PURPOSE: To provide the positive brake action of a safety cylinder to improve safety even if a servo motor is accidentally operated, by always filling with liquid the safety cylinder for restraining feed speed of a grinding wheel bed.
CONSTITUTION: When feed speed of a grinding wheel bed 2 is changed higher than quick feed speed by any failure, hydraulic pressure in a cylinder chamber 17b is raised higher than a set value by the relative movement between a cylinder 17 and a piston 18 after an abutting member 26 abuts against a reference member 25, and correspondingly a pressure responsive closing valve 21 is oprated to close a throttle path. Thus oil flow from the cylinder chamber 17b to a cylinder chamber 17a is shut off to stop forcibly the movement of a grinding wheel bed 2.
TSUJIUCHI TOSHIO
ODA YUKIO
YAMADA RIYOUJI
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