Event: Coil Car Traveling Cylinder - Back to Coiler (Retract)

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

 

1)    Proportional Directional Control Valve 339 is energized to the crossover flow pattern allowing pressurized hydraulic fluid to pass through the valve from P to B.

2)    Next, the fluid flows through Counterbalance Valve 295. Note that this valve assembly is comprised of two sections. One section is a pressure relief valve preventing the cylinder from overpressure due to external load forces caused by the momentum of the weight of a coil as the cylinder is extended. The other section consists of a pilot operated, spring-return 2-position, 2-way directional control valve. During this event, the directional control valve section remains offset by the spring, as the pilot pressure line is vented by virtue of its connection to the A-side of the circuit. The flows freely through the check valve shown in the right-side valve envelope, then into the rod end of Coil Car Traveling Cylinder 803 causing the cylinder to retract. Note that the retraction speed is controlled by Proportional Directional Control Valve 339.

3)    Exhaust fluid from the cap end of the cylinder flows through the proportional directional, passing from A to T, then to tank through Duplex Return Line Filter 045.03.