Pilot operated control device

Claim 1

IN A GAS-ARC SYSTEM ADAPTED TO BE SUPPLIED WITH SHIELDING GAS AND ELECTRIC WELDING CURRENT, AND COMPRISING A GAS-ARCH TORCH, A VALVE INTERPOSED IN THE CONDUIT THROUGH WHICH SAID SHIELDING GAS IS SUPPLIED TO SAID TORCH, AND A SWITCH INTERPOSED IN A CIRCUIT CONTROLLING THE FLOW OF ELECTRIC WELDING CURRENT TO SAID TORCH: APPARATUS FOR THE SEQUENTIAL CONTROL OF THE FLOW OF SAID SHIELDING GAS RELATIVE TO WELDING CURRENT FOR PROPER PRE-WELD AND POST-WELD GAS FLOW, COMPRISING A CONTROL FLUID CHAMBR, A CONTROL ELEMENT ASSOCAITED WITH SAID CONTROL FLUID CHAMBER WHICH IS DISPLACED IN A FORWARD DIRECTION UPON ADMISSION OF CONTROL FLUID UNDER PRESSURE TO SAID CONTROL FLUID CHAMBER AND WHICH IS DISPLACED IN THE REVERSE DIRECTION UPON DISCHARGE OF CONTROL FLUID FROM SAID CONTROL FLUID CHAMBER, MEANS RESPONSIVE TO THE DISPLACEMENT OF SAID CONTROL ELEMENT TO OPERATE SAID VALVE AND SAID SWITCH IN PRE-DETERMINED SEQUENCE IN A FORWARD DIRECTION AND IN A REVERSE SEQUENCE IN THE REVERSE DIRECTION AND METERING RATE MEANS FOR CONTROLLING AT DIFFERING RATES THE RESPECTIVE ADMISSION AND DISCHARGE OF CONTROL FLUID TO AND FROM SAID CHAMBER, TO THEREBY CAUSE A TIME DELAY PERIOD OF A DIFFERENT DURATION AS BETWEEN OPERATION OF SAID VALVE AND OPERATION OF SAID SWITCH IN THAT ORDER IN THEIR FORWARD DIRECTION, AND OPERATION OF SAID SWITCH AND OPERATION OF SAID VALVE IN THAT ORDER IN THE REVERSE DIRECTION.