Electrical controls for friction welding machine

Claim 1

IN COMBINATION WITH A FRICTION WELDER INCLUDING A VOLTAGE-RESPONSIVE PRESSURE REGULATING DEVICE, A CONTROL SYSTEM FOR SUPPLYING TO SAID DEVICE A SERIES OF SELECTED DIRECT CURRENT VOLTAGES SUCH AS TO PRODUCE OPTIMUM OPERATION OF THE WELDER IN ALL PHASES OF AN AUTOMATIC WELDING CYCLE INCLUDING A SLOPE PERIOD IN WHICH ON OF THE SUPPLIED VOLTAGES GRADUALLY INCREASES FROM ZERO TO ITS RELECTED VALUE, SAID SYSTEM INCLUDING AN A.C. VOLTAGE SOURCE, AN EXTERNAL SIGNAL SOURCE, A PLURALITY OF TRANSFORMERS PRESET TO DIFFERENT VALUES, AN ADJUSTABLE RESISTOR, A RECTIFIER HAVING ONE SET OF TERMINALS NORMALLY CONNECTED SEPARATELY TO SAID A.C. SOURCE THROUGH SAID TRANSFORMERS AND HAVING D.C. VOLTAGE TERMINALS WHICH IS THE PERIOD PRIOR TO START TO SLOPE ARE CONNECTED THROUGH SAID ADJUSTABLE RESISTOR TO SAID DEVICE, AND SWITCHING MEANS RESPONSIVE TO SIGNALS FROM SAID EXTERNAL SOURCE TO SWITCH THE CONNECTIONS OF SAID ONE SET OF BRIDGE TERMINALS IN THAT PERIOD TO RECEIVE FULL VOLTAGE DIRECTLY FROM SAID A.C. SOURCE, INSTEAD OF THROUGH ONE OF SAID TRANSFORMERS, WITH THE RESULT THAT