RADIATOR 4S7833 - Caterpillar

Hydraulic Fan 988K
Illustration 1 g03410815
(1) Piston pump (Hydraulic fan)
(2) Hydraulic oil filter (Oil cooler return)
(3) Hydraulic oil cooler
(4) Piston motor (Hydraulic fan)
(5) Hydraulic oil filter (Case drain) The main components of the fan hydraulic system are piston motor (4) and piston pump (1).Piston pump (1) draws oil from the hydraulic tank. The piston pump sends oil to piston motor (4). The amount of oil that is sent to the motor by the pump is regulated by the engine ECM. The engine ECM adjusts the current to the pump compensator valve. The pump compensator valve controls the pressure of the oil that is sent to the piston motor. When a higher pressure is maintained, the fan drive motor turns faster. The fan drive pump will increase flow to maintain the desired pressure. The oil from the outlet side of the piston motor flows through hydraulic oil cooler (3) and hydraulic oil filter (2). Case drain oil from piston pump (1) and fan motor (4) flow through case drain oil filter (5).When the hydraulic oil is cold, the oil from the outlet side of piston motor (4) bypasses the hydraulic oil cooler (3). After the hydraulic oil warms, the oil will flow through the hydraulic oil cooler in order to keep the oil at a predetermined temperature.The hydraulic fan provides cooling air flow across the cooler group.