Introduction

NOTE: For Testing and Adjusting of the Power Train Electrical System, make reference to the POWER TRAIN TESTING AND ADJUSTING (ELECTRICAL SYSTEM), Form No. SENR3018. For Testing and Adjusting of the remainder of the Power Train, make reference to the POWER TRAIN TESTING AND ADJUSTING for 768C TRACTOR & 769C TRUCK, Form No. SENR2935.

NOTE: For Specifications with illustrations, make reference to SPECIFICATIONS FOR 768C TRACTOR & 769C TRUCK POWER TRAIN, Form No. SENR2933. If the Specifications in Form SENR2933 are not the same as in the Systems Operation and the Testing and Adjusting, look at the printing date on the back cover of each book. Use the Specifications given in the book with the latest date.

Power Train Systems

General Description

The power train is made up of four basic systems.

1. Transmission Control (Electrical System).

2. Torque Converter.

3. Transfer Gears and Transmission.

4. Differential and Final Drives.

These four basic systems connect to each other either electrically, hydraulically or mechanically. A basic diagram shows what components are common to each system.

POWER TRAIN SYSTEMS BASIC DIAGRAM (SIMPLIFIED)

COMPONENTS OF THE POWER TRAIN
1. Differential and bevel gear. 2. Pinion. 3. Transmission. 4. Transfer gears. 5. Front drive shaft. 6. Torque converter. 7. Final drives and axles. 8. Wheels and tires. 9. Rear drive shaft. 10. Lockup clutch. 11. Engine.

REAR OF CAB
12. Transmission control.

Transmission control (12) matches the transmission speed to the selected speed of transmission shift lever (13). The transmission control gets information of the selected speed of operation through the electrical system. The transmission control electrical system activates the hydraulic systems (transmission and torque converter) through solenoids (upshift, downshift and lockup solenoids).

RIGHT SIDE OF OPERATOR'S SEAT
13. Transmission shift lever. 14. Shift lever switch (inside console).

Torque converter (6) has a lockup clutch (10) for direct drive and a one-way clutch for torque converter drive. The torque converter is fastened directly to the flywheel of engine (11).

FRONT OF TRANSFER GEARS
15. Transmission speed sender.

The torque converter drives transmission (3) hydraulically, unless the lockup clutch is activated. When the lockup solenoid is activated, the lockup clutch is hydraulically engaged. The rotating (input) housing of the torque converter is now mechanically connected to the output shaft of the torque converter. The drive shaft mechanically connects the torque converter to transfer gears (4). The transfer gears are fastened directly to the transmission.

RIGHT SIDE OF TRANSMISSION
16. Downshift solenoid. 17. Upshift solenoid. 18. Plug for access to the rotary selector spool.

Upshift solenoid (17) and downshift solenoid (16) hydraulically activate the transmission hydraulic control group. The transmission hydraulic control group activates the transmission clutches which cause the mechanical connection to the transmission output shaft. The transmission clutches will not drive the transmission output shaft unless the torque converter is activated (either hydraulically or mechanically).

The transmission has seven forward speeds and one reverse speed. The selection of speed is done manually, in REVERSE, NEUTRAL and FIRST. The selection of SECOND through SEVENTH speeds is dne either manually or automatically.

LEFT SIDE OF MAIN FRAME
23. Return oil screen. 24. Return oil filter. 25. Hydraulic oil tank. 26. Transmission oil tank.

REVERSE is torque converter drive only. FIRST has both a torque converter drive and a direct drive. SECOND through SEVENTH speeds are direct drive only with a very short time of converter drive during transmission clutch engagement to make shifts smooth. The transmission output shaft is fastened directly to differential and bevel gear (1). The differential and bevel gear are fastened directly to the rear axle housing.

INSIDE RIGHT FRAME
19. Torque converter oil filter. 21. Transmission oil filter. 22. Secondary and parking brake valve.

BEHIND FRONT LEFT TIRE
20. Parking brake release oil filter.

LEFT OF AND BELOW ENGINE
28. Transmission oil cooler.

After the transmission and torque converter are connected, power can now be supplied from the engine (through the transmission and torque converter) to the differential. The rear axles mechanically connect the differential to the final drives. The final drives are connected to the rear wheels. Power is now sent to the tires.

RIGHT SIDE OF ENGINE
27. Oil cooler for torque converter and brakes.

When the transmission is in the correct speed position, the mechanical movement of the rotary selector spool causes the transmission switch to electrically signal the transmission control that the shift is complete. With the rotation of the output shaft of the transmission, transmission speed sender (15) electrically signals the transmission control that the machine has moved.

REAR OF ENGINE
29. Transmission oil breather. 30. Hydraulic oil breather.

The torque converter has a hydraulic system that uses oil that is also common with the brake cooling system, the parking brake release system and the hoist or wagon (trailing unit) hydraulic system. These systems all use the same SAE 10W oil from hydraulic oil tank (25). Lockup clutch and solenoid valve group (31), inlet relief valve (32), outlet relief valve (33), oil pump (34), charging oil filter (19) and lockup clutch (10) are some of the components in this system.

REAR OF TORQUE CONVERTER
31. Lockup clutch and solenoid valve group. 32. Inlet relief valve. 33. Outlet relief valve.

Pressure oil to engage the lockup clutch comes from the parking brake release system. The oil goes through oil filter (20) and divides. Some oil goes to lockup clutch and solenoid valve group (31). This valve group controls the operation of lockup clutch (10). The rest of the oil goes to secondary and parking brake valve (22).

REAR OF TORQUE CONVERTER
34. Oil pump for torque converter and brakes. 35. Oil pump for transmission.

Oil from outlet relief valve (33) is used to cool the wheel brakes. Oil that is not needed by the hoist or wagon hydraulic system also is used to cool the wheel brakes. These two oils go through oil coolers (27) before they go to the brakes. The oil then goes back through return oil screen (23) and into hydraulic oil tank (25).

BOTTOM OF TRANSFER GEAR CASE
36. Magnetic screen.

The transmission has its own hydraulic system. It uses SAE 30W oil from transmission oil tank (26). Other components in this system are: a transmission hydraulic control group, oil pump (35) with two sections, oil filter (21), magnetic screen (36), return oil filter (24) and transmission oil cooler (28).

The basic components of the transmission hydraulic control group are downshift solenoid (16), upshift solenoid (17), pressure control group (37), selector group (38) and rotary actuator (39). The solenoids are the connection between the electrical and hydraulic systems. The solenoids are activated electrically and send oil to rotary actuator (39). The rotary actuator turns rotary selector spool (40) in selector group (38) which sends pilot oil to pressure control group (37). Pressure control group (37) then sends oil at the correct rate to smoothly engage the correct clutches in the transmission.

LEFT SIDE OF TRANSMISSION HYDRAULIC CONTROL GROUP
16. Downshift solenoid. 17. Upshift solenoid. 37. Pressure control group. 38. Selector group. 39. Rotary actuator. 40. Rotary selector spool.

When plug (18) is removed, rotary selector spool (40) can be manually moved through all of its positions when the engine is off. When rotary selector spool (40) is turned clockwise as far as it will go, the spool [and rotary actuator (39)] is in NEUTRAL position. From NEUTRAL each detent position in the counterclockwise direction is REVERSE, FIRST, SECOND, THIRD, FOURTH, FIFTH, SIXTH, SEVENTH and EIGHTH speeds respectively (EIGHTH speed position is not used on 700 series machines).

Hydraulic And Transmission Oil Tanks

LEFT SIDE OF MAIN FRAME (769C Shown)
1. Return oil screen for torque converter and brake cooling. 2. Return oil filter for transmission. 3. Cover for access to adjust relief valves. 4. Hydraulic oil tank for torque converter, brakes and hoist or wagon (trailing unit). 5. Transmission oil tank.

The transmission oil tank is separate from the hydraulic oil tank. Transmission oil tank (5) has SAE 30W oil. This oil is used only for operation of the transmission. Hydraulic oil tank (4) has SAE 10W oil. This oil has several uses: for torque converter operation, for brake cooling and hydraulic brake operation and for hoist or wagon hydraulic system operation.

Cover (3) can be removed from hydraulic oil tank (4) to easily adjust the relief valve for the hoist or wagon hydraulic system and the oil cooler relief valve.

REAR OF ENGINE
6. Breather for hydraulic oil tank, torque converter cover and oil pump drive. 7. Breather for transmission oil tank and transmission case.

Oil Line Identification

TOP OF OIL TANKS
8. Line to breather (6). 9. Return line for rear brake cooling oil. 10. Makeup line for front brake master cylinder. 11. Makeup oil tank for brake master cylinders. 12. Bleeder line for retarder brake master cylinder. 13. Bleeder line for rear brake master cylinder. 14. Makeup line for rear brake master cylinder. 15. Return line for transmission scavenge oil. 16. Inlet tube for makeup oil. 17. Return line for torque converter scavenge oil. 18. Line to breather (7). 19. Breather line to transmission case.

INNER (RIGHT) SIDE OF OIL TANKS
8. Line to breather (6). 9. Return line for rear brake cooling oil. 10. Makeup line for front brake master cylinder. 12. Bleeder line for retarder brake master cylinder. 13. Bleeder line for rear brake master cylinder. 14. Makeup line for rear brake master cylinder. 15. Return line for transmission scavenge oil. 16. Inlet tube for makeup oil. 20. Makeup line for retarder brake master cylinder. 21. Outlet to head ends of hydraulic cylinders. 22. Outlet to rod ends of hydraulic cylinders. 23. Inlet from hydraulic (hoist or wagon. pump. 24. Drain line from secondary and parking brake valve. 25. Outlet for transmission charging oil. 26. Outlet for hydraulic (hoist or wagon) oil. 27. Outlet for torque converter charging oil and parking brake release oil. 28. Outlet for brake cooling oil (from hydraulic control valve). 29. Drain line from torque converter inlet relief valve.

Power Train Electrical System

TRANSMISSION CONTROL ELECTRICAL SYSTEM

The power train electrical system is made up of a sealed, solid state transmission control, a transmission switch, a shift lever switch, three solenoids (upshift, downshift and lockup), a transmission speed sender, a retarder brake switch, a secondary brake switch, a service brake switch, a bed raise switch for trucks [a XMSN (transmission) test switch for tractors], and electrical harnesses and connectors.

The main component in this electrical system is the transmission control. The transmission control must get information from six sources: the shift lever switch, the transmission switch, the transmission speed sender, the bed raise (XMSN test) switch, the retarder brake switch or the secondary brake switch. Then the transmission control will send output current to one of the three solenoids.

Transmission Control

The transmission control gets current through a fuse on the fuse block. The transmission control then sends the different currents to the switches and solenoids.

The transmission control has 15 lights (LED's) across the top. The lights are for the five (control) wires to the shift lever switch and the transmission switch, a speed pickup light (from the transmission speed sender), a retarder brake light, a lockup solenoid light, an upshift solenoid light and a downshift solenoid light.

A light for the shift lever switch or transmission switch is ON when the control wire for that light is at electrical ground, (normally through the switch). A light for the upshift, downshift or lockup solenoid is ON when the output from the transmission control for that solenoid wire has +24 volts. The retarder brake light is ON when the service brakes, parking brakes, secondary brakes or retarder lever is activated. When the speed pickup light is OFF, the signal from the pickup (transmission speed sender) gives the indication the machine is moving.

TRANSMISSION CONTROL

SCHEMATIC SYMBOL

There are six wires that go from the transmission control to each switch (shift lever and transmission). The transmission control puts a potential of +5 volts on these six wires. Five of these six wires (control wires) give the transmission control the information (from the switches) of as many as nine different speed positions (REVERSE, NEUTRAL and FIRST through SEVENTH speed) for the transmission. The sixth wire is put to vehicle or machine (electric) ground through the switch. The sixth wire is a GROUND VERIFY signal. This wire gives the transmission control an indication of the connectors and harnesses between the switches (transmission and shift lever) and the transmission control. If the sixth wire is not a machine (electric) ground, the transmission control has +5 volts on this wire. With this voltage on the wire, the transmission control will not operate correctly. This sixth wire is at machine ground only when the switch is connected. A more complete explanation of this sixth wire is given in the section on switch operation.

Switch Operation (Shift Lever Or Transmission)

Except for different pin numbers at the switch, the transmission switch and shift lever switch operate basically the same. The shift lever or transmission switch is a mechanical switch with diodes in it. In this way, the switch can be built (made) smaller because less contacts and rotors are needed. The diodes let current flow in one direction only.

Many of the same pins can be used for different speeds, because a diode can send the current flow to the correct pin. If you remember from the earlier description of the transmission control, the switch will supply (give) a path, to (electric) ground, to light two out of the five lights (LED's) for the switch. The shift lever switch has two pins that are connected inside the switch (Pin 1 and Pin 2). In the harness, Pin 2 connects to machine (electric) ground. This pin must be connected to machine (electric) ground, or all of the LEVER lights (for the shift lever switch) on the transmission control will be OFF. If only the wire for ground verify (Pin 1) is not at machine (electric) ground, the LEVER lights on the transmission control will be ON, but the solenoid lights (LED's) will be OFF. The ground verify wire can only send a ground (electric) to the transmission control if all of the harnesses and connectors operate (function) correctly.

SHIFT LEVER SWITCH

The five control wires connect to Pins 3, 4, 5, 8 and 9 of the shift lever switch. Each of the control wires have a +5 volts potential when disconnected from the circuit. When the switch is connected, two out of the five control wires are at machine (electric) ground. For explanation of the current path (flow) through the switch, the transmission shift lever is in NEUTRAL position, the rotor connects to the neutral contact. This connection lets current go through the two diodes to machine (electric) ground as shown.

This current path puts grounds on Pins 5 and 9 of the shift lever switch. Normally, this causes LEVER 3 and LEVER 5 lights respectively (on the transmission control) to come (turn) ON.

