Tools – Tool jaw – With means to immobilize jaws
Patent
1993-12-23
1995-11-28
Meislin, D. S.
Tools
Tool jaw
With means to immobilize jaws
81352, 81367, 269228, B25B 712
Patent
active
054697654
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an improved construction of hand tool or wrench having a pair of opposed jaws which may be brought together by operation of hand grips so as to firmly clamp the workpiece, such as a nut or head of a belt, between the two jaws.
Many different constructions of adjustable wrenches are known including a construction commonly referred to as a "mole-grip" wherein the hand grips apply substantial force to the jaws through a lever action following which, by means of an over-centre lock, the jaws are maintained tightly in the closed position until disengaged by a lever which releases the over-centre lock means. An advantage of such a wrench is that a large force may be applied to the hand grips to firmly cause the jaws to be clamped around the workpiece and following operation of the over-centre lock, said force is maintained so that the workpiece is firmly gripped without the need to sustain a hand grip. A disadvantage of the construction is that an adjusting means, usually a screw jack, has to be provided to set the over centre lock so that it operates with an appropriate spacing between the jaws. Thus, the over-centre lock adjuster must be pre-set according to the workpiece to be gripped and such presetting often involves a certain amount of trial and error before the over-centre lock operates following application of sufficient force to ensure firm gripping of the workpiece by the jaws.
One of the objects of this invention is to provide an adjustable wrench wherein an over-centre lock operates following the application of a predetermined force to the hand grips, regardless of the particular spacing between the jaws at any instant. Thus, this invention seeks to provide an adjustable wrench in which the jaws are simply offered up to the workpiece with the hand grips then being forced together following which, and after application of a predetermined force, the over-centre lock operates to retain the jaws in the closed position.
Thus and in accordance with a first aspect of this invention, there is provided a self-locking hand tool including two pivotally interconnected jaws which may be moved together or apart to embrace a workpiece, hand grips pivotally connected to each jaw, an articulated linkage pivotally interconnecting the hand grips and the jaws whereby a force applied between the hand grips causes the jaws to be forced together and an over-centre locking means operatively coupled with the hand grips and the articulated linkage and associated with a spring member whereby on application of a predetermined force to the hand grips, the over-centre lock is caused to be tripped into a position retaining the hand grips and the jaws in a fixed position.
In accordance with a second aspect of this invention, there is provided 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.
In accordance with a third aspect of this invention there is provided 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 resp
REFERENCES:
patent: 1772428 (1930-08-01), Palotce
patent: 2499201 (1950-02-01), Thayer
patent: 2620697 (1952-12-01), Sarvie
patent: 2635496 (1953-04-01), Marasco
patent: 3104571 (1963-09-01), Trybus
patent: 3815894 (1974-06-01), Olson
patent: 4344215 (1982-08-01), Dearman
patent: 4850254 (1989-07-01), Burney
Litman Richard C.
Meislin D. S.
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