Hoisting coupling for concrete slabs

A remotely releasable hoisting coupling for selective engagement with a concrete slab having a surface, a passage formed in the slab in generally perpendicular relationship to the surface and opening therethrough, and an annular abutment within the passage below the surface, said coupling comprising:

• a body sized for entry into said passage, said body having a longitudinally extending bore formed therein;
• at least one pair of lugs engageable with said abutment and supported in said body for rocking movement about a diametric axis extending normal to the body and for movement relative to the body between a position protruding laterally from said body at which said lugs engage the abutment and a position retracted into said body at which said lugs are disengaged from the abutment;
• an actuator rod axially moveable within said bore;
• means operatively connecting said lugs to said actuator rod so that in response to axial movement of the actuator rod in one direction relative to said body said lugs are moved to the protruding position and, in response to axial movement of the actuator rod in an opposite direction relative to said body, said lugs are moved to the retracted position;
• a lifting bail carried by said body so as to be disposed to the exterior of a slab engaged by the coupling, said bail being pivotal about an axis extending parallel to the diametric axis about which the lugs are mounted for rocking movement;
• a compression spring interposed between the rod and body to normally bias the rod in said one direction;
• and a lever having a portion pivotally secured to the rod and a hinge having an axis to one side of the rod whereby the lever may be pivoted about said axis to move the rod against the bias of the spring in said opposite direction.

A remotely releasable hoisting coupling for selective engagement with a concrete slab having a surface, a passage formed in the slab in generally perpendicular relationship to the surface and opening therethrough, and an annular abutment within the passage below the surface, said coupling comprising:

• a body sized for entry into said passage, said body having a longitudinally extending bore formed therein;
• at least one pair of lugs engageable with said abutment and supported in said body in diametrically opposed positions for movement relative to the body between a position protruding laterally from said body at which said lugs engage the abutment and a position retracted into said body at which said lugs are disengaged from the abutment, said lugs having cam surfaces formed on the inner ends thereof;
• an actuator rod axially movable within said bore and having cam surfaces formed on diametrically opposite sides thereof for complemental engagement with the cam surfaces on the lugs to force the lugs to the protruding position upon axial movement of the rod in one direction relative to the body;
• complementally engageable means carried by the lugs and rod to the interior of the tapered surfaces on the rod to force the lugs to the retracted position in response to axial movement of the rod in an opposite direction relative to said body;
• a lifting bail carried by said body so as to be disposed to the exterior of a slab engaged by the coupling;
• a compression spring interposed between the rod and body to normally bias the rod in said one direction;
• and a lever having a portion pivotally secured to the rod and a hinge having an axis to one side of the rod whereby the lever may be pivoted about said axis to move the rod against the bias of the spring in said opposite direction.