TRANSMISSION SWITCH

SCHEMATIC SYMBOL

Sensor - Magnetic (Transmission Speed Sender)

The transmission speed sender gets power from the transmission control. This current and voltage (power) must be at the transmission speed sender so a signal (electric frequency) can be sent back to the transmission control. To get this signal (electric frequency) to the transmission control, there is a rotation of gear teeth near (past) the transmission speed sender. The gear for the transmission speed sender has 120 teeth and is connected to the transmission output shaft. To cause the speed pickup light (LED) on the transmission control to turn (go) OFF, the machine must move and turn the transmission output shaft (and the gear). When 125 teeth (on the gear) go past the transmission speed sender each second, the speed pickup light turns (goes) OFF. The speed of the gear teeth (on the gear on the transmission output shaft) sends signals (electric frequency) from the transmission speed sender to the transmission control. This tells the transmission control the ground speed of the machine. From this information and the information from the shift lever switch (of the selected speed), the transmission will automatically shift as ground speed changes until the information from the transmission switch tells the transmission control to stop automatic shifts. The speed selection on the transmission shift lever is now the same as the transmission. The transmission control will not permit the transmission to go into a speed higher (upshift) than the position of the transmission shift lever. When the signals from the transmission speed sender give an indication for a downshift, the transmission control will downshift automatically.

TRANSMISSION SPEED SENDER

Switch - Bed Raise Or [XMSN (Transmission) Test Switch For Tractors)]

The bed raise switch has two purposes. The secondary purpose of the bed raise switch and the primary purpose for the XMSN test switch (for tractors only) is to check the 15 lights (LED's) on the transmission control when the switch is open. All of the 15 lights must turn (come) ON when the switch is open. If all of the lights do not turn ON, the switch circuit or transmission control is bad.

The primary purpose of the bed raise switch is to keep the transmission control in a FORWARD or NEUTRAL speed position while the bed is raised. The switch will be open (activated) when the hoist lever is in the LOWER or RAISE position. An open circuit on Pin 7 of the transmission control will prevent the transmission from shifting into REVERSE until the switch is closed (deactivated). After the bed raise switch is closed (deactivated), the shift lever must be put in NEUTRAL before a shift to REVERSE can be made.

BED RAISE SWITCH

Solenoids (Upshift, Downshift and Lockup)

Upshift and Downshift Solenoids

The solenoids receive an electrical signal from the transmission control and supply hydraulic pressure to do mechanical work. The upshift and downshift solenoids, when activated (electrically by the transmission control), let hydraulic oil flow to the rotary actuator. The hydraulic oil pressure turns the rotary actuator until the solenoid (upshift or downshift) stops the hydraulic flow. The transmission control keeps the solenoid activated until the correct signal (code) from the transmission switch is received. The rotary actuator is connected to the rotary selector spool and the transmission switch is connected to rotary selector spool by a flexible coupling. When the rotary selector spool is in the correct position, (transmission control receives the correct signal from the transmission switch) the transmission control stops the current flow to the solenoid. The solenoid stops the oil pressure to the rotary actuator and the rotation of the rotary selector spool stops. This sequence is done for every upshift or downshift of the transmission. Only in the NEUTRAL position will the transmission control keep the downshift solenoid activated after the shift is complete.

UPSHIFT SOLENOID ACTIVATED

DOWNSHIFT SOLENOID ACTIVATED

Lockup Solenoid

For speed positions that need direct drive, the lockup solenoid must be activated after the upshift or downshift solenoid is deactivated (made not active). The position (signal) of the transmission switch and the ground speed signal from the transmission speed sender tell the transmission control when to activate the lockup solenoid. The hydraulic oil pressure for the lockup solenoid comes from the parking brake release pump through the lockup clutch reduction valve to the solenoid. When the transmission control activates the lockup solenoid, hydraulic oil pressure goes through the lockup clutch modulation valve to the lockup clutch. The lockup clutch will stay in direct drive until the oil pressure is removed by the lockup solenoid.

LOCKUP SOLENOID ACTIVATED

Switch - Pressure (Secondary and Service Brake)

Some input (electrical) signals to the transmission control during a shift can cause a "hunting" condition of the transmission. The design of the transmission control will help keep the transmission from this "hunting" condition. A hunting condition is an unwanted rapid upshift and downshift of the transmission caused by fluctuations (changes) in ground speed, while the machine is operating at or near a transmission shift point. For example, the machine upshifts then downshifts, then upshifts, then downshifts, etc.

The transmission control is designed to make only one "turn around" shift approximately every two seconds. A turn around shift is when the transmission upshifts or downshifts to the next speed position, then shifts back to the original speed position (before the shift). This design helps keep the transmission from the "hunting" condition.

In normal operating conditions, a rapid shift may be needed, for example to stop the vehicle. If a rapid downshift was not made in this common condition, the engine would stop. When activated, the secondary brake switch and service brake switch will tell the transmission control that rapid shifts, (less than the two seconds for normal turn around shifts) are needed. The secondary brake switch will open when the secondary brakes or parking brakes are engaged. The service brake switch will open when the brake pedal is engaged (pushed).

When both switches are closed (secondary brake released, parking brake released, and service brake not activated), the transmission control gets a ground (electric) through the switches to Pin 20 of the transmission control. This ground (electric) tells the transmission control to let only one turn around shift happen in approximately two seconds. When one or both switches are open, the ground (electric) is removed from Pin 20 of the transmission control. This tells the transmission control a rapid shift time is needed. Each time the secondary brakes, parking brakes, or service brakes are engaged the transmission control will shift more rapidly.

SECONDARY BRAKE SWITCH

SERVICE BRAKE SWITCH

Switch - Pressure (Retarder Brake)

The retarder brake switch will signal the transmission control when a higher engine rpm is needed for an upshift or downshift of the transmission. When the retarder brake switch is closed (NOT activated), the transmission control gets a ground (electric) through the switch to Pin 6 of the transmission control. This ground, put on Pin 6, tells the transmission control that normal engine rpms for upshifts and downshifts are needed.

When the retarder brake switch is open (activated), the transmission control will upshift and downshift at a higher engine rpm.

RETARDER BRAKE SWITCH

Sequence For Manual Shifts

Neutral

TRANSMISSION CONTROL ELECTRICAL SYSTEM

When the transmission shift lever is in NEUTRAL position, LEVER 3 and LEVER 5 lights on the transmission control turn (come) ON. This is an indication that the rotor for the shift lever switch is in NEUTRAL position. With the shift lever switch in this position, current flows from the transmission control on wires 713-OR and 715-GN through the shift lever switch to machine ground. This path (way) for current flow lets the lever lights turn ON. This information (current flow) also tells the transmission control a downshift is needed. At this time, the transmission control sends current to the downshift solenoid through 704-GY wire to ground. When the downshift solenoid activates, hydraulic oil pressure goes to the rotary actuator and causes the rotary selector spool to turn.

SWITCH LEVER SWITCH (NEUTRAL Position)

The transmission switch rotor is connected to the rotary selector spool by a flexible coupling. When the rotor in the transmission switch is in the correct position (NEUTRAL), a ground (electric) is put on 724-YL and 725-GN wires. With these wires at machine ground, current flows from the transmission control through the transmission switch to machine ground. This path for current flow makes GEAR 4 and GEAR 5 lights turn ON. Normally this information (current flow) tells the transmission control that the shift is complete and to deactivate (make not active) the downshift solenoid. In NEUTRAL position, this information causes the transmission control to keep the downshift solenoid activated. This holds (locks) the rotary selector spool in NEUTRAL position.

TRANSMISSION SWITCH (NEUTRAL Position)

Neutral to Reverse (Converter Drive)

TRANSMISSION CONTROL ELECTRICAL SYSTEM

When the transmission shift lever is put in REVERSE position, LEVER 4 and LEVER 5 lights on the transmission control turn ON. This is an indication that the rotor for the shift lever switch has turned and the shift lever switch is in REVERSE position. With the shift lever switch in this position, current flows from the transmission control on wires 714-YL and 715-GN through the shift lever switch to machine ground. This path for current flow lets the lever lights turn ON. This information (current flow) also tells the transmission control an upshift is needed. At this time, the transmission control sends current to the upshift solenoid through 703-BU wire to ground. When the upshift solenoid activates, hydraulic oil pressure goes to the rotary actuator and causes the rotary selector spool to turn.

SHIFT LEVER SWITCH (REVERSE Position)

When the rotary selector spool turns, the rotor in the transmission switch turns. As long as the upshift solenoid is activated, the hydraulic oil pressure makes the rotary selector spool turn. When the rotor in the transmission switch gets to the correct position (REVERSE), a ground (electric) is put on 723-OR and 725-GN wires. With these wires at machine ground, current flows from the transmission control through the transmission switch to machine ground. This path for current flow makes GEAR 3 and GEAR 5 lights turn ON. This information (current flow) tells the transmission control that the shift is complete and to deactivate the upshift solenoid.

TRANSMISSION SWITCH (NEUTRAL Position)

TRANSMISSION SWITCH (REVERSE Position)

Neutral to First

Converter Drive

When the transmission shift lever is put in FIRST speed position, the shift lever switch moves to FIRST speed position. Current flows from the transmission control on wires 712-WH and 715-GN through the shift lever switch to machine ground and causes LEVER 2 and LEVER 5 lights on the transmission control to turn ON. Because an upshift is needed at this time, the transmission control sends current to the upshift solenoid through 703-BU wire to ground. When the upshift solenoid activates, the rotary selector spool and the rotor in the transmission switch turn.

SHIFT LEVER SWITCH (FIRST Speed Position)

When the rotor in the transmission switch gets to the correct position (FIRST speed), a ground (electric) is put on 722-WH and 725-GN wires. Current now flows from the transmission control through the transmission switch to machine ground and GEAR 2 and GEAR 5 lights turn ON. This information tells the transmission control that the shift is complete and to deactivate the upshift solenoid.

Direct Drive

After the shift to FIRST speed is complete, the transmission control will monitor the signal (electric frequency) from the transmission speed sender. This current flow, plus the signal (electric frequency) from the transmission speed sender tells the transmission control when direct dirve (lockup) is needed. The change from converter drive to direct drive is automatic when the correct ground speed signal (electric frequency) from the transmission speed sender gets to the transmission control.

At this time, the transmission control sends current to the lockup solenoid through 705-PK wire to (electric) ground. When the lockup solenoid activates, hydraulic oil pressure goes through the lockup clutch modulation valve to the lockup clutch. The lockup clutch will stay activated until there is an upshift, downshift or a decrease in ground speed to a converter drive condition.

TRANSMISSION SWITCH (NEUTRAL Position)

TRANSMISSION SWITCH (FIRST Speed Position)

Sequence For Automatic Upshifts

First to Second

TRANSMISSION CONTROL ELECTRICAL SYSTEM

Converter Drive

For an automatic upshift to SECOND speed, move the transmission shift lever to SECOND speed position. The transmission control automatically upshifts until SECOND speed is made (reached).

When the transmission shift lever is moved to SECOND speed position, LEVER 1 and LEVER 5 lights on the transmission control turn (come) ON. This is an indication that the rotor for the shift lever switch has turned and the shift lever switch is in SECOND speed position. Current goes from the transmission control on wires 711-BR and 715-GN through the shift lever switch to machine (electric) ground. This permits the lever lights to turn ON. This current flow, plus a signal (electric frequency) from the transmission speed sender, tells the transmission control that an upshift is needed. The upshift to SECOND speed position from FIRST speed position is automatic when the correct ground speed signal (electric frequency) from the transmission speed sender gets to the transmission control.

SHIFT LEVER SWITCH (SECOND Speed Position)

At this time, the transmission control sends current to the upshift solenoid through 703-BU wire to (electric) ground. When the upshift solenoid activates, hydraulic oil pressure goes to the rotary actuator and the rotary selector spool turns. The rotary selector spool turns the rotor in the transmission switch. When the alignment of the rotor in the transmission switch changes from FIRST speed position to SECOND speed position, a (electric) ground is put on 721-BR and 725-GN wires. GEAR 2 and GEAR 5 lights for FIRST speed position now change to GEAR 1 and GEAR 5 lights for SECOND speed position. This new current flow tells the transmission control that the transmission is now in SECOND speed position. With the transmission switch and the shift lever switch in the same speed, the upshift solenoid is deactivated by the transmission control. The automatic shift is complete.

TRANSMISSION SWITCH (SECOND Speed Position)

Direct Drive

After the shift to SECOND speed is complete, the transmission control will monitor the signal (electric frequency) from the transmission speed sender. This current flow, plus the signal (electric frequency) from the transmission speed sender tells the transmission control when direct drive (lockup) is needed. The change from converter drive to direct drive is automatic when the correct ground speed signal (electric frequency) from the transmission speed sender gets to the transmission control.

At this time, the transmission control sends current to the lockup solenoid through 705-PK wire to (electric) ground. When the lockup solenoid activates, hydraulic oil pressure goes through the lockup clutch modulation valve to the lockup clutch. The lockup clutch will stay activated until there is an upshift, downshift, or a decrease in ground speed to a converter drive condition.

Second to Third

TRANSMISSION CONTROL ELECTRICAL SYSTEM

This explanation shows how an automatic upshift is made. Except for different electrical wires that must be grounded or activated, the automatic upshift sequence is basically the same for all speeds.

For an automatic upshift to THIRD speed, move the transmission shift lever to THIRD speed position. The transmission control automatically upshifts until THIRD speed is made (reached).

SHIFT LEVER SWITCH (THIRD Speed Position)

When the transmission shift lever is moved to THIRD speed position, LEVER 3 and LEVER 4 lights on the transmission control turn (come) ON. The shift lever switch is now in THIRD speed position. Current comes from the transmission control on wires 713-OR and 714-YL through the shift lever switch to machine (electric) ground. This permits the lever lights to turn ON. This current flow, plus a signal (electric frequency) from the transmission speed sender, tells the transmission control that an upshift is needed. The upshift to THIRD speed position from SECOND speed position is automatic when the correct ground speed signal (electric frequency) from the transmission speed sender gets to the transmission control.

