TURN OFF
Figure 15. Control System Diagnostics Flowchart
SHIFT TO NEUTRAL ANY TIME TO EXIT PRESS TEST TO STEP - % C U R R E N T - 00, 05, 10, 15.....90, 95, XX
APPLY BRAKES, ENGINE IDLE, SHIFT FROM NEUTRAL 5, XX
5
PRESS TEST CAUTION! TRANSMISSION SHIFTS INTO 5TH RANGE VEHICLE MAY MOVE
PRESSURE TEST OPTIONAL
SHIFT TO NEUTRAL
RECORD CLUTCH PRESSURE AND % OF CURRENT
NEUTRAL WITH MOD CLUTCH ENGAGED
Twin Disc, Incorporated
Power Shift Transmission System Service Manual
DISPLAY WILL CONTINUALLY CYCLE T2 T H R U T9. PRESS T E S T TO ENTER DISPLAYED TEST NUMBER
P
T7 SOLENOID POWER
Troubleshooting
Twin Disc, Incorporated
Pressure Test of System NOTE: Measurement and recording of all of the pressures listed can be very helpful in determining the cause of and a solution to a problem. A shortcut taken here to only measure the pressure that is of concern can result in erroneous conclusions. Install quick connect fittings on the following ports. Refer to Figures 2 through 5 in Operation. !
Main pressure
!
Converter outlet
!
Lube
!
Lockup clutch
!
Modulated input clutch
!
Clutch 1
!
Clutch 2
!
Clutch 3
!
Clutch 4
!
Clutch 5
!
Clutch 6
!
Differential clutch
!
Pto clutch
Multiple gauges should be used, otherwise fewer gauges must be moved to accomplish the test. One fitting with a short open ended hose should be used to vent the suggested port. The measurement of leakage from the vented port will aid in determining if internal leakages could be causing partial application of the opposing clutch on the same shaft. It is normal that a few drips will be present from the vented location when the opposing clutch is engaged. A steady stream may be an indication of excessive leakage due to seal ring damage. Power Shift Transmission System Service Manual
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Refer to Troubleshooting for instructions for test 7 and test 8 procedures. Engine speed should be held at approximately 715 rpm during test if possible. If not possible, run complete test at consistent engine rpm. Oil temperature should be warmed to operating temperatures if possible. If not, this must be taken into consideration during the analysis of the results. Use Test 7 to select solenoids for clutches 1, 2, 3, 4, differential, and pto. Use Test 8 to select solenoids for clutches 5, 6, lockup, and modulated input clutch. Use the value at 95% of full current when recording pressures in Table 5 in Troubleshooting. Troubleshooting the proportional effects of the shift profiles requires that pressure versus current be measured and recorded in Table 6 in Troubleshooting. The charts that follow will aid in determining if a possible problem may exist
NOTE: All of the solenoids with the exception of the PTO clutch solenoid are interchangeable, and two of them could be swapped to aid in trouble shooting.
Refer to Description and Specifications for expected pressures. Note that these values may differ somewhat with temperature and engine speed variations. An analysis of the measured results will aid in determining the cause of potential problems. Significant variations from the specifications and differences among the individual clutches are indications of problem areas.
