Friction device operating mechanism

Claim 1

A FRICTION DEVICE OPERATING MECHANISM COMPRISING A CYLINDER HAVING OPPOSED END WALLS, PISTON MEANN SLIDABLE IN SAID CYLINDER AND DEFINING WITH ONE OF SAID END WALLS AN EXPANSIBLE FLUID PRESSURE CHAMBER AND WITH THE OTHER OF SAID END WALLS AN EXPANSIBLE SPRING CHAMBER, A SHAFT SLIDABLY MOUNTED ON SAID PISTON MEANS AND SAID ONE END WALL AND HAVING A WORK END EXTENDING EXTERIORLY OF SAID CYLINDER, SPRING MEANS ENGAGED BETWEEN SAID PISTON MEANS AND SAID OTHER END WALLS, AND THREADED MEANS REMOVABLY SECURED TO SAID PISTON MEANS AND NORMALLY IN DRIVING ENGAGEMENT WITH SAID SHAFT, SAID SPRING MEANS SERVING TO CONCERTEDLY MOVE SAID PISTON MEANS AND SHAFT TO ACTUATE THE WORKING END THEREOF IN RESPONSE TO FLUID PRESSURE IN SAID CHAMBER LESS THAN A PREDETERMINED VALUE, SAID THREADED MEANS BEING ADAPTED FOR COMPLETE REMOVAL FROM SAID PISTON MEANS AND DRIVING ENGAGEMENT WITH SAID SHAFT TO PROVIDE UNRESTRICTED RELATIVE MOVEMENT OF SAID PISTON MEANS INDEPENDENTLY OF SAID SHAFT INTO ENGAGEMENT WITH SAID ONE END WALL WHEREIN THE COMPRESSIVE FORCE OF SAID SPRING MEANS IS POSITIVELY CONTAINED BETWEEN SAID END WALLS, AND SAID THREADED MEANS BEING CONTAINED WITHIN SAID SPRING CHAMBER AND ACCESSIBLE THROUGH A RELATIVELY SMALL ACCESS OPENING IN SAID OUTER END WALL TO PREVENT EXPULSION OF SAID THREADED MEANS UPON COMPLETE REMOVAL FROM SAID PISTON MEANS.