IMPROVEMENTS IN SCREW WRENCHES OR SCREW SPANNERS AND IN GAS GRIPS
Year: 1877

page_text: LETTERS PATENT to Thomas Chatwin, of Birmingham, in the County of Warwick,
Machinist, for the Invention of "IMPROVEMENTS IN SCREW WRENCHES OR
SCREW SPANNERS AND IN GAS GRIPS."
Scaled the 13th July 1877, and dated the 6th February 1877.
PROVISIONAL SPECIFICATION left by the said Thomas Chatwin at the
Office of the Commissioners of Patents on the 6th February 1877.
THOMAS CHATWIN, of Birmingham, in the County of Warwick, Machinist.
"IMPROVEMENTS IN SCREW WRENCHES OR SCREW SPANNERS AND IN GAS GRIPS."
My Invention consists of the improvements herein-after described, having for
their object the rapid and accurate adjustment of the moveable jaws of screw
wrenches or screw spanners and gas grips.
My said improvements are in part applicable to those kind of wrenches or
spanners commonly called Budding's spanners. In the said Budding's spanners the
bar of the spanner on which the moveable jaw slides has on its back edge a rack
or a series of inclined teeth, a milled screw or wheel working between a fork at the
back of the moveable jaw engaging with the said rack teeth. By turning the said
milled screw or wheel the moveable jaw may be adjusted the required distance
from the fixed jaw at the head of the wrench or spanner.
For the purpose of permitting of the milled screw or wheel of the said spanner
being rapidly thrown into and out of gear with the rack teeth described I construct
the parts in the following manner:-I mount the milled screw or wheel upon an
axis jointed at one end to the top branch of the fork of the moveable jaw and
capable of turning upon the said joint as a lever. The other and free end of the
lever axis passes through and works in a slot in the bottom branch of the said fork,
the projecting end of the lever axis being provided with a short handle or thumb
plate. By pressing the thumb plate of the lever axis outwards, that is, from the
back edge of the bar, the lever axis takes an inclined position and withdraws or
ungears the milled screw or wheel from the rack teeth. The moveable jaw is now
at liberty to be moved by a sliding motion on the bar, so as to rapidly adjust it at
the required distance from the fixed jaw. On removing the pressure from th
thumb plate end of the lever axis, a spring in the slot in the lower branch of th

page_text: fork bearing against the lever axis presses it into its normal position and re-engages
the milled screw or wheel with the rack teeth, and by now turning the said milled
screw or wheel the fine adjustment of the moveable jaw may be effected.
My Invention consists further of the following improvements in screw wrenches
or screw spanners :-Instead of using a milled screw or wheel for engaging with the
rack teeth on the back edge of the screw wrench or spanner, as before described,
I use a sliding bolt, working in a slot at the back of the moveable jaw. The front
or inner end of this bolt is made into rack teeth corresponding with the rack teeth
on the back edge of the bar. The said toothed bolt is worked by a lever, the said
lever being pressed outwards by a spring so as to press the sliding bolt into gear
with the rack teeth on the bar. By pressing the thumb plate end of the lever
inwards or towards the back of the bar the sliding toothed bolt is moved outwards
and disengaged from the rack teeth on the bar, and the moveable jaw is released
and may be adjusted nearer to or further from the fixed jaw by sliding it on the
bar. After the adjustment of the moveable jaw the lever of the sliding bolt is
released, when the said bolt is pressed inwards and its toothed end made to engage
with the rack teeth on the bar and fix the moveable jaw in its adjusted position.
For the purpose of obtaining a finer adjustment of the moveable jaw than that
afforded by the last described arrangement two independent sliding bolts and levers,
situated side by side, may be employed. In this arrangement the teeth of the
toothed ends of the sliding bolts are not situated opposite one another, but the bases
of the teeth on one bolt are situated equidistant between the bases of the teeth on
the adjacent bolt, the distance between a tooth on one bolt and the next tooth on
the adjacent bolt being equal to one-half the length of a tooth on the back edge of
the bar of the spanner. The result of this differential arrangement of the teeth of.
the sliding bolts is that by pressing alternately one or other of the levers a fine
adjustment of the moveable jaw from the fixed jaw, equal to the length of half a
tooth, may be effected.
