COMPONENT OPERTATION / Control Valve Arm Regenerative Valve and Bucket Regenerative Valve NOTE: Operational principle of the arm regenera- tive valve is identical to that of the bucket regenerative valve. Therefore, the bucket generative valve is explained as an exam- ple. Operation 1. During bucket roll-in operation (arm roll-in opera- tion in case of the arm regenerative valve), return oil from the cylinder rod side flows to the hydraulic oil tank through external circumference of the plunger in switch valve and hole on the sleeve. 2. Return oil from the cylinder rod enters hole on the spool and acts on the check valve through spool inside. 3.
When roll-in operation is done with the bucket roll-out, the bucket moves faster as compared with pressure oil supply from the pump. 4. Therefore, pressure in the circuit between pump and bucket cylinder bottom decreases. 5. When pressure in the cylinder bottom side be- comes lower than that in the rod side, the check valve opens. 6. Therefore, return oil from the cylinder rod side flows to the bottom side, is combined with pres- sure oil from the pump, and is supplied to the cylinder bottom side. 7. Consequently, the regenerative operation is done and speed of the cylinder increases. 8.
When the cylinder is moved full stroke or the roll-in load increases, pressure in the cylinder bottom side circuit increases more than the rod side. 9. Therefore, the check valve is closed and the re- generative operation stops. 10. As pressure in the cylinder bottom side circuit in- creases, the piston of switch valve pushes the plunger. 11. Consequently, as amount of oil which flows to the hydraulic oil tank from the cylinder rod side in- creases, speed of the cylinder is kept increasing in spite of overload state. During Regenerative Operation: Bucket Cylinder Check Valve Bucket Roll-In Pilot Pressure Pressure Oil from Pump 1 Switch Valve T450-03-03-043 During Normal Operation:
Bucket Cylinder Check Valve Bucket Roll-In Pilot Pressure Pressure Oil from Pump 1 Switch Valve T450-03-03-039 T3-3-34