IMPROVEMENTS IN CRAMPS
Year: 1877

page_text: LETTERS PATENT to John Malin, of Sheffield, in the County of York, Engineer,
for the Invention of "IMPROVEMENTS IN CRAMPS."
PROVISIONAL SPECIFICATION left by the said John Malin at the Office
of the Commissioners of Patents on the 18th December 1877.
JOHN MALIN, of Sheffield, in the County of York, Engineer.
IN CRAMPS."
"IMPROVEMENTS
My Invention relates to improvements in cramps, such as are used by carpenters,
builders, shipwrights, and others, and the object of such improvements is to obtain
increased facility in adjusting the cramp to its work and to reduce the cost of
manufacture.
In carrying out my Invention in the manufacture of an ordinary carpenter's
cramp, for example, I provide a bar, by preference of iron, and of proportionate
dimensions, having at one end a projecting head with the usual tightening screw,
but in lieu of pin holes, which weaken the bar, being made down the centre of the
bar for the purpose of securing the loose head at regular distances, I form, by means
of punching or other suitable means, a series of bracket-shaped teeth, having their
upper edges at right angles to the line of the bar. The loose or sliding head is
provided with a slot or opening corresponding at one end with the size, or nearly
so, of the bar, on which it slides easily from end to end; the lower end of the
opening is enlarged to allow of an amount of side movement, rather more in extent
than the depth of the teeth in the bar. A fixed jaw being part of the loose head is
also provided with teeth similar to and engaging with those formed in the bar.
These teeth are held in contact with those of the bar by the action of a spring,
which is let into a recess formed in the back of the loose head, and which presses
against the back of the bar.
In order to release the loose or sliding head from the teeth of the bar it is simply
necessary to press the back of the sliding head close to the bar, thereby compressing
the spring and disengaging the teeth; the head can then be slipped along the bar

page_text: to the desired position, and on the pressure being removed the action of the spring
draws the teeth into gear with each other. The pressure of the screw on to the
work held between the two heads has simply a tendency to hold the teeth more
firmly together.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Malin in the Great Seal Patent Office on the 18th June
1878.
JOHN MALIN, of Sheffield, in the County of York, Engineer. "IMPROVEMENTS IN
CRAMPS."
My said Invention relates to improvements in cramps, such as are used by car-
penters, builders, shipwrights, and others, and the object of such improvements is
to obtain increased facility in adjusting the cramp to its work and to reduce the
cost of manufacture.
The accompanying Drawings illustrate several modes of carrying out the said
Invention, which I shall now proceed to describe, the same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 of the Drawings represents a side elevation of a "sash" cramp or light
joiner's cramp constructed according to my said Invention; Figure 2 is a similar
view of a heavy carpenter's cramp or ship cramp.
Figure 3 is an enlarged detail view, partly in section, shewing the sliding head
constructed according to one modification, and applied to a portion of the bar of a
cramp.
Figure 4 is a detail elevation of the sliding head constructed according to another
modification, and also applied to a portion of the bar of a cramp.
Figure 5 is an elevation of a portion of the bar of a cramp illustrating another
modification of its construction.
In carrying out my said Invention I provide a bar a, having at one end a pro-
jecting head b with the usual tightening screw c, but in lieu of pin holes, which
weaken the bar, being made down the centre of the bar for the purpose of securing
the loose or sliding head d at regular distances, I form, by means of punching or
other suitable means, a series of teeth, serrations, or indentations e, either throughout
the acting length of the bar, as shewn in Figures 1 to 4, or at intervals, as shewn
in Figure 5. The loose or sliding head d is provided with a slot or opening corre-
sponding, or nearly so, at the end f (see detail Figure 3) with the size of the bar a,
on which it slides easily from end to end, but the lower end of the opening is
enlarged, as shewn at g, to allow of an amount of side movement rather more in
extent than the depth of the teeth, serrations, or indentations in the bar, and which
movement is controlled by a spring h. A fixed jaw or detent i forming part of the
loose or sliding head d is also provided
serrations, or projections e¹, similar to
indentions e formed in the bar a.
with a tooth or projection or with teeth,
and engaging with the teeth, serrations, or
The teeth, serrations, or projections e' are held

page_text: in contact with the teeth, serrations, or indentations e of the bar by the action of
the spring h, which is let into a recess formed in the back of the loose or sliding
head d, and which presses against the back of the bar.
In order to release the loose or sliding head d from the teeth, serrations, or
indentations e of the bar, it is simply necessary to press the back of the loose or
sliding head d close to the bar, thereby compressing the spring h and disengaging
the jaw or detent i; the head d can then be slipped along the bar to the desired
position, and on the pressure being removed the action of the spring / draws the
jaw or detent i into gear with the teeth, serrations, or indentations on the bar. The
pressure of the screw c on to the work held between the two heads has simply &
tendency to hold the parts more firmly together.
The jaw or detent i may be made separate from the sliding head d, and con-
nected thereto by a pink (as shown in Figure 4) so as to be capable of turning
thereon, a spring h acting against the tail end of the detent being employed in
order to maintain it in position. In this case no side play is allowed, as in the
arrangement of sliding head shewn in Figure 3.
The bar a is by preference made of steel, either rolled] (the teeth, serrations, or
indentations in that case being formed by punching or otherwise) or cast to shape
in the usual manner.
The form of the teeth, serrations, or indentations may be varied according to
circumstances.
Having now described and particularly ascertained the nature of my said Inven-
tion, and the manner in which the same is or may be used or carried into effect, I
would observe in conclusion that what I consider to be novel and original, and
therefore claim as the Invention secured to me by the herein-before in part recited
Letters Patent is, constructing the bar of cramps with teeth, serrations, or inden-
tations, and employing in combination theree with a sliding head, having a jaw or
detent capable of engaging with the said teeth, serrations, or indentations, sub-
stantially as herein-before described.
In witness whereof, I, the said John Malin, have to this my Specification set
my hand and seal, this Fifteenth day of June, One thousand eight hundred
and seventy-eight.
JOHN MALIN. (L.S.)