IMPROVEMENTS IN SEWING MACHINES
Year: 1861

page_text: LETTERS PATENT to William McIntyre Cranston, of No. 58, King William
Street, in the City of London, for the Invention of "IMPROVEMENTS IN
SEWING MACHINES."-A communication from abroad by James Frost, of
the City of New York, in the United States of America.
COMPLETE SPECIFICATION filed by the said William McIntyre Cranston
at the Office of the Commissioners of Patents, with his Petition and
Declaration, on the 22nd March 1861, pursuant the 9th Section of the
Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
MCINTYRE CRANSTON, of 58, King William Street, in the City of London, send
greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
SEWING MACHINES," and have petitioned Her Majesty to grant unto me, my
executors, administrators, and assigns, Her Royal Letters Patent for the
same, and have made solemn declaration that it has been communicated
to me from abroad by James Frost, of the City of New York, in the United
States of America.
NOW KNOW YE, that I, the said William McIntyre Cranston, do hereby
declare that the following, Complete Specification under my hand and seal
fully describes and ascertains the nature of the said Invention, and in what
manner the same is to be performed, in and by the following statement and
accompanying Drawings (that is to say):-
This Invention relates to the manner of communicating motion to the
needle of a sewing machine, giving it the proper periods of rest and motion,
or the requisite irregular motion, whereby the needle is moved rapidly where

page_text: there is a little resistance, slower when passing through the material, and caused
to pause
for a short period after it has risen sufficiently to slack the thread,
thus adopting the motion to the resistance, and giving time for the passage
of the shuttle through the loop of the thread by means of a certain
combination and arrangements of levers and connections, or by a slotted
arm driven by a rod connected to a crank pin and sliding in a swivel guide.
This Invention relates to the means of imparting a proper motion to the
needle bar in those machines in which a shuttle is used.
The nature of this Invention consists in the use of a slotted arm driven in
the manner fully explained below, by a rod connected to a crank pin, and
sliding in a swivel guide, the whole combined and serving in the relations to
each other explained below for the purpose of giving the requisite irregular
motion to the needle bar, whereby the needle is moved rapidly where there
is little resistance, slower when passing through the material, aud caused
to pause for a short period of time to slack the thread, thus adopting its motion
to the resistance, and giving time for the passage of the shuttle through the
loop of the thread.
Plate 1st. Fig. 1 to 9 inclusive are Diagrams showing the motions of the
parts; Fig. 10 is a view of the novel portion of the back end of the machine;
Fig. 11 is a side view of the same, and. Fig. 12 is a view of the front of
the machine, or the end opposite to that shown in Fig. 10.
Plate 2nd.-Fig. 1st is a rear view of a portion of a sewing machine,
shewing Fig. 2 is a side elevation, and Fig. 3 is a front elevation of the
same; Fig. 4 to 12 are Diagrams illustrating the motion of the parts.
Plate 1st. A is the rocking shaft which gives motion to the needle bar, and
A¹ is an arm fixed thereon. B is the needle bar, and C is a link connecting
A to B; D is another arm fixed on A. It is slotted as represented. The
motion is received from a crank, the path of which is shown by the dotted
line E in the Diagrams Figs. 1 to 9 inclusive; F is a bar attached to the crank
E, and sliding through a swivel guide G near its upper extremity. The
swivel guide G is attached to the frame of the machine, and the only motion
of which it is susceptible is a simple oscillation or rocking as the bar F
changes its inclination by the rotation of the crank. H is a pin or projection
fixed on the side of the bar F, and travelling loosely in the slot in D as
represented. The working of the bar F, by the action of the crank E,
modified by the effect of the guide G, causes the pin H to move in a peculiarly
curved line analogous in form to the Arabic numeral 8. This motion of H is
shown very clearly by Fig. 9. The slot is of such width as to allow H to
travel freely therein. It follows that while the curve and the position of the

