SUPPORT 5339184 - Caterpillar

Illustration 1 g02573623
Compartment for the main control valve (return circuit) (typical example) (1) Return line (from main control valve) (2) Check valve (3) Line (makeup oil to swing motor) (4) Line (to oil cooler inlet) (5) Line (from oil cooler outlet)
Illustration 2 g02573636
Slow return check valve and bypass check valve (2) Check valve (5) Port (from main control valve) (6) Port (from auxiliary circuit) (7) Port (makeup oil to swing motor) (8) Port (from auxiliary circuit) (9) Slow return check valve (10) Port (to oil cooler inlet) (11) Port (from oil cooler outlet) (12) Port (return flow to return filter) (13) Bypass check valve (14) Hydraulic oil coolerSlow return check valve (9) is contained in check valve (2). Slow return check valve (9) 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 port (5), port (6) and port (7) .If cavitation occurs in the swing motor, oil from return port (7) flows into makeup line (3). 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 (9) is divided into two flow paths. The path of the oil flow is dependent on the temperature and viscosity of the oil. When the temperature of the oil is low, the oil has a high viscosity. When the temperature of the oil is high, the oil has a low viscosity.Oil that has a high viscosity flows through bypass check valve (13). Oil that has a low viscosity flows through hydraulic cooler (14) .The oil that flows through either bypass check valve (13) or hydraulic cooler (14) flows to port (12). The oil flows from port (12) to the return filter.Note: For more information on the bypass check valve operation, refer to System Operation, "Bypass Valve (Return)".