Improved Pipe Wrenches.
Year: 1891

page_text: Date of Application, 2nd Sept., 1891-Accepted, 16th Jan., 1892
COMPLETE SPECIFICATION.
Improved Pipe Wrenches.
I, GUSTAF GUNNARSON, Steam Fitter, residing at the City and County of
San Francisco, State of California, one of the United States of America, do
hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:
My invention relates to improvements in pipe wrenches, and the objects of my
improvement is :-
:-
First. To provide a self adjusting wrench that can be shifted instantly from one
size of pipe to another, and still afford a similar grip for small or large pipes, at
the same time being very simple and strong.
Second-To provide a wrench that will grasp the pipes on three different sides
with series of teeth graduated in size to the size of pipe they are bound to work
upon thereby affording a very strong hold, and preventing the pipe from being
crushed or flattened under hard screwing.
I attain these objects by the mechanism illustrated in the accompanying drawing,
in which-
Figure 1. is a side view of the wrench (handle excluded) showing the principle
of construction and its working.
Fig. 2. is an edge view of the wrench in Fig. 1.
Fig. 3. is a side view of plyers and tongs constructed on exactly the same
principle as Fig. 1 and referring to the same description, the object is to provide a
tool that can be worked with one hand.
Similar letters refer to similar parts throughout the several views.
The hook formed jaw A, is provided with two series of teeth, m and n, at an
angle to each other m, l, n, which is determined by the leverage c-1 of the jaw B,
as hereinafter stated, and is calculated to gripe the pipe on two sides equally
distant and opposite the grip of jaw B, the teeth are decreased in size toward the
corner, in proportion, with the pipes they work upon, and the jaw is further
extended to pivot c, in a curved shape in order to give room for jaw B, when
brought up close together with this jaw, its joining end is split and divided, so as
to receive and hinge to the jaw B, by means of a bolt or pivot c, or simply bolted
one across the other as shown in Fig. 3.
The self adjusting jaw B which is extended as a lever d, forming the handle of
the wrench, is provided with a toothed curve o, gradually raising from the pivot c,
in such a shape that when it is brought against any size of pipe that can be held
by the jaw A, it will grasp any pipe at the same angle of leverage c,—i,-1,
from a line drawn through the pivot c, to the centre of each pipe; this curved
shape of jaw B is obtained by combining the tangents to all the circle a, b, and
intermediate, at the respective points 1, 2, 3, and intermediates, found by laying off
the angle of leverage c, i, 1, on each circle from a line running through the pivot c
to the centre of each circle, the teeth decrease in size toward the end of the jaw
proportionally with the pipes they act upon.
Two different positions of jaw B against the pipes are shown by the dotted
lines fand g.
As light pipe or tubing affords less resistance to pressure, it requires a wrench
built on a larger angle (longer leverage) which divides the pressure more evenly
around the pipe, but which has not so powerful grip as if the angle be smaller (the
leverage shorter). I therefore do not confine my invention to any certain degree
of angle or leverage, although 35° angle as shown in Fig. 1 has given good results
or ordinary pipework.

page_text: When planning a wrench I first draw the largest circle a, and across its centre
draw the dotted line j, on which I lay the pivot c, as shown in Fig. 1, and Fig. 3,
in the latter figure, at a distance from the pipe that will give a moderate motion
to the shanks; then I mark off the desired angle of leverage c, i, 1, from point 1,
I draw the line h, across centre of circle a, and lay the toothed side m of jaw A,
square across the line j, close to circle, the other toothed side n, is laid in a
corresponding position on the opposite side of line h, which line is indicating the
corner l, of this jaw.
Then I draw all the different circles on the line h, close to jaw A marking off
their angle of leverage 1, 2, 3 etc. and the corresponding tangents as shown, and lay
off the jaw B, on a separate piece of tracing paper, fastened rotary on the pivot c,
so it can be swung up to all the circles, commencing on the largest ; and their
tangents be marked off, forming the bend o, of jaw B.
In using this wrench the workman only has to close the jaws tight around the
pipe with one hand, while he pulls the handle with the other in the direction
indicated by the teeth.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1st. In a self-adjusting wrench plyers and tongs for screwing pipes and fittings,
the combination of a jaw A having two series of graduated teeth m and n, at an
angle to each other m,, n, determined by the angle of leverage c, i, 1 for griping
the pipes on two sides equally opposite the grip of jaw B, with which jaw it is
hinged by the bolt c all substantially as set forth.
2nd. The combination in a wrench, plyers and tongs for screwing pipes and
fittings etc. of a self-adjusting jaw B, extended as a lever, and having a curved
serie of graduated teeth o, constructed after the angle of leverage c, i, 1, which may
be varied according to purpose, the jaw griping the various pipes at this same
angle, and directly opposite the two grips of jaw A with, which, it is hinged by
pivot c, all substantially as shown, for the purpose specified.
Dated this 12th day of August 1891.
GUSTAF GUNNARSON.