EDGE AS 2500538 - Caterpillar

Illustration 1 g00643448
Torque converter lockup clutch valve (1) Solenoid valve (2) Modulation reduction valve (3) Pressure reduction valveFor the speed positions that require direct drive, the solenoid valve (1) for the torque converter lockup clutch valve must be activated after the upshift solenoid valve or the downshift solenoid valve is deactivated. The position of the transmission gear switch and the ground speed signal from the transmission speed sensor command the Power Train Electronic Control Module (Power Train ECM) to activate the solenoid valve (1) for the torque converter lockup clutch valve at the correct time.The parking brake release section of the gear pump for the torque converter sends oil to the power train oil filter. The oil is split after passing through the power train oil filter. Some of the oil goes to the torque converter lockup clutch valve. This pump oil goes through pressure reduction valve (3) in the torque converter lockup clutch valve. This converts the pump oil to pilot oil, and the pilot oil flows to the solenoid valve (1) for the torque converter lockup clutch valve. When the Power Train ECM energizes the solenoid valve (1) for the torque converter lockup clutch valve, the pilot oil will flow to modulation reduction valve (2) in the torque converter lockup clutch valve. Modulation reduction valve (2) allows pump oil to flow to the torque converter lockup clutch. The torque converter lockup clutch will stay in direct drive until the Power Train ECM de-energizes the solenoid valve (1) for the torque converter lockup clutch valve.