Hydraulic line wiper

Claim 1

IN A WIPER DEVICE ATTACHABLE TO A WELL PIPE; A HOUSING; A CENTRAL BORE IN THE HOUSING; A RESILIENT WIPER ELEMENT SLIDABLY DISPOSED IN THE BORE, AND HAVING A PASSAGE THERETHROUGH ADAPTED TO RECEIVE AN ELONGATE ELEMENT TO BE WIPED; A RETAINER MEMBER DETACHABLY POSITIONED IN THE OUTER END OF THE BORE FOR PREVENTING THE WIPER ELEMENT FROM MOVING OUTWARDLY OF THE BORE; A TUBULAR MEMBER POSITIONED IN THE BORE BELOW THE WIPER ELEMENT; AN ENLARGED HEAD ON THE TUBULAR MEMBER SLIDABLY AND SEALINGLY ENGAGED WITH THE BORE WALL, SAID TUBULAR MEMBER BEING ADAPTED FOR ATTACHMENT TO A WELL PIPE; INWARDLY DIRECTED PISTON MEANS ATTACHED TO THE HOUSING AND BEING SLIDABLY SEALED TO THE TUBULAR MEMBER AND WORKING AGAINST THE ENLARGED HEAD, WHEREBY THE HOUSING MOVES DOWNWARDLY WITH RESPECT TO THE TUBULAR MEMBER WHEN FLUID PRESSURE IS EXERTED BETWEEN THE PISTON AND THE ENLARGED HEAD; AND MEANS TO ADMIT FLUID UNDER PRESSURE TO THE INTERIOR OF THE HOUSING BETWEEN THE PISTON MEANS AND THE ENLARGED HEAD TO CAUSE RELATIVE MOVEMENT BETWEEN THE HOUSING AND THE TUBULAR MEMBER TO RADIALLY EXPAND THE WIPER ELEMENT.