IMPROVEMENTS IN SEWING MACHINES
Year: 1877

page_text: LETTERS PATENT to Thomas Low, of Blairgowrie, in the County of Perth,
North Britain, for the Invention of "IMPROVEMENTS IN SEWING MACHINES."
PROVISIONAL SPECIFICATION left by the said Thomas Low at the Office of
the Commissioners of Patents on the 24th May 1877.
THOMAS LOW, of Blairgowrie, in the County of Perth, North Britain. "IMPROVE-
MENTS IN SEWING MACHINES."
This Invention, which relates to certain improvements in sewing machines, has
for its object to produce seaming stitching more closely resembling hand-sewn
seaming work than stitching of this class has hitherto been produced by the sewing
machine.
The Invention consists in imparting to the feed a combined backwards and
forwards movement, so that immediately after a stitch has been made forwards the
feed moves backwards to a less extent than the length of the forward stitch, thus a
more or less redoubled stitching is produced, which has the effect of imparting
elasticity to the sewing, whereby the stitching will stretch equally or nearly so with
that of hand stitching.
For the purpose of imparting the aforesaid backward and forward movement to
the feed a second shaft is applied to the machine, which is driven at half the speed
of the driving shaft. On the second shaft the cambs or wipers are placed for
imparting to the driving gear of the feed the alternate backward and forward
movement, and it is preferred that the working surfaces of the cambs or wipers,
vizt., those which bear upon the levers of the feed gear, should be made inclined or
conical, so that by varying the position of the cambs or wipers relatively with the
feed gear levers, or that of these levers relatively with the cambs or wipers, the
requisite degree of variation in throw of the wipers or cambs is attained, and the
length of the stitching varied accordingly.
The foregoing arrangements apply to machines in which the main shaft is driven
faster than what is necessary for actuating the feed motion, but in cases where the

page_text: driving shaft or its equivalent is driven more slowly, then the second motion shaft
may be dispensed with.
In any case the essential feature of the Invention is, the arrangement by which
the feed has imparted to it a motion backwards, of a less length than the motion
forwards, so that forward and backward stitches are alternately produced, the
backward stitch being always of less length than the forward stitch.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Thomas Low in the Great Seal Patent Office on the 20th November
1877.
. THOMAS LOW, of Blairgowrie, in the County of Perth, North Britain. "IMPROVE-
MENTS IN SEWING MACHINES."
My said Invention relates-to, certain improvements in sewing machines, and has
for its object to produce seaming stitching more closely resembling hand-sewn
seaming work than stitching of this class hitherto produced by the sewing machine.
The Invention consists in imparting to the feed a combined backwards and
forwards movement, so that immediately after a stitch has been made forwards the
feed moves backwards to a less extent than the length of the forward stitch,
whereby a redoubled stitching is produced:
:
And in order that my said Invention may be properly understood I now proceed
more particularly to set forth the system, mode, or manner in or under which the
same is or may be used or practically carried into effect, reference being had to the
annexed Sheet of Drawings and to the letters and figures marked thereon, that is
to say,-
Figure 1 represents a side elevation of the under mechanism of a sewing machine
having my improvements applied thereto, the bed plate being in section and the
shuttle race and parts unnecessary for the explanation of my Invention being
omitted; Figure 2 is a front elevation of the said under mechanism, part of the
bed plate being in section; and Figure 3 is a plan of the same, with part of the
bed plate broken away.
Figure 4 is a detail of the feed wheel.
Figure 5 is a modification herein-after referred to.
The main shaft which drives the shuttle is marked A.. A second shaft B is
supported and turns on bearings 6 under the bed plate, receiving a motion of
revolution from the toothed wheel a on the shaft A gearing into a toothed wheel b¹
keyed on the shaft B. The wheel b¹ has double the number of teeth that the
wheel a has, whereby the said shaft B is driven at half the speed of the shaft A,
and consequently the needle descends twice during each revolution of the shaft B.
The feed wheel is marked C. It is provided with two feed levers D, D¹, each of
which acts after the manner of the ordinary feed lever, turning on centres d, d¹, in
the brackets c, c¹, but in a manner as herein-after described to move the feed wheel
alternately backward and forward.
The shaft B is furnished with two cams or wipers E, F, which act upon
projections G, H; from the shafts I, J, respectively. These shafts are provided with
other projections K, L, opposite the feed wheel, which projections are connected by

