Tools – Wrench – screwdriver – or driver therefor – Slidable jaw adjustments
Reexamination Certificate
2000-02-24
2001-07-31
Smith, James G. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Slidable jaw adjustments
C081S186000
Reexamination Certificate
active
06267029
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to hand tools, and more specifically to an improved structure for an adjustable wrench and method for making the same.
BACKGROUND OF THE INVENTION
An example of typical adjustable wrench
10
found in the prior art is shown in
FIGS. 1A and 1B
. Wrench
10
is comprised of three main pieces, namely body
11
(which includes handle
12
and upper jaw
14
), lower jaw
16
, and thumbwheel
17
. As one skilled in the art will immediately recognize, lower jaw
16
contains angled threads
18
which intermesh with similarly angled threads
20
on thumbwheel
17
in a screw-like fashion such that when thumbwheel
17
is rotated, lower jaw
16
will move to or from upper jaw
14
depending on the direction of rotation.
During manufacture, main body
11
is typically formed of hot forged steel. Then a bore hole
30
and slot
32
are formed in main body
11
to allow lower jaw
16
to be slid within. Bore hole
30
is formed by drilling a hole in the main body
11
, usually straight through to the top of the handle. Then, slot
32
can be formed by a saw, usually a reciprocating broach bar. After bore hole
30
and slot
32
are formed, lower jaw
16
can be slid into place within main body
11
. Thereafter, thumbwheel
17
is slipped into place so as to mesh threads
18
and
20
and is then permanently attached to main body
11
by a rivet
34
.
The steps of forming bore hole
30
and slot
32
in the main body
11
add significant expense to the cost of manufacturing wrench
10
. Moreover, the design of wrench
10
tends to rattle in the hand of the user when shaken. This is due to the fact that the lower jaw
16
is held steady within the bore hole
30
and slot
32
by its mechanical connection with thumbwheel
17
. As shown in the cross-sectional view of
FIG. 2
, and due to the generally cylindrical shape of thumbwheel
17
, thumbwheel
17
(or more specifically the threads
20
of the thumbwheel
17
) comes into contact with the lower jaw
16
(or more specifically the threads
18
of lower jaw
16
) at a single point. Because lower jaw
16
and thumbwheel
17
are not securely braced against one another, the lower jaw
16
will rattle in the user's hand when shaken back and forth in direction
25
. This unsteadiness is perceived by prospective purchasers as being indicative of a wrench that is not constructed with good mechanical tolerances and hence is of poor quality.
The present invention solves these problems of the prior art by providing an improved design for an adjustable wrench which is less costly to manufacture and more stable in the user's hands.
SUMMARY OF THE INVENTION
The present invention comprises an improved design for an adjustable wrench and a method for making the same. In accordance with one exemplary embodiment, the inventive wrench includes a main body which includes a handle, upper jaw, and an attachment portion such as a groove or tab. The lower jaw of such wrench, which contains two ribs with threaded surfaces, is slipped over the attachment portion. The threaded surfaces of the ribs are made to meet with the threads on a thumbwheel, thus allowing the distance between the upper and lower jaws to be varied by turning the thumbwheel. Because the lower jaw slips over the attachment portion of the main body, such a wrench can be manufactured with reduced expense. Moreover, this configuration provides for increased stability because the ribs of the lower jaw contact the thumbwheel at two points. This configuration also allows the lower jaw to be easily removed and replaced.
REFERENCES:
patent: 591743 (1897-10-01), Drew
patent: 3948120 (1976-04-01), Hancock
patent: 3955450 (1976-05-01), Evans
patent: 4028970 (1977-06-01), Pelczar
patent: 4048876 (1977-09-01), Cagle
patent: 4706528 (1987-11-01), Inoue
patent: 4735121 (1988-04-01), Coulson
patent: 4766786 (1988-08-01), Jeremic
patent: 4831903 (1989-05-01), Dausey et al.
patent: 5022290 (1991-06-01), Duffy
patent: 5048380 (1991-09-01), Caldwell
patent: 5103697 (1992-04-01), Masbaum
patent: 5231904 (1993-08-01), Masbaum
patent: 5239898 (1993-08-01), Douglas
patent: 5806383 (1998-09-01), Hsieh
patent: 5809852 (1998-09-01), Haskell
patent: 544950 (1921-04-01), None
patent: 20928 (1892-01-01), None
Emerson Electric Co.
Howrey Simon Arnold & White , LLP
Smith James G.
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