PISTON-CLUTCH 1627214 - Caterpillar

Illustration 1 g03645769
(1) Line to the oil cooler inlet
(3) Return line to the hydraulic tank
(4) Check valve housing
Illustration 2 g03645777
(4) Check valve housing
(5) Cooler passage
(6) Tank passage
(7) Bypass check valve
(8) Slow return check valve The return oil flow through the slow return check valve is divided into two flow paths. A portion of the oil flows out passage (5) to the hydraulic oil cooler. The oil flow from the hydraulic oil cooler flows to outlet line (2) and through return line (3) to the return filter in the hydraulic tank. The remainder of the return oil flows out passage (6) to the return filter in the hydraulic tank.When the temperature of the return oil in inlet line (1) is low, the viscosity of the oil is high. The flow resistance of the return oil in inlet line (1) is high. Thus, the pressure of the return oil is high.As a result of the high pressure of the return oil, check valves (7) and (8) open. Most of the return oil flows through the bypass check valve (7) and return line (3) to the return filter in the hydraulic tank. The remainder of the oil flows through slow return check valve (8) and passage (5) to the hydraulic oil cooler. Since a small amount of the return oil flows to the oil cooler, the temperature of the oil increases. As the oil temperature increases, the return oil pressure decreases. Bypass check valve (7) begins to close. A greater portion of the return oil flows to the hydraulic oil cooler. Slow return check valve (8) maintains the hydraulic oil at the optimum operating temperature.