SENSOR GP-POS 2566913 - Caterpillar

THIRD CONTROL VALVE IN CLOSE OR LOWER 1. Third control valve spool.2. Springs.3. Load check valve.4. Passage to head end of attachment cylinders.5. Passage to rod end of attachment cylinders.6. Passage.7. Passage.8. Inlet passage.9. Outlet passage.10. Spring.This optional valve is for the operation of an additional or third circuit to control the multi-purpose bucket and/or ripper. This valve is before (ahead of) the lift and tilt control valve in the series hydraulic circuit.Third Control Valve Spool
Oil from the oil pump goes through inlet passage (8) to third control valve spool (1). This spool is a spring-centered, manually operated spool with three positions: OPEN or RAISE, HOLD and CLOSE or LOWER. Spring (10) keeps the spool in the HOLD position. Movement of the spool is controlled by the third control lever, forward or backward from the HOLD position.When third control valve spool (1) is in HOLD position, pump oil goes from inlet passage (8), through passage (6) and outlet passage (9) to the inlet passage of the lift and tilt control valve. The position of the spool holds (blocks) the oil in passages (4) and (5) and keeps the attachment (multi-purpose bucket or ripper) cylinders from movement.When the third control lever is moved to the OPEN or RAISE position, third control valve spool (1) moves up from the HOLD position. Pump oil goes from inlet passage (8) through passage (7) to load check valve (3). The load check valve opens when the pump pressure becomes greater than the force of spring (2) and the rod end pressure of the attachment cylinders. The oil is now free to go through passage (5) to the rod end of the attachment cylinders and causes the multi-purpose bucket to open or the ripper to lift.Oil from the head end of the attachment cylinders comes through passages (4) and (6) to outlet passage (9). From the outlet passage, the oil goes to the lift and tilt control valve and back to the oil tank.When the third control lever is moved to the CLOSE or LOWER position, third control valve spool (1) moves down from the HOLD position. Oil flow in the CLOSE or LOWER position is the reverse of oil flow in OPEN or RAISE position. Pump oil goes from inlet passage (8) to load check valve (3). The load check valve opens when the inlet pressure becomes greater than the force of spring (2) and the head end pressure of the attachment cylinders. The oil goes out passage (4) to the head end of the attachment cylinders and causes the multi-purpose bucket to close or the ripper to lower.Oil from the rod end of the attachment cylinders comes through passages (5) and (6) to outlet passage (9). From the outlet passage, the oil goes to the lift and tilt control valve and back to the oil tank.Load Check Valve
The operation of load check valve (3) is the same as the load check valves in the lift and tilt control valve. The load check