Improvements in Sewing Machines.
Year: 1898

page_text: Date of Application, 24th May, 1898-Accepted, 9th July, 1898
COMPLETE SPECIFICATION.
Improvements in Sewing Machines.
I, JAMES YATE JOHNSON, of 47, Lincoln's Inn Fields, in the County of
London, Gentleman, do hereby declare the nature of this invention (which has
been communicated to me from abroad by Walter Shaw, of Boston, Massachusetts,
Trustee of the Manufacturers' Shoe Machinery Association, of same place), and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :—
65
This invention relates to that class of sewing machines in which a hook-needle
is used; and it consists of a device termed a loop-keeper" which enters the loop
of thread as it is drawn out by the needle; which loop-keeper while the needle is
taking a fresh loop, holds so much of the previous loop as is needed to form about
one half of the fresh loop; and which when the needle is drawing out the fresh
loop through the work, supplies portion of the previous loop, to the needle, so as
to furnish about one half of the thread needed for the fresh loop, the remaining
half being supplied from the spool or other source of thread supply. The loop-
keeper is thus in effect a measurer which by holding the previously formed loop
at a certain point and then supplying it to the needle as it draws out a fresh
loop furnishes to the said loop the needed length of thread, to prevent the thread
in the hook of the needle (as the latter is drawing the fresh loop through the work)
from moving or dragging cross-wise in the hook, which action, as is well known
frequently results in the abrasion and cutting of the thread.
«
"
When the sewing mechanism is one in which a "take-up" is used to set or tighten
the stitch in the work, the loop-keeper also has the function of receiving and
resisting the strain exercised by the take-up, thus preventing that strain from
acting upon the needle. The final strain occasioned by the action of the take-up
comes upon the loop-keeper at the time it is at rest in the position it occupies when
holding the half-loop or length of thread needed to furnish about one half of the
fresh loop in process of formation.
The invention will be readily understood by reference to the accompanying
drawings, in which:
Figure 1 is a side elevation of so much of a sewing machine as is necessary for
the purpose of explaining the invention.
Figures 2 to 5 inclusive illustrate the operation of the loop-keeper, in its
different stages of operation and
Figure 6 is a table shewing the relation of the driving mechanism for the loop-
keeper, and the needle, during each revolution of the main shaft in the machine
shewn.
The particular form of machine which has been selected for the purpose of
illustrating the invention, is shewn as being employed for sewing the welts to boots
or shoes, many details of the machine being omitted from the drawings, only such
of the principal parts being retained as is sufficient for the purpose of explanation.
The awl (except in so far as it is shewn diagrammatically in Figures 2 to 5), the
channel gage, and the looper (except so far as is represented in the conical passage
for the awl and needle in the lower end of the back gage B) are omitted. Any
suitable form of looper can be used.

page_text: D is the needle; B is the back gauge; 37 and 35 constitute what is termed the
multiple purchase take-up" (although the present improvement is not limited to
this particular form of take-up); and 38 is the tension device.
The loop-keeper A is fast on a rock shaft a the rocking of which gives the keeper
its proper motions.
This device constitutes the essential feature of the present invention. In the
particular combination herein illustrated the loop-keeper serves to relieve the
needle D of the strