SUPPORT AS 3681710 - Caterpillar

Coupler Valve Hold Position
The HOLD position of valve spool (4) stops the oil in passages (9) and (11). With the oil in the circuits to the coupler cylinder stopped, the cylinder cannot move until the control lever and valve spool (4) are moved to either the ENGAGED or DISENGAGED position.
VALVE SECTION FOR COUPLING (DISENGAGED Position) 1. Passage from pump.2. Passage to next section.3. Passage from pump.4. Valve spool.5. Passage to tank.6. Passage from pump.7. Relief valve for implement dump circuit.8. Relief valve for implement tilt back circuit.9. Passage to rod ends of tilt cylinders.10. Check valve.11. Passage to head ends of tilt cylinders.Coupler Valve Disengaged Position
When the control lever moves valve spool (4) to the DISENGAGE position, the pump oil in passages (1) and (3) cannot go into passage (2), through the next valve section (if so equipped) or the manifold and through passages (5) to the tank.The oil in passage (6) gets an increase in pressure which opens check valve (10). The pump oil in passage (6) goes through the open check valve into passage (9) and to the head end of the coupling cylinder. If there is no supply oil to passages (1) and (3) (blocked by either tilt or lift lever), pressure has already had an increase in passage (6).The pump oil going into the head end of the coupling cylinder extends the rod right and pushes the cylinder case left. The oil from the rod end of the cylinder goes through passage (11) and then through passage (5) to the filter and tank.Coupler Valve Engaged Position
When the valve spool is in the ENGAGED position (not shown) the pump oil in passage (6) opens check valve (10) and the flow of pump oil is through passage (11) to the rod end of the coupling cylinder. The rod and cylinder case retract, freeing the implement. The oil from the head end of the coupling cylinder goes through passage (9), through passage (5) and to the filter and tank.Coupling Relief Valves
The location of the two coupling relief valves is in the coupling control valve section. The setting on the head end passage is about 20 670 kPa (3000 psi). The setting on the rod end passage is about 20 670 kPa (3000 psi).
COUPLING RELIEF VALVE (Lever in DISENGAGED Position)
5. Drain passage. 9. Passage. 12. Spring. 13. Piston. 14. Passage. 15. Passage. 16. Passage.If the pump oil pressure in passage (9) becomes greater than the return oil pressure in spring (12) chamber plus the force of spring (12), then piston (13) moves left. Some of the pump oil from passage (9) now goes through passage (15) and passage (14) to passage (5). Oil in passage (5) goes to tank. Passage (16) allows equal pressures in spring (12) chamber and drain passage (5).Attachment Control Valve (Optional)
If the machine is equipped with the attachment control valve it is located between the control valve section for coupling and the end manifold. The attachment control valve is the same as the coupling