CORE AS 7W0433 - Caterpillar

When the lift control lever is moved to the RAISE position, the position sensor for the lift control lever sends a pulse width modulated signal (PWM) to the implement electronic control module (ECM). The ECM analyzes this signal and the signals from the tilt linkage position sensor and from the lift linkage position sensor. The implement ECM then sends a proportional signal that energizes the solenoid for pilot control actuators (23) and (26) on the main control valves.The solenoid valves in the pilot control actuators (23) and (26) shift and the pilot oil at the raise end of the lift stems (18) and (21) is released to the hydraulic tank. This reduces the pilot pressure at the end of stems (18) and (21). The combination of the spring force and the oil pressure on the lower end of the lift stems begins to shift stems (18) and (21) to the RAISE position.The oil from variable displacement piston pumps (31) and (32) flows around the control valve spool to the head end of each lift cylinder (1). The oil at the rod end of each lift cylinder (1) flows around stem (18) and (21) to the hydraulic tank.As the lift control lever is pushed further into the RAISE position, the implement ECM will increase the current solenoid valves for variable displacement piston pumps (31) and (32). This will cause the pumps to upstroke. Additional oil will be directed to each main control valve. The speed of the raise operation will increase.LOWER Position
When the lift control lever is moved to the LOWER position, operation is similar to the raise operation. Solenoid valves for pilot control actuators (12) and (15) are energized. This reduces the pressure on the lower end of the tilt stems. The lift stems shift to the LOWER position. Implement supply oil is directed to the rod end of each lift cylinder. Oil from the head end of each lift cylinder is directed to the hydraulic tank.Float Position
Illustration 4 g01443120
Hydraulic system operation (float position) (1) Lift cylinders (2) Regenerative valve (dump) (3) Tilt cylinder (4) Shuttle valve (dead engine lower) (5) Pressure reducing valve (dead engine lower) (6) Rod end line relief valve for lift cylinders (7) Head end line relief valve for lift cylinders (8) Rod end line relief valve for tilt cylinders (9) Head end line relief valve for tilt cylinders (10) Main relief valve (left) (11) Main relief valve (right) (12) Pilot control actuator (lower) (13) Pilot control actuator (tilt back) (14) Pilot control actuator (tilt back) (15) Pilot control actuator (lower) (16) Tilt cylinder rod end dual pressure relief (17) Solenoid valve (hydraulic lockout) (18) Lift stem (left) (19) Tilt stem (left) (20) Tilt stem (right) (21) Lift stem (right) (22) Manual lowering valve (23) Pilot control actuator (raise) (24) Pilot control actuator (dump) (25) Pilot control actuator (dump) (26) Pilot control actuator (raise) (27) Pilot pressure reducing valve (28) Float valves (29) Pilot oil filter (30) Pilot oil accumulator (31) Implement pump (250 cc