Event: Switch Cylinder - Opening (Retract)

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

 

When the Switch Cylinders are opened (retracted) the strip is deflected toward Coiler 1 preventing the strip from passing to Coiler 2.

 

1)    Directional Control Valve 310.22 is energized to the crossover flow pattern allowing pressurized hydraulic fluid to flow through the valve passing from P to B. Next, the fluid flows freely through the B-port check valve of Pilot Operated Check Valve module 170.21 and through the B-port check valve of Flow Control Module 177.21 and then into the rod ends of Switch Cylinders 804.01 and 804.02.

2)    Exhaust fluid from the rod ends of the cylinders first flows through the reverse-free-flow check valve in Pressure Reducing Valve 278.04. Next, the fluid is forced by the A-port check valve of the flow control module to flow through the A-port needle valve of the module, thereby achieving meter-out speed control of the retraction speed of the cylinders.

3)    Next, the exhaust fluid flows through the A-port check valve of the pilot operated check valve module, which has been piloted open by pilot pressure from the B-side of the circuit. Finally, the exhaust fluid flows through the directional control valve, passing from A to T, then back to tank through Duplex Return Line Filter 045.03.

4)    Note that the rod ends of the cylinders are protected from overpressure by pressure relief Valve 284.25 and the cylinders are prevented from drifting by the pilot operated check valve module when the directional control valve is de-energized.