Triple drive open-end wrench

Details Triple drive open-end wrench Triple drive open-end wrench

1998-10-21

2001-06-05

Scherbel, David A. (Department: 3723)

Tools

Wrench, screwdriver, or driver therefor

Rigid jaws

C081S124300, C081S186000

Reexamination Certificate

active

06240812

ABSTRACT:

FIELD OF THE INVENTION
This invention relates in general to wrenches, and in particular to an open end wrench that provides three surfaces upon which to drive a nut.
DESCRIPTION OF THE PRIOR ART
In a conventional open end wrench, a rigid jaw having flat parallel faces slides over a nut and attempts to engage fully, the flat parallel nut sides. However, because typical hexagonal nuts are built within manufacturing tolerances, a practical wrench must be designed to accommodate variations in the spacing of parallel sides that may be encountered within a nominal nut size. This necessitates clearances between the parallel sides of the nut and the parallel faces of the wrench. These clearances cause the flat parallel faces to engage primarily the nut corners rather than the whole side and may cause the nut corners to become rounded off if torque is applied to the nut with less than perfect wrench to nut contact. This problem is exacerbated when the user cannot or does not slide the wrench completely over the nut and drives the nut with the tips of the wrench jaw. A nut whose corners have been rounded off cannot be driven by a conventional wrench. Further, many times it may be desirable to drive the nut with the wrench tips or while not fully seated in the wrench to save the time of having to seat the wrench fully for each stroke or because space does not allow the wrench to seat fully on the nut.
A number of patents have dealt with the tendency of a conventional wrench to engage the corners of a nut by using arcuate surfaces in lieu of flat parallel surfaces. The arcuate surfaces curve away from the nut corners and engage the nut closer to nut side center. Unfortunately, however, in the same way the arcuate surfaces protect the nut corners, they prevent driving of the nut with the wrench tips or while not fully seated in the wrench. The arcuate surfaces curve away from the nut at the wrench tips, and thus, the wrench tips cannot engage the nut. When the nut is driven while not fully seated, the wrench engages the nut corners and, like the flat parallel faces, can cause the nut corners to become rounded off. Also, some wrenches with arcuate drive surfaces require the wrench head to be larger than a conventional wrench head to withstand the stresses involved in driving a nut. The larger head requires a larger and generally more expensive blank from which to make the wrench. Furthermore, the larger head cannot fit in as small of a space as that of a conventional wrench.
SUMMARY OF THE INVENTION
A wrench of in accordance with this invention has a fixed head comprising an upper jaw and a lower jaw. The upper jaw has an upper forward drive face, an upper intermediate drive face, and an upper rearward drive face. The upper forward, intermediate, and rearward drive faces generally face the lower jaw. The upper forward and upper intermediate drive faces are separated by an upper forward notch. The upper intermediate and upper rearward drive faces are separated by an upper rearward notch. The lower jaw is substantially a mirror image of the upper jaw having a lower forward drive face, lower intermediate drive face, and lower rearward drive face separated by notches. A back stop face joins the upper and rearward drive faces. The forward, intermediate, and rearward drive faces are adapted to allow the wrench to drive a nut in three different positions in plane to plane contact.


REFERENCES:
patent: 4889020 (1989-12-01), Baker
patent: 5074171 (1991-12-01), Annis et al.
patent: 5117714 (1992-06-01), Pagac et al.
patent: 5239899 (1993-08-01), Baker
patent: 5381710 (1995-01-01), Baker

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