Tools – Wrench – screwdriver – or driver therefor – Plural pivoted jaws and handle-lever
Reexamination Certificate
2000-01-06
2001-09-11
Smith, James G. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Plural pivoted jaws and handle-lever
C081S090300, C081S091200
Reexamination Certificate
active
06286398
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to carpentry tools and more particularly to a combination wrench with adjustable heads which can be automatically adjusted to consist with the size of an object such as a nut to which it rotates.
People usually use different sizes of combination wrenches to work at different sized nut which is uneconomical. A typical adjustable combination wrench (as shown in
FIG. 1
) is thus worked out which comprises a handle
1
and a pair of rotatable boxes
3
of irregular hexgon pivoted at two ends of the handle
1
. The handle
1
has a jaw
2
at each ends. When engages the box
3
with a working object such as a hexgon nut and rotates the handle
1
, the jaw
2
presses a side of the object to reduce the size of the box
3
in order to fit the shape of the object and further to faster or unfasten the object. This type of combination wrench provides a limited range to fit some of the hexgon nuts. However, it has the advantages set forth as follows:
a) because of a greater wondering clearance, it causes a free run which damages or deforms the working object,
b) the repeated engagement and/or disengagement with the object requires a rotation angle that greater the 60° which causes an operation limitation to the user, and
c) it does not fit a small working object or operate within a small space.
SUMMARY OF THE PRESENT INVENTION
The present invention has a main object to provide a combination wrench with adjustable heads which heads can automatically stretched open to fit a working object.
Another object of the present invention is to provide a combination wrench with adjustable heads which can firmly engage the working object during rotation and the handle can be back run.
Accordingly, the combination wrench of the present invention comprises generally a handle, an open end pivoted to one end and box head pivoted to the other end of the handle. The heads each has a first and a second jaw pivoted together in a shear arrangement and biased at their inner ends with a spring means to force the jaws to stretch open. The jaws each has serration on inner surface and a stop block against a side of the handle. So that the jaws are usually stretched open to fit the size of a working object and firmly engage with the object when the handle rotates. Further the handle enables to back run during fastening or unfastening the working object.
The present invention will become more fully understood by reference to the following detailed description thereof when read in conjunction with the attached drawings.
REFERENCES:
patent: 4913011 (1990-04-01), Ma
patent: 5050464 (1991-09-01), Hurtig
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