Jack fastener employing a bolt having two-threaded sections

Claim 1

IN COMBINATION, A SUPPORTING STRIP AND A FASTENER FOR SECURING AN OBJECT AGAINST SAID SUPPORTING STRIP WHICH INCLUDES AT LEAST ONE TAPPED HOLE THEREIN AND AN INDEXING RIDGE THEREON, SAID FASTENER COMPRISING A TWO-ENDED BOLT HAVING A HEAD AT ONE OF THE ENDS AND TWO THREADED SECTIONS OF DIFFERENT DIAMETERS AND PITCH AT THE OTHER END, THE LARGER DIAMETER SECTION BEING THREADED INTO A CLAMPING BAR INCLUDING A TAPPED BUSHING THEREIN, SAID BUSHING FORMING A FRICTION CLUTCH WITH SAID LARGER DIAMETER SECTION, WHEREBY ROTATION OF THE BOLT IN ONE DIRECTION DRIVES THE SMALLER DIAMETER SECTION INTO THE TAPPED HOLE UNTIL SAID CLAMPING BAR IS SEATED ON SAID SUPPORTING STRIP AND EXTENDED AWAY FROM SAID INDEXING RIDGE AND ROTATION OF THE BOLT IN THE OTHER DIRECTION WITHDRAWS THE SMALLER DIAMETER SECTION FROM SAID TAPPED HOLE AND PLACES THE CLAMPING BAR IN LINE WITH SAID RIDGE AND ELEVATED ABOVE SAID STRIP, AND MEANS FOR LIMITING THE ELEVATION OF SAID CLAMPING BAR ABOVE THE INDEXING RIDGE AND ROTATION OF THE BOLT IN THE DIRECTION OF EXTRACTION, SAID LIMITING MEANS FURTHER COMPRISING A LOCKING SPACER CLIPPED ABOUT THE BOLT BETWEEN THE HEAD THEREOF AND THE CLAMPING BAR, SAID SPACER HAVING A WIDTH TO LIMIT THE ELEVATION OF THE CLAMPING BAR TO A DISTANCE LESS THAN THE HEIGHT OF THE INDEXING RIDGE.