At this time, the transmission control sends current to the upshift solenoid through 703-BU wire to (electric) ground. When the upshift solenoid activates, hydraulic oil pressure goes to the rotary actuator and the rotary selector spool turns. The rotary selector spool turns the rotor in the transmission switch. When the alignment of the rotor in the transmission switch changes from SECOND speed position to THIRD speed position, a (electric) ground is put on 723-OR and 724-YL wires. GEAR 1 and GEAR 5 lights for SECOND speed position now change to GEAR 3 and GEAR 4 lights for THIRD speed position. This new current flow tells the transmission control that the transmission is now in THIRD speed position. With the transmission switch and the shift lever switch in the same speed, the upshift solenoid is deactivated by the transmission control. The automatic shift is complete.

TRANSMISSION SWITCH (THIRD Speed Position)

Direct Drive

After the shift to THIRD speed is complete, the transmission control will activate the lockup solenoid. This change to direct drive is automatic when the transmission speed sender gives a signal (electric frequency) and the transmission switch gives a signal (code) to the transmission control that a direct drive condition is present.

At this time, the transmission control sends current to the lockup solenoid through the 705-PK wire to (electric) ground. When the lockup solenoid activates, hydraulic oil pressure goes to the lockup clutch. The lockup clutch will stay activated until there is an upshift, downshift, or a decrease in ground speed to a converter drive (R-N-1-2) condition.

Sequence For Automatic Downshifts

Third to Second

TRANSMISSION CONTROL ELECTRICAL SYSTEM

This explanation shows how an automatic downshift is made. Except for different electrical wires that must be grounded or activated, the automatic downshift sequence is basically the same for all speeds.

For an automatic downshift to SECOND speed, move the transmission shift lever to SECOND speed position. The transmission control automatically downshifts until SECOND speed is made (reached).

When the transmission shift lever is moved to SECOND speed position, LEVER 1 and LEVER 5 lights on the transmission control turn (come) ON. The shift lever switch is now in SECOND speed position. Current comes from the transmission control on wires 711-BR and 715-GN through the shift lever switch to machine (electric) ground and permits the lever lights to turn ON. This current flow, plus a signal (electric frequency) from the transmission speed sender, tells the transmission control that a downshift is needed. The downshift to SECOND speed position from THIRD speed position is automatic when the correct ground speed signal (electric frequency) from the transmission speed sender gets to the transmission control.

SHIFT LEVER SWITCH (SECOND Speed Position)

At this time, the transmission control sends current to the downshift solenoid through 704-GY wire to (electric) ground. When the downshift solenoid activates, hydraulic oil pressure goes to the rotary actuator. The rotary selector spool turns the rotor in the transmission switch. When the alignment of the rotor in the transmission switch changes from THIRD speed position to SECOND speed position, a (electric) ground is put on 721-BR and 725-GN wires. GEAR 3 and GEAR 4 lights for THIRD speed position now change to GEAR 1 and GEAR 5 lights for SECOND speed position. This new current flow tells the transmission control that the transmission is now in SECOND speed position. With the transmission switch and the shift lever switch in the same speed, the downshift solenoid is deactivated by the transmission control. The automatic downshift is complete.

Direct Drive

After the shift to SECOND speed is complete, the transmission control will monitor the signal (electric frequency) from the transmission speed sender. This current flow, plus the signal from the transmission speed sender will tell the transmission control when direct drive is needed. The change from direct drive to converter drive is automatic when the correct ground speed signal from the transmission speed sender gets to the transmission control.

At this time, the transmission control stops current to the lockup solenoid through 705-PK wire to (electric) ground. When the lockup solenoid deactivates, hydraulic oil pressure stops and the lockup clutch disengages. The lockup clutch will stay activated until there is an upshift, downshift, or a decrease in ground speed to a converter drive condition.

TRANSMISSION SWITCH (SECOND Speed Position)

Torque Converter Hydraulic System

Operation Of The Torque Converter Hydraulic System

Neutral Operation

When the engine is started, oil goes from hydraulic oil tank (25) through suction screen (28) to parking brake release section (19) and torque converter charging section (20) of the oil pump. Also, oil goes through suction screen (32) to oil pump (27) for hoist or wagon hydraulics and rear brake cooling.

Torque converter charging section (20) sends the oil through torque converter oil filter (16) to inlet relief valve (11) and torque converter (12). Inlet relief valve (11) controls the maximum pressure of the oil that goes to the torque converter. From the torque converter, the oil goes to outlet relief valve (7). This valve controls the maximum pressure of the oil in the torque converter.

The oil from torque converter (12) goes around the valve spool in outlet relief valve (7). This oil now becomes brake cooling oil.

The flow of oil combines with oil from oil pump (27). The oil goes through screen (18), oil cooler (13) and on to either left rear wheel brake (23) or right rear wheel brake (24). From the rear wheel brakes, the oil then combines and goes through return oil screen (26) into hydraulic oil tank (25).

NOTE: Some of the oil from oil cooler (13) is used for lubrication of oil pump drive (14).

Parking release section (19) sends oil through parking brake release oil filter (15) to secondary and parking brake valve (8) and on to lockup clutch and solenoid valve group (5). The oil that goes to lockup clutch and solenoid valve group (5) is used to engage the lockup clutch. The oil that goes to the secondary and parking brake valve is used to release the parking brakes. Relief valve (9) controls the maximum pressure of the parking brake release system. When the oil pressure gets too high, relief valve (9) opens and sends the extra oil back to hydraulic oil tank (25).

Drain (return) oil from lockup clutch and solenoid valve group (5) and oil pump drive (14) goes into the bottom of the torque converter cover. Any leakage in torque converter (12) also goes to the bottom of the cover. Torque converter scavenge section (21) pulls this oil through scavenge screen (22) and sends it back to hydraulic oil tank (25) through return oil screen (26).

Oil pump (27) sends oil to control valve (30) for use in the hoist or wagon hydraulic system. The oil that is not used in the hoist or wagon hydraulic system is used for brake cooling also. Oil cooler relief valve (29) controls the maximum pressure of this brake cooling oil. The flow of oil then combines with the brake cooling oil from the torque converter and goes through screen (18) and oil cooler (13). The oil then either goes to right rear wheel brake (24) or left rear wheel brake (23).

TORQUE CONVERTER HYDRAULIC SYSTEM IN DIRECT DRIVE, (Lockup Clutch Engaged), ENGINE RUNNING

1. Lockup solenoid.

2. Selector piston for lockup clutch.

3. Load piston for lockup clutch.

4. Pressure reduction valve.

5. Lockup clutch and solenoid valve group.

6. Modulation reduction valve for lockup clutch.

7. Outlet relief valve for torque converter.

8. Secondary and parking brake valve.

9. Relief valve for brake release system.

10. Passage to rear wheel brakes.

11. Inlet relief valve for torque converter.

12. Torque converter.

13. Oil cooler for torque converter and brakes.

14. Oil pump drive.

15. Parking brake release oil filter.

16. Torque converter oil filter.

17. Lockup clutch for the torque converter.

18. Screen.

19. Parking brake release section of oil pump.

20. Torque converter charging section of oil pump.

21. Torque converter scavenge section of oil pump.

22. Scavenge screen.

23. Left rear wheel brake.

24. Right rear wheel brake.

25. Hydraulic oil tank.

26. Return oil screen for torque converter and brake cooling.

27. Oil pump for hoist hydraulics and rear brake cooling.

28. Suction screen.

29. Oil cooler relief valve for rear brakes.

30. Control valve for hoist or wagon hydraulics.

31. Return oil screen for hoist or wagon hydraulics.

32. Suction screen.

P. Pressure tap for pilot oil.

R, V. Pressure taps for parking brake release oil.

S. Pressure tap for torque converter lockup clutch.

T. Pressure tap for torque converter outlet.

U, X, Y, Z, AA, BB. Pressure taps for brake cooling.

W. Pressure tap for torque converter inlet.

Lockup Operation (Direct Drive)

The machine is in converter drive in NEUTRAL and REVERSE. SECOND through SEVENTH speeds are direct drive speeds. FIRST speed is in converter drive at lower ground speeds and direct drive at higher ground speeds.

In FIRST speed, torque converter (12) is used until the ground speed gets high enough for direct drive. At this time, the transmission speed sender tells the transmission control that direct drive (lockup) is needed.

The transmission control activates (opens) lockup solenoid (1). Pilot oil goes to selector piston (2). Modulation reduction valve (6) moves down and lockup clutch oil goes to lockup clutch (17) on the front of the torque converter. Modulation now takes place between load piston (3) and modulation reduction valve (6) until maximum pressure is reached (made). The lockup clutch is now engaged and the machine is in direct drive in FIRST speed.

When an upshift is made to SECOND speed, the transmission control deactivates (closes) lockup solenoid (1). Pilot oil to selector piston (2) is stopped. The selector piston, load piston (3) and modulation reduction valve (6) go back to their original positions. Lockup clutch oil is stopped and lockup clutch (17) is disengaged (released). The machine is again in converter drive for a short moment. After the correct clutches in the transmission are engaged for SECOND speed, the lockup clutch is again engaged in the same way as shown above. This makes for smooth shifts when the machine goes into converter drive for a moment between shifts from a direct drive speed to a direct drive speed. This same operation takes place during upshifts from SECOND through SEVENTH speeds and during downshifts from SEVENTH through FIRST speeds.

When the machine is in direct drive in FIRST speed and ground speed decreases enough, the transmission control again deactivates lockup solenoid (1). The lockup clutch disengages and the machine goes back into converter drive.

Oil Pump For the Torque Converter And Brakes

REAR OF TORQUE CONVERTER
1. Parking brake release section. 2. Torque converter charging section. 3. Torque converter scavenge section.

The oil pump for the torque converter and brakes has three sections: parking brake release section (1), torque converter charging section (2) and torque converter scavenge section (3). The pump is driven by a gear on the torque converter.

The scavenge section on the drive end takes oil that goes to the bottom of the torque converter cover. The oil goes through a scavenge screen on its way to scavenge section (3). The oil is then sent back to the hydraulic oil tank.

The inlet side of sections (1) and (2) are connected and get their oil from the hydraulic oil tank. Charging section (2) in the center sends the oil under pressure to the torque converter oil filter and on to the inlet relief valve and torque converter.

Parking brake release section (1) sends oil under pressure to an oil filter and the secondary and parking brake valve. This oil flow is then divided. Some of the oil goes to the rear wheel brakes to release the parking brakes. Some of the oil goes on to the lockup clutch and solenoid valve group. This oil is used to engage the lockup clutch in the torque converter.

Oil Filters For Parking Brake Release System And Torque Converter

LOCATION OF THE OIL FILTERS
1. Torque converter oil filter. 2. Parking brake release oil filter.

The oil filter for parking brake release system is fastened to the left side of the main frame behind the wheel. The torque converter oil filter is fastened to the inner right side of the main frame behind the torque converter. Oil from the hydraulic tank goes to the oil pump. The parking brake release section of the pump sends oil to parking brake release oil filter (2). The torque converter section of the pump sends oil to torque converter oil filter (1).

Both filters work the same. Oil goes through inlet passage (6) and fills the space between the inside of housing (10) and element (9). During normal operation, the oil goes through element (9) and outlet passage (5) to the remainder of the hydraulic system. Element (9) stops any debris that is in the oil.

If the filter elements become full of debris, the restriction to the flow of oil causes a pressure increase inside the filter. The pressure oil causes bypass valve (4) to move against the force of spring (8). The oil then goes past the open bypass valve and to the remainder of the hydraulic system. When the oil does not go through the filter elements, the debris in the oil will cause damage to other components in the hydraulic system.

Correct maintenance must be used to make sure that element (9) does not become full of debris and stop the flow of clean oil to the hydraulic system.

TORQUE CONVERTER OIL FILTER
4. Bypass valve. 5. Outlet passage. 6. Inlet passage. 7. Base. 8. Spring. 9. Element. 10. Housing. 11. Plug.

PARKING BRAKE RELEASE OIL FILTER
4. Bypass valve. 5. Outlet passage. 6. Inlet passage. 7. Base. 8. Spring. 9. Element. 10. Housing. 11. Plug.

Inlet And Outlet Relief Valves For The Torque Converter

LOCATION OF RELIEF VALVES
1. Inlet relief valve. 2. Outlet relief valve.

Inlet relief valve (1) and outlet relief valve (2) are installed on the outside of the torque converter cover.

COMPONENTS OF THE RELIEF VALVE
3. Body. 4. Inlet passage. 5. Outlet passage. 6. Poppet valve. 7. Valve spool. 8. Shims. 9. Spring.

Inlet relief valve (1) controls the maximum pressure of the oil to the torque converter. The setting of the inlet relief valve is approximately 930 kPa (135 psi). Extra oil from inlet relief valve (1) goes back to the hydraulic tank through outlet passage (5).

Show/hide table

NOTICE
Inlet pressure to the torque converter MUST NOT be over 930 kPa (135 psi) with COLD OIL. Pressures greater than the maximum setting will damage the torque converter.

Outlet relief valve (2) controls the maximum pressure inside the torque converter. The setting of the outlet relief valve is approximately 410 kPa (60 psi). From outlet relief valve (2), the oil goes through outlet passage (5) to the brake and torque converter oil cooler.

The operation of both valves is the same. Oil goes into body (3) through inlet passage (4). The oil goes through a hole in valve spool (7) into the chamber between poppet valve (6) and valve spool (7). The oil moves valve spool (7) against the force of spring (9) when the pressure of the oil becomes greater than the force of the spring. The movement of valve spool (7) permits the oil to flow through outlet passage (5).

Lockup Clutch And Solenoid Valve Group

REAR OF TORQUE CONVERTER
1. Lockup clutch and solenoid valve group. 2. Inlet line from the parking brake release system. 3. Torque converter cover. 4. Pressure tap for lockup clutch.

Lockup clutch and solenoid valve group (1) controls the operation of the lockup clutch of the torque converter. Pressure oil from the valve group engages the lockup clutch. Pressure tap (4) is used to measure the pressure of this oil [in passage (23)]. This oil comes from the parking brake release pump section. The oil goes to the secondary and parking brake valve and then goes through inlet line (2) into pump inlet (32) of valve body (30).

