Note: Two different types of solenoid valves can be used on the dropbox. 198-1515 Solenoid Valve Gp is a 12V solenoid. 225-0300 Solenoid Valve Gp is a 24V solenoid.
Transmission Hydraulic System
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| Illustration 1 | g01428749 |
TH31 Transmission Hydraulic Schematic without Drop Box (1) Bypass valve (Oil filter) (2) Modulating valve (Torque converter lockup clutch) (3) Torque converter lockup clutch (4) Torque converter (5) Oil filter element assembly (Transmission) (6) Temperature sensor (Transmission oil) (7) Relief valve (Transmission hydraulic control) (8) Transmission bearing lubrication (9) Relief valve (Torque converter outlet) (10) Oil cooler (11) Relief valve (Torque converter inlet) (12) Temperature sensor "Torque converter out temperature" (13) Gear pump (Transmission oil) (14) Modulating valves (Electronic clutch pressure control) (15) Suction tube (16) Transmission sump | |
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| Illustration 2 | g01609041 |
TH31 Transmission Hydraulic Schematic with 2WD Drop Box (1) Bypass valve (Oil filter) (2) Modulating valve (Torque converter lockup clutch) (3) Torque converter lockup clutch (4) Torque converter (5) Oil filter element assembly (Transmission) (6) Solenoid valves (Drop box) (7) Relief valve (Transmission hydraulic control) (8) Transmission bearing lubrication (9) Relief valve (Torque converter outlet) (10) Oil cooler (11) Relief valve (Torque converter inlet) (12) Temperature sensor "Torque converter out temperature" (13) Gear pump (Transmission oil) (14) Modulating valves (Electronic clutch pressure control) (15) Suction tube (16) Transmission sump (17) Gear Pump (18) Oil filter group (19) Drop box bearing lubrication (20) Drop box sump (21) Temperature sensor (Transmission oil) | |
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| Illustration 3 | g01523619 |
TH31 Transmission Hydraulic Schematic with 4WD Drop Box (1) Bypass valve (Oil filter) (2) Modulating valve (Torque converter lockup clutch) (3) Torque converter lockup clutch (4) Torque converter (5) Oil filter element assembly (Transmission) (6) Solenoid valves (Drop box) (7) Relief valve (Transmission hydraulic control) (8) Transmission bearing lubrication (9) Relief valve (Torque converter outlet) (10) Oil cooler (11) Relief valve (Torque converter inlet) (12) Temperature sensor "Torque converter out temperature" (13) Gear pump (Transmission oil) (14) Modulating valves (Electronic clutch pressure control) (15) Suction tube (16) Transmission sump (17) Gear Pump (18) Oil filter group (19) Drop box bearing lubrication (20) Drop box sump (21) Temperature sensor (Transmission oil) | |
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| Illustration 4 | g01428744 |
TH35 Transmission Hydraulic Schematic without Drop Box (1) Bypass valve (Oil filter) (2) Modulating valve (Torque converter lockup clutch) (3) Torque converter lockup clutch (4) Torque converter (5) Oil filter element assembly (Transmission) (6) Temperature sensor (Transmission oil) (7) Relief valve (Transmission hydraulic control) (8) Transmission bearing lubrication (9) Relief valve (Torque converter outlet) (10) Oil cooler (11) Relief valve (Torque converter inlet) (12) Temperature sensor "Torque converter out temperature" (13) Gear pump (Transmission oil) (14) Modulating valves (Electronic clutch pressure control) (15) Suction tube (16) Transmission sump | |
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| Illustration 5 | g01609035 |
TH35 Transmission Hydraulic Schematic with 2WD Drop Box (1) Bypass valve (Oil filter) (2) Modulating valve (Torque converter lockup clutch) (3) Torque converter lockup clutch (4) Torque converter (5) Oil filter element assembly (Transmission) (6) Solenoid valves (Drop box) (7) Relief valve (Transmission hydraulic control) (8) Transmission bearing lubrication (9) Relief valve (Torque converter outlet) (10) Oil cooler (11) Relief valve (Torque converter inlet) (12) Temperature sensor "Torque convertor out temperature" (13) Gear pump (Transmission oil) (14) Modulating valves (Electronic clutch pressure control) (15) Suction tube (16) Transmission sump (17) Gear Pump (18) Oil filter group (19) Drop box bearing lubrication (20) Drop box sump (21) Temperature sensor (Transmission oi) | |
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| Illustration 6 | g01548595 |
TH35 Transmission Hydraulic Schematic with 4WD Drop Box (1) Bypass valve (Oil filter) (2) Modulating valve (Torque converter lockup clutch) (3) Torque converter lockup clutch (4) Torque converter (5) Oil filter element assembly (Transmission) (6) Solenoid valves (Drop box) (7) Relief valve (Transmission hydraulic control) (8) Transmission bearing lubrication (9) Relief valve (Torque converter outlet) (10) Oil cooler (11) Relief valve (Torque converter inlet) (12) Temperature sensor "Torque convertor out temperature" (13) Gear pump (Transmission oil) (14) Modulating valves (Electronic clutch pressure control) (15) Suction tube (16) Transmission sump (17) Gear Pump (18) Oil filter group (19) Drop box bearing lubrication (20) Drop box sump (21) Temperature sensor (Transmission oil) | |
The transmission is controlled, cooled, and lubricated by oil that is supplied from transmission sump (16) of the planetary transmission by transmission oil pump (13) .
