ALARM AS-BACKUP 2277045 - Caterpillar

Modulating Valves
Illustration 1 g00833980
Transmission modulating valve (1) Cartridge (2) Valve housing (3) Valve spool (4) Spring
Illustration 2 g00833993
Transmission modulating valve (5) Solenoid (6) Pressure tap (clutch pressure) (7) Modulating valve (C) Clutch (J) Pilot Drain Passage (K) Drain (L) SupplyThe transmission hydraulic controls are attached to the top of the planetary transmission on the inside of the transmission case.Proportional solenoid valves (7) 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, SENR8367, "Powertrain Electronic Control Systems" for the calibration procedures.
Illustration 3 g00761302
Transmission hydraulic control (1) Transmission output speed sensor (2) Transmission output speed sensor (3) Transmission intermediate speed sensor (if equipped) (4) Transmission intermediate speed sensor (if equipped) (5) Solenoids (6) Pressure taps (7) Modulating valves (E) No. 1 clutch (F) No. 2 clutch (G) No. 3 clutch (H) No. 4 clutch (J) No. 5 clutchRelief Valve Manifold
Illustration 4 g00465277
Top view of the relief valve manifoldThe 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
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