Drain passages (12), (22), (27) and (31) are all connected. The return (drain) oil goes into torque converter cover (3) on its way back to the hydraulic oil tank.

The purpose for pressure reduction valve (21) is to decrease oil pressure [to approximately 2410 kPa (350 psi)] in pump inlet (32) so it can be used by lockup solenoid (24). This oil in pilot passage (10) is pilot oil and is used to activate selector piston (6). Oil pressure goes through an orifice in pressure reduction valve (21), opens ball check (17) and goes into the slug chamber at the end of the valve. This pressure works against the force of springs (20). When the pressure in pilot passage (10) gets too high, the pressure reduction valve moves against the force of springs (20). This lets some of the oil in pilot passage (10) go into drain passages (31). Pressure reduction valve (21) moves to the right and left to keep a constant pressure in pilot passage (10).

Modulation reduction valve (19) operates the same as the seven modulation reduction valves in the transmission hydraulic control group. This valve controls the pressure and time that it takes to engage and release the lockup clutch. Pump oil goes through passage (13) to the modulation reduction valve. This oil is at the same pressure as the parking brake release system [approximately 3170 kPa (460 psi)].

Lockup Started (Clutch Filling)

When the transmission control gets the indication for direct drive (to engage the lockup clutch), it sends an electric signal to lockup solenoid (24). The lockup solenoid activates (opens) and lets pilot oil from pilot passage (10) go into pilot passage (25). This oil pushes shuttle valve (26) over which closes drain passage (27). The oil moves the ball inside the shuttle valve and goes through the valve and pilot passage (18) to the end of selector piston (6).

This causes selector piston (6) along with load piston (7) to move against the force of spring (14). This causes modulation reduction valve (19) to move against the force of spring (29). Now, passage (23) is not open to drain passage (22). Passage (23) is open to passage (13). Pump oil now goes to fill the lockup clutch.

At this time, oil also goes through load piston orifice (16) and passage (11). This oil goes between selector piston (6) and load piston (7).

Lockup Completed (Clutch Engaged)

After the lockup clutch is full of oil, the pressure increases in the clutch. This causes load piston (7) to move against the force of spring (14). Lockup clutch oil also goes through an orifice in modulation reduction valve (19), opens ball check (28) and goes into the slug chamber at the end of the valve. This pressure works against the pressure at the end of load piston (7). The pressure increases until the load piston is moved all the way down against its stop. The pressure in the clutch is now at its maximum [approximately 1500 kPa (220 psi)]. Modulation reduction valve (19) moves up and down to keep a constant pressure in passage (23).

Two components control the amount of time it takes for the pressure in the lockup clutch to get to its maximum: the size of load piston orifice (16) and the force of spring (14). The force of spring (14) can be changed by the removal or addition of shims in load piston (7).

LOCKUP CLUTCH AND SOLENOID VALVE GROUP

5. Cover.

6. Selector piston.

7. Load piston.

8. Load piston body.

9. Selector piston plug.

10. Pilot passage.

11. Passage in selector piston.

12. Drain passage.

13. Passage for pump oil.

14. Spring.

15. Load piston plug.

16. Load piston orifice.

17. Ball check.

18. Pilot passage.

19. Modulation reduction valve.

20. Springs.

21. Pressure reduction valve.

22. Drain passage.

23. Passage to lockup clutch.

24. Lockup solenoid.

25. Pilot passage.

26. Shuttle valve.

27. Drain passage.

28. Ball check.

29. Spring.

30. Valve body.

31. Drain passages.

32. Pump inlet.

Lockup Clutch Disengaged (Released)

When the transmission control gets the indication to go to converter drive from direct drive (to disengage the lockup clutch), it stops the electric signal to lockup solenoid (24). The lockup solenoid deactivates (closes) and stops the flow of pilot oil into pilot passage (25) and drains the passage. The force of spring (14) moves selector piston (6) up which causes the pressure oil in pilot passage (18) to push against shuttle valve (26). This causes the ball inside the shuttle valve to move to the left. The oil pressure causes shuttle valve (26) to also move to the left which opens pilot passage (18) to drain passage (27). Selector piston (6) now moves up against load piston body (8).

Passage (11) is now in alignment with drain passage (12). The force of spring (14) moves load piston (7) all the way up against selector piston (6). Modulation reduction valve (19) now moves all the way up because of the force of spring (29). In this position, pump oil in passage (13) can not go into passage (23). Passage (23) is now open to drain passage (22) and the pressure in the lockup clutch is released.

Oil Cooler For The Torque Converter And Brakes

Oil cooler (27) for the torque converter and brakes is fastened to the right side of the engine cylinder block. Engine coolant, from the water pump, goes into the oil cooler at the front of the engine. The coolant goes through long tubes in the oil cooler. The coolant then goes into the engine cylinder block at the rear.

The oil cooler gets oil from two places. Some oil comes from the outlet relief valve of the torque converter (converter outlet oil). Some oil comes from the control valve for the hoist or wagon (trailing unit) hydraulics. This oil is cooled and sent out of the oil coolers to the rear wheel brakes.

LOCATION OF OIL COOLER (27)

Torque Converter

The torque converter is driven by the engine flywheel. It is made up of an impeller, turbine, lockup clutch and a stator with a one-way clutch. The lockup clutch permits the machine to operate in direct drive to keep the power loss to a minimum. The one-way clutch holds the stator when the converter is used and lets the stator turn freely when the torque converter is not used. The converter cover is fastened directly to the flywheel housing and provides an oil reservoir and a place to fasten two valves and a pump. The flange of the output shaft of the torque converter is connected to the drive shaft.

The transmission is driven by the torque converter in FIRST, NEUTRAL and REVERSE. During shifts from SECOND through SEVENTH speeds, the torque converter is activated for a moment (the lockup clutch disengages for a moment) to make the shifts smooth. Once the transmission clutches are engaged, the lockup clutch engages and the transmission is in direct drive.

In FIRST speed, the operation of the lockup clutch is controlled by the transmission control. The transmission can be in either torque converter or direct drive in FIRST speed.

Torque Converter Drive

The engine flywheel turns rotating housing (1) which turns impeller (3). The impeller moves (directs) the oil to the blades of turbine (2) and causes the turbine to turn. The turbine directs the oil to stator (10) and causes the stator to try to turn in the opposite direction of the turbine. The movement of the stator causes rollers (14) of one-way clutch (9) to move (roll) between stator (10) and the carrier for the stator. The action of the one-way clutch keeps the stator from rotation. The stator now directs most of the oil back to impeller (3). The remainder of the oil goes out of the torque converter through outlet passage (6). The oil, that goes back to impeller (3) from stator (10), moves in the same direction as the rotation of the impeller.

Turbine (2) turns hub (7) and hub (7) turns output shaft (12). Power is sent through the output shaft to the drive shaft and the transfer gears of the transmission.

FLOW OF OIL IN TORQUE CONVERTER DRIVE
1. Rotating housing. 2. Turbine. 3. Impeller. 4. Drive gear for the torque converter pump. 5. Inlet passage for converter oil. 6. Outlet passage for converter oil. 7. Hub. 8. Lockup clutch. 9. One-way clutch. 10. Stator. 11. Carrier. 12. Output shaft.

One-Way Clutch

Splines connect stator (10) to cam (13). Cam (13) is turned by the stator. Carrier (17) does not turn. The mechanical connection between cam (13) and carrier (17) is rollers (14). Rollers (14) are in openings (16) of cam (13). Springs (15) are also in openings (16). The left side of openings (16) is smaller than the right side of openings (16) because the opening has a taper. Normally, springs (15) keep rollers (14) in the taper at the left side of openings (16).

When the speed of impeller (3) and turbine (2) is slow, stator (10) is held stationary. Rollers (14) are held in the taper of openings (16) by springs (15). There is a mechanical connection between cam (13) and carrier (17). Since carrier (17) is held stationary, cam (13) is held stationary. Since the cam can not turn, the stator does not turn. The stator can send oil back to the impeller.

As the speed of impeller (3) and turbine (2) increases, stator (10) starts to turn in the same direction as the impeller and turbine. When the stator starts to turn, cam (13) starts to turn. The movement of cam (13) causes rollers (14) to move from the tapers of openings (16). The mechanical connection between cam (13) and carrier (17) is broken. Stator (10) and cam (13) turn freely. The stator does not send oil back to the impeller.

DETAL OF ONE-WAY CLUTCH
13. Cam. 14. Rollers. 15. Springs. 16. Openings in cam. 17. Carrier.

Lockup Clutch

OIL FLOW TO THE LOCKUP CLUTCH
1. Rotating housing. 2. Turbine. 3. Impeller. 7. Hub. 11. Carrier. 12. Output shaft. 18. Piston. 19. Plates (two). 20. Plate. 21. Pilot. 22. Discs (two). 23. Inlet passage.

Lockup clutch (8) is part of the torque converter and is between the engine flywheel and turbine (2). The lockup clutch is engaged when the transmission is in SECOND through SEVENTH speeds (direct drive). The lockup clutch does engage in FIRST speed as the output speed of the transmission increases. When the lockup clutch is engaged, impeller (3) and turbine (2) turn at the same speed as the engine and there is no loss of power in the torque converter. The connection between the engine and the transmission is now direct.

Rotating housing (1) is connected to the engine flywheel by splines and is fastened to impeller (3) by bolts. Piston (18), plates (19) and plate (20) are also connected to rotating housing (1) by splines. Discs (22) and output shaft (12) are connected to hub (7) by splines. Turbine (2) is fastened to hub (7).

Operation

The transmission (electronic) control activates the lockup clutch and solenoid valve group which sends pressure oil for operation of the lockup clutch. Oil from the lockup clutch and solenoid valve group goes through inlet passage (23) in carrier (11). The oil goes through a passage in the center of output shaft (12), and through pilot (21) and rotating housing (1) to piston (18). The pressure of the oil causes piston (18) to move toward plate (20). This causes plates (19) and discs (22) to be held together and to turn at the same speed. The plates and discs become a direct connection between rotating housing (1) and output shaft (12). The machine is in direct drive.

When the lockup clutch is not engaged, the operation of the torque converter is normal.

Direct Drive

FLOW OF POWER IN DIRECT DRIVE
1. Rotating housing. 2. Turbine. 3. Impeller. 4. Drive gear for the torque converter pump. 7. Hub. 8. Lockup clutch. 9. One-way clutch. 10. Stator. 12. Output shaft.

Oil under pressure from the lockup clutch and solenoid valve group causes lockup clutch (8) to engage. As the engine flywheel turns, lockup clutch (8) connects rotating housing (1) with hub (7). This causes turbine (2) and impeller (3) to turn at the same speed. Stator (10) turns freely (freewheels). At this time, the torque converter is not in operation.

The flow of power is from rotating housing (1), through lockup clutch (8), hub (7) and output shaft (12). The power goes directly through the torque converter, through the drive shaft, to the transfer gears of the transmission.

Transfer Gears And Transmission Hydraulic System

Transfer Gears

The transfer gears are in the transfer gear case that is fastened to the front of the transmission case. The drive shaft connects the torque converter to yoke (3).

Yoke (3) is connected to drive gear (2) by splines. The teeth on drive gear (2) are engaged with the teeth on driven gear (4). Driven gear (4) is connected by splines to the input shaft of the transmission.

Yoke (3) turns drive gear (2) which turns driven gear (4). Driven gear (4) then turns the input shaft of the transmission.

Shims (1) are used to make adjustment to the end play of drive gear (2). Shims (6) are used to make adjustment to the end play of driven gear (4).

Oil for lubrication of the transfer gears comes from the transmission lubrication circuit. The oil comes through a passage in the transmission case and case (5) into a tube assembly which puts (sprays) oil on both drive gear (2) and driven gear (4). The gears then throw the oil around inside case (5) which provides lubrication for the bearings in the transfer gear case. The extra oil in the bottom of case (5) goes through a drain passage into the transmission case.

COMPONENTS OF THE TRANSFER GEARS
1. Shims. 2. Drive gear. 3. Yoke. 4. Driven gear. 5. Case. 6. Shims.

Operation Of The Transmission Hydraulic System

Neutral Operation

When the engine is started, oil goes from transmission oil tank (46) through suction screen (49), charging section (33) of the transmission oil pump and transmission oil filter (35) to downshift solenoid (36), upshift solenoid (37), and priority reduction valve (54) and reset spool (55) of selector group (57). As the oil pressure increases, priority reduction valve (54) moves down. This lets pump oil also go to rotary selector spool (56), relief valve (68) and pressure control group (42).

If the engine is started with the transmission out of NEUTRAL position, the position of rotary selector spool (56) stops the flow of pump oil to reset spool (55). The reset spool does not move down. In this position, reset spool (55) stops the flow of pilot oil from priority reduction valve (54) to rotary selector spool (56). The clutches in the transmission can not engage.

When the engine is started with the transmission in NEUTRAL position, the transmission control activates downshift solenoid (36). The downshift solenoid sends pump oil to rotary actuator (38). This causes the rotor of the rotary actuator [and rotary selector spool (56)] to be held (locked) in position N. This prevents any movement of the rotary selector spool. The position of rotary selector spool (56) lets pump oil go to reset spool (55). The reset spool moves down and lets pilot oil go to the rotary selector spool. The position of rotary selector spool (56) lets pilot oil go to selector piston (58) of pressure control group (42). This causes selector piston (58) along with load piston (59) to move to the right. The force of the springs causes modulation reduction valve (60) to move to the right. Pump oil now goes around the modulation reduction valve and starts to fill No. 1 clutch. The clutch oil also goes through a load piston orifice and goes between selector piston (58) and load piston (59).

The pressure of the clutch oil increases after the clutch is full of oil. As the pressure of the oil in No. 1 clutch increases, modulation reduction valve (60) moves to the left and load piston (59) moves to the right. The load piston orifice in the supply passage to load piston (59) lets oil go to the load piston at a specific rate. The pressure in the clutch increases gradually. This gradual increase in pressure is known as modulation. When the load piston gets all the way to the right against its stop, modulation stops. The pressure in No. 1 clutch is now at its maximum. No. 1 clutch is engaged and the transmission is in NEUTRAL.

