VALVE GP-SHUTTLE 3871096 - Caterpillar

Illustration 1 g00421143
(1) Upshift solenoid (2) Downshift solenoid (3) Lockup clutch solenoidFor the speed positions that require the option for direct drive, lockup clutch solenoid (3) must be activated after upshift solenoid (1) or downshift solenoid (2) is deactivated. The position of the transmission gear switch and the ground speed signal from the transmission speed sensor command the Electronic Programmable Transmission Control (EPTC II) to activate lockup clutch solenoid (3) at the correct time.Pump oil from the parking brake release pump section sends oil to the torque converter lockup clutch and synchronizing valve. This pump oil goes through the pressure reduction valve in the torque converter lockup clutch and synchronizing valve. This converts the pump oil to pilot oil. The pilot oil flows to the relay valve in the torque converter lockup clutch and synchronizing valve.Lockup clutch solenoid (3) sends signal oil to the relay valve in the torque converter lockup clutch and synchronizing valve. This allows the pilot oil to flow past the relay valve. The oil then flows to the modulation reduction valve in the torque converter lockup clutch and synchronizing valve. The modulation reduction valve allows pump oil to flow to the lockup clutch. The lockup clutch will stay engaged until the oil pressure is removed by lockup clutch solenoid (3). While the lockup clutch is engaged the machine is in direct drive.