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Table 5. Pressure Data
Record none Pressure Main
1
2
3
Solenoid energized 4 5 6 Lock up Mod In
Diff
Pto
--
--
--
--
Converter Lube Lock-up
--
--
--
--
--
--
--
Mod. Cl
--
--
--
--
--
--
--
--
Diff. Cl
--
--
--
--
--
--
--
--
--
Pto Cl
--
--
--
--
--
--
--
--
--
--
Clutch 1
--
V E NT
--
--
--
--
--
--
--
--
Clutch 2
--
V ENT
--
--
--
--
--
--
--
--
Clutch 3
--
--
--
V EN T
--
--
--
--
--
--
Clutch 4
--
--
--
V ENT
--
--
--
--
--
--
Clutch 5
--
--
--
--
--
V ENT
--
--
--
--
Clutch 6 Flow from vented port
--
--
--
--
--
---
---
---
---
V ENT
--
--
--
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Table 6. Proportional Valve Pressure
Coils up Clutch Clutch 5 6
Pressure, PSI Coils down max min Lock up 0 0
Current % of full 0
min
5
0
0
0
0
10
0
0
0
0
15
0
0
0
0
20
0
0
0
0
25
0
0
0
0
30
0
15
0
0
35
8
29
3
12
40
25
46
10
31
45
46
70
30
50
50
69
90
52
71
55
90
110
74
92
60
109
129
93
112
65
130
148
112
132
70
150
170
135
152
75
172
189
155
172
80
192
210
177
192
85
212
226
195
210
90
227
230
215
225
95
227
230
223
230
100 Main Pressure Lub e P ressure
227 --
230 --
223 --
230 --
--
--
--
--
116
0
Mod. max Conv 0
Power Shift Transmission System Service Manual
Twin Disc, Incorporated
Troubleshooting
Transmission In Vehicle Test Following the installation of any major components such as the transmission or torque converter, it is important that certain tests be performed to insure proper installation and function of the components. This vehicle is equipped with an oil filtering system with a bypass warning indicator. During the following engine running tests, monitor the bypass warning that will be displayed in the transmission system display unit. If the filter bypass (FP code) is indicated, and the engine is at idle, it is important to change oil filter elements. Repeat this as necessary to clean up the oil of contaminants that may have been trapped in various locations in the transmission hydraulic system. A data sheet and procedure guide are on the following pages.
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Troubleshooting
Twin Disc, Incorporated
Data Sheet: In Vehicle Testing Chassis# ________ Hour Meter __________ Km Serial #’s: Transmission________ Converter __________ Control Date:
________ Tested By
__________ __________
__________ Location __________
Electronic Diagnostic Tests Engine not running (See diagnostic test in the troubleshooting section of this manual) Table 7. Diagnostic Test T est
Description
T1
Display check
T2
Range Selector Check
T3
I np ut Sw itches
T4
Throttle Pedal, (0.5/1.5 to 3.4/ 3.5 Volts)
T5
Speed sensors
T6
Solenoid integrity
Results
Start engine for the following tests:
Check Oil Level Oil level should be in the middle of the upper glass when in neutral with engine at low idle, with oil at operating temperature.
Low Idle Pressure Check Check with the engine speed at low idle, the transmission in neutral, and the oil temperature still cold: Engine rpm
____________________ (600 to 700 rpm)
Main pressure
____________________ (185 psi minimum)
Converter outlet pressure ____________________ (50 to 70 psi) Lube regulator 118
____________________ ( 5 to 15 psi) Power Shift Transmission System Service Manual
Troubleshooting
Twin Disc, Incorporated
High Speed Pressure Test Test with warm oil to 100 deg C by shifting to D6 with vehicle parking brakes on and engine speed up to about 1200 to 1500 RPM. When oil is hot shift to N and set engine speed at 2150 RPM. Engine RPM
____________________ ( 2100 to 2200 RPM)
Oil temp
____________________ Deg C
Main pressure
____________________ (228 to 235 psi)
Converter outlet pressure ____________________ (70 to 90 psi) Lube regulator
____________________ (35 to 50 psi)
Clutch Pressure Test - Test T7 While in test mode start engine and select T7, and set engine at 2100 to 2200 RPM, selector must be in D6 position.
Table 8. Solenoid Pressures
Solenoid Engaged
Main Pressure Psi. (228/235psi)
Clutch Apply Pressure Psi. (within 12 psi of main)
Lube Pressure at Shaft Cover, Psi (15-35psi)
Lube Pressure M easured at this Shaft (G)
S1
1-2
S2
1-2
S3
3-4
S4
3-4
SD (dif)
NOTE: Clutch apply pressures on disengaged clutch packs should be 0 psi. Shaft lube pressures should not change when solenoids are on or off.
