Event: Mandrel Gear Change Over Cylinder - Stage 1 (Extend)

For previous steps in this sequence see the event “HPU – On.”

 

1)    Directional Control Valve 304.07 is energized to the parallel flow pattern allowing pressurized hydraulic fluid to flow through the valve passing from P to A. Next, the fluid flows freely through the A-port check valve of Pilot Operated Check Valve Module 172.32, then through the A-port check valve of Flow Control Valve Module 179.31 and then into the cap end of Mandrel Gear Change Over Cylinder 812, causing the cylinder to extend.

2)    Exhaust flow from the rod end of the cylinder is forced by the B-port check valve of the flow control valve module to flow through the B-port needle valve of the module, thereby achieving meter-out speed control of the extension speed of the cylinder.

3)    Next, the exhaust fluid flows freely through the B-port check valve of the pilot operated check valve module, which has been piloted open by pilot pressure from the A-side of the circuit.

4)    Finally, the exhaust fluid flows back to tank through the directional control valve, passing from B to T, then back to tank through Check Valve 159.41 and Duplex Return Line Filter 045.03.