SEAL 3V8398 - Caterpillar

Illustration 1 g06207754
(1) Fixed-displacement gear-type pump
(2) Electric brakes retract motorThe electric brake (towing) pump assembly is located inside the left frame rail,below and slightly forward of the park brake valve. The fixed-displacement gear-type pump (1) is driven by the electric brake retract motor (2). The motor is energized by the brake retract relay (located in the cab) is depressed. The pump is used to release the parking brakes for servicing or towing in a dead engine situation.The towing pump sends oil to charge the park brake accumulator and to pressurize and release the parking brakes. Oil from the towing pump flows through the pilot pressure reducing valve in the park brake valve. Pilot pressure oil is sent to the electronic proportional reducing valves (EPRVs). This strategy allows the body to be lowered in a dead engine situation, using the hoist controls.Towing pump pressure is controlled by a relief valve integrated into the pump case.