Power Shift Transmission System Service Manual
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Troubleshooting
Twin Disc, Incorporated
Test T8 - Modulated Clutches Select test T8, set engine at 2100 to 2200 RPM, selector must be in D6 position. Increase % engagement to modulated clutch and record clutch pressure.
Table 9. Modulated Pressures
Pressure, PSI Coils dow n
Coils up Current % of full 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 Main @95% Lube @95%
120
m in 0 0 0 0 0 0 0 8 25 46 69 90 109 130 150 172 192 212 227 227
Clutch Clutch 5 6
Lock up
Mod. Conv
m ax 0 0 0 0 0 0 15 29 46 70 90 110 129 148 170 189 210 226 230 230
m in 0 0 0 0 0 0 0 3 10 30 52 74 93 112 135 155 177 195 215 223
m ax 0 0 0 0 0 0 0 12 31 50 71 92 112 132 152 172 192 210 225 230
--
--
--
--
--
--
--
--
Power Shift Transmission System Service Manual
Troubleshooting
Twin Disc, Incorporated
Range Engagement Test This verifies that the truck is shifting properly. Keep the engine at low idle, and vehicle brakes on, pressure gages still connected.
Table 10. Shift Results
Selected R an ge
T est Port
Pressu re Psi
C o m m en ts
T9
1 6
______
T ruck should m ove forw ard in 5th r ange
T9
1 6
Stall C heck
Apply brakes. Engine at full throttle; R ecord converter stall R PM ___________.
D1
2 5
______
T ruck should m ove forw ard in 1st range
D2
1 5
______
T ruck should m ove forw ard in 2nd ra nge
R
4 5
______
T ruck s hould m ove in reverse
m anual override
3 5
______
Select ed R an ge
Final Drive Test Drive truck, verify proper operation in all ranges and lockup. Look for leaks. Recheck oil level.
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Troubleshooting
Twin Disc, Incorporated
PRESSURE VS CURRENT COIL up Main Pressure 230
Pressure, PSI
280 240 200 160 120 80 40 0 0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Current, Amps Figure 16. Pressure vs. Current Coil Up Graph
Pressure, PSI
PRESSURE VS CURRENT COIL down 280 240 200 160 120 80 40 0 0.1
Main pressure 230
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Current, Amps Figure 17. Pressure vs. Current Coil Down Graph
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Power Shift Transmission System Service Manual
Engineering Drawings
Twin Disc, Incorporated
Engineering Drawings
The following pages include the engineering drawings that are specific to this model. The engineering drawings included are listed below. !
1018316
(System, Elect. Control)
!
1017753
(Schematic, Hydraulic)
!
1017754
(Diagram, Piping)
!
1018601A (page 1 of 3)
(Transmission Parts)
!
1018601A (page 2 of 3)
(Transmission Parts)
!
1018601A (page 3 of 3)
(Transmission Installation)
!
1018068A
(Clutch Assembly, 2-5, Reverse)
!
1018065A
(Clutch Assembly, 1-4, 3-6)
!
1017956B
(Clutch Assembly, 1-2-3, 4-5-6)
!
1018205
(Differential Assembly)
!
1018460
(Valve Assembly, Differential)
!
1017752
(Valve Assembly, Main Regulator)
!
1018465 (page 1 of 2)
(Torque Converter Installation)
!
1018465 (page 2 of 2)
(Torque Converter Parts)
!
1018360 (partial)
(Valve Assembly, Solenoid)
!
1017261
(Power Take Off Assembly)
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Engineering Drawings
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Twin Disc, Incorporated
Power Shift Transmission System Service Manual
#1019864 04/00
TWIN DISC, INCORPORATED
RACINE, WISCONSIN 53403, U.S.A.
262-638-4000/262-638-4482 (FAX)
WWW.TWINDISC.COM
