 | |
| Illustration 1 | g00356578 |
Transmission modulating valve (1) Cartridge assembly (2) Body (3) Spool assembly (4) Spring | |
 | |
| Illustration 2 | g00356581 |
Transmission modulating valve (5) Connector (6) Solenoid (7) Disconnect group (clutch pressure) (8) Modulating valve (B) Drain (C) Clutch (D) Supply | |
The transmission hydraulic controls are attached to the top of the planetary transmission on the inside of the transmission case.
Proportional solenoid valves (8) are mounted on the main relief valve. There is one modulating valve (8) for each clutch.
Each modulating valve has a pilot stage that is similar to the steering clutch and brake valves. Each modulating valve also contains a pressure reducing spool. Modulating valve (8) allows the corresponding clutch to fill to a pressure that is proportional to the current to solenoid (6) .
The electronic control module determines the amount of current that is required by the solenoids. The current is based on the response of the machine that is measured by speed sensors.
Modulating valves (8) are designed to be individually replaced if a malfunction occurs.
Transmission clutch pressures can be measured from the disconnect group (7) on each valve.
Note: Transmission modulating valves (8) must be recalibrated when any of the following tasks are performed:
- A transmission modulating valve and/or a solenoid is replaced.
- The transmission is serviced or replaced.
- The electronic control module is replaced.
Reference: See Service Manual, SENR8367, "Powertrain Electronic Control Systems" for the calibration procedures.
 | |
| Illustration 3 | g00356582 |
Transmission hydraulic control group (5) Connector (6) Solenoid (7) Disconnect group (8) Modulating valves (E) Clutch (one) (F) Clutch (two) (G) Clutch (three) (H) Clutch (four) (J) Clutch (five) | |
 | |
| Illustration 4 | g00356583 |
Main relief valve (9) Valve manifold (10) Drain (11) Supply from the oil filter to the clutches (12) Passage to the transmission lubrication (13) Drain (14) Relief valve adjustment (15) Spring (16) Spool assembly (17) Slug | |
The main relief valve is located in manifold (9) on the top of the transmission planetary group. The main relief valve maintains the system pressure in the control section of the power train oil pump.
The oil from the control section is used to control steering clutches, brakes and transmission clutches. The excess oil that passes the main relief valve is used to lubricate the transmission.
The main relief valve has slug (17) which is connected to the pump outlet by an orifice in spool assembly (16) . Slug (17) provides a reaction chamber that balances the spring force in order to maintain the pressure. Spring (15) has adjustment (14) for adjustment of the main relief valve pressure. Adjustment (14) is located on the side of manifold (9) .
 | |
| Illustration 5 | g00356584 |
Top view of the relief valve manifold (E) Clutch (one) (F) Clutch (two) (G) Clutch (three) (H) Clutch (four) (J) Clutch (five) (K) Drain (L) Supply | |
 | |
| Illustration 6 | g00356586 |
Bottom view of the relief valve manifold (E) Clutch (one) (F) Clutch (two) (G) Clutch (three) (H) Clutch (four) (J) Clutch (five) | |