TUBE A 0307033 - Caterpillar

Illustration 1 g00576598
Lockup Clutch Selector Valve (1) Spool (2) Passage (3) Passage (4) Passage (5) Spring (6) Cover (7) Screw (8) Stop (9) Spool (10) Passage (11) Passage (12) Body (13) Cover
Illustration 2 g00577426
(14) Lockup clutch selector valveThe lockup clutch selector valve (14) is fastened to the front of the transmission case above the input shaft.The lockup clutch selector valve (14) controls the lockup clutch in the torque converter. Two different conditions control the lockup clutch.
Transmission input shaft speed (rpm)
Load piston in the selector and the pressure control valveTransmission Input Shaft Speed
A pitot tube on the input shaft of the transmission monitors the input shaft speed. When the input shaft is rotating at 1480 rpm or above 1480 rpm, oil is forced into the passage (3) from the pitot tube. The oil pressure from the passage (3) goes through the passage (2). The oil pressure then causes the spool (9) to move to the right. As the spool (9) moves to the right, the lockup clutch signals that the oil in the passage (4) is blocked. The oil cannot flow to the drain through passage (10). The pressure in the lockup signal circuit will increase. The spool in the reducing valve will move due to this increase. Oil pressure is then sent to the lockup clutch in the torque converter. The machine will now be in direct drive.If the load increases and the transmission input shaft decreases to 1360 rpm or below 1360 rpm, the pressure of the oil in passage (3) will decrease. The spring (5) will move the spool (9) to the left. When the spool (9) is on the left, the lockup clutch signals that the oil pressure in passage (4) will flow to the drain. The oil pressure will flow through passages (10) and (11). Movement of the spool (9) in the reducing valve will block the flow of pressure oil to the lockup clutch. The lockup clutch will disengage and the machine will now be in converter drive. The screw (7) is used to adjust the rpm. Load Piston
When the machine is in direct drive and the operator changes the position of the transmission control lever, the load piston will move to the right. This will open a passage to the drain. The lockup clutch signals that the oil pressure will decrease. The lockup clutch also signals that the spool in the reducing valve will move. This will then block the flow of pressure oil to the lockup clutch. The pressure in the lockup clutch signals that the circuit will increase as the load piston moves to the left.