An Improved Wrench for Pipes and Rods.
Year: 1891

page_text: Date of Application, 23rd June, 1891
Complete Specification Left, 11th Feb., 1892-Accepted, 12th Mar., 1892
PROVISIONAL SPECIFICATION.
An Improved Wrench for Pipes and Rods.
DIXON PROVAND, of Sandon Villa, Cambuslang, in the County of Lanarkshire,
Scotland, Engineer, do hereby declare the nature of this invention to be as
follows:-
The construction of a wrench in which the gripping power is obtained by the use
of a flexible band, either of metal or other strong material, attached to a lever and
acting in the manner of a band friction brake; so arranged that pressure on the
lever in one direction tightens the band, and at the same time turns the pipe or rod
to which it is applied; while movement of the lever in the opposite direction
slackens the band, which may then be slid back on the pipe or rod so as to take a
new grip. The band is easily detachable from the lever, so as to be passed round
the pipe, or to be exchanged for another band; and bands of different lengths and
different materials can be used with the same lever, according to the diameter of the
tube or rod, to the power required to turn it, and according to whether or not it has
a delicate surface which would be injured by a hard or roughened band. When the
tube or rod is of soft material or polished, a smooth band, of metal such as spring
steel or flat chain, or of leather, canvas, wire-cloth, or similar strong material, can
be used; and, if necessary to increase the grip, an adhesive powder such as resin
can be rubbed over the band.
The wrench may be made in any one of three forms, according to the circum-
stances under which it is intended to be used. These are as under :-
First. In the most simple form the head of the lever, to which both ends of the
band are attached, rests and rolls on the pipe or rod. In this form the pressure of
the head comes on a small surface of the pipe, which, if delicate, might be liable to
be flattened. In this form the band is tightened principally at one end, but also
slightly at the other.
Second. In this form, which is suitable for the most delicate pipes or rods, the
head of the lever does not touch the pipe. There is a solid curved jaw which rests
on the pipe, and into this the head of the lever is pivoted. One end of the band is
attached to the head of the lever, and the other to the jaw. The band is tightened
only at the end attached to the lever; the end attached to the jaw remains
stationary.
Third. This form will be the most generally useful. In it, as in the second, the
head of the lever does not touch the pipe, but is pivoted into a curved jaw. This
jaw, instead of being solid, is composed of two plates, which may however be
connected, with room between them for the band to pass. Both ends of the band
are attached to the head of the lever, and the band is tightened at both ends
simultaneously by the movement of the lever. In this form the pressure of the
lever falls on a larger surface of the pipe than in form 1, and on less surface than
form 2; but the gripping power is greater than in the latter.
When the pipes or rods to be gripped are not delicate, the band in the first form,
and both band and jaw in the second and third, may be roughened or toothed so as
to grip more readily.
Any strong and convenient fastenings may be used for fixing the ends of the
band but to allow for slight differences in diameter of the pipes or rods, an
attachment is preferable which will allow of varying, at one end, the length of band
;
in use.
The curve of the jaws should be as nearly as possible an arc of the pipe or rod to
be grinned. Where there is considerable difference in the sizes of the pipes or rods,

page_text: jaws of different curves may be made to fit to the same lever so as to be exchangable.
If preferred the jaws instead of being curved, may be of an open Y shape, so as to fit
more readily on slightly varying diameters of pipe or rod.
Dated this 22nd day of June 1891.
DIXON PROVAND.
COMPLETE SPECIFICATION.
An Improved Wrench for Pipes and Rods.
DIXON PROVAND, of Sandon Villa, Cambuslang, in the County of Lanarkshire,
Scotland, Engineer, 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 consists in the construction of a wrench for pipes and rods, in which
the gripping power is obtained by the friction of a flexible band strained tightly
round the pipe or rod by a lever, which, at the same time, serves to turn the pipe or
rod the gripping action being somewhat similar to that in a band friction brake,
and, like it, capable of being increased by rubbing the band with an adhesive powder
such as rosin.
In most of the wrenches at present in use the gripping power is obtained by
biting into the pipe with teeth cut on a rigid jaw. The rigidity of the jaw making
it impossible for any considerable surface to be in contact with the pipe there would
be little friction, or grip, were it not for the teeth.
In my invention owing to the large surface of contact. and friction obtained by
the flexible band, teeth are not necessary, and injury to the pipe, or rod, is
avoided.
The accompanying drawings will explain clearly how the flexible band and lever
are combined to form the wrench.
As will be seen from these drawings and the following explanations, the head of
the lever, in the act of tightening the band, may either rest and roll on the pipe or
rod, as in Figs. 1, 2, and 3; or it may be pivoted into a jaw which rests on the pipe
or rod, as in Fig. 4, 5, and 6. Where a jaw is used, it can either be formed of two
plates with room for the band to pass between them, as in Figs. 4 and 5 or may
be solid and have one end of the band fixed to it, as in Fig. 6. The form of lever
in Fig. 1, or any similar form, can be used either, as there shown, without a jaw, or
with a jaw such as those shown in Figs. 4 and 5. When to be used with a jaw the
pin at 6, (Fig. 1), will be long enough to serve as a pivot for the jaw. In the same
way, the forms of levers shown in Figs. 4 and 5, with jaws, can also be used
without the jaws there shown, and they will then rest and roll on the pipe as in
Figs. 1 and 3.
The lever will generally be of metal, but it may be all or partly of wood or other
material.
The arm of the lever will be of a size proportioned to the force to be applied.
The end of the lever which grips the band must however be at least as broad as the
band, and, in order to avoid giving too sharp a bend to the band, it will generally
be considerably deeper than is necessary for the arm. I shall, therefore, refer to
the lever as consisting of two parts:-the arm, and the head. These two may be
formed in one piece, or the arm may be a separate piece let into a mortice or recess
in the head. However made, they must be rigidly connected.
The arm of the lever is a simple bar, which may be either straight, as shown,
or slightly curved. Its length and strength will depend on the force to be
applied.
The form of the head of the lever admits of considerable variation without
substantially altering the working of the wrench. The amount of variation allow-
able will be evident from the following explanation of the principle on which the
wrench acts.