TRANSMISSION HYDRAULIC SYSTEM IN NEUTRAL, ENGINE RUNNING

33. Charging section of transmission oil pump.

34. Scavenge section of transmission oil pump.

35. Transmission oil filter.

36. Downshift solenoid.

37. Upshift solenoid.

38. Rotary actuator.

39. Selector piston for No. 3 clutch.

40. Load piston for No. 3 clutch.

41. Modulation reduction valve for No. 3 clutch.

42. Pressure control group.

43. Modulation reduction valve for No. 5 clutch.

44. Load piston for No. 5 clutch.

45. Selector piston for No. 5 clutch.

46. Transmission oil tank.

47. Return oil filter.

48. Magnetic screen.

49. Suction screen.

50. Reservoir in transmission case.

51. Modulation reduction valve for No. 4 clutch.

52. Load piston for No. 4 clutch.

53. Selector piston for No. 4 clutch.

54. Priority reduction valve.

55. Reset spool.

56. Rotary selector spool.

57. Selector group.

58. Selector piston for No. 1 clutch.

59. Load piston for No. 1 clutch.

60. Modulation reduction valve for No. 1 clutch.

61. Modulation reduction valve for No. 6 clutch.

62. Load piston for No. 6 clutch.

63. Selector piston for No. 6 clutch.

64. Selector piston for No. 2 clutch.

65. Load piston for No. 2 clutch.

66. Modulation reduction valve for No. 2 clutch.

67. Oil cooler relief valve.

68. Relief valve.

69. Transmission oil cooler.

70. Passage for transmission lubrication.

71. Modulation reduction valve for No. 7 clutch.

72. Load piston for No. 7 clutch.

73. Selector piston for No. 7 clutch.

A. Pressure tap for No. 3 clutch.

B. Pressure tap for No. 1 clutch.

C. Pressure tap for No. 2 clutch.

D. Not used.

E. Pressure tap for No. 5 clutch.

F. Pressure tap for No. 4 clutch.

G. Pressure tap for No. 6 clutch.

H. Pressure tap for No. 7 clutch.

J. Pressure tap for upshift pressure.

K. Pressure tap for downshift pressure.

L. Pressure tap for pump.

M. Pressure tap for pilot oil.

N. Pressure tap for transmission lubrication.

Relief valve (68) controls the maximum pressure in the system. The extra oil from relief valve (68) goes to transmission oil cooler (69). Oil cooler relief valve (67) controls the maximum pressure of the oil that goes to the oil cooler. From the oil cooler, the oil goes to the transmission for lubrication.

Extra oil from leakage in the transfer gears and the transmission goes into reservoir (50) in the bottom of the transmission case. Scavenge section (34) takes the oil from reservoir (50) through magnetic screen (48) and sends it back through return oil filter (47) into transmission oil tank (46).

Manual Shifts

Neutral to Reverse

When the transmission shift lever is moved from NEUTRAL to REVERSE, the transmission control activates (opens the valve in) upshift solenoid (37). The upshift solenoid sends pump oil to rotary actuator (38). This causes the rotor of the rotary actuator and rotary selector spool (56) to move in a clockwise direction from position N toward position R. When the rotary selector spool gets to position R, the transmission switch, connected to the rotary selector spool, sends an electric signal (tells that the shift has been made) to the transmission control which deactivates (closes the valve in) upshift solenoid (37). Movement of the rotor in rotary actuator (38) and rotary selector spool (56) stops.

The position of the rotary selector spool sends pilot oil to selector pistons (39) and (73) and drains the pilot oil at selector piston (58). Selector piston (58) moves against the load piston body and drains the oil between selector piston (58) and load piston (59). Now load piston (59) and modulation reduction valve (60) move toward selector piston (58). Pump oil to No. 1 clutch is stopped by modulation reduction valve (60) and clutch oil in No. 1 clutch is drained. No. 1 clutch is released. The pilot oil now moves selector pistons (39) and (73). No. 3 and No. 7 clutches start to fill. Modulation takes place between load piston (40) and modulation reduction valve (41) for No. 3 clutch. Modulation also takes place between load piston (72) and modulation reduction valve (71) for No. 7 clutch. When the load pistons get all the way against their stops, modulation stops. The pressures in the clutches are at their maximum. No. 3 and No. 7 clutches are now engaged and the transmission is in REVERSE.

Reverse to Neutral

When the transmission shift lever is moved from REVERSE to NEUTRAL, the transmission control activates (opens) downshift solenoid (36). The downshift solenoid sends pump oil to rotary actuator (38). This causes the rotor of the rotary actuator and rotary selector spool (56) to move in a counterclockwise direction from position R toward position N. When the rotary selector spool gets to position N, the transmission control keeps downshift solenoid (36) activated. Movement of the rotor in rotary actuator (38) and rotary selector spool (56) stops and they are locked in position N.

The position of the rotary selector spool sends pilot oil to selector piston (58) and drains the pilot oil at selector pistons (39) and (73). Selector pistons (39) and (73) move against their load piston bodies and drain the oil between selector pistons (39) and (73) and load pistons (40) and (72).

Now the load pistons and modulation reduction valves move toward their respective selector pistons. Pump oil to No. 3 and No. 7 clutches is stopped by the modulation reduction valves and clutch oil is drained. No. 3 and No. 7 clutches are released.

The pilot oil now moves selector piston (58). No. 1 clutch starts to fill. Modulation takes place between load piston (59) and modulation reduction valve (60) for No. 1 clutch. When the load piston gets all the way against its stop, modulation stops. The pressure in the clutch is at its maximum. No. 1 clutch is now engaged and the transmission is in NEUTRAL.

Neutral to First

When the transmission shift lever is moved from NEUTRAL to FIRST, the transmission control activates upshift solenoid (37). The upshift solenoid sends pump oil to rotary actuator (38). This causes rotary selector spool (56) to move in a clockwise direction from position N toward position 1. When the rotary selector spool gets to position 1, the transmission switch sends an electric signal to the transmission control which deactivates upshift solenoid (37). Movement of rotary selector spool (56) stops.

The position of the rotary selector spool sends pilot oil to selector pistons (64) and (63) and drains the pilot oil at selector piston (58). Selector piston (58) moves against the load piston body and drains the oil between selector piston (58) and load piston (59). Now load piston (59) and modulation reduction valve (60) move toward selector piston (58). Pump oil to No. 1 clutch is stopped by modulation reduction valve (60) and clutch oil in No. 1 clutch is drained. No. 1 clutch is released.

The pilot oil now moves selector pistons (64) and (63). No. 2 and No. 6 clutches start to fill. Modulation takes place between load piston (65) and modulation reduction valve (66) for No. 2 clutch. Modulation also takes place between load piston (62) and modulation reduction valve (61) for No. 6 clutch. When the load pistons get all the way against their stops, modulation stops. The pressures in the clutches are at their maximum. No. 2 and No. 6 clutches are now engaged and the transmission is in FIRST speed.

First to Neutral

When the transmission shift lever is moved from FIRST to NEUTRAL, downshift solenoid (36) sends pump oil to rotary actuator (38). The downshift from FIRST to NEUTRAL is now just the opposite of the upshift from NEUTRAL to FIRST. Rotary selector spool (56) moves from position 1 to position N.

The position of the rotary selector spool sends pilot oil to selector piston (58) and drains the pilot oil at selector pistons (64) and (63). Selector pistons (64) and (63) move against their load piston bodies and drain the oil between selector pistons (64) and (63) and load pistons (65) and (62). Now the load pistons and modulation reduction valves move toward their respective selector pistons. Pump oil to No. 2 and No. 6 clutches is stopped by the modulation reduction valves and clutch oil is drained. No. 2 and No. 6 clutches are released. The pilot oil now moves selector piston (58). No. 1 clutch starts to fill. Modulation takes place between load piston (59) and modulation reduction valve (60) for No. 1 clutch. When the load piston gets all the way against its stop, modulation stops. The pressure in the clutch is at its maximum. No. 1 clutch is now engaged and the transmission is in NEUTRAL.

Automatic Upshifts

The transmission speed sender and the transmission control cause all automatic upshifts and downshifts. The transmission control makes a conversion of ground speed to engine rpm through the transmission speed sender. The speed sender feels (senses) the rpm of a gear on the output shaft of the transmission. The conversions of each shift (speed) position are stored (kept) in the transmission control. As the ground speed of the machine increases, the transmission control will then activate upshift solenoid at the correct speed. As ground speed decreases, downshift solenoid is activated.

First to Second

When the transmission shift lever is moved from FIRST to SECOND, an upshift will occur when the output shaft of the transmission gets to the correct rpm. The transmission control then activates upshift solenoid (37). The upshift solenoid sends pump oil to rotary actuator (38). This causes rotary selector spool (56) to move from position 1 toward position 2. When the rotary selector spool gets to position 2, upshift solenoid (37) is deactivated. Movement of rotary selector spool (56) stops.

The position of the rotary selector spool sends pilot oil to selector pistons (63) and (58) and drains the pilot oil at selector piston (64). Selector piston (64) moves against the load piston body and drains the oil between selector piston (64) and load piston (65). Now load piston (65) and modulation reduction valve (66) move toward selector piston (64). Pump oil to No. 2 clutch is stopped by modulation reduction valve (66) and clutch oil in No. 2 clutch is drained. No. 2 clutch is released.

During a shift from FIRST to SECOND, selector piston (63) still gets pilot oil. No. 6 clutch is kept engaged. The pilot oil also moves selector piston (58). No. 1 clutch starts to fill. Modulation takes place between load piston (59) and modulation reduction valve (60) for No. 1 clutch. When the load piston gets all the way against its stop, modulation stops. The pressure in No. 1 clutch is at its maximum. No. 1 and No. 6 clutches are now engaged and the transmission is in SECOND speed.

Second to Third

When the transmission shift lever is moved from SECOND to THIRD, an upshift will occur when the output shaft of the transmission gets to the correct rpm. Upshift solenoid (37) is then activated which sends pump oil to rotary actuator (38). This causes rotary selector spool (56) to move from position 2 toward position 3. When the rotary selector spool gets to position 3, upshift solenoid (37) is deactivated. Movement of rotary selector spool (56) stops.

The position of the rotary selector spool sends pilot oil to selector pistons (39) and (63) and drains the pilot oil at selector piston (58). Selector piston (58) moves and drains the oil between selector piston (58) and load piston (59). Now load piston (59) and modulation reduction valve (60) move toward selector piston (58). Pump oil to No. 1 clutch is stopped by modulation reduction valve (60) and clutch oil in No. 1 clutch is drained and released.

During a shift from SECOND to THIRD, selector piston (63) still gets pilot oil. No. 6 clutch is kept engaged. The pilot oil also moves selector piston (39). No. 3 clutch starts to fill. Modulation takes place between load piston (40) and modulation reduction valve (41) for No. 3 clutch. When the load piston gets all the way against its stop, modulation stops. The pressure in No. 3 clutch is at its maximum. No. 3 and No. 6 clutches are now engaged and the transmission is in THIRD speed.

TRANSMISSION HYDRAULIC SYSTEM IN FOURTH SPEED, ENGINE RUNNING

33. Charging section of transmission oil pump.

34. Scavenge section of transmission oil pump.

35. Transmission oil filter.

36. Downshift solenoid.

37. Upshift solenoid.

38. Rotary actuator.

39. Selector piston for No. 3 clutch.

40. Load piston for No. 3 clutch.

41. Modulation reduction valve for No. 3 clutch.

42. Pressure control group.

43. Modulation reduction valve for No. 5 clutch.

44. Load piston for No. 5 clutch.

45. Selector piston for No. 5 clutch.

46. Transmission oil tank.

47. Return oil filter.

48. Magnetic screen.

49. Suction screen.

50. Reservoir in transmission case.

51. Modulation reduction valve for No. 4 clutch.

52. Load piston for No. 4 clutch.

53. Selector piston for No. 4 clutch.

54. Priority reduction valve.

55. Reset spool.

56. Rotary selector spool.

57. Selector group.

58. Selector piston for No. 1 clutch.

59. Load piston for No. 1 clutch.

60. Modulation reduction valve for No. 1 clutch.

61. Modulation reduction valve for No. 6 clutch.

62. Load piston for No. 6 clutch.

63. Selector piston for No. 6 clutch.

64. Selector piston for No. 2 clutch.

65. Load piston for No. 2 clutch.

66. Modulation reduction valve for No. 2 clutch.

67. Oil cooler relief valve.

68. Relief valve.

69. Transmission oil cooler.

70. Passage for transmission lubrication.

71. Modulation reduction valve for No. 7 clutch.

72. Load piston for No. 7 clutch.

73. Selector piston for No. 7 clutch.

A. Pressure tap for No. 3 clutch.

B. Pressure tap for No. 1 clutch.

C. Pressure tap for No. 2 clutch.

D. Not used.

E. Pressure tap for No. 5 clutch.

F. Pressure tap for No. 4 clutch.

G. Pressure tap for No. 6 clutch.

H. Pressure tap for No. 7 clutch.

J. Pressure tap for upshift pressure.

K. Pressure tap for downshift pressure.

L. Pressure tap for pump.

M. Pressure tap for pilot oil.

N. Pressure tap for transmission lubrication.

Third through Seventh

The sequence of each automatic upshift is the same except different selector pistons get pilot oil. With the transmission shift lever in SEVENTH speed, there is an upshift from THIRD to FOURTH speed at the correct rpm of the output shaft of the transmission. No. 3 and No. 6 clutches drain and release. No. 1 and No. 5 cluthes fill and engage.

As the ground speed of the machine increases more, there is an upshift from FOURTH to FIFTH speed. No. 5 clutch is kept engaged. No. 1 clutch drains and releases. No. 3 clutch fills and engages.

As the ground speed increases more, there is an upshift from FIFTH to SIXTH speed. No. 3 and No. 5 clutches drain and release. No. 1 and No. 4 clutches fill and engage.

