Control apparatus for welding machines and the like

Claim 1

IN A CONTROL APPARATUS ADAPTED TO BE USED IN A MACHINE, SUCH AS A WELDING MACHINE, REQUIRING FIRST A RELATIVELY SLOW FEED AND THEN A SUDDEN RAPID FEED IN COMBINATION, FIRST PISTON-AND-CYLINDER MEANS INCLUDING AT LEAST ONE PISTON MEMBER AND AT LEAST ONE CYLINDER MEMBER DEFINING WITH EACH OTHER A WORKING CHAMBER ADAPTED TO RECEIVE FLUID UNDER PRESSURE TO MOVE ONE OF SAID MEMBERS IN A GIVEN DIRECTIONS WITH RESPECT TO THE OTHER OF SAID MEMBERS, AND A RETURN CHAMBER ADAPTED TO RECEIVE FLUID UNDER PRESSURE TO RETURN SAID ONE MEMBER WITH RESPECT TO SAID OTHER MEMBER TO A GIVEN STARTING POSITION; HIGH PRESSURE DISCHARGE CONDUIT MEANS AND LOW PRESSURE DISCHARGE CONDUIT MEANS RESPECTIVELY COMMUNICATION WITH SAID RETURN CHAMBER OF SAID FIRST CYLINDER-AND-PISTON MEANS, THE FLUID IN SAID RETURN CHAMBER DISCHARGING AT A RELATIVELY SLOW RATE THROUGH SAID HIGH PRESSURE DISCHARGE CONDUIT MEANS DURING RELATIVELY SLOW ADVANCE OF SAID ONE MEMBER WHEN FLUID UNDER PRESSURE IS SUPPLIED TO SAID WORKING CHAMBER AND SAID ONE MEMBER ADVANCING AT A HIGH RATE OF SPEED WHEN SAID RETURN CHAMBER COMMUNICATES WITH SAID LOW PRESSURE DISCHARGE CONDUIT MEANS WHILE FLUID UNDER PRESSURE IS SUPPLIED TO SAID WORKING CHAMBER; VALVE MEANS CONTROLLING THE COMMUNICATION BETWEEN SAID RETURN CHAMBER AND SAID LOW PRESSURE CONDUIT MEANS, SAID VALVE MEANS WHEN IT IS IN A CLOSED POSITION CUTTING OFF COMMUNICATION BETWEEN SAID LOW PRESSURE CONDUIT MEANS AND SAID RETURN CHAMBER AND WHEN IT IS IN AN OPEN POSITION PROVIDING COMMUNICATION BETWEEN SAID RETURN CHAMBER AND SAID LOW PRESSURE CONDIT MEANS, THE FLUID UNDER PRESSURE IN SAID RETURN CHAMBER URGING SAID VALVE MEANS TO SAID OPEN POSITION THEREOF; SECOND CYLINDER-ANDPISTON MEANS COOPERATING WITH SAID VALVE MEANS AND HAVING A PISTON MEMBER AND A CYLINDER MEMBER DEFINING A WORKING CHAMBER, SAID SECOND CYLINDER-AND PISTON MEANS MAINTAINING SAID VALVE MEANS IN SAID CLOSED POSITION THEREOF IN OPPOSITION TO THE PRESSURE IN SAID RETURN CHAMBER WHEN SAID WORKING CHAMBER OF SAID SECOND CYLINDER-ANDPISTON MEANS IS PROVIDED WITH FLUID UNDER PRESSURE; AND MEANS COOPERATING WITH SAID WORKING CHAMBER OF SAID SECOND CYLINDER-AND-PISTON MEANS FOR PLACING SAID LATTER WORKING CHAMBER AT A RELATIVELY LOW PRESSURE FREEING SAID VALVE MEANS FOR MOVEMENT BY THE PRESSURE IN SAID RETURN CHAMBER SUDDENLY TO SAID OPEN POSITION WHERE SAID RETURN CHAMBER THEN COMMUNICATES WITH SAID LOW PRESSURE DISCHARGE CONDUIT MEANS TO PROVIDE A SUDDEN RAPID ADVANCE OF SAID ONE MEMBER OF SAID FIRST CYLINDER-AND-PISTON MEANS.