Tools – Wrench – screwdriver – or driver therefor – Rigid jaws
Patent
1991-07-25
1992-12-22
Meislin, D. S.
Tools
Wrench, screwdriver, or driver therefor
Rigid jaws
811251, 811771, B25B 1302
Patent
active
051726149
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a composite improved wrench, that is to say one which is produced from plastic and the nut-engaging heads of which comprise an embedded metal insert forming a clamping bit or jaw. However, this invention can be adapted perfectly well to traditional steel wrenches.
The production of composite wrenches has already been known for a long time (see, for example, US-A-2,909,954, GB-A-1,251,419). Nevertheless, this type of wrench has undergone virtually no development in view of its prohibitive disadvantages.
In fact, whatever the shape or dimensional characteristics of the metal inserts, the wrenches obtained are unsatisfactory, on the one hand because said inserts tend to rotate in the head, and on the other hand because the strength of the wrenches is often scarcely different from that of the plastic handle, thus considerably restricting their use, and at all events is below the lower limit of the industrial standards in force at the present time.
The U.S. Pat. No. 1,793,714 describes a wrench which has a head at each of its ends, but in which the two heads are arranged in two separate nonparallel planes intersecting at the center of the wrench along a line perpendicular to the general direction of the handle of the wrench. Although this embodiment has the advantage of assisting work in terms of the particular location, especially nuts of difficult access, nevertheless the special morphology of the handle, changing the way in which the wrench is grasped, reduces the amount of force which can be exerted on the handle, thereby making this type of wrench of limited use.
The invention mitigates these disadvantages. It is aimed at an improved wrench of the type in question, that is to say one produced from plastic advantageously reinforced with glass fibers and having metal inserts in the region of the heads for performing the function of clamping bits or jaws, which is easy to manufacture and, above all, do (sic) not have the above-described disadvantages, especially where strength is concerned. More specifically, the invention relates to an improved wrench which is light and the overall size of which is comparable to that of corresponding metal wrenches in existence at the present time.
This improved wrench consists of a handle possessing at each of its ends a clamping head in the form of an open fork, ring or socket of polygonal crosssection, the two nut-engaging heads being arranged in two separate non-parallel planes and each being extended by a coplanar portion forming part of the handle.
It is characterized:
in that the two coplanar portions constitute the entire handle and intersect over the entire length of the latter;
and in that the straight line defined by the intersection of the two planes extends from one end of the handle to the other and along its diagonal over the entire length of the latter.
In other words, the invention involves producing a non-plane wrench, the two heads of said wrench being in two different planes extended in the region of the handle, in order to define a likewise non-plane handle, each of the plane parts performing the function of a girder for the other, thus resulting in an appreciable increase in the strength of this handle, especially its bending strength.
Advantageously, in practice:
the angle defined by the two planes is between 90.degree. and 170.degree. . It was found, in fact, that if this angle was larger than 170.degree. , hence coming near to a configuration of the flat-wrench type, the disadvantages inherent in this configuration occurred again, namely on the one hand difficult grasping and on the other hand a relatively large overall size of the handle attributable to the composite structure, unsuitable for some uses; in contrast, if this angle was smaller than 90.degree. , the configuration obtained is of little value because, although the overall size remains small, the grasping and actuation of the wrench are not made easier;
the two heads are in the form of a stationary or even movable open fork;
the wrenches are produced from plastic
REFERENCES:
patent: 1793714 (1931-02-01), Newberg
patent: 2083131 (1937-06-01), Tornebohm
patent: 2909954 (1959-10-01), Rhoads
patent: 3298260 (1967-01-01), Rothenberg
patent: 4738169 (1988-04-01), Wyka
Demurger Jean P.
Monnet Pierre
Demurger et Cie
Meislin D. S.
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