Apparatus for forming pre-stressing windings on concrete or like pipes

Claim 1

APPARATUS FOR FORMING A PRESTRESSING WINDING ON A CONCRETE PIPE COMPRISING A HYDRAULIC SYSTEM, A VARIABLE DISPLACEMENT PUMP FOR PUMPING FLUID INTO SAID SYSTEM TO DEVELOP HYDRAULIC PRESSURE IN SAID SYSTEM, ROTATABLE MENAS FOR ROTATING A PIPE ON ITS LONGITUDINAL AXIS IN ONE DIRECTION, MEANS OPERATIVELY CONNECTED TO SAID ROTATABLE MEANS TO PREVENT THE PIPE BEING ROTATED IN THE REVERSE DIRECTION, A VARIABLE DISPLACEMENT MOTOR OPERATIVELY CONNECTED TO SAID SYSTEM FOR ROTATING SAID ROTATABLE MEANS, WIRE-FEEDING MEANS FOR FEEDING WIRE TO THE PIPE AS THE PIPE IS BEING ROTATED, AND A MOTOR/PUMP OPERATIVELY CONNECTED TO SAID WIRE-FEEDING MEANS AND TO SAID SYSTEM AND ADAPTED TO UTILIZE THE PRESSURE DEVELOPED IN SAID SYSTEM SO AS TO APPLY TENSION TO THE WIRE IRRESPECTIVE OF WHETHER OR NOT THE WIRE IS IN MOTION AND TO DEVELOP PRESSURE IN SAID SYSTEM WHEN IT FUNCTIONS AS A PUMP AS THE WIRE IS BEING FED TO THE PIPE, SAID VARIABLE DISPLACEMENT PUMP INCLUDING SERVO-CONTROL MEANS ADAPTED TO BE SET SO THAT THE PRESSURE DEVELOPED IN SAID SYSTEM BY SAID PUMP IS SUFFICIENT TO CAUSE SAID MOTOR/PUMP TO APPLY TENSION TO SAID WIRE AND IS INSUFFICIENT TO OPERATE SAID VARIABLE DISPLACEMENT MOTOR TO ROTATE SAID ROTATABLE MEANS, AND SAID VARIABLE DISPLACEMENT MOTOR INCLUDING SERVO-CONTROL MEANS ADPATED TO BE SET TO OPERATE AT A PRESSURE IN SAID SYSTEM AS WILL CAUSE SAID MOTOR/PUMP TO APPLY TENSION TO SAID WIRE, IN COMBINATION WITH MEANS FOR OVERRIDING THE SERVO-CONTROL MEANS ON SAID PUMP TO INCREASE THE DISPLACEMENT OF SAID PUMP THEREBY TO INCREASE THE PRESSURE IN SAID SYSTEM SUFFICIENTLY TO ACTUATE THE SERVO-CONTROL MEANS ON SAID MOTOR TO INCREASE THE DISPLACEMENT OF SAID MOTOR AND CAUSE SAID MOTOR TO ROTATE SAID ROTATABLE MEANS.