Captive fastener

Claim 1

A CAPTIVE FASTENER TO BE HELD WITHIN A MEMBER HAVING A BORE, A COUNTER BORE AND AN ANNULAR SHOULDER AT THE JUNCTURE OF SAID BORE AND SAID COUNTER BORE COMPRISING, A SHANK, A STEPPED GROOVE AROUND SAID SHANK, A SPLIT RETAINING RING, ONE END OF SAID SHANK BEING ADAPTED TO BE INSERTED THROUGH SAID BORE AND INTO SAID COUNTER BORE OF SAID MEMBER, THE LARGEST DIAMETER PORTION OF SAID STEPPED GROOVE BEING NEAREST SAID ONE END OF SAID SHANK, SAID RING BEING COMPRESSIBLE INTO THE SMALLEST DIAMETER PORTION OF SAID STEPPED GROOVE FOR INSERTION OF SAID ONE END OF SAID SHANK THROUGH SAID BORE AND INTO SAID COUNTER BORE, SAID RING HAVING A FREE OUTER RING DIAMETER LARGER THAN THE DIAMETER OF SAID COUNTER BORE IN SAID MEMBER AND AN INNER DIAMETER WHEN IN ENGAGEMENT WITH SAID COUNTER BORE SMALLER THAN THE DIAMETER OF SAID SHANK WHEREBY SAID RING PROVIDES A POSITIVE INTERFERENCE PREVENTING REMOVAL OF SAID SHANK FROM SAID BORE OF SAID MEMBER, SAID RING WHEN COMPRESSED INTO ENGAGEMENT WITH THE SMALLER OF SAID CYLINDRICAL SURFACES OF SAID GROOVE HAVING AN OUTER DIAMETER LESS THAN THE DIAMETER OF SAID BORE IN SAID FIRST MEMBER, SAID RING WHEN COMPRESSED INTO ENGAGEMENT WITH SAID LARGER OF SAID CYLINDRICAL SURFACES OF SAID GROOVE HAVING AN OUTER DIAMETER LARGER THAN THE DIAMETER OF SAID BORE IN SAID FIRST MEMBER, SAID SMALLER DIAMETER PORTION HAVING A DIAMETER LESS THAN THAT OF SAID SHANK BY AN AMOUNT AT LEAST AS GREAT AS TWICE THE MAXIMUM TRANSVERSE DIMENSION OF THE CROSS SECTION OF SAID RING, SAID LARGER DIAMETER PORTION HAVING A DIAMETER LESS THAN THAT OF SAID SHANK BY AN AMOUNT LESS THAN TWICE SAID MAXIMUM TRANSVERSE DIMENSION OF SAID RING.