As the ground speed increases more, there is an upshift from SIXTH to SEVENTH speed. No. 4 clutch is kept engaged. No. 1 clutch drains and releases. No. 3 clutch fills and engages.

Automatic Downshifts (Seventh through First)

The speed sender and the transmission control cause all automatic downshifts and upshifts. The speed sender feels (senses) the rpm of a gear on the output shaft of the transmission. As the ground speed of the machine decreases, the transmission control will then activate downshift solenoid (36) at the correct speed. As ground speed increases, upshift solenoid (37) is activated.

When the transmission shift lever is moved from SEVENTH to SIXTH for a downshift, the transmission control activates downshift solenoid (36) at the correct rpm (speed). The downshift solenoid sends pump oil to rotary actuator (38). This causes rotary selector spool (56) to move in a counterclockwise direction from position 7 toward position 6. When the rotary selector spool gets to position 6, the downshift solenoid is deactivated. Movement of rotary selector spool (56) stops.

Pilot oil is kept at selector piston (53) and also goes to selector piston (58). Pilot oil at selector piston (39) drains. No. 4 clutch is kept engaged, No. 3 clutch releases and No. 1 clutch is engaged. The transmission is now in SIXTH speed.

Each automatic downshift is just the opposite of the automatic upshift. The transmission will downshift automatically from SEVENTH through FIRST speeds.

Shift Inhibiting

A shift from any speed into NEUTRAL is not inhibited (prevented). The transmission can always be shifted to NEUTRAL. The transmission control makes a conversion of ground speed to engine rpm through the transmission speed sender. This is done by rotation of gear teeth (on a gear fastened to the output shaft of the transmission) near (past) the transmission speed sender. The conversions of each shift (speed) position are stored (kept) in the transmission control.

If the transmission is in any forward speed and the transmission shift lever is moved to REVERSE, the transmission will immediately make a shift to NEUTRAL. The transmission will only make a shift into REVERSE from NEUTRAL position, but the ground speed must decrease to approximately 5 km/h (3 mph) to permit the shift.

Oil Pump For The Transmission

LOWER PART OF OIL PUMP DRIVE
1. Charging section. 2. Scavenge section. 3. Oil pump drive.

The oil pump for the transmission has two sections: charging section (1) and scavenge section (2). The pump is driven by oil pump drive (3).

The charging section on the cover end gets oil from the transmission oil tank. It sends the oil under pressure to the transmission oil filter and on the transmission hydraulic control group.

The scavenge section on the drive end gets oil from the bottom of the transmission case. The oil goes through the magnetic screen to scavenge section (2) which sends the oil back to the transmission oil tank.

Oil Pump Drive

Oil pump drive (1) is fastened to the inner left side of the main frame directly behind the torque converter. The accessory drive gear in the flywheel housing drives pump drive shaft (2). Pump drive shaft (2) is connected to yoke assembly (6).

LEFT REAR SIDE OF TORQUE CONVERTER
1. Oil pump drive. 2. Pump drive shaft (under guard).

Splines connect yoke assembly (6) to drive gear (7). Drive gear (7) turns idler gear (9) which turns driven gear (15).

Shims (3) are used to adjust the end play of drive gear (7). Shims (10) are used to adjust the end play of idler gear (9). Shims (16) are used to adjust the end play of driven gear (15).

Three pumps are driven by the oil pump drive. The hoist (or wagon) hydraulic pump is fastened to cage (8) and is driven by drive gear (7). The oil pump for the transmission is fastened to cage (13). The steering pump is fastened opposite the oil pump for the transmission, directly to housing (4). Driven gear (15) drives both the steering pump and the oil pump for the transmission.

Lubrication of the oil pump drive is provided by oil from the brake cooling oil circuit. The oil comes from the oil cooler for the torque converter and brakes. The oil is put (sprayed) on drive gear (7). Holes, in housing (4), send oil to each bearing. An oil level is kept in housing (4) so that the teeth on driven gear (15) are in oil. The gears throw oil around in the housing. Extra oil in housing (4) goes to the torque converter cover.

COMPONENTS OF OIL PUMP DRIVE
3. Shims. 4. Housing. 5. Bearings. 6. Yoke assembly. 7. Drive gear. 8. Cage. 9. Idler gear. 10. Shims. 11. Shaft. 12. Bearings. 13. Cage assembly. 14. Bearings. 15. Driven gear. 16. Shims.

Oil Filter For The Transmission

OIL FILTER FOR THE TRANSMISSION
1. Outlet line. 2. Inlet line.

The oil filter for the transmission is fastened to the inner right side of the main frame in front of the transmission. Oil from the transmission oil tank goes to the oil pump for the transmission. The pump sends oil through inlet line (2) to the transmission oil filter.

COMPONENTS OF THE OIL FILTERS
3. Plug. 4. Bypass valve. 5. Outlet passage. 6. Inlet passage. 7. Base. 8. Spring. 9. Element. 10. Housing. 11. Plug.

Oil goes through inlet passage (6) and fills the space between the inside of housing (10) and element (9). During normal operation, the oil goes through element (9) and outlet passage (5) and outlet line (1) to the transmission hydraulic control group. Element (9) stops any debris that is in the oil.

If the filter element becomes full of debris, the restriction to the flow of oil causes a pressure increase inside the filter. The pressure oil causes bypass valve (4) to move against the force of spring (8). The oil then goes past the open bypass valve and to the remainder of the hydraulic system. When the oil does not go through the filter element, the debris in the oil will cause damage to other components in the hydraulic system.

Correct maintenance must be used to make sure that element (9) does not become full of debris and stop the flow of clean oil to the hydraulic system.

Magnetic Screen

Magnetic screen (4) is in the bottom of transfer gear case (1). Oil from the bottom of transmission case (3) goes through the inlet tube at the rear. Magnets are installed on the tube so that the same magnetic ends are next to each other.

BOTTOM OF TRANSFER GEAR CASE
1. Transfer gear case. 2. Outlet to scavenge pump section. 3. Transmission case. 4. Magnetic screen (behind cover).

As the oil goes over the magnets, metal particles are stopped and held by the magnets. The oil then goes through a screen on its way to outlet (2). As the oil goes through the screen, other foreign particles are stopped and can not go into the hydraulic system. From outlet (2), the oil is sent to the inlet passage of the scavenge section of the oil pump for the transmission.

Oil Cooler For The Transmission

Oil cooler (28) for the transmission is on the right side of the engine just below the oil cooler for the torque converter and brakes. Engine coolant goes through the oil cooler to cool the oil. The oil from the transmission hydraulic control group goes out of the transmission case to the oil cooler. After the oil is cooled, it comes back to the transmission case for lubrication of the transmission.

LOCATION OF OIL COOLER (28) FOR TRANSMISSION

Transmission Hydraulic Control Group

TRANSMISSION HYDRAULIC CONTROL GROUP (LEFT SIDE)

1. Manifold.

2. Downshift solenoid.

3. Upshift solenoid.

4. Cover.

5. Pressure control group.

6. Selector group.

7. Rotary actuator.

8. Plate.

9. Sleeve for oil to transfer gears.

10. Sleeve for oil from pump (far side).

11. Sleeve for oil from oil cooler.

12. Sleeve for oil to oil cooler.

13. Manifold.

BOTTOM VIEW OF MANIFOLD (13)
14. Passage to No. 1 clutch. 15. Passage to No. 3 clutch. 16. Passage to No. 7 clutch. 17. Passage to No. 2 clutch. 18. Passage to No. 6 clutch. 19. Passage for transmission lubrication. 20. Passage to No. 5 clutch. 21. Passage to No. 4 clutch. 22. Passage for transmission lubrication.

Rotary Actuator

ROTARY ACTUATOR DURING A SHIFT FROM NEUTRAL TO REVERSE
1. Body. 2. Stationary vane. 3. Drain passage. 4. Downshift valve. 5. Ball. 6. Passage from downshift solenoid. 7. Ball. 8. Rotor. 9. Vane of rotor. 10. Upshift valve. 11. Drain passage. 12. Passage from upshift solenoid. A. Chamber. B. Chamber.

The rotary actuator is controlled by the upshift and downshift solenoids. Pressure oil from either solenoid goes into body (1) and pushes against stationary vane (2) and vane (9) of rotor (8). This pressure oil causes the rotor to turn. Rotor (8) is connected to the rotary selector spool of the selector group and causes it to turn.

During an upshift, pressure oil from the upshift solenoid goes through passage (12). This causes upshift valve (10) to move to the left as shown. Drain passage (11) is now closed (blocked) by the upshift valve. The pressure oil goes into upshift valve (10), moves ball (7) to the left and goes into chamber (B) between vanes (2) and (9). This causes rotor (8) to turn in a clockwise direction.

The oil in chamber (A) on the opposite side of vane (9) pushes against downshift valve (4). This causes ball (5) to move to the right side which will not permit oil to go out passage (6). As the rotor turns, the oil in chamber (A) pushes downshift valve (4) to the right until the valve opens drain passage (3). The oil in chamber (A) is now free to drain.

When the rotary selector spool [and rotor (8)] gets to the correct speed position, the transmission switch, connected to the rotary selector spool, sends an electric signal to the transmission control. The transmission control closes (deactivates) the upshift solenoid. This stops the flow of pressure oil in passage (12) and the movement of rotor (8) stops.

During a downshift, the movement of rotor (8) is in a counterclockwise direction. Pressure oil from the downshift solenoid goes through passage (6) and moves downshift valve (4) to the left. This closes drain passage (3). The pressure oil from passage (6) now goes into downshift valve (4) moves ball (5) to the left and goes into chamber (A). This causes rotor (8) to turn in a counterclockwise direction.

The oil in chamber (B) pushes against upshift valve (10). This causes ball (7) to move to the right which will not permit oil to go out passage (12). As the rotor turns, the oil in chamber (B) pushes the upshift valve to the right until drain passage (11) is open to chamber (B).

When the rotor gets to the correct speed position, the transmission control deactivates the downshift solenoid. Pressure oil in passage (6) is now stopped which stops the movement of rotor (8).

When the transmission is in NEUTRAL, rotor (8) is in the position shown. The downshift solenoid is always activated in NEUTRAL position so that the rotor is held (locked) in position.

Selector Group

SELECTOR GROUP IN NEUTRAL WITH ENGINE RUNNING

1. Passage to solenoids.

2. Priority reduction valve.

3. Neutralizer valve.

4. Rotary selector spool.

5. Passage from pump.

6. Passage for pump oil.

7. Chamber (with screen filter).

8. Chamber.

9. Chamber.

10. Oil cooler relief valve.

11. Passage to transmission oil cooler.

12. Relief valve.

13. Spring assemblies (two).

14. Cam.

15. Passage to pressure control group.

The selector group controls the pressure of the oil that goes to the shift solenoids, transmission oil cooler and the pressure control group. It is made up of five valves. The chart gives the basic operation (function) of each valve.

Priority Reduction Valve

At the selector group, the oil from the charging section of the transmission pump goes to several different places. The oil comes in passage (5). Some of the oil goes through passage (1) to the upshift and downshift solenoids. The remainder of the pump oil goes to priority reduction valve (2). The oil goes through an orifice in the valve, opens a check (poppet) valve and goes to the upper end of priority reduction valve (2).

As the pressure increases, it moves the valve down against the force of its spring. The pressure of the oil from priority reduction valve (2), that goes to neutralizer valve (3), is controlled by the priority reduction valve. When the neutralizer valve is moved down, the oil goes on to chamber (7) of rotary selector spool (4). This oil can then go to the pressure control group. This pressure oil is the "pilot oil" that controls the movement of the selector pistons in the pressure control group.

As priority reduction valve (2) moves down, it also permits pump oil in passage (5) to go out passage (6). Some of this oil goe to relief valve (12) which controls the maximum pressure in passages (1), (5), (6) and (15). Some of the oil goes through passage (15) to the pressure control group. This oil is used to fill the clutches in the transmission. Some of the oil also goes to rotary selector spool (4). This oil is used to activate neutralizer valve (3). When the rotary selector spool is in NEUTRAL position, it lets oil go to chamber (8). This causes neutralizer valve (3) to move down. Pilot oil is now free to go to chamber (7) of rotary selector spool (4).

The pressure setting of the priority reduction valve is approximately 1725 kPa (250 psi). This pressure can be changed by the removal or addition of shims.

Neutralizer Valve

Neutralizer valve (3) will not permit movement of the machine if the engine is started with the transmission shift lever out of NEUTRAL position.

When the engine is started with the transmission in NEUTRAL, pressure oil from passage (6) goes to rotary selector spool (4) and on to chamber (8). The pressure in chamber (8) moves neutralizer valve (3) down against the force of its spring. This lets pilot oil go around the neutralizer valve to chamber (7) of the rotary selector spool. The clutches can now be engaged in the transmission.

As neutralizer valve (3) moves down, pilot oil can then go through an orifice in the valve to the upper end of the valve. The valve is now held in the position shown by the pressure of the pilot oil.

When rotary selector spool (4) is moved from NEUTRAL position, pressure oil from passage (6) can not go to chamber (8). Chamber (8) is now open to chamber (9) because of the position of the rotary selector spool.

When the engine is started with the transmission in any speed position except NEUTRAL, the position of rotary selector spool (4) stops the flow of pump oil to chamber (8). Neutralizer valve (3) will not move down to make pilot oil available to chamber (7). No oil can go to the selector pistons of the pressure control group. The clutches in the transmission will not engage.

Rotary Selector Spool

Rotary selector spool (4) determines which selector pistons in the pressure control group get pilot oil and which selector pistons are drained. Orifices in the spool provide the correct sequence for the clutches to engage. The rotary actuator is connected to the upper end of the rotary selector spool. The rotary actuator hydraulically turns the rotary selector spool. The transmission switch is also connected to the upper end of the rotary selector spool. Cam (14) is fastened to the lower end of the spool. Spring assemblies (13) are in contact with cam (14) to hold the spool correctly in each speed position.

