Shut off valve system for robotic welding devices

A valving and sensing system responsive to variations in pressure in a coolant circulating system including a source of fluid under pressure, said valving and sensing system comprise;

• a shut-off valve, and a pressure sensor valve, said shut-off valve comprising a valve body having a bore therethrough, inlet and outlet ports communicating with said bore, a valve seat in said bore between said inlet and outlet ports and a valve element in said bore downstream of said valve seat movable towards and away from said valve seat, a piston in said bore upstream of said valve seat, means for selectively supplying fluid under pressure to said piston, a shaft movably positioned axially of said seat, means in said piston frictionally engaging said shaft, one of said shaft positions for movement through said valve seat against said valve element to move same downstream of said valve seat, said pressure sensor valve comprising a main body member having multiple inlet ports and outlet ports in communication with a pair of interconnected chambers, valve seats in each of said chambers between said inlet and outlet ports, valve elements in said chambers movable towards and away from said valve seats, means for positioning said valve elements in said chambers, a passageway between said valve seats of said respective chambers, means for interengaging said valve elements of said interconnected chambers and means for communication between said passageway and some of said outlet ports and said control means on said shut-off valves.