Improvements in Lock-stitch Sewing Machines.
Year: 1894

page_text: Date of Application, 15th Nov., 1894-Accepted, 5th Jan., 1895
COMPLETE SPECIFICATION.
Improvements in Lock-stitch Sewing Machines.
I BENJAMIN WILLCOX of 47 Lincoln's Inn Fields in the County of London
Patent Agent do hereby declare the nature of this invention (which has been
communicated to me from abroad by Heinrich Springmann of 40 Hindersinstrasse 3
Berlin in the Empire of Germany Patent Agent) and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement :-
The object of this invention is to improve the construction, combination and
arrangement of the operative parts of sewing machines so as to obviate the
disadvantages attending that class of sewing machines wherein the loop of the
upper thread is carried round the lower thread by means of a rotary thread-catcher
or loop-taker.
The disadvantages herein referred to arise from the unsatisfactory way in which,
in the machines hitherto constructed, the diameter of the spool or bobbin and that
of the loop-taker
are proportioned in relation, to each other, and to the comparatively
large stroke of the thread tension-device, this being the chief reason that hinders
the proper operation of the machine at a certain speed.
This invention mainly consists in arranging the rotary loop-taker between the
plane of the needle, which is supposed to be situated at right angles to the loop-
taker spindle, and the bearing of the said loop-taker spindle, or in other words,
shifting the plane of the needle from the position which it now occupies to a
position in front of the remaining operative parts of the sewing machine, which
arrangement enables the loop-taker to be so constructed that it may receive a lower
thread spool of the maximum size consistent with a given diameter and at the same
time reducing the capability of the loop of the upper thread, of being enlarged, as
it is carried round the spool-carrier, and also consequently largely reducing the
extent of the movement or stroke of the tension device.
A further important feature of this invention is the provision of means (preferably
in conjunction with the device which serves to retain the spool-carrier in position)
for insuring the result that a sufficiently wide or open loop is at all times presented
to the point of the loop-taker, such means preferably consisting of a loop-retaining
wall or guard plate which as it rises from the needle groove, causes a loop with an
enlargement or "swelling." on one side to be formed, so that the loop-taker point
is under all circumstances compelled to engage in this enlarged or extended loop.
And furthermore it is desirable to provide means for enabling the loops to move
or pass through the mechanism freely and without any friction, which result 'may
be attained by means of suitable recesses or notches made both in the loop taker
and the spool-carrier.
A machine embodying these several improvements in the construction and
arrangement of its operative parts, and in which the threads are subjected to a
very small amount of friction, enables the work to be carried on at the greatest
possible speed and in a perfectly reliable manner, even though thread of a common
or inferior quality be used, while it will very rarely require the supply of lower
thread to be supplemented, or the spool to be changed, whilst the machine is in
operation, and will enable, comparatively speaking, the smallest possible upper
thread loop to be utilised.
And in order that my said invention may be fully understood I shall now proceed

page_text: more particularly to describe the same and for that purpose shall refer to the
several figures on the accompanying drawings which illustrate by way of example
as much as is required of one form of sewing machine constructed according to
this invention.
Figures 1 to 4 shew in elevation, side view cross section and plan the spool carrier
and spool.
Figures 5 to 8 are views of the annular loop-taker.
Figure 9 illustrates the arrangement of the operative parts, shewing the position
which they assume when viewed from the front of the machine and together with
Figures 10 to 13 represents the loop-taker and its accessory parts in some of the
characteristic positions which it is adapted to take in the course of its operation.
The disc-shaped spool 1, on which is wound the lower thread a, is fitted within
a cylindrical spool-carrier 2, provided with a slot 3 (Figures 2 and 4) and a guide
piece 4 for guiding the said thread a, the spool being capable of being readily
removed and replaced, as required, by means of a spring controlled folding device 5.
The spool carrier 2 has a projection 6 on its front side, which serves a double
purpose; firstly, by loosely engaging with the holder 7 (Figure 9) so as to permit
the thread loop to be readily passed over it, it retains the said spool-carrier firmly
in position; and secondly, by presenting a passage or perforation 8 to the needle 9,
it affords a convenient channel or way for the said needle. At the same time its
rear side prevents the formation of a regular loop on both sides of the needle 9,
while causing a loop to form on one side only, a feature which is all the more
advantageous as it compels the point 10 of the loop-taker under all circumstances
to engage in the loop. Thus the projection 6 is a reliable means of ensuring the
formation of the required loop. At its rear part the spool carrier 2 is provided
with a circular guiding annular edge or rib 11, interrupted at a given point by the
break or notch 12. The annular rib 11 is arranged to travel within a guide
groove 13 provided in the cylindrical portion of the loop-taker 14 which by means
of its boss is firmly secured to the shaft from which it receives rotary motion.
Part of the periphery of the loop-taker, preferably of cylindrical shape, extends
into the plane of the needle, and it is this part which forms the loop-taker proper,
as at 16 (Figure 9), the point 10 of which, tapering rearwardly, terminates in the
notch 17, which forms a practically radial extension 18 in the rear wall of the
loop-taker, and the commencement of a cut away portion 19, which in its turn
completes the cylindrical portion 14 of the loop-taker Figure 5. The loop-taker
carries a thread stop 20 at its front edge, the object of which is to deflect the thread
(see Figures 8 and 12). This stop may assume, for example, the shape of a
projection, tappet or bead or that of a notch (as shown in Figure 8^) provided in
the edge of the cylindrical enlargement, in which case the said enlargement
gradually passes off from that notch down to the portion 14. The remaining parts
of the machine such as the cloth-feeder thread-winder or the like form no part of
this invention.
The operation of the machine is as follows:
:-
After the needle 9 has entered the material in front of the loop-taker (passing
through the protecting channel 8, or behind the guard plate 6), it will form, as it
recedes, the loop of the upper thread above referred to,-
-on one side only,-for
the point 10 of the loop taker to engage in (Fig. 10). As the loop-taker continues
to revolve its point 10 further opens the loop (Fig. 11) and places the portion c of
the loop behind the rear wall of the spool carrier (passing for the purpose through
the break 12); while in consequence of the rotation of the loop-taker, the portion d
of the loop slides along the conical edge of the loop-taker and is retained, for the
time being, in the notch 17 situated behind the plane of the rear wall of the spool-
carrier (Figs. 12 and 13). It will be seen from Fig. 12 that as the rotation
continues, the thread stop 20 becomes the means of preventing the portion d of the
loop from further extending in a straight line between the notch 17 and the
stitching aperture, and of deflecting that portion of the loop at a certain angle,
with the result that, instead of taking up its position around the periphery of the

