Releasable clamping apparatus

An apparatus for selectively clamping a sized lifting member comprising

• a generally hollow housing having an end wall provided with a pair of extending side walls defining a clamping region, said side walls each having an opening therethrough, with said openings aligned about a common axis, and said end wall having a bore disposed normal to said axis;
• an inwardly biased latch member reciprocally mounted in each said opening and including a latch portion extending into said clamping region, said latch portions each having a tapered outer face for engagement by said lifting member for urging said latch portions out of said clamping region, whereby said lifting member is then received into said clamping region, after which said latch portions enclose said lifting member therein, and said latch portions each further including an inwardly facing first clamping face generally normal to said first bore, for clamped engagement with said lifting member;
• a pair of elongated linkage members mounted in spaced relation in said housing and having first and second ends, each linkage member being pivotally secured at said first end to one of said latch members and pivotally secured at said second end in said hollow housing, said linkage members each having an inwardly facing linkage cam follower disposed between said first and second ends;
• a clamp member disposed for selected movement in said bore and having a clamp cam follower on one end and a second clamping face on an opposite end for clampably engaging said lifting member;
• a cam member rotatably disposed in said housing and having a pair of first, like, opposed cam lobes disposed to bear on each said linkage cam follower, for simultaneously moving each said latch portion in said opening out of said clamping region, and further having a pair of second, dissimilar, opposed cam lobes positioned generally 90.degree. from said pair of first cam lobes so that a selected one of said pair of second cam lobes bears on said clamp cam follower of said clamp member, for selectively moving said clamp member a predetermined distance into said clamping region, clamping a selected said lifting member between said first and second clamping faces of said latch member and said clamp member;
• and
• rotation means including a handle, connected to said cam member for rotating said cam member in a selected direction, said rotation means including means for decoupling said handle from said cam member while maintaining rotational bias thereon, said handle including locking means for locking said handle in a predetermined position over said housing, whereby as said handle is rotated to a selected side of said housing, decoupled from said cam member and locked in a said predetermined position, a lifting member of one thickness is clamped, and as said handle is rotated to the opposite side of said housing, decoupled and locked in another predetermined position, a lifting member of different thickness is clamped.