Tools – Wrench – screwdriver – or driver therefor – Rigid jaws
Reexamination Certificate
2000-09-08
2002-01-01
Meislin, D. S. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Rigid jaws
Reexamination Certificate
active
06334374
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an open-end wrench for an hexagon object consisting of a wrench head and a wrench handle.
Different embodied examples of rigid open-end wrenches of this kind are known in the art. In their simplest form with parallel inner jaw surfaces, they are the basic model of a wrench. The customary position of the wrench handle, offset at a 15° angle in relation to the wrench head, allows twisting hexagon objects, in particular nuts and screws, by turning the wrench around after each twisting step, even if the swivel space that is available for the swivel motion of the wrench handle is less than 60°. However, the twisting of the open-end wrench, which is required for this process, increases the labor intensity considerably.
Thus, numerous attempts have been made to develop open-end wrenches that allow grasping hexagon objects with simple changes, i.e. without turning the wrench head around in respective increments of approximately 30°, which means that hexagon objects can be twisted by simple changes in between the individual twisting steps even if less than 60° is available for the swivel motion of the wrench handle. These wrenches have in common, however, that varying impact conditions result for the different point of impact positions on the hexagon object, in particular, upon application of the turning moment, the points of impact are formed at different distances in relation to the respectively adjacent edges of the hexagon object. Thus, depending on the respective point of impact position, different turning moments are transferred to the hexagon object. For example, as a result, in the first point of impact position a comparatively high turning moment can be transferred, but in the next position, offset by approximately 30°, this same turning moment can no longer be transferred causing the wrench head to slip off the hexagon object or causing damage to the hexagon object. In general, this leads to insecurity when handling wrenches of this kind.
The same is also valid for a wrench known in the art (EP 0 747 173 A1) which envisions a recess in one or in both of the diametric wrench surfaces of the two wrench jaws between a front point of impact and a rear point of impact. Said recess accommodates one edge of the hexagon object in one of the two possible point of impact positions that are offset by 30° in relation to each other.
With another wrench known in the art (U.S. Pat. No. 3,921,476) one of the two wrench jaws has an extension and features two outer points of impact on the extended part that are separated from each other by a recess. This rigid wrench known in the art, however, is not conceived for engaging point of impact positions on the same hexagon object that are offset in relation to each other by 30°. Rather, the wrench known in the art is intended to be applied optionally on two hexagon objects of different sizes. A smaller hexagon object is accommodated between the diametric surfaces of the wrench. A larger hexagon object, that does not fit between the two diametric surfaces of the wrench, is received with one of its edges between the two outer points of impact of the one wrench jaw while the rounded outer end on the other wrench jaw is applied in the proximity of the opposite edge of the hexagon object. The point of impact conditions of the open-end wrench are very different for the two sizes of hexagon objects, for which the wrench is envisioned, in particular the respectively effective length of the wrench lever differs. Since the two outer points of impact of the one wrench jaw are protruding in relation to the plane of the allocated inner wrench surface, the open-end wrench can not be applied sideways on the smaller hexagon object. Instead, in the manner of an open ring wrench, it must be pushed axially onto the smaller hexagon object.
Thus, it is the subject-matter of the present invention to provide an open-end wrench featuring approximately the same turning moment transfer conditions in a first point of impact position for both twisting directions as well as in a second point of impact position offset by 30°; furthermore, a wrench is to be provided that can be slipped on from the side and can also be used as a ratchet wrench while having all the advantages of
SUMMARY OF THE INVENTION a simple, rigid open-end wrench in terms of its physical conception. All of these individual tasks must be fulfilled simultaneously by one and the same open-end wrench.
According to the invention this objective is achieved with an open-end wrench for an hexagon object which is equipped with a wrench head and a wrench handle with the diametric surfaces of two wrench jaws forming, respectively, a front point of impact and a rear point of impact. The front point of impact is applied in a first position of the hexagon object on one of two opposite side surfaces of the hexagon object at a predetermined edge distance (a) from the adjacent edge of the hexagon object. In a second position of the hexagon object, twisted by 30°, the front point of impact of one wrench jaw and one outer point of impact, which is located before the front point of impact of the other wrench jaw and separated from the latter by a recess, are also applied, respectively, at the predetermined edge distance (a) from the adjacent edge of the hexagon object.
The two front points of impact are preferably located symmetrically to each other. These front points of impact as well as the additional outer point of impact on the one of the two wrench jaws are, in relation to the respective hexagon object that is to be accommodated, preferably arranged in such a manner that all of them grasp at approximately the same predetermined, optimal edge distance from the adjacent edge of the hexagon object. This means in all point of impact positions a constant edge distance is maintained, which is why approximately the same, highest possible turning moment can be transferred for all point of impact positions. Consequently, the highest possible safety for the handling of the open-end wrench is achieved. The open-end wrench cannot be standardized until this requirement is fulfilled.
According to a preferred embodied example of the invention it is envisioned that the two diametric surfaces have inner jaw surfaces, which are arranged parallel to each other and located respectively between the rear point of impact and the front point of impact. Beyond the respective points of impact, the diametric surfaces recede in relation to the planes of these inner jaw surfaces. Thus, recesses or groves which could weaken the wrench head have been avoided in the area of the parallel inner jaw surfaces. Consequently, it is possible to realize the wrench head with relatively narrow wrench jaws.
REFERENCES:
patent: 2652753 (1953-09-01), Wilder
patent: 2671368 (1954-03-01), Diebold
patent: 3850057 (1974-11-01), Evans
patent: 3868873 (1975-03-01), Evans
patent: 3921476 (1975-11-01), Evans
patent: 430 508 (1938-10-01), None
patent: 981069 (1976-01-01), None
patent: 990983 (1976-06-01), None
patent: 1943953 (1971-03-01), None
patent: 0 747 173 (1996-12-01), None
patent: 2 080 171 (1982-02-01), None
Burns Doane , Swecker, Mathis LLP
Hirse-Patent-Lizenz-GmbH
Meislin D. S.
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