When it is required to completely disengage the moveable jaw from the bar for
sliding it on the said bar both levers are simultaneously pressed, so as to withdraw
both bolts from the rack teeth.
The several improvements, herein-before described, may be applied to the adjust-
ment of the moveable jaws of gas grips.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Chatwin in the Great Seal Patent Office on the 31st July
1877.
THOMAS CHATWIN, of Birmingham, in the County of Warwick, Machinist.
"IMPROVEMENTS IN SCREW WRENCHES OR SCREW SPANNERS AND IN GAS GRIPS."
My Invention consists of the improvements herein-after described, having for
their object the rapid and accurate adjustment of the moveable jaws of screw
wrenches or screw spanners and gas grips.
My said improvements are in part applicable to those kinds of wrenches or
spanners commonly called Budding's spanners. In the said Budding's spanners the
bar of the spanner on which the moveable jaw slides has on its back edge a rack
or a series of inclined teeth, a milled screw or wheel working between a fork at the
back of the moveable jaw engaging with the said rack teeth. By turning the said
milled screw or wheel the moveable jaw may be adjusted the required distance
from the fixed jaw at the head of the wrench or spanner.
For the purpose of permitting of the milled screw or wheel of the said spanner
being rapidly thrown into and out of gear with the rack teeth described, I construct
the parts in the following manner:-I mount the milled screw or wheel upon an
axis jointed at one end to the top branch of the fork of the moveable jaw and

page_text: capable of turning upon the said joint, as a lever. The other and free end of the
lever axis passes through and works in a slot in the bottom branch of the said fork,
the projecting end of the lever axis being provided with a short handle or thumb
plate. By pressing the thumb plate of the lever axis outwards, that is, from the
back edge of the bar, the lever axis takes an inclined position and withdraws or
ungears the milled screw or wheel from the rack teeth. The moveable jaw is now
at liberty to be moved by a sliding motion on the bar so as to rapidly adjust it at
the required distance from the fixed jaw. On removing the pressure from the
thumb plate end of the lever axis a spring in the slot in the lower branch of the
fork bearing against the lever axis presses it into its normal position and re-engages
the milled screw or wheel with the rack teeth, and by now turning the said milled
screw or wheel the fine adjustment of the moveable jaw may be effected.
This part of my Invention is illustrated in Figures 1, 2, 3, and 4 of the accom-
panying Drawings; Figure 1 representing a side elevation of a wrench or spanner
with the milled screw or wheel geared to the rack teeth on the bar of the said
wrench or spanner; Figure 2, a longitudinal section of the same; and Figure 3, an
end elevation partly in cross section of the same; Figure 4 is the same view as
Figure 1, with the milled screw or wheel ungeared from the rack teeth and tho
moveable jaw ready to be adjusted.
The same letters of reference indicate the same parts in Figures 1, 2, 3, and 4.
a is the bar of the spanner, and b is the fixed jaw at the head of the said bar;
c is the moveable jaw capable of sliding on the said bar a; d is the milled screw
or wheel situated and working between the fork e, e³, of the moveable jaw c; fare
the rack teeth on the back edge of the bar a, with which rack teeth f the milled
screw or wheel & may be engaged; g is the lever axis on which the milled screw
or wheel & turns loosely. This lever axis turns on the pin or joint and the
enlarged jointed end g is fitted into and has a little play in a hole in the branch e
of the fork of the moveable jaw. The other or free end of the lever axis y of the
milled wheel or screw d works in a slot in the other branch e of the fork (sec
Figure 2). The free end of the lever axis g is furnished with a thumb plate i. By
means of a strong coiled spring in the branch e of the fork (see Figure 2) bearing
upon the lever axis g near its free end, the said axis is pressed down and the milled
screw or wheel forced into gear with the rack teeth f. When the parts of the
spanner are in the respective positions represented in Figures 1, 2, and 3, the milled
screw d is in gear with the rack teeth fand the moveable jaw is locked by the said
.milled screw.
