ELBOW 0028170 - Caterpillar

Fan Pump and Control Valve
Operation at Clip Speed
Illustration 1 g02056093
Fan Pump and Control Valve (Clip Speed) (1) Actuator Piston (2) Swashplate (3) Bias Spring (4) Drive Shaft (5) Fan Pump (6) Piston and Barrel Assembly (7) Case Drain Passage (8) Output to Fan Motor (9) Pin (10) Plunger (11) Spring (12) Solenoid (13) Adjustment Screw (14) Spring (15) Orifice (16) Signal Passage (17) Pump Control Spool (18) Pressure Control Spool (19) Adjustment Screw (20) Pump Control Valve (BB) Cutaway Section (CC) Component Surface (FF) Activated Components (GG) Tank Pressure (KK) High PressureWhen fan clip speed is required, the engine ECM sends minimum signal current to solenoid (12). Plunger (10) blocks signal passage (16). The force of spring (14) plus the signal pressure holds pump control spool (17) downward.When pump control spool (17) is held downward, the passage to actuator piston (1) is open to the case drain. The force of bias spring (3) moves swashplate (2) toward the maximum angle.The