Electric circuit breakers of the type which are temporarily pneumatically opened

Claim 1

A PNEUMATICALLY OPENABLE ELECTRIC CIRCUIT BREAKER COMPRISING A FIXED CONTACT, A MOVABLE CONTACT, A SPRING TENDING TO FORCE SAID MOVABLE CONTACT AGAINST SAID FIXED CONTACT, A CYLINDER, A PISTON MOUNTED FOR RECIPROCATION IN SAID CYLINDER AND DIVIDING SAID CYLINDER INTO AN ACTIVE CHAMBER AND AN INACTIVE CHAMBER, PASSAGES FOR LEADING GAS UNDER PRESSURE INTO SAID ACTIVE CHAMBER AND AGAINST AN ACTIVE FACE OF SAID PISTON, A SECOND SPRING TENDING TO FORCE SAID PISTON INTO A POSITION OF REST, MEANS DIVIDING THE ACTIVE CYLINDER CHAMBER AND THE AREA OF THE ACTIVE FACE OF THE PISTON EACH INTO TWO PARTS WHEN THE PISTON IS IN ITS POSITION OF REST AND INOPERATIVE TO SO DIVIDE THE PISTON AND ACTIVE CHAMBER UPON MOVEMENT OF THE PISTON FROM ITS POSITION OF REST, THE PASSAGES FOR SUPPLYING GAS UNDER PRESSURE OPENING INTO ONE OF SAID PARTS OF THE ACTIVE CYLINDER CHAMBER, AND COUPLING MEANS FOR CONNECTING SAID PISTON WITH SAID MOVABLE CONTACT TO MOVE THE LATTER CONTACT AWAY FROM THE FIXED CONTACT UPON EXPOSURE OF THE ACTIVE FACE OF THE PISTON TO GAS PRESSURE EXCEEDING A PREDETERMINED VALUE, SAID PISTON HAVING A LOST MOTION BETWEEN ITS POSITION OF REST AND A COUPLING POSITION IN WHICH IT IS CONNECTED TO SAID MOVABLE CONTACT BY SAID COUPLING MEANS, WHEREBY THE APPLICATION OF GAS UNDER PRESSURE EXCEEDING SAID PREDETERMINED VALUE ACTS FIRST ON ONLY PART OF THE ACTIVE FACE OF THE PISTON TO SLOWLY MOVE THE PISTON FROM ITS POSITION OF REST WHICH MOVEMENT TAKES UP SAID LOST MOTION AND OPENS BOTH SAID CHAMBER AND PISTON PARTS TO GAS PRESSURE.