Hydraulic or pneumatic control valve for presses etc. - with electric circuit indicating if valve is closed so accidents can be avoided

摘要

The valve body contains a metal valve seat ring located below a metal cylinder contg. a spring-loaded metal valve piston. The electric monitoring circuit includes the piston, seat and the earthed metal valve body. Piston is insulated from the cylinder by two piston rings made of electrically non-conducting material; and the path of piston is restricted by at least one limit stop made of insulating material. The spring pressing down on the piston is supported at its top end by an electric contact plate located in the lid of the valve body via an insulating cup. A completely reliable electric signal can be obtd. indicating that the valve is closed.