page_text: The dotted line in Fig. 3. represents the lever, which is a tangent to the circum-
ference of the pipe or rod; the point of contact, at 6. in the same fig., is the
fulcrum, and near this point one end of the band is firmly held; the other end of
the band is held by the short arm of the lever, as at 4 in Fig. 3. On pressure
being applied to the long arm of the lever, in such a direction as to tighten the
band, that end of the band held at or near the fulcrum will remain stationary, while
the other end of the band attached to the extremity of the short arm will tend to
describe an arc of a circle, and will strain the band round the pipe; as the band is
tightened the friction on the pipe, or rod, will be increased, as opposed to any
tendency to slip round the pipe. The pipe and wrench will then act as one lever of
which the fulcrum is the centre of the pipe, and pressure on the long arm of the lever
will tend to make the pipe revolve on its axis.
In practice the form of the head of the lever will be such, as to give facility for
holding the end, and altering the length of the band, and as to avoid bending the
band so abruptly as to risk breaking it.
The comparative flexibility or rigidity of the band, and the size of pipe to be
gripped, will also influence the determination of the most convenient form of lever,
and of the proportionate length of its arms. There must be sufficient tightening
power to bend the band to the form of the pipe, and also to cause sufficient friction
to prevent the band from slipping.
With large pipes it is easier to bend the band to their form, and there is more
surface of contact for such pipes, therefore, there should be less proportionate
difference in length between the arms of the lever, than for smaller pipes.
From this explanation it will be evident that different forms may be given to the
lever without substantially altering the principle of construction of the wrench.
The accompanying drawings give some convenient forms.
When a jaw is interposed between the head of the lever and the pipe, the
fulcrum, at the first tightening of the band, is the pin on which the lever is pivoted
to the jaw.
In such a
case as Fig. 4, the band would also be strained at both ends
simultaneously. Beyond this the action is the same as without a jaw.
The band must be flexible and of strong material, such as chain, thin sheet
metal, leather, canvas, or wire-cloth; the essential points being strength, and
sufficient flexibility to come in contact, when strained, with the greater part of the
circumference of the pipe or rod. It must therefore be either of a flexible material
or of a rigid material linked so as to form a flexible band. When sheet metal is
employed, it may be permanently bent to a form nearly corresponding to the
circumference of the pipe to be gripped.
The length, width, and strength required in the band will depend on the size of
pipe and the probable force required to turn it. Both strength, and grip, from
friction, are increased by increasing the width of the band.
Bands of different lengths, strengths, and materials, may be used with the same
lever as required.
The band must be attached to, or held by, the lever, and several different ways
are shown. Any other convenient method of attachment may be adopted.
In order that the same band may serve for different sizes of pipe it is preferable
to have an attachment which allows the lengthening or shortening of the band.
A few different ways of obtaining this are shown.
If the wrench is only intended for one size of pipe, or if it is preferred to use
different bands for the different sizes, all provision for altering the length of the
band may be omitted.
In the accompanying drawings the same numbers are used to denote similar
parts.
The mode of working in all the forms shown is identical. The free or most
easily detachable end of the band is passed round the pipe, or rod, to be gripped,
and fixed at a length which will bring the wrench and pipe into nearly the relative
positions shown; which are nearly the same in all the drawings.