page_text: links k, l, with the tails of the feed levers D, D'. By reason of the shaft B receiving
but one revolution for two descents of the needle, and by virtue of the position of
the cams or wipers E, F, the shafts I, J, receive through their projections G, H,
motions which alternately pull outwards the tails of the feed levers D, D¹, and
cause their heads to bear against and give a feeding motion alternately in either
direction to the feed wheel.
The cam E, before one descent of the needle bearing against the projection G on
the shaft I, and through the link k and feed lever D giving a motion to the feed
wheel in a direction to impart a forward feed to the material being sewn, and the
cam F after the descent of the needle and before its next descent, by bearing against
the projection H on the shaft J, giving through the link and feed lever D¹ a
motion to the feed wheel in the reverse direction, imparts a backward movement to
the material being sewn, and these motions of the feed wheel are repeated alternately,
a forward movement before one descent of the needle, and a backward movement
before the next descent, and so on.
The links k, l, are adjustable by screw nuts m, n, by which the length of throw
of the feed levers may be regulated, the throw of the feed lever D' giving the
backward movement of the feed wheel, being such that the said backward movement
is always less than. the length of the forward movement given by the other
feed lever D. Springs bring the parts to their normal positions when the
projections G, H, are not acted upon by the cams.
The brackets c, c', carrying the centres for the feed levers are each formed with
forked outer extremities e, e¹, so that each embraces the rim of the feed wheel
without interfering with the motion of the other bracket, the one lying inside of
the other, as shewn at Figure 4.
In order to render the machine capable of use for both the ordinary and the
improved stitch, I provide the arrangement of cams shewn in Figure 5. The cams
in this case are formed upon a tubular piece M, which may be slid upon the shaft B,
by the forked lever N, turning upon a centre p, on the framing of the machine,
taking into a groove o in the tubular piece M, so as to allow of the revolution of
the shaft B. The revolution of the tubular piece M with the shaft B is caused by
the feather q on the said shaft taking into a groove in the said tubular piece M.
In addition to the cams or wipers E, F, another wiper O is provided. When the
tubular piece is in the position shewn in the Drawings the wipers E, F, will act
upon the projections and actuate the feed levers so as to give the herein-before
alternate backward and forward movement to the feed wheel, and the machine will
produce my improved stitch.
When it is desired to produce the ordinary stitch the lever N is turned so as to
slide the tubular piece M upon the shaft B until the cams E and F are both clear of
the projections G, H, and consequently do not act upon the feed mechanism.
The wiper O is by the same movement brought into such a position as to act
upon the projection G, and through it upon the feed lever D. As the shaft B
revolves but once for two descents of the needle the said wiper O is necessarily a
double wiper to give two movements to the feed wheel during each revolution, so
that a forward feed is given to the material before each descent of the needle. The
feed lever D' for the backward feed in this case remains inoperative, the feed
lever D for the forward feed only being operated upon, and thus the ordinary stitch
is produced.
The improved stitch herein-before described has the effect of imparting elasticity
to the sewing, whereby the stitching will not restrain the stretching of the fabric
sewn, but will have equal elasticity with the said fabric.
Having now described and particularly ascertained the nature of my said
Invention, and having shewn means by which the same may be practically carried
into effect, I desire to observe in conclusion that the kind of stitching herein-before
described may be produced by means of several modified arrangements of the
mechanisin, which I have shewn in the appended Drawings, so long as the alternate
backward and forward movements of the feed wheel or equivalent feed apparatus

page_text: are maintained. 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,
First. The feed mechanism for sewing machines wherein the feed wheel or its
equivalent feeder is moved alternately backwards and forwards, and with it the
cloth being sewn, for the purpose of producing the stitch, substantially as herein-
before described.
Second. The mechanical arrangements or their equivalent, as herein-before
described and illustrated in Figure 5 of the accompanying Drawings, for converting
the feed mechanism of sewing machines into the ordinary single feed or alternate
backwards and forwards feed as required.
In witness whereof, I, the said Thomas Low, have hereunto set my hand and
seal, this Fifteenth day of November, in the year of our Lord One thousand
eight hundred and seventy-seven.