COOLER GP-ENGINE OIL 3628401 - Caterpillar

Illustration 1 g00853108
(1) Outlet port to the remote pressure tap for the cooling loop pressure (2) Inlet port for cooled, lubricating oil from the hydraulic oil cooler (3) Inlet port for return oil from the bank valve (4) Outlet port to the bearings for the drive motors (5) Poppet (6) Poppet (7) Outlet port to the return hydraulic block (8) Spring (9) SpringThe return oil from the bank valve is divided into two flow paths. A portion of the oil flow continues to flow to the hydraulic oil cooler. The remainder of the return oil flows through port (3) to poppet (5) of the oil cooler bypass valve.When the temperature of the return oil from the bank valve is very low, the viscosity of the return oil is very high. The flow resistance to the hydraulic oil cooler is high. Thus, the pressure of the return oil from the bank valve is high.As a result of the high pressure of the return oil through port (3), the pressure oil overcomes the force of spring (8) and poppet (5) moves downward in order to open the oil cooler bypass valve. Most of the return oil flows past poppet (5) to port (7) and the oil flows through the return hydraulic block back to the hydraulic tank. The remainder of the oil flows to the hydraulic oil cooler. Since a small amount of return oil flows to the hydraulic oil cooler, the temperature of the oil increases. As the oil temperature increases, the return oil pressure decreases. The force of spring (8) begins to overcome the pressure of the return oil and the oil cooler bypass valve begins to close. A greater portion of the return oil flows to the hydraulic oil cooler. The oil cooler bypass valve maintains the hydraulic oil at the optimum operating temperature. For SAE 10W hydraulic oil, the oil cooler bypass valve maintains an operating temperature of 60 °C (140 °F).The return oil returns from the hydraulic oil cooler as cooled, lubricating oil to port (2). The lubricating oil is divided into two flow paths. A portion of the oil flows to the bearings of the drive motors. The remainder of the lubricating oil flows to poppet (6) of the bypass valve for the motor bearings.When the pressure of the lubricating oil overcomes the force of spring (9), poppet (6) moves downward in order to open the bypass valve for the motor bearings. Most of the oil flows past poppet (6) to port (7) and the oil flows through the return hydraulic block back to the hydraulic tank.As the oil pressure against poppet (6) decreases, the force of spring (9) begins to overcome the pressure of the lubricating oil and the bypass valve for the motor bearings begins to close.