BEARING (.020 U''SIZE) 3B7938 - Caterpillar

Lift Circuit
Raise Operation
When the lift control lever is moved to RAISE detent position, lift valve spool (23) moves to RAISE position. Lift cylinder oil (head end) flows through lift valve spool (23) and becomes signal oil.Implement oil flows through inlet valve group (1) and tilt control valve (14) to get to lift control valve (22). The oil flows through the slots of priority flow control valve (17) and moves it against the force of its spring to get to the lift control valve. When implement oil pressure is less than approximately 360 60 kPa (52 8.5 psi), the oil flows through signal loading valve (25) and adds to the head end oil. This makes sure that enough signal oil is available to unloading valve (8).The signal oil flows through shuttle valve (20) of the lift control valve and shuttle valve (13) of tilt control valve (14) to unloading valve (8) and margin stem (7) of inlet valve group (1). Unloading valve (8) moves completely to the left and implement oil pressure increases. Margin stem (7) is held to the left and does not move.The implement oil now opens load check valve (24). The oil flows around lift valve spool (23) and out lift control valve (22) to the head ends of lift cylinders (21). The cylinder rods extend. The lift arms cause the bucket to lift.The movement of the cylinder rods pushes the oil out of the rod ends of the lift cylinders. This oil comes into the lift control valve and flows around lift