LINES GP-PUMP 3844187 - Caterpillar

Illustration 1 g03039537
Control valve compartment
(1) Line to the oil cooler inlet
(2) Makeup line
(3) Line from the oil cooler outlet
(4) Valve housing
(5) Return line to the hydraulic tank
Illustration 2 g03039540
Section view of the main control valve and check valve housing
(1) Line to the oil cooler inlet
(3) Line from the oil cooler outlet
(4) Valve housing
(5) Return line to the hydraulic tank
(6) Bypass check valve
(7) Slow return check valve Slow return check valve (7) is contained in check valve housing (4). Slow return check valve (7) is located between the main control valve and the hydraulic tank in the return circuit. The slow return check valve restricts the return oil flow. This restriction causes a pressure increase in the return hydraulic system and makeup line (2).If cavitation occurs in the swing motor, oil from return line (5) flows into makeup line (2). This makeup oil is supplied to the inlet port of the swing motor in order to prevent cavitation in the swing motor.Note: For more information on the makeup operation, refer to System Operation, "Oil Makeup (Swing System)".The return oil flow through slow return check valve (7) is divided into two flow paths. A portion of the oil flows through inlet line (1) to the hydraulic oil cooler. The cooled oil from the hydraulic oil cooler flows through outlet line (3) and to the return filter in the hydraulic tank. The remainder of the oil flow from slow return check valve (7) flows through bypass check valve (6) to the return filter in the hydraulic tank. Bypass check valve (6) is contained in check valve housing (4).