PIPE GP 5044149 - Caterpillar

Illustration 1 g00567909
(1) Load control valve for the loader lift circuit (if equipped), (2) Lift cylinder and (3) Lift armsTwo load control valves for the lift circuit are used. The control valve (if equipped) is used in order to hold the lift arms in place in case of a hose failure in the loader lift circuit.One load control valve for the lift circuit is located on each lift cylinder.
Illustration 2 g00567923
(1) Line to the rod end of the loader lift cylinder, (2) Line to the head end of the loader lift cylinder, (3) Solenoid, (4) Line to the control valve, (5) Line to the control valve, (6) Check valve and (7) Check valveMove the control for the loader to the RAISE position. The oil flows from the control valve to lines (4). The oil flows past check valve (6) and the oil flows into the head end of the loader lift cylinder. This causes the rod to extend. As the rod extends this causes the loader lift arms to raise.Move the control for the loader to the LOWER position. The oil flows from the control valve to lines (5). The oil is blocked at check valve (7). The oil flows to the relief valve and the oil flows to the orifice. The orifice causes the pressure to rise at the relief valve. As the pressure rises the valve opens and the valve sends oil to the rod end of lift cylinder (1). This causes the rod to retract. As the rod retracts this causes the loader lift arms to lower.If you have no signal pressure, the springs for the relief valves will not compress. This causes the oil to be blocked in the head end of cylinder. This will prevent the loader lift arms from falling in case of a hose failure in the loader lift circuit.Move the control for the loader to the LOWER position. The solenoid (3) opens in order to allow the oil in line (2) to flow back to the tank.If there is a loss of hydraulic power, refer to Operation and Maintenance Manual, SEBU6873-04, "Equipment Lowering with Engine Stopped".