page_text: 4, is the flexible band ;
5, and 6, are the ends of the band where they are held by the lever;
7, (in Figs. 5, and 6), is the jaw which rests on the pipe and into which the
head of the lever is pivoted.
One
I shall now proceed to explain the different drawings more in detail.
Fig. 1. In this the head, 3, of the lever rests and rolls on the pipe 1.
method of attaching the band is here shown. The end, 6, of the band is held by
a pin passing through the head, 3, of the lever. This end is only intended to be
detached in order to change the band. The end, 5, of the band is shown hooked
on to a sliding piece which is held at whatever point it may be placed, by the
teeth formed on the arm of the lever. This sliding piece being placed at such a
point as to allow the band to take the position more or less as shown, can be fixed
there by a spring, by a set-screw, or otherwise; the band can then be hooked and
unhooked at 5 as required; the sliding piece only requiring to be shifted when pipe
of a different diameter has to be gripped.
Fig. 2 shows a plan of the wrench in Fig. 1, but without the band. It will
be seen that the head, 3, is considerably wider than the thickness of the arm, 2.
This is to support the band.
Fig. 3. The head of the lever here also rests and rolls on the point 1 ; but a
different method of gripping the band is shown. The end, 5, is fixed to a shackle
held by a pin passing through it and through holes in the arm of the lever 2.
The different holes in the lever admit of lengthening and shortening the band.
The end, 6, of the band is not attached to the lever; it is merely folded round the
pipe as shown, and is held by the pressure on it of the head, 3, of the lever. The
lower part of the head of the lever, where it rests on the band, may have
transverse ridges or corrugations to enable it to hold the band more securely.
Where the band is a chain, these corrugations will correspond with the undulations
of the chain. Another way of increasing the grip of the band is to thicken the
end at 6. Small differences in diameter of pipe may be allowed for by passing the
end, 6, of the band more or less round the pipe; greater variations in length will
be made, as explained above, at 5.
Fig. 4. In this form, the head of the lever does not touch, but swings clear of
the pipe 1, the pressure being taken by the jaw, 7, into which the lever is pivoted.
The jaw consists of two plates made with a curve to fit the pipe to be operated
on, and allowing the end, 6, of the band to pass between them. To fit different
sizes of pipes, jaws with different curves will be required; or instead of being
curved the jaw may be of a wide V form, so as to take several sizes of pipe. The
two plates forming the jaw should be riveted or otherwise fixed together so as to
move as one the only thing necessary being that room be left for the head of the
lever to move, and for the end of the band to pass between the plates. In this
figure the end, 5, of the band is shown with a pin through it, which can be held in
any of the hooked projections formed on the arm of the lever; the end, 6, of the
band is held by a pin passing through the head of the lever which will have a
recess on, its under side to allow the band to enter and pass round the pin. This
pin is shown long enough for its ends to pass through slots in the plates forming
the jaw. With the end, 6, of the band held in the position shown in this fig., it
'

page_text: will be seen that movement of the lever will, simultaneously, strain the band at
both ends.
Fig. 5. In this case, as in the last, a jaw is interposed between the lever and
the pipe. This jaw, 7, also consists of two plates, but these plates are nearly
circular in form, and have a number of curves on their circumferences, to take
different sizes of pipes, and obviate the necessity for changing the jaws. In order
to make the two plates move together and keep the curves of equal radius corre-
sponding, the pin at 6 may have square ends fitting into square holes in the
plates. The end, 6, of the band is here held by the pin on which the jaw is
pivoted, the jaw having a recess as explained in Fig. 4. The end, 5, of the band
is here shown with a thickened end which is jammed or nipped under a sliding
piece on the arm of the lever.
Fig. 6. In this case also a jaw, 7, is interposed between the lever and the pipe.
This jaw however is made solid instead of being of two plates. The object is to
distribute the pressure over a greater surface of the pipe in case the latter should
be very delicate and apt to be crushed. The part of the jaw which rests on the
pipe is curved to fit it, and of course different jaws are required for different sizes
of pipe. Owing to the jaw being solid, the band, at its end 6, is fastened to the
jaw instead of to the head of the lever. The end, 5, of the band is shown with a
hooked shackle, which engages in pins fixed in the arm of the lever.
In each of the drawings, as above explained, it will be noticed that an example
of a different way of fastening the ends of the band is shewn. Any other device.
for fastening them may be used, as long as the two ends of the band, when
pressure is applied, are firmly held, and the relative positions of the lever, band,
and pipe are maintained nearly as shown in the drawings.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, declare that what I
claim is :
1. The construction of a wrench, in which the necessary grip is obtained by the
friction of a flexible band strained round the pipe or rod by a lever, which holds
both ends of the band and tightens it at one end, or at both ends simultaneously;
acting substantially as herein before described and shown.
Dated this 10th day of February 1892.
DIXON PROVAND,
Applicant.