Safety weight control and compensating apparatus for subsurface well bore devices

Claim 1

IN AN APPARATUS FOR MAINTAINING A PREDETERMINED STRESS IN A RUNNING-IN STRING DISPOSED IN A WELL BORE AND WHICH IS SUPPORTED BY A RIG: ELONGATE CYLINDER MEANS; PISTON MEANS SLIDABLE LONGITUDINALLY IN SAID CYLINDER MEANS; ONE OF SAID MEANS BEING ADAPTED FOR OPERATIVE CONNECTION TO THE RUNNING-IN STRING; THE OTHER OF SAID MEANS BEING ADAPTED FOR OPERATIVE CONNECTION TO THE RIG; MEANS FOR MAINTAINING FLUID UNDER PRESSURE IN SAID CYLINDER MEANS ON ONE SIDE OF SAID PISTON MEANS AS SAID PISTON MEANS AND CYLINDER MEANS MOVE LONGITUDINALLY RELATIVE TO ONE ANOTHER IN BOTH LONGITUDINAL DIRECTIONS, WHEREBY THE STRESS OF SAID RUNNING-IN STRING IS TRANSFERRED BETWEEN SAID PISTON MEANS AND CYLINDER MEANS TO THE RIG; AND MEANS FOR RESTRICTING RELATIVE LONGITUDINAL MOVEMENT BETWEEN SAID CYLINDER MEANS AND PISTON MEANS AT AN ABNORMAL RATE UPON LOSS OF PRESSURE IN SAID CYLINDER MEANS AND WHILE SAID PISTON MEANS IS BETWEEN THE ENDS OF ITS RELATIVE TRAVEL IN SAID CYLINDER MEANS.