Security device for linear actuator on machine tools - has non return valve inside piston rod which equalises pressure on either side of piston

摘要

The piston rod (5) has a hollow section (50 ) in which a non return valve is placed connecting the pressurised chamber (30) with the exhaust chamber (20) through channels (60,70) in the piston rod. An obstruction during the forward stroke causes pressure build up in the pressurised chamber (30) which operates the non return valve (16,71,72). This equalises pressure on either side and stops the piston. This action is prevented at the end of the stroke where the radial channel (70) vents into an enclosed chamber (10).