page_text: loop-taker, it will pass over the spool and also, consequently, slip round the lower
thread a (Fig. 13), whereas the loop portion c is carried round the rear wall of the
spool-carrier further and further, being assisted in its progress by a free space 21
left between the rear wall of the spool-carrier and the loop-taker (Fig. 6). In
Fig. 13 the loop is supposed to have been carried round sufficiently far to enable
the thread-taker-in (not shown) to perform its function, and also to enable the loop
itself to be drawn over the loop-taker point and spool-carrier practically without
friction, since, owing to the loop-taker being cut away at 19, and the spool-carrier
at 12, the loop is enabled to issue and be taken up, as the loop-taker continues to
turn (which operative position of the parts is illustrated in Fig. 9). The loop, as it
is about to be fully taken up, is passed over the projection 6 and then takes up its
position about the lower thread a, thereby completing a stitch.
For the further purpose of obviating, in this arrangement of the operative parts
of a sewing-machine, the inconvenience resulting from the loop being soiled, as it is
opened out, by the lubricated guiding rib 11, it is advisable to adopt a special
arrangement of which Figs. 14 to 17 represent one form by way of example.
On both sides of the said guiding rib, there are provided, on the portion of the
periphery of the spool carrier which the liberated loop touches-protecting edges or
ribs 11 and 11 (Fig. 14), the diameter of which is larger than that of the guiding
rib, but which do not come into any lateral contact with the outwardly extending
guide-groove 13 of the loop-taker (Fig. 17), so that the thread does not come into
contact with the oil, and the lubricated guiding rib 11 cannot soil the liberated loop,
which is a very material advantage wherever particularly neat work is required.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. A lock-stitch sewing machine, comprising a loop-taker, the main feature of
which is the means provided for attaining the maximum speed in sewing, while at
the same time ensuring perfect reliability in the performance of the work, by
arranging the rotary loop-taker in the rear of the plane of the needle, the point of
such loop-taker being adapted to enter the upper thread loop which is presented to
it, and which provided for the purpose with an enlargement or "swelling " on one
side and is suitably protected, the said loop-taker point deflecting the said loop
without any appreciable friction by means of a projection or raised portion provided on
the periphery of the said loop-taker, and then reliably throwing off such loop at
an early period of its operation, while causing at the same time, the loop to be
drawn or opened freely and without friction, owing to the provision of suitable
notches or indentations substantially as described.
2. A loop-taker, such as is represented in Figs. 5 to 8, applicable to sewing
machines such as are characterised in the first claiming clause, such loop-taker being
provided internally with a groove, such as 13, for the reception of a guide-rib, such
as 11, projecting from the stationary spool-carrier, such as 2, with a projection,
tappet, bead or notch, such as 20, situated near its edge or margin, for deflecting
and throwing off the upper thread loop, and with cut away portions, such as 18
and 19, for the purpose of facilitating the free passage of the loop, substantially as
set forth.
3. A spool-carrier, such as is shown in Figs. 1 to 4, applicable to sewing machines
of the class described in the first claiming clause such spool-carrier being provided
with a projection 6 situated in front of the needle-channel, such as 8, which
projection by means of its rear wall, causes the loop to be enlarged on one side,
while at the same time affording protection for the loop, a cut away portion or
notch, such as 12, forming a break in the guiding rib, such as 11, for the purpose of
affording a free passage for the loop, as it is drawn, and relieving it from friction,
substantially as described.
4. A modification of the spool-carrier referred to in the third claiming clause,
consisting in the arrangement of protecting ribs or edges, such as 11ª and 11°, on

page_text: both sides of the guiding rib 11, for the purpose of protecting the loop from contact
with lubricated parts, and from being soiled, substantially as described with
reference to Figs. 14 to 17 of the accompanying drawings.
Dated this 15th day of November 1894.
JOHNSONS & WILLCOX,
Agents.