TUBE ASSEM. 8N4755 - Caterpillar

Illustration 1 g01475333
Hydraulic schematic for the axle oil cooler pumps (1) Rear axle (2) Rear axle oil cooler (3) Rear axle oil cooler pump and motor (4) Test port (5) Thermal bypass valve (6) Filter (7) Pressure switch (8) Front axle oil cooler (9) Thermal bypass valve (10) Test port (11) Front axle oil cooler pump and motor (12) Front axle (13) Implement pilot oil (14) Hydraulic pump (Implement pilot oil) (15) Case drain (16) Pressure switch (17) FilterEach axle has a closed oil system for cooling the axle oil. Each oil cooling system consists of the following components:
Axle oil cooler
Axle oil cooler pump and motor
Thermal bypass valve
Pressure switchThe axle oil cooler pump circulates sump oil from the axle through an oil cooler before flowing back to the axle. The axle oil cooler system helps keep the axle housings and internal brake components cool. The axle oil cooler pump and motors are fastened to the left side of the frame near the front axle and the rear axle. The hydraulic motors that drive the axle oil cooler pumps are driven by the flow from implement pilot pump (14) which is located on the output side of the torque converter.Axle oil cooler pumps (3) and (11) send the axle oil through filter (6) for the rear axle and filter (17) for the front axle. The filtered oil will then flow to thermal bypass valve (5) for the rear axle and thermal bypass valve (9) for the front axle. The thermal bypass valve will bypass the oil cooler when the temperature of the oil is below 82 °C (180 °F). At temperatures between 82 °C (180 °F) and 96 °C (205 °F), the thermal bypass valve modulates flow to the cooler. When the oil temperature is above 96 °C (205 °F) the valve will be wide open and all oil will be sent to axle oil cooler (2) for the rear axle and axle oil cooler (8) for the front axle. When the oil is cooled, the oil will be sent to the axle. When the oil pressure reaches 345 kPa (50 psi) the oil will bypass the cooler through the thermal bypass internal relief valve.Front Axle Oil Cooler
Illustration 2 g01476103
Front axle oil cooler (right side view) (8) Front axle oil cooler (11) Front axle oil cooler pump and motor
Illustration 3 g01476112
Front axle oil cooler cores (bottom view) (18) Outlet for axle oil (19) Inlet for axle oilFront axle oil cooler (8) is mounted inside the loader frame above the front axle. Pilot oil drives the motor and pump (11) for the front axle oil cooler. The pilot oil then flows into the top rear port of the cooler core assembly. The pilot oil flows through long tubes inside each core. When the oil reaches the bonnet at the front of the assembly, the oil flows through the outlet on the top of the bonnet. The pilot oil returns to the main hydraulic tank.Axle oil cooler pump and motor (11) sends axle oil