PULLEY-WATER PUMP 4W9021 - Caterpillar

FAST RAISE
Illustration 6 g00539403
Control lever positions for the hook and the boom (A) Quick drop (B) Power down (C) Modulated lower (D) Neutral (E) Slow raise (F) Fast raise (G) Hook winch (H) Boom winchAs the operator begins to move either winch control lever from position (D) to FAST RAISE, the speed selector spool moves.The first movement of the control lever to the left for the hook winch will move speed selector spool (1) to the left.The first movement of the control lever to the right for the boom winch will move speed selector spool (1) to the left.The movement of speed selector spool (1) to the left directs oil flow from line (12) past the spool. The oil flows to chamber (2) (high speed clutch). The oil engages the face clutch in the winch for high speed operation. Moving the control lever rearward toward position (F) moves the control spool in the winch motor control valve. This movement directs oil flow to the winch motor. The movement of the control spool also moves brake control spool (4) to the left with no effect.As the control lever is moved rearward to position (F), the oil flow to the winch motor is increased. As the oil flow increases, the speed of rotation of the winch drum increases.SLOW RAISE (No Illustration)
When the operator moves the control lever to the SLOW RAISE position, the oil flow in the winch control circuit is identical except that speed selector spool (1) moves to the right. The movement to the right directs the oil flow to chamber (3) for the low speed clutch. The oil flow engages the face clutch in the winch for low speed operation.LOWER (Stopped Engine)
Illustration 7 g00539184
LOWER (Stopped Engine) (4) Brake control spool (7) Chamber (9) Inlet check valve for initial pressure (10) Brake accumulator piston (11) Brake (16) Pump inlet check valve (18) Metering pump outlet relief valve (20) Accumulator (21) Metering pump (22) Metering pump outlet check valve (23) Passage (AA) Pressure oil from accumulator (BB) Brake oil (CC) Metering pump oilLOWER (Stopped Engine)
The hook and the boom can be lowered for approximately three hours after the engine has been shutdown.The pressure of hydraulic oil that is stored in accumulator (20) is felt in chamber (7). The pressure in chamber (7) is prevented from going back into the transmission hydraulic system by pump inlet check valve (16) .When brake control spool (4) is shifted to the LOWER position, pressure oil from accumulator (20) flows through passage (23) to brake accumulator piston (10) and brake (11) begins to release the brakes.The pressure from brake control spool (4) to brake accumulator piston (10) and brake (11) is prevented from flowing into passage (13) by inlet check valve (9) (initial pressure).As brake (11) is released, the winch drum begins to turn. Metering pump (21) also begins to turn. The purpose of metering pump (21) is maintaining a constant oil pressure to the brakes for any given position of brake control spool (4) .The