IMPROVEMENTS IN WRENCHES OR SCREW KEYS."
Year: 1864

page_text: LETTERS PATENT to Robert Maclean Black, of Glasgow, in the County
of Lanark, North Britain, Commission Merchant, for the Invention of
"IMPROVEMENTS IN WRENCHES OR SCREW KEYS."
PROVISIONAL SPECIFICATION left by the said Robert Maclean Black
at the Office of the Commissioners of Patents, with his Petition, on the
23rd August 1864.
I, ROBERT MACLEAN BLACK, of Glasgow, in the County of Lanark, North
Britain, Commission Merchant, do hereby declare the nature of the said
Invention of "IMPROVEMENTS IN WRENCHES OR SCREW KEYS," to be as follows,
that is to say:
This Invention relates to improvements in wrenches or screw keys, and is
designed to render such tools conveniently self-adjusting, simple, and strong
in construction, and durable in use.
In carrying out the Invention two movable jaw pieces are arranged so
that their gripping faces approach each other when the handle is turned,
which result is obtained by fitting the jaw pieces so that they can move about
different centres.
In one simple modification the solid jaw is formed with two strong pins
projecting downwards, and on these pins the jaw. pieces are fitted loosely,

page_text: being made with their inner faces flat or otherwise shaped to adapt
themselves to the nut, bolt, pipe, or other article to be turned by the wrench
or screw key.
In other modifications the movable jaw pieces are fitted to the fixed jaws
with dovetail or other grooves and feathers, such grooves being curved to the
centres about which the jaw pieces are to move. The handle of the tool may
be shaped like a brace, or it may be curved out of the plane of the jaws
instead of being in that plane, as in common wrenches or screw keys.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Maclean Black in the Great Seal Patent Office on
the 23rd February 1865.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
MACLEAN BLACK, of Glasgow, in the County of Lanark, North Britain, Com-
mission Merchant, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of August, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-eighth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Robert Maclean Black, Her special licence that I, the
said Robert Maclean Black, my executors, administrators, and assigns, or
such others as 1, the said Robert Maclean Black, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from time
to time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN WRENCHES OR SCREW KEYS," upon the condition
(amongst others) that I, the said Robert Maclean Black, my executors or
administrators, by an instrument in writing under my, or their, or one of their
hands and scals, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within
six calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Robert Maclean Black, do hereby
declare the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the

page_text: following statement in writing, reference being had to the accompanying
Drawings, and to the letters and figures marked thereon, that is to say :-
My said Invention relates to improvements designed to render wrenches
or screw keys conveniently self-adjusting, simple, and strong in construcion,
and durable in use.
In carrying out my Invention two movable jaw pieces are arranged
so that their gripping faces approach each other when the handle is turned,
which result is obtained by fitting the said jaw pieces so that they can move
about different centres in a plane at right angles to their faces.
And in order that my said Invention may be properly understood, I have
hereunto appended a Sheet of explanatory Drawings to be herein-after
referred to, and representing three modifications of wrenches or screw keys
embodying my improvements.
In one simple modification, shown in elevation in Figure 1, and in section
in Figure 2, the jaw 1 is made with two strong pins 2 projecting down-
wards, and on these pins the jaw pieces 3 are fitted loosely, being mado
with their inner faces flat (or otherwise shaped) to adapt themselves
to the nut 4, bolt, pipe, or other article to be turned by the wrench or
screw key.
In another modification, shown in elevation in Figure 3, and in section
in Figure 4, the movable jaw pieces 3 are fitted to the jaws 2 with dovetail
or other equivalent grooves and feathers, such grooves being curved to the
centres about which the jaw pieces 3 are to move.
Figure 5 is a plan, and Figure 6 is a section of another modification, in
which the movable jaw pieces 3 are fitted with dovetail grooves and
feathers, as in the modification shown in Figures 3 and 4, but whilst.in one
case the grooves are convex towards each other, they are concave towards
each other in the other case, Figure 5, but the resulting action is the same in
both cases.
The handle of the tool may be shaped like a brace, as shown in Figures 1
and 3, or it may be in the plane of the jaws, as in Figure 5, or, again, it
may be similar to that shown in Figure 5, but curved out of the plane of
the jaws.
In Figure 1 the jaw pieces 8 are represented as held by rivetting over the
ends of the pins 2, the holes in the jaw pieces being slightly countersunk
for the purpose. In the arrangement shown in Figures 3 and 4, the jaw
pieces are prevented from coming off by pins screwed into the ends
of the dovetail grooves. In the arrangement shown in Figures 5 and 6
the jaw pieces 3 are prevented from falling out by a cover plate 5, which

page_text: is shaped with a dovetail, and is screwed on after the jaw pieces are
inserted.
The action of the tool depends upon geometrical principles, and will be
easily apprehended from the Drawing.
In Figure 5 the jaw pieces 3 are shown in different positions, and gripping
nuts of different sizes.
Taving thus particularly described my said Invention, and the manner
in which the same is or may be performed, I have to state that I do not
restrict myself to the precise details herein described or delineated; but
that what I believe to be novel and original, and claim as the Invention
secured to me by the herein-before in part recited Letters Patent is, the
construction of wrenches or screw keys with jaw pieces movable about
different centres and with gripping faces at right angles to the plane of
their motion, and which faces approach each other when the tool is
turned with a nut or the like between them, substantially as herein-beforo
described.
In witness whereof, I, the said Robert Maclean Black, have hereunto
set my hand and seal, this Twenty-second day of February, in the
year of our Lord One thousand eight hundred and sixty-five.
Witness,
EDMUND HUNT,
Patent Agent,
28, St. Enoch Square,
Glasgow.
ROBERT M. BLACK. (L.B.)