Pipe bending machine

Claim 1

IN A PIPE BENDING MACHINE HAVING A PAIR OF MEMBERS PROJECTED LONGITUDINALLY OF A PIPE TO BE RECEIVED BETWEEN THE MEMBERS, ONE MEMBER PRESENTING A PIPE ENGAGING THE DIE FACE CURVED LONGITUDINALLY AND OUTWARDLY FROM THE CENTER POINT THEREON FOR PIPE BEND CONFORMATION THERETO AND THE OTHER MEMBER BEING A LONGITUDINALLY STRAIGHT STIFF BACK HAVING ITS OPPOSITE END PORTION SPACED IN OPPOSITE DIRECTIONS LONGITUDINALLY FROM THE CENTER POINT OF SAID DIE FACE, TOGETHER WITH A HOLDING SHOE CO-OPERATING WITH THE MEMBERS AND SPACED LONGITUDINALLY FROM ONE END OF THE STIFF BACK AND ENGAGEABLE WITH A PIPE ON THE SIDE THEREOF TO BE ENGAGED BY THE STIFF BACK AND FORCE APPLYING MEANS JOINED TO THE STIFF BACK ADJACENT EACH OF SAID END PORTIONS AND OPERATIVE TO MOVE THE STIFF BACK INTO PIPE CLAMPING RELATION AGAINST SAID DIE FACE AND THEREAFTER TO ROCK THE STIFF BACK FOR PROGRESSIVELY BENDING THE PIPE ALONG THE DIE FACE; THE IMPROVEMENT IN SAID FORCE APPLYING MEANS WHICH COMPRISES A PRESSURE FLUID RESPONSIVE MOTOR DEVICE CONNECTED WITH THE STIFF BACK END PORTION BETWEEN SAID CENTRAL PORTION OF THE DIE FACE AND SAID HOLDING SHOE, A PRESSURE FLUID DELIVERY CONNECTION WITH SAID DEVICE AND PRESSURE RELIEF MEANS IN SAID DELIVERY CONNECTION RESPONSIVE TO SELECTED BACK PRESSURE THEREIN FOR LESSENING FORCE APPLICATION ON THE STIFF BACK AT ITS LAST MENTIONED END PORTION FOR A BACK-OFF ACTION THEREON AS THE APPLICATION OF FORCE CONTINUES ON THE OTHER END PORTION FOR THE ROCKING ACTION OF THE STIFF BACK.