DETECTOR 3664743 - Caterpillar

Illustration 1 g00847799
Location of the Pilot Control Actuators
Illustration 2 g00582703
Pilot Control Actuator (1) Stabilizing spring. (2) Centering spring. (3) Return oil port. (4) Actuator solenoid. (5) Pilot spool. (6) Feedback spring. (7) Spring retainer. (8) Main spool. (9) Pilot oil port. (10) Actuator solenoid.When the operator moves an implement control lever from the centered position, the implement ECM energizes the actuator solenoid with a PWM signal.The Left Solenoid Energized
When the left solenoid is energized, the solenoid moves the pilot spool (5) to the right. The pilot spool directs the pilot oil on the left side of the main spool (8) to drain. This decreases the pilot oil pressure at the left end of the main spool.The right actuator solenoid (10) is de-energized. When the solenoid is de-energized, the feedback spring holds the pilot spool to the right. The pilot spool directs pilot oil (9) to the right end of the main spool. The pilot oil pressure at the right end of the main spool moves the main spool to the left. As the main spool moves to the left toward the pilot spool, the centering springs (2) and the feedback spring (6) are compressed.Hold Position
In the HOLD position, both solenoids for the pilot control actuator are de-energized. When both solenoids are de-energized, the pilot spools direct pilot oil to the ends of the main spool (8). The pilot pressure at each end of the main spool, and the force of the centering springs (2) cause the main spool to be centered in the control valve.The centering springs and retainers (7) help stabilize the movement of the main spool. The stabilizing spring dampens the movement of the pilot spools by holding the pilot spools in contact with the feedback springs.The Left Actuator Is Balanced
When the left solenoid (4) is energized, the main spool (8) moves to the left which compresses the centering springs (2) and the feedback spring (6). The force of the feedback spring will move the pilot spool (5) to the left until the force of the feedback spring is equal to the force of actuator solenoid and the stabilizing spring. When the pilot spool moves far enough to the left, the pilot oil port and the return oil port are blocked. When the oil in the actuator is blocked the main spool stops moving. The main spool will stay in this balanced position until the current to the actuator solenoid changes.If the operator moves the implement control lever further in the same direction, the implement ECM will increase the duty cycle of the signal to the actuator solenoid. This increases the current which increases the force on the pilot spool. The pilot spool will move to the right which opens the return oil port. The decreased oil pressure inside the left actuator will allow the main spool to move further to the left due to the pilot oil pressure on the right end of the main spool. As the main spool moves to the left, the feedback spring