Oil is taken from transmission sump (16) of the planetary transmission by gear pump (13) and transmission oil is fed via oil filter element assembly (5) to the following components:
- Modulating valve (2) (Torque converter lockup clutch)
- Modulating valves (14) (Electronic clutch pressure control)
- Relief valve (7) (Transmission hydraulic control)
Test points for oil pressure and an oil temperature sensor are incorporated in the hydraulic system. Temperature sensor (12) monitors the temperature of the hydraulic oil.
Control of the planetary transmission is achieved by electronically activated modulating valves (14) that allow oil to fill the various clutches in the planetary transmission.
Torque converter (4) allows the power to be transmitted smoothly from the engine to the planetary transmission. The torque converter allows the speeds of the engine and the transmission to be matched smoothly. Once the speeds are matched, modulating valve (2) for the torque converter lockup clutch engages torque converter lockup clutch (3) in the torque converter. The torque converter provides direct drive from the engine to the planetary transmission.
Oil is fed to the torque converter and the oil transmits the drive from the engine to the planetary transmission. Outlet oil from the torque converter goes via relief valve (9) to oil cooler (10) and forward as lubricant for the transmission.
The transmission is equipped with the following speed sensors:
- Engine output speed sensor
- Torque converter output speed sensor
- Transmission output speed sensor
- Work mode output speed sensor (dropbox)
- Rear wheel drive disconnect speed sensor (dropbox)
- Front wheel drive disconnect speed sensor (4WD dropbox)
All of the speed sensors are located on the right side of the transmission case.
Drop Box
The drop box has the same requirements for the oil type and viscosity as the base TH31 and TH35 transmissions.
A power train consists of an engine and an engine mounted transmission that serves dual functions. The power train provides propulsion to the driveline for the vehicle and provides power to draw works.
The drop box is attached to the basic transmission. This drop box serves two purposes:
- Lower the axis of the driveline.
- Connect and disconnect the two drivelines from the power module for the transmission.
When the transmission is used for propulsion, the lower driveline is connected to the engine and the transmission. When the transmission is used for propulsion, the draw works driveline is disconnected from the engine and the transmission. When the transmission is in the well service mode, the draw works driveline is connected to the engine and transmission. The driveline for the propulsion is disconnected.
The drop box system has an additional gear pump (17) that pumps oil through the drop box. This additional drop box system also includes oil filter group (18) . The oil is transferred through this filter group and then through the bearings of the drop box. The sump for the drop box collects oil which is then pumped back through the system.
The drop box is set up so that the top and bottom engage solenoids have pilot pressure when the disengage solenoid is activated. Disengaged solenoid valves (6) are continuously in the ON position when disconnect is in the DISENGAGE position.
Connected solenoid valves (6) remain in the ON position when the disconnected solenoid is in the ENGAGE position. Solenoids control the oil flow to the clutches in the transmission. When a direction and gear are selected by the operator, the control module activates the appropriate solenoid. Two solenoids are activated in order to move the machine. One solenoid is activated for the direction and one solenoid is activated for the gear.