Chamber (7) of rotary selector spool (4) has pilot oil in it. The position of the spool will send this oil out a passage to the pressure control group. The oil goes to a selector piston and causes it to move. This will cause a clutch or clutches to engage in the transmission. Chamber (7) has a screen filter in it to keep foreign material out of the pressure control group.

At the same time, the clutches of the transmission that are to be disengaged (not engaged) will send any pressure oil from their respective selector pistons back into chamber (9). Chamber (9) lets the oil go back to the reservoir (drain).

In NEUTRAL position, rotary selector spool (4) sends pump oil to chamber (8) to move neutralizer valve (3). In all other speed positions, chamber (8) is blocked from pump oil and is open to chamber (9).

Relief Valve

Relief valve (12) controls the maximum pressure in the transmission hydraulic system. Pump oil comes from passage (6) to the relief valve. The oil goes through an orifice in the valve, opens a poppet (check) valve and fills a slug chamber at the lower end of relief valve (12). As the pressure increases, it moves the relief valve up against the force of its spring. When the pressure of the oil gets to approximately 2690 kpa (390 psi), the relief valve moves up far enough to let oil go to oil cooler relief valve (10) and out passage (11) to the transmission oil cooler.

The pressure setting of relief valve (12) can be changed by the removal or addition of shims.

Oil Cooler Relief Valve

Oil cooler relief valve (10) controls the maximum pressure of the oil to the transmission oil cooler. The transmission oil cooler gets its oil from relief valve (12) whenever the relief valve is open. If the pressure of the oil in passage (11) gets to approximately 930 kPa (135 psi), oil cooler relief valve (10) will move to the left against the force of its spring. This permits the extra oil to drain back to the reservoir.

Shift Started (Clutch Filling)

PRESSURE CONTROL GROUP IN NEUTRAL WITH ENGINE RUNNING

1. Drain passage (seven).

2. Passage to No. 3 clutch.

3. Drain passages.

4. Passage to No. 5 clutch.

5. Pilot passage (seven).

6. Passage to No. 1 clutch.

7. Drain passage (seven).

8. Passage to No. 2 clutch.

9. Passage to No. 4 clutch.

10. Selector piston (seven).

11. Load piston (seven).

12. Modulation reduction valve (seven).

13. Passage to No. 6 clutch.

14. Passage from pump.

15. Passage to No. 7 clutch.

A, B, C, E, F, G, H. Load piston body identification.

D. Not used.

The pressure control group has seven pressure modulation reduction valves (12); one valve for each clutch in the transmission. This gives separate control to the pressure and time that it takes to engage and release each clutch. This is known as Individual Clutch Modulation (ICM). Each load piston body has a letter identification on it for disassembly and assembly purposes. Pilot passages (5) are connected to passages from the rotary selector spool of the selector group. Pump oil from the selector group is in passage (14). Drain passages (3) are connected to the reservoir (drain).

All of the modulation reduction valves operate in a similar way. For this reason, only the basic operation of one valve is given.

Shift Started (Clutch Filling)

MODULATION REDUCTION VALVE AT START OF SHIFT

1. Drain passage.

2. Passage for pump oil.

3. Passage to clutch.

4. Drain passage.

5. Springs.

6. Load piston.

7. Passage in selector piston.

8. Selector piston.

9. Pilot passage.

10. Spring.

11. Modulation reduction valve.

12. Ball check.

13. Load piston orifice.

14. Load piston plug.

15. Decay orifice.

16. Drain passage.

17. Selector piston plug.

18. Load piston body.

When a shift is started (a clutch is to be engaged), pilot passage (9) gets pilot oil at the correct sequence from the rotary selector spool. This causes selector piston (8) along with load piston (6) to move against the force of springs (5). This causes modulation reduction valve (11) to move against the force of spring (10). Now, passage (3) is not open to drain passage (4). Passage (3) is open to passage (2). The pump oil now goes to fill the clutch.

At this time, oil also goes through load piston orifice (13) and passage (7). This oil goes between selector piston (8) and load piston (6).

Shift Completed (Clutch Engaged)

MODULATION REDUCTION VALVE AT END OF SHIFT

1. Drain passage.

2. Passage for pump oil.

3. Passage to clutch.

4. Drain passage.

5. Springs.

6. Load piston.

7. Passage in selector piston.

8. Selector piston.

9. Pilot passage.

10. Spring.

11. Modulation reduction valve.

12. Ball check.

13. Load piston orifice.

14. Load piston plug.

15. Decay orifice.

16. Drain passage.

17. Selector piston plug.

18. Load piston body.

After the clutch is full of oil, the pressure of the pump oil increases in the selected clutch. This causes load piston (6) to move against the force of springs (5). Clutch oil also goes through an orifice in the modulation reduction valve, opens ball check (12) and goes into the slug chamber at the left end of the valve. This pressure works against the pressure at the end of load piston (6). The pressure increases until the load piston is moved all the way to the left against its stop. The pressure in the clutch is now at its maximum. Modulation reduction valve (11) moves to the right and left to keep the pressure in passage (3) constant.

Two components control the amount of time it takes for the pressure in the clutch to get to its maximum: the size of load piston orifice (13) and the force of springs (5). The force of springs (5) can be changed by the removal or addition of shims in load piston (6).

Clutch Disengaged (Released)

MODULATION REDUCTION VALVE WITH CLUTCH DISENGAGED

1. Drain passage.

2. Passage for pump oil.

3. Passage to clutch.

4. Drain passage.

5. Springs.

6. Load piston.

7. Passage in selector piston.

8. Selector piston.

9. Pilot passage.

10. Spring.

11. Modulation reduction valve.

12. Ball check.

13. Load piston orifice.

14. Load piston plug.

15. Decay orifice.

16. Drain passage.

17. Selector piston plug.

18. Load piston body.

When a clutch is disengaged (released), pilot passage (9) is open to drain through the rotary selector spool. The force of springs (5) moves selector piston (8) all the way to the right against load piston body (18). Passage (7) is now in alignment with drain passage (16). The force of springs (5) moves load piston (6) all the way to the right against selector piston (8).

Modulation reduction valve (11) now moves all the way to the right by the force of spring (10). In this position, pump oil in passage (2) can not go into passage (3). Passage (3) is now open to drain passage (4) and the pressure in the clutch is released. Decay orifice (15) in drain passage (16) controls the amount of time it takes for the pressure in the clutch to decay to zero.

Transmission

TRANSMISSION COMPONENTS

1. Input shaft.

2. No. 1 hub gear.

3. No. 2 and No. 3 sun gear.

4. No. 1 clutch.

5. No. 2 ring gear.

6. No. 2 and No. 3 planetary carrier.

7. No. 2 clutch.

8. Planetary input gear.

9. No. 3 rotating clutch.

10. No. 3 rotating clutch housing.

11. Center shaft.

12. No. 4 rotating clutch housing.

13. No. 4 ring gear and No. 5 sun gear.

14. No. 4 clutch.

15. No. 5 planetary carrier.

16. No. 5 planetary gear.

17. No. 5 clutch.

18. No. 5 ring gears.

19. No. 6 planetary gears.

20. No. 6 sun gear.

21. No. 6 clutch.

22. No. 6 ring gear.

23. No. 7 planetary gears.

24. No. 7 ring gear.

25. No. 7 planetary carrier.

26. No. 7 sun gear.

27. No. 6 planetary carrier.

28. Output yoke.

29. No. 7 clutch.

30. No. 3 planetary gears.

31. No. 2 planetary gears.

Power from the engine goes to the torque converter, through the front drive shaft, to the transfer gears which are fastened directly to the front of the transmission case. The power then goes through the planetary transmission, the rear drive shaft and the pinion to the differential.

The transmission has seven speeds forward and one reverse. REVERSE is torque converter drive only. FIRST speed can have either torque converter drive or direct drive. As ground speed in FIRST speed increases, the lockup clutch of the torque converter engages. This gives direct drive to FIRST speed forward. SECOND through SEVENTH speeds are direct drive only with a short period of converter drive while the clutches engage in the transmission. This makes each shift smooth.

As the transmission shifts either up or down from FIRST through SEVENTH speeds, the lockup clutch automatically engages after both the transmission clutches are engaged.

The transmission has a combination of five stationary clutches, two rotating clutches and five planetary units to give seven forward and one reverse speed. No. 3 clutch (9) and No. 4 clutch (14) are the rotating clutches.

The torque input and output are on opposite ends of the transmission. Torque from the input transfer gears goes to the input shaft (1) which drives the input gear components. No. 1 clutch (4), No. 2 clutch (7) and No. 3 clutch (9) are the clutches in the input section of the transmission. The remainder of the clutches are in the output section of the transmission. Center shaft (11) carries the sun gears which drive the output section of the transmission. The center shaft turns the same direction as input shaft (1).

Power Flow In Neutral

POWER FLOW IN NEUTRAL

1. Input shaft.

2. No. 1 hub gear.

3. No. 2 and No. 3 sun gear.

4. No. 1 clutch.

5. No. 2 ring gear.

6. No. 2 and No. 3 planetary carrier.

7. No. 2 clutch.

8. Planetary input gear.

9. No. 3 rotating clutch.

10. No. 3 rotating clutch housing.

11. Center shaft.

19. No. 6 planetary gears.

20 No. 6 sun gear.

21. No. 6 clutch.

22. No. 6 ring gear.

25. No. 7 planetary carrier.

27. No. 6 planetary carrier.

28. Output yoke.

30. No. 3 planetary gears.

31. No. 2 planetary gears.

Only No. 1 clutch (4) is engaged in NEUTRAL. No. 1 clutch holds No. 1 hub gear (2) which is splined to and now holds No. 2 and No. 3 sun gear (3). Torque is transferred from the transfer gears to input shaft (1). Planetary input gear (8) is splined to and turns with the input shaft. The planetary input gear turns No. 3 planetary gears (30). Since No. 2 and No. 3 sun gear (3) is being held, No. 3 planetary gears walk around No. 3 sun gear. This drives No. 2 and No. 3 planetary carrier (6) in the same direction as the input shaft. No. 2 and No. 3 planetary carrier (6) is bolted to clutch No. 3 housing (10) which is splined to center shaft (11). The center shaft now turns the same direction as the input shaft. No output clutches are engaged. Since the output clutches are slipping, torque does not flow to output yoke (28).

Power Flow In First Speed

No. 2 clutch (7) and No. 6 clutch (21) are engaged in FIRST speed. No. 2 clutch holds No. 2 ring gear (5). Torque is transferred from the transfer gears to input shaft (1). Planetary input gear (8) is splined to and turns with the input shaft. The planetary input gear turns No. 3 planetary gears (30) which now turn No. 2 and No. 3 sun gear (3). No. 2 and No. 3 sun gear (3) turn the No. 2 planetary gears (31). Since No. 2 ring gear (5) is being held, No. 2 planetary gears walk around the inside of No. 2 ring gear. This drives No. 2 and No. 3 planetary carrier (6) in the same direction as the input shaft. No. 2 and No. 3 planetary carrier is bolted to clutch No. 3 housing (10) which is splined to center shaft (11). The center shaft now turns the same direction as the input shaft.

No. 6 clutch (21) holds No. 6 ring gear (22). No. 6 sun gear (20) is splined to and turns with center shaft (11). No. 6 sun gear turns No. 6 planetary gears (19). Since No. 6 ring gear is being held, No. 6 planetary gears walk around the inside of No. 6 ring gear. This drives No. 6 planetary carrier (27) in the same direction as the center shaft. No. 6 planetary carrier is splined to No. 7 planetary carrier (25) which is splined to output yoke (28). Power is now delivered from the output yoke, through the rear drive shaft and pinion, to the differential.

Power Flow In Second Speed

No. 1 clutch (4) and No. 6 clutch (21) are engaged in SECOND speed. No. 1 clutch holds No. 1 hub gear (2) which is splined to and now holds No. 2 and No. 3 sun gear (3). Torque is transferred from the transfer gears to input shaft (1). Planetary input gear (8) is splined to and turns with the input shaft. The planetary input gear turns No. 3 planetary gears (30). Since No. 2 and No. 3 sun gear (3) is being held, No. 3 planetary gears walk around No. 3 sun gear. This drives No. 2 and No. 3 planetary carrier (6) in the same direction as the input shaft. No. 2 and No. 3 planetary carrier (6) is bolted to clutch No. 3 housing (10) which is splined to center shaft (11). The center shaft now turns the same direction as the input shaft.

No. 6 clutch (21) holds No. 6 ring gear (22). No. 6 sun gear (20) is splined to and turns with center shaft (11). No. 6 sun gear turns No. 6 planetary gears (19). Since No. 6 ring gear is being held, No. 6 planetary gears walk around the inside of No. 6 ring gear. This drives No. 6 planetary carrier (27) in the same direction as the center shaft. No. 6 planetary carrier is splined to No. 7 planetary carrier (25) which is splined to output yoke (28). Power is now delivered from the output yoke, through the rear drive shaft and pinion, to the differential.

Power Flow In Third Speed

No. 3 rotating clutch (9) and No. 6 clutch (21) are engaged in THIRD speed. No. 3 rotating clutch holds the planetary input gear (8) which is splined to and turns with the input shaft (1). No. 3 rotating clutch housing (10) is splined to center shaft (11). When No. 3 clutch is engaged the input shaft, the planetary input gear, the No. 3 clutch housing and the center shaft turn together.

No. 6 clutch (21) holds No. 6 ring gear (22). No. 6 sun gear (20) is splined to and turns with center shaft (11). No. 6 sun gear turns No. 6 planetary gears (19). Since No. 6 ring gear is being held, No. 6 planetary gears walk around the inside of No. 6 ring gear. This drives No. 6 planetary carrier (27) in the same direction as the center shaft. No. 6 planetary carrier is splined to No. 7 planetary carrier (25) which is splined to output yoke (28). Power is now delivered from the output yoke, through the rear drive shaft and pinion, to the differential.

Power Flow In Fourth Speed

POWER FLOW IN FOURTH

1. Input shaft.

2. No. 1 hub gear.

3. No. 2 and No. 3 sun gear.

4. No. 1 clutch.

6. No. 2 and No. 3 planetary carrier.

8. Planetary input gear.

9. No. 3 rotating clutch.

10. No. 3 rotating clutch housing.

11. Center shaft.

12. No. 4 rotating clutch housing.

13. No. 4 ring gear and No. 5 sun gear.

14. No. 4 clutch.

15. No. 5 planetary carrier.

16. No. 5 planetary gear.

17. No. 5 clutch.

18. No. 5 ring gears.

19. No. 6 planetary gears.

20. No. 6 sun gear.

22. No. 6 ring gear.

23. No. 7 planetary gears.

24. No. 7 ring gear.

25. No. 7 planetary carrier.

26. No. 7 sun gear.

27. No. 6 planetary carrier.

28. Output yoke.

29. No. 7 clutch.

30. No. 3 planetary gears.

Only No. 1 clutch (4) and No. 5 clutch (17) are engaged in FOURTH speed. No. 1 clutch holds No. 1 hub gear (2) which is splined to and now holds No. 2 and No. 3 sun gear (3). Torque is transferred from the transfer gears to input shaft (1). Planetary input gear (8) is splined to and turns with the input shaft. The planetary input gear turns No. 3 planetary gears (30). Since No. 2 and No. 3 sun gear (3) is being held, No. 3 planetary gears walk around No. 3 sun gear. This drives No. 2 and No. 3 planetary carrier (6) in the same direction as the input shaft. No. 2 and No. 3 planetary carrier (6) is bolted to clutch No. 3 housing (10) which is splined to center shaft (11). The center shaft now turns the same direction as the input shaft.

When No. 5 clutch (17) is engaged it holds No. 5 ring gear (18). The combination No. 4 ring and No. 5 sun gear (13) and No. 6 sun gear (20) are splined to and turn with center shaft (11). Combination No. 4 ring and No. 5 sun gear (13) turns No. 5 planetary gears (16). Since the No. 5 ring gear is being held, the No. 5 planetary gears walk around the inside of the ring gear. This causes No. 5 planetary carrier (15) to turn in the same direction as, but slower than, the center shaft. No. 5 planetary carrier is splined to No. 6 ring gear (22) and they turn together. Now No. 6 sun gear (20) drives No. 6 planetary gears (19) around the inside of the slower moving No. 6 ring gear (22). This drives No. 6 planetary carrier (27) in the same direction as the center shaft. No. 6 planetary carrier is splined to No. 7 planetary carrier (26) which is splined to the output yoke (28). Power is now delivered from the output yoke through the rear drive shaft and pinion, to the differential.

Power Flow In Fifth Speed

No. 3 rotating clutch (9) and No. 5 clutch (17) are engaged in FIFTH speed. No. 3 rotating clutch holds the planetary input gear (8) which is splined to and turns with the input shaft (1). No. 3 rotating clutch housing (10) is splined to center shaft (11). When No. 3 clutch is engaged the input shaft, the planetary input gear, the No. 3 clutch housing and the center shaft turn together.

When No. 5 clutch (17) is engaged it holds No. 5 ring gear (18). The combination No. 4 ring and No. 5 sun gear (13) and No. 6 sun gear (20) are splined to and turn with center shaft (11). Combination No. 4 ring and No. 5 sun gear (13) turns No. 5 planetary gears (16). Since the No. 5 ring gear is being held, the No. 5 planetary gears walk around the inside of the ring gear. This causes No. 5 planetary carrier (15) to turn in the same direction as, but slower than, the center shaft. No. 5 planetary carrier is splined to No. 6 ring gear (22) and they turn together. Now No. 6 sun gear (20) drives No. 6 planetary gears (19) around the inside of the slower moving No. 6 ring gear (22). This drives No. 6 planetary carrier (27) in the same direction as the center shaft. No. 6 planetary carrier is splined to No. 7 planetary carrier (26) which is splined to the output yoke (28). Power is now delivered from the output yoke through the rear drive shaft and pinion, to the differential.

Power Flow In Sixth Speed

No. 1 clutch (4) and No. 4 clutch (14) are engaged in SIXTH speed. No. 1 clutch holds No. 1 hub gear (2) which is splined to and now holds No. 2 and No. 3 sun gear (3). Torque is transferred from the transfer gears to input shaft (1). Planetary input gear (8) is splined to and turns with the input shaft. The planetary input gear turns No. 3 planetary gears (30). Since No. 2 and No. 3 sun gear (3) is being held, No. 3 planetary gears walk around No. 3 sun gear. This drives No. 2 and No. 3 planetary carrier (6) in the same direction as the input shaft. No. 2 and No. 3 planetary carrier (6) is bolted to clutch No. 3 housing (10) which is splined to center shaft (11). The center shaft now turns the same direction as the input shaft.

When No. 4 rotating clutch (14) is engaged, it holds onto and turns with combination No. 4 ring and No. 5 sun gear (13) which is splined to and turns with center shaft (11). No. 4 rotating clutch housing (12) is bolted to No. 5 planetary carrier (15). No. 5 planetary carrier is splined to No. 6 ring gear (22). When clutch No. 4 is engaged, No. 6 sun gear (22) turns with the center shaft. No. 6 sun gear (20) is splined to and turns with the center shaft. Since both No. 6 ring gear and No. 6 sun gear turn at the same speed, No. 6 planetary gears (19) are being held. This drives No. 6 planetary carrier (27) in the same direction and at the same speed as the center shaft. No. 6 planetary carrier is splined to No. 7 planetary carrier (25) which is splined to output yoke (28). Power is now supplied from the output yoke through the rear drive shaft and pinion to the differential.

Power Flow In Seventh Speed

No. 3 rotating clutch (9) and No. 6 clutch (14) are engaged in SEVENTH speed. No. 3 rotating clutch holds the planetary input gear (8) which is splined to and turns with the input shaft (1). No. 3 rotating clutch housing (10) is splined to center shaft (11). When No. 3 clutch is engaged the input shaft, the planetary input gear, the No. 3 clutch housing and the center shaft turn together.

When No. 4 rotating clutch (14) is engaged, it holds onto and turns with combination No. 4 ring and No. 5 sun gear (13) which is splined to and turns with center shaft (11). No. 4 rotating clutch housing (12) is bolted to No. 5 planetary carrier (15). No. 5 planetary carrier is splined to No. 6 ring gear (22). When clutch No. 4 is engaged, No. 6 sun gear (22) turns with the center shaft. No. 6 sung gear (20) is splined to and turns with the center shaft. Since both No. 6 ring gear and No. 6 sun gear turn together, No. 6 planetary gears (19) are being held. This drives No. 6 planetary carrier (27) in the same direction as the center shaft. No. 6 planetary carrier is splined to No. 7 planetary carrier (25) which is splined to output yoke (28). Power is now supplied from the output yoke through the rear drive shaft and pinion to the differential.

Power Flow In Reverse

No. 3 rotating clutch (9) and No. 7 clutch (29) are engaged in reverse speed. No. 3 rotating clutch holds the planetary input gear (8) which is splined to and turns with the input shaft (1). No. 3 rotating clutch housing (10) is splined to center shaft (11). When No. 3 clutch is engaged the input shaft, the planetary input gear, the No. 3 clutch housing and the center shaft turn together.

No. 7 clutch (29) holds No. 7 ring gear (24). No. 6 sun gear (20) is splined to and turns with the center shaft. The No. 6 sun gear turns No. 6 planetary gears (19) which turns No. 6 ring gear (22). The No. 6 ring gear is splined to No. 7 sun gear (26) and they turn together. The No. 7 sun gear now turns No. 7 planetary gear (23). Since No. 7 ring gear is being held the No. 7 planetary gear walks around the inside of the ring gear. This drives No. 7 planetary carrier (25) in the opposite direction of the center shaft. The No. 7 planetary carrier is splined to both the No. 6 planetary carrier (27) and the output yoke (28). Both now turn the opposite direction of the center shaft. The No. 6 planetary carrier acts as the reactionary unit for the No. 6 planetary train. The output yoke sends power through the rear drive shaft and pinion to the differential. The vehicle is now in REVERSE.

Transmission Lubrication

TRANSMISSION LUBRICATION

1. Input shaft.

10. No. 3 rotating clutch housing.

11. Center shaft.

13. No. 4 ring gear and No. 5 sun gear.

25. No. 7 planetary carrier.

27. No. 6 planetary carrier.

32. Passage.

33. Passage.

34. Passage.

35. No. 4 balance piston.

36. No. 5 planetary carrier center shaft.

37. No. 6 planetary carrier center shaft.

38. No. 7 planetary carrier center shaft.

39. Output yoke taper roller bearing.

40. Ball bearing.

41. No. 3 balance piston.

42. No. 2 and No. 3 planetary carrier center shaft.

43. No. 2 and No. 3 planetary carrier front bushing.

44. No. 1 hub gear ball bearing.

Oil for lubrication of the transmission is provided by the relief valve of the transmission hydraulic control group. Oil from the relief valve goes down to the distribution manifold in the bottom of the transmission hydraulic control group.

Most of the oil from the distribution manifold goes through passage (33) to lubricate ball bearing (40). Some of this oil goes back to the No. 4 balance piston (35) and the No. 4 clutch pack. Some of the oil from ball bearing (40) goes back past center shaft (11), through No. 4 ring gear and No. 5 sun gear (13) to lubricate the No. 5 planetary carrier center shaft (36) and the No. 5 clutch pack, as well as No. 6 planetary carrier center shaft (37), and finally the No. 6 clutch pack. The remainder of the oil from ball bearing (40) goes forward through No. 3 rotating clutch housing (10) into a gap between input shaft (1) and center shaft (11). Some of this oil goes forward to lubricate No. 3 balance piston (41) and the No. 3 clutch pack, as well as No. 2 and No. 3 planetary carrier center shaft (42), the No. 1 clutch pack and the No. 2 clutch pack. The remaining oil leaves the gap between the input shaft and the center shaft and goes back through the center shaft, between No. 6 planetary carrier (27) and No. 7 planetary carrier (25) to lubricate No. 7 planetary carrier center shaft (38) and the No. 7 clutch pack.

Part of the oil goes from the distribution manifold through passage (34) to provide lubrication for the output yokes taper roller bearing set (39).

The remainder of the oil from the distribution manifold goes through passage (32) for lubrication of No. 1 hub gear ball bearing (44) and the No. 2 and No. 3 planetary carrier front bushing (43).

Operation of the Balance Pistons in the Rotating Clutches

The oil that goes to balance piston (41) for No. 3 clutch and balance piston (35) for No. 4 clutch is used to balance the force of the oil (centrifugal force) caused by the rotation of No. 3 and No. 4 clutches. The centrifugal force of the oil behind the clutch piston in the rotating clutches causes a small amount of clutch engagement (clutch drag) in the rotating clutch. The centrifugal force of the oil behind the balance piston balances or removes the centrifugal force of the oil on the clutch piston.

Differential And Final Drives

Differential And Bevel Gear

The differential and bevel gear is fastened to the rear axle housing. It connects the output shaft of the transmission to the drive axles. The output shaft of the transmission is connected to bevel pinion (1) by splines. Bevel pinion (1) turns bevel gear (5). Bevel gear (5) is fastened to housing (2). There are four pinions in the differential. The pinions turn freely on spider (6). Each pinion has a double bearing assembly to carry the drive load of the pinion. Housing (2) and housing (7) are bolted together to hold the spider. They rotate together with bevel gear (5). The housing is driven by bevel gear (5), and supported by bearings. Correct adjustment of all the bearings in the differential are very important. See Power Train Specifications for correct adjustment procedures.

The pinions are engaged at a 90° angle with two straight bevel side gears (3). The side gears are connected to the drive axles by splines.

When the machine is moving in a straight direction with the same amount of traction under each drive wheel, the same amount of torque on each axle holds the pinions so they will not turn on spider (6). This gives the same effect as if both drive wheels were on one axle.

DIFFERENTIAL AND BEVEL GEAR
1. Bevel pinion. 2. Housing. 3. Side gears (two). 4. Thrust pin. 5. Bevel gear. 6. Spider. 7. Housing. 8. Carrier assembly. 9. Thrust washers.

When different amount of loads are put on the drive wheels, as in a turn, different amount of forces are put on opposite sides of the differential causing the pinions to turn. Turning the pinions makes the inside wheel go slower and the outside wheel goes faster and the vehicle is driven with full power in a turn.

Side gears (3) turn against thrust washers (9), which take the end thrust against the differential housing. The bearing assembly must be changed in sets of two.

The differential gets lubrication from the oil in the axle housing. As the parts rotate, the oil is thrown around inside of the housing (splash lubricated). Radial grooves in thrust washers (9) let the lubricant flow between thrust washers and side gears (3).

Thrust pin (4), in the rear housing, provides support for carrier assembly (8) which carries heavy thrust load.

Final Drive

Each final drive has a planetary gear system. Ring gear (3) is fastened to final drive hub (2). Splines connect final drive hub (2) to the axle housing. Ring gear (3) is held in a stationary position. Planetary gears (4) are held by planetary carrier (6). Planetary carrier (6) is fastened to the wheel assembly. Splines connect sun gear (5) to axle shaft (1). Splines connect axle shaft (1) to the side gear of the differential.

When the side gear of the differential turns, it turns the axle shaft. The axle shaft turns sun gear (5). Sun gear (5) turns planetary gears (4). Since ring gear (3) is held stationary by hub (2), planetary gears (4) move around the inside of ring gear (3). The planetary gears move in the same direction as sun gear (5) but at a slower speed. The movement of the planetary gears causes planetary carrier (6) to turn. Since the planetary carrier is connected to the wheel assembly, the planetary gears cause the wheels to turn.

The final drives get lubrication by the rotation of the gears in oil (splash lubrication). The differential and final drives use the same lubricant.

FINAL DRIVE
1. Axle shaft. 2. Final drive hub. 3. Ring gear. 4. Planetary gears. 5. Sun gear. 6. Planetary carrier.