When it is wished to adjust the moveable jaw c nearer to or further from tho
fixed jaw b the thumb plate i of the lever axis g is lifted outwards or from.the back -
edge of the bar a, as illustrated in Figure 4. The said lever axis is thereby made
to take an inclined position and the milled screw or wheel d is ungeared or with-
drawn from the rack teeth f. The moveable jaw is thereby released from the rack
teeth and may be rapidly moved by a sliding motion on a bar a to the required
distance from the fixed jaw b. On removing the pressure from the thumb plate i
of the lever axis g the spring / restores the said axis g to its normal position, as
illustrated in Figures 1, 2, and 3, and re-engages the milled screw d with rack
teeth. The turning of the milled screw d now effects the fine adjustment of the
moveable jaw, as will be understood by an examination of the Drawing.
The improvements described in Budding's spanners may also be applied to the
adjustment of the moveable jaws of gas grips.
My Invention consists further of the following improvements in screw wrenches
or screw spanners :-Instead of using a milled screw or wheel for engaging with
the rack teeth on the back edge of the screw wrench or spanner, as before described
and illustrated, I use a sliding bolt working in a slot at the back of the moveable
jaw. The front or inner end of this bolt is made into rack teeth corresponding with
the rack teeth on the back edge of the bar. The said toothed bolt is worked by a
lever, the said lever being pressed outwards by a spring so as to press the sliding
bolt into gear with the rack teeth on the bar. By pressing the thumb plate end of

page_text: the lever inwards or towards the back of the bar the sliding toothed bolt is moved
outwards and disengaged from the rack teeth on the back of the bar, and the
moveable jaw is released, and may be adjusted nearer to or further from the fixed
jaw by sliding it on the bar. After the adjustment of the moveable jaw the lever
of the sliding bolt is released when the said bolt is pressed inwards, and its toothed
end made to engage with the rack teeth on the bar, and fix the moveable jaw in its
adjusted position.
For the purpose of obtaining a finer adjustment of the moveable jaw than that
afforded by the last described arrangement, two independent sliding bolts and levers
situated side by side may be employed. In this arrangement the teeth of the
toothed ends of the sliding bolts are not situated opposite one another, but the bases
of the teeth on one bolt are situated equidistant between the bases of the teeth on
the adjacent bolt, the distance between a tooth on one bolt and the next tooth on
the adjacent bolt being equal to one half the length of a tooth on the back edge
of the bar of the spanner. The result of this differential arrangement of the teeth of
the sliding bolts is that by pressing alternately one or other of the levers a fine
adjustment of the moveable jaw equal to the length of half a tooth may be effected.
When it is required to completely disengage the moveable jaw from the bar for
sliding it on the said bar both levers are simultaneously pressed so as to withdraw
both bolts from the rack teeth.
This part of my Invention as applied to a wrench or spanner having two inde-
pendent sliding lever bolts with a differential arrangement of teeth is illustrated in
Figures 5, 6, 7, 8, and 9; Figures 5 and 6 representing side elevations partly in
section of the spanner, the toothed bolts being engaged with the rack teeth on the
spanner bar in Figure 5, and disengaged therefrom in Figure 6, and Figure 7 is an
edge view of the spanner; Figure 8 is a side elevation and plan of under side of the
two sliding toothed bolts, and Figure 9 represents the lovers of the same.
The sanie letters of reference indicate the same parts in Figures 5, 6, 7, 8, and 9.
a is the bar of the spanner, b is the fixed jaw, and c is the moveable jaw; d are
the rack teeth on the back edge of the bar a; e, f, are the independent sliding bolts
working side by side in a slot at h in the back of the moveable jaw c. The front
or inner ends of these sliding bolts are made into rack teeth corresponding with
the rack teeth d on the bar a, but the teeth of the two bolts e, f, are arranged with
respect to one another in the manner represented in Figure 8, and as herein-after
particularly explained. The toothed bolts e, f, are worked by the levers e, f,
turning on the common pin or centre g. The inner ends of the said levers c², f
take into slots in the said bolts, and their outer ends are furnished with thumb
plates ef. By means of a coiled spring i under the thumb plate ends of the
levers e, f, the said ends of the levers are pressed outwards or from the bar a, and
their inner ends pressed inwards or towards the bar a, and the sliding toothed
bolts e, f, thereby engaged with the rack teeth d on the bar a as illustrated in
Figure 5. To rapidly adjust the moveable jaw c it is necessary to press down both
of the thumb plates e³, f³, of the levers e, f The two sliding bolts e, f, are
thereby simultaneously lifted from the rack teeth d, as illustrated in Figure 6, and
the moveable jaw is released and may be adjusted nearer to or further from the
fixed jaw b by sliding it on the bar a. After the adjustment of the moveable jaw c
the levers e, f, are released, when the toothed bolts e, f, are pressed inwards by the
action of the spring i bearing on the levers c², f, and the toothed ends of the said
bolts c, f, are made to engage with the rack teeth d, and again fix the moveable
jaw c in its adjusted position as illustrated in Figure 5.
The differential arrangement of the teeth of the sliding bolts e, f, is shown in
Figure 8. By an examination of the said Figure S it will be seen that the teeth of
the sliding bolt e are not arranged opposite the teeth of the sliding bolt f, but the
bases of the teeth on the bolt care situated equidistant between the bases of the
teeth on the adjacent bolt f, the distance between the base of a tooth on one bolt e
and the base of the next tooth on the adjacent bolt of being equal to one half the
length or pitch of a tooth d on the back edge of the bar a. By this differential

page_text: arrangement of the teeth of the two sliding bolts e, f, a fine adjustment of the
moveable jaw c from the fixed jaw b, equal to the length of one half of one of the
teeth d, may be effected by alternately pressing one or other of the levers e³, f*.
Where a differential arrangement of the teeth of the sliding bolts is not required
for producing a fine adjustment of the moveable jaw, a single sliding toothed bolt
with a lever for working it is used in place of the two toothed bolts, described and
represented in the Drawings.
The improvements in screw wrenches or screw spanners herein-before described
and illustrated in Figures 5, 6, 7, 8, and 9, may be applied to the adjustment of the
moveable jaws of gas grips.
Having now described the nature of my Invention and the manner in which
the same is to be performed, I wish it to be understood that I claim as my
Invention,
First. The improvements in screw wrenches or screw spanners of the kind
commonly called Budding's spanners, and in gas grips, berein-before described and
illustrated in Figures 1, 2, 3, and 4, of the accompanying Drawings, that is to say,
mounting the milled screw or wheel of the moveable jaw of the spanner or gas grip
upon a lever axis pressed into its normal position by a spring for the purpose of
rapidly and readily adjusting the said moveable jaw, substantially as described and
illustrated.
Secondly. The improvements in screw wrenches or screw spanners, and in gas
grips herein-before described and illustrated in Figures 5, 6, 7, 8, and 9, of the
accompanying Drawings, that is to say, the construction and arrangement of the
sliding toothed bolt worked by a lever situated in the moveable jaw, the said
toothed bolt engaging with the rack teeth on the bar of the spanner or gas grip
for rapidly and accurately adjusting the noveable jaw of the spanner or gus grip;
also the arrangement of two independent toothed bolts and levers situated side by
side, and the differential arrangement of the teeth of the said toothed bolts for
obtaining a fine adjustment of the moveable jaw of the spanner or gas grip, sub-
stantially as described and illustrated.
In witness whereof, I, the said Thomas Chatwin, have hereunto set my hand
and seal, this Twenty-eighth day of July, in the year of our Lord One
thousand eight hundred and seventy-seven.
Witness,
GEORGE SHAW,
THOMAS CHATWIN. (L.S.)