Modulating Valves
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| Illustration 1 | g01854562 |
Transmission modulating valve (1) Cartridge (2) Valve housing (3) Valve spool (4) Spring | |
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| Illustration 2 | g01854567 |
Transmission modulating valve (5) Solenoid (6) Pressure tap (clutch pressure) (7) Modulating valve (C) Clutch (J) Pilot Drain Passage (K) Drain (L) Supply | |
The transmission hydraulic controls are attached to the top of the planetary transmission on the inside of the transmission case.
Proportional solenoid valves are mounted on the relief valve manifold. The machine has one modulating valve (7) for each clutch.
Each modulating valve has a pilot stage that is similar to the type of proportional solenoid valve that is used for the brakes. Each modulating valve also contains a pressure reducing spool. Modulating valve (7) allows the corresponding clutch to fill to a pressure that is proportional to the current to solenoid (5) .
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, which is measured by speed sensors.
Modulating valves (7) are designed to be individually replaced if a malfunction occurs.
Transmission clutch pressures can be measured from the pressure tap (6) on each valve.
Note: Transmission modulating valves (7) 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 the transmission is replaced.
- The electronic control module is replaced.
ReferenceRefer to Service Manual, RENR9867, "Machine Electronic Control Systems" for the calibration procedures.
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| Illustration 3 | g01221072 |
Transmission hydraulic control (5) Solenoids (7) Modulating valves (8) Transmission output speed sensor (9) Transmission output speed sensor (E) No. 1 clutch (F) No. 2 clutch (G) No. 3 clutch (H) No. 4 clutch (J) No. 5 clutch | |
Main Relief Valve
The main relief valve is located in the relief valve manifold on the top of the planetary transmission. The main relief valve maintains the system pressure in the high pressure circuit (control section) of the power train oil pump. Refer to Systems Operation, "Main Relief Valve" that is in this manual for more information about the operation of the main relief valve.
Relief Valve Manifold
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| Illustration 4 | g00465277 |
Top view of the relief valve manifold The main relief valve is in the left side of the manifold. (E) No. 1 clutch (F) No. 2 clutch (G) No. 3 clutch (H) No. 4 clutch (J) No. 5 clutch (K) Drain (L) Supply | |
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| Illustration 5 | g00465279 |
Bottom view of the relief valve manifold (E) No. 1 clutch (F) No. 2 clutch (G) No. 3 clutch (H) No. 4 clutch (J) No. 5 clutch | |