Abstract: A device (20) having a pair of jaws (22, 23) cooperating with a pair of threaded rods (24, 25) and which displace equally from a midpoint (36) of device (20) along threaded rods (24, 25). A spirally-wound rod (40) with sets (41, 42) of keyways rides in sets (50, 51) of keys positioned in jaws (22, 23). A center plate (44) for the rods (24, 25, 40) maintains them at a midpoint (36) for device (20). Sliding assemblies (60, 94) lock and unlock barrel nuts (71, etc.) in the jaws (22, 23) from threaded rods (24, 25). Different senses of threads for threaded rods (24, 25) extend to each side of rod (40). In another embodiment, a push handle (116) directly actuates the ‘quarter-turn’ threads in bores (122) of barrel nuts (115) into and out of engagement with threaded rods (121).

Abstract: A clamp mechanism (20) having a pair of jaws (22, 23) cooperating with a pair of threaded rods (24, 25) that displace equally from a midpoint (36) of mechanism (20) along threaded rods (24, 25) by means of a spirally-wound rod (40) with sets (41, 42) of keyways riding in sets (50, 51) of keys positioned in jaws (22, 23). A center 20. Sliding assemblies (60, 94) lock and unlock barrel nuts (71, etc.) in the jaws from threaded rods (24, 25). Different senses of threads for threaded rods (24, 25) extend to each side of rod 40. In another embodiment, a push handle (116) directly actuates the ‘quarter-turn’ threads in bores (122) of barrel nuts (115) into and out of engagement with threaded rods (121).