Roll lift device

Claim 1

A LIFTING DEVICE FOR SECURELY ENGAGING THE INNER WALL OF A HOLLOW OBJECT HAVING AN OPENING COMMUNICATING WITH THE INTERIOR THEREOF COMPRISING A FLUID CYLINDER, A PISTON RECIPROCALLY MOUNTED WITHIN SAID CYLINDER, A PISTON ROD CONNECTED TO SAID PISTON AND EXTENDING OUT OF ONE END OF SAID CYLINDER, A SPACER SLEEVE OF A SIZE SMALLER THAN THE OPENING IN SAID HOLLOW OBJECT SLIDABLY MOUNTED ON SAID PISTON ROD ADJACENT SAID ONE END OF THE CYLINDER AND ADAPTED TO BE INSERTED INTO SAID HOLLOW OBJECT, AN ENLARGED STOP ALSO OF A SIZE SMALLER THAN THE OPENING IN SAID OBJECT SECURED TO THE PISTON ROD AT A POINT SPACED FROM SAID SLEEVE, A DEFORMABLE HOLLOW PLUG OF A SIZE SMALLER THAN SAID OPENING WHEN UNDEFORMED MOUNTED ON SAID PISTON ROD BETWEEN SAID SPACER SLEEVE AND SAID STOP, MEANS FOR INTRODUCING FLUID INTO SAID CYLINDER WHEN SAID SPACER SLEEVE, PLUG, AND STOP ARE DISPOSED WITHIN SAID HOLLOW OBJECT TO EXERT A FORCE ON THE PISTON IN ONE DIRECTION FOR MOVING SAID STOP TOWARD SAID CYLINDER AND SAID SLEEVE INTO ENGAGEMENT WITH SAID ONE END OF THE CYLINDER TO COMPRESS SAID PLUG BETWEEN SAID STOP AND SLEEVE IN A DIRECTION ALONG THE LONGITUDINAL AXIS OF SAID PISTON ROD WHEREBY SAID PLUG IS EXPANDED IN A DIRECTION PERPENDICULAR TO SAID AXIS BETWEEN SAID STOP AND SAID SLEEVE TO SECURELY ENGAGE THE INNER WALL OF SAID OBJECT AT A LOCATION SPACED FROM SAID OPENING IN THE OBJECT BY SAID SLEEVE, AND MEANS FOR INTRODUCING FLUID INTO SAID CYLINDER TO EXERT A FORCE ON THE PISTON IN THE OPPOSITE DIRECTION TO CAUSE SAID PLUG TO RETURN TO ITS ORIGINAL SHAPE.