TUBE AS 3376689 - Caterpillar

Modulating Valves
Illustration 1 g00761852
Transmission control valve (1) Solenoids (2) Pressure taps (3) Modulating Valves (4A) Main relief valve (4) Transmission intermediate speed sensor (5) Transmission intermediate speed sensor (6) Transmission output speed sensor (E) Clutch (one) (F) Clutch (two) (G) Clutch (three) (H) Clutch (four) (I) Clutch (five) (J) Oil supply (K) Oil drainThe transmission control valve is attached to the top of the planetary transmission on the inside of the transmission case.
Illustration 2 g00761755
Solenoid (1) Modulating valve (3) (7) Connector (8) Pressure tap (clutch pressure) (B) Drain (C) Clutch (D) Supply
Illustration 3 g00761772
(9) Cartridge assembly (10) Body (11) Spool assembly (12) SpringModulating valves (3) are mounted on the transmission control valve. There is one modulating valve (3) 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 (3) allows the corresponding clutch to fill to a pressure that is proportional to the current to solenoid (1) .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 (3) are designed to be individually replaced if a malfunction occurs.Transmission clutch pressures can be measured from the pressure tap (8) on each valve.Note: Modulating valves (3) 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.Main Relief Valve
Illustration 4 g00761925
Main relief valve (4A) (1) Drain (2) Inlet passage (3) Outlet passage to the torque converter (4) Drain (5) Relief valve adjustment (6) Spring (7) Spool assembly (8) Oil chamber (9) SlugMain relief valve (4A) is located in the transmission control valve on the top of the transmission planetary group. Main relief valve (4A) maintains the system pressure in the control section of the power train oil pump.Pump oil flows through passage (2). Oil from inlet passage (2) flows through a hole in spool assembly (7). The oil then flows into oil chamber (8). When the force of the oil pressure in chamber (8) becomes higher than the force of spring (6), spool assembly (7) moves to the right. This allows oil flow to outlet passage (3). The oil goes from outlet passage (3) to the priority valve group.The compressed length of spring (6) determines the force that is applied by spring (6) to oil chamber (8). An increase or a decrease in the force that is applied by spring (6) changes the pressure setting of the main relief valve.Loosen the locknut and turn setscrew (5) clockwise in order to increase the pressure setting. Loosen the locknut and turn setscrew (5) counterclockwise in order to decrease the pressure setting.The pressure setting for main relief valve (4A) is 2990 135 kPa (435 20 psi).