BODY A. 3D6353 - Caterpillar

Valve Ports
Illustration 3 g01336456
Bottom View of Modulating Valve (Transmission) (5) To sump (7) Charge pressure oil (8) To transmission clutchIllustration 3 shows the bottom view of the modulating valve (transmission). The bottom view shows the porting for the inlet and outlet flow of hydraulic oil.Valve Operation
There are three basic stages of the controlled operation of the modulating valve:
No signal current
Partial signal current
Maximum signal currentThe operation of the modulating valve is not a simple on/off cycle. The transmission ECM varies the strength of the signal current through a programmed cycle in order to control the movement of the proportional solenoid valve spool.No Signal Current (Clutch Disengaged)
Illustration 4 g00774321
Modulating Valve (Transmission) (1) Modulating valve (transmission) (2) Test port (4) Spring (5) Line to sump (6) Spool orifice (7) Charge pressure oil (8) To transmission clutch (9) Solenoid (10) Ball (11) Valve spool (12) Drain orifice (13) PinThe transmission ECM controls the rate of oil flow through modulating valve (1) by changing the strength of the signal current to solenoid (9). When signal current is not being sent to the solenoid, the solenoid will be de-energized.Oil Flow in a De-energized Valve
Spring (4) holds the valve spool to the left in the valve body.The valve spool opens the passage between transmission clutch (3) and the sump.The valve spool blocks the passage between the transmission clutch and the charge pressure oil. Consequently, pressurized oil flow is blocked to the transmission clutch.Charge pressure oil (7) flows from the charge pump into the valve body and around valve spool (11) .The oil flows through the drilled passage that is in the valve spool and into spool orifice (6). The Spool orifice is on the left side of the valve spool. The oil then flows onto