Releasing compressed working fluid instantly back to a reservoir generates shock waves. Compressed working fluid must be released gradually. In Fig. 15.7, compressed working fluid in the cylinder cap is released gradually through the flow control valve. This reduces circuit pressure slowly, thus preventing shock waves.
After completion of pressure release, this circuit achieves automatic lift of the cylinder by electric signals from the pressure switch.
After compressing working fluid in the cylinder cap, the solenoid of the decompression valve is turned ON. Then, the compressed working fluid is released back to the reservoir through the flow control valve. Pressure in the circuit drops until it hits a certain point set in the switch PS. Then, the switch transmits signals out, and turns the solenoid valve ON to lift the cylinder. By this sequence, a smooth lift-up-and-down motion is achieved.
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