Self-locking hand tools

A self-locking hand tool including two pivotally interconnected jaws adapted to receive and clamp a workpiece, hand grip members pivotally connected to each respective jaw, a brace member pivotally connected to the pivotal interconnection between the two jaws at its one end, with the other end thereof connected by articulated linkages to pivots on each respective hand grip, one hand grip having a locking member co-operating with the brace member and the other hand grip having a spring means with the relevant articulated linkage forming an over-centre lock, the arrangement being such that the one hand grip freely moves the jaw connected therewith and wherein the second hand grip following application of a force above a predetermined level, actuates the over-centre lock displacing the brace member and further locking the first hand grip.

A self-locking hand tool including two pivotally interconnected jaws adapted to receive and clamp a workpiece, hand grip members pivotally connected to each respective jaw, a brace member pivotally connected to the pivotal interconnection between the two jaws at its one end, with the other end thereof connected by respective articulated linkages to pivots on each respective hand grip, one hand grip having a displacement member to lockingly engage the brace member and the other hand grip being connected through a spring means with the brace member, and further being coupled with the relevant articulated linkage, said linkage forming an over-centre lock, the arrangement being such that the one hand grip freely moves the jaw connected therewith and wherein the second hand grip following application of a force above a predetermined level to overcome the spring means moves and actuates the over-centre lock causing movement of the brace member such that the displacement member is locked therewith to prevent movement of the first hand grip.

A self-locking clamp including two interconnected parallel clamp jaws which may be moved together or apart linearly and by drive means to embrace and clamp a workpiece therebetween, an over-centre locking means operatively coupled with one clamp jaw and biassed to a first position by a spring member whereby on application of a predetermined force by the drive means acting between the jaws, the over-centre lock overcomes the bias of the spring member and is caused to be tripped into a second position retaining the other clamp jaw through the drive means in a fixed position.