page_text: slot coincide with the motion of H, no motion is communicated thereto by the
rotation of the crank E, but whenever the slot is in any other position motion
is communicated. I curve the lower portion of the slot to correspond with
the motion of H from a to s (see Fig. 9), and arrange the parts relatively to
each other in the manner represented. By turning the crank E the needle
bar is caused to rise and fall with precisely the motion desired, the arm D
descending while the crank E revolves from M to P, then ascending while
it moves from P to Q, which is just sufficient to slacken and bend the thread,
then standing still while the crank travels from Q to S, and then rising while
it completes the circuit; by so curving the slot that the position of the slot
does not exactly coincide with the travel of H during its motion from q
to s, the needle bar can be caused to descend slightly instead of remaining
quiet while the shuttle is passing; or by varying the curve of the slot a little
in the opposite direction the needle will continue to ascend though very slowly.
Within certain limits either of these motions will serve the purpose. The
Drawings represent the curve as an arc of a circle which is not exactly the
correct curve, and which allows the needle to rise slowly instead of standing
quiet during the interval it should rest, but it is suficiently near the truth to
illustrate the operation of my Invention.
Plate 2nd. A is the frame of an ordinary sewing machine, and B the main
shaft; C is a crank pin on B, from which I derive the motion of the needle
bar by means of the following mechanism :-To the crank C, I connect the
lever D, which is hinged at a point d near its centre to a radius bar E attached
to a point e upon the frame. This connection is such that the lever D is free
to move at the point d only in the curve described by the radius bar E, while
the lower end is moved in a circle by the crank C. The effect of this com-
pound motion is to give the upper end d' of D a motion in an irregular curve
approximating the form of a spherical triangle. This is shown in Fig. 4,
which represents the positions of the parts at every sixteenth of the revolution
of C. Through the upper part of the frame A, I pass a shaft F, having on its
rear end a crank or lever G, which is connected to d¹ by a short link H. At
the other end of F is another crank I, placed at an angle to G, as shown in
dotted lines in Figs. 5 to 12, inclusive. This crank I is connected to the
needle bar K by a link i, as shown in Fig. 3. The crank G and link H are
arranged relatively to the curved triangular path described by d¹ in such a
manner that at the point shown in Figs. 1, 6, and 7, the curve described by D
exactly coincides with the arc of a circle described with the end of G for a
centre, and with H for a radius, from which it follows that during that portion
of the movement of D, the shaft F, and consequently the needle bar, is at rest,

page_text: while at all other points it has a motion more or less rapid in proportion as
the path of d¹is nearer to or further from the centre of F. The point of rest
of G may be made to correspond with any desired position of the needle bar K
by adjusting the relative. position of the crank I; but in the position shown in
the Drawings it occurs just after the needle has commenced to rise, or when
the thread is slackened sufficiently for the passage of the shuttle through the
loop. In this position, the fastest motion of K is when it is passing through
the last part of its upward movement, when a quick motion is required for the
purpose of releasing the thread from the shuttle before the return movement
of the latter, while the slowest motion is during the passage of the needle
through the cloth. The position of the needle bar relatively to that of the
crank C at each eighth of the revolution is shown by P in Figs. 5 to 12,
inclusive. By varying the proportions and positions of the several parts
different motions may be given to the needle bar, causing the needle to pause
longer, or even to return somewhat on its course instead of standing absolutely
stationary during the passage of the shuttle.. By making the crank G of a
greater length than represented, and placing it in a higher position with a
relative proportion in the other parts of the combination, the shaft F
caused to vibrate instead of revolving, but it will in such case give the same
motion to the needle bar I have herein described, and I consider it only an
equivalent therefor. These motions are by these means produced in a manner
almost noiseless, and with very little friction.
may
مرا
Having now fully described this Invention, what I claim and desire to
secure by Letters Patent is,-
The employment of the slotted arm, Plate 1st, D, the rod and pin F, H,
and the swiveling guide G, or their respective equivalents, in combination with
each other and with the crank E.
I also claim the combination and arrangement of the crank C, Plate 2nd,
lever D, radius bar E, crank or lever G, and connection H, for the purpose of
giving the proper periods of rest and motion to the needle of a sewing machine,
substantially as herein described.
In witness whereof, I, the said William McIntyre Cranston, have here-
unto set my hand and seal, this Twenty-second day of March, in the
year of our Lord One thousand eight hundred and sixty-one.
CRANSTON
LIAM MCINTYRE CRANSTON.
(L.C.)