Event: Pinch Roll Exit Side Cylinder - Lifting (Retract)

For previous sequences in this event see the event “Roll Change HPU – On.”

 

1)    Incoming pressure is reduced to 70 bar by Pressure Reducing Valve 277.03.

2)    Directional Control Valve 302.38 is energized to the crossover flow pattern allowing pressurized hydraulic fluid to flow through the valve passing from P to B. Then the fluid flows unrestricted through the B-port check valve of Dual Pilot Operated Check Valve Module 172.26. Next, the fluid branches into two lines.

3)    Fluid in the left line flows unrestricted through the check valve of Flow Control Valve 182.02. However, the check valve in Flow Control Valve 182.01 forces the fluid to flow through the needle valve section of 182.01, thereby achieving meter-in flow control of the retraction speed of Exit Side Pinch Roll Cylinder 653.01 as the cylinder retracts.

4)    Similarly, fluid in the right line flows unrestricted through the check valve of Flow Control Valve 182.04. However, the check valve in Flow Control Valve 182.03 forces the fluid to flow through the needle valve section of 182.03, thereby achieving meter-in flow control of the retraction speed of Exit Side Pinch Roll Cylinder 653.02 as the cylinder retracts.

5)    Exhaust fluid from the cap ends of the cylinders flows unrestricted through the A-port check valve of the pilot operated check valve module, as the A-port check valve has been piloted open by pilot pressure from the B-side of the circuit.

6)    Then the exhaust fluid flows through the directional control valve, passing from A to T. Finally, the exhaust fluid flows back to tank after flowing through Check Valve 122.07 and Duplex Return Line Filter 045.01.

7)    Note that Pressure Relief Valve 268.18 protects the cap end of the cylinders from overpressure caused by external load forces. In the event the cylinders are forced to retract, Check Valve 159.37 will provide makeup fluid to the rod ends of the cylinders to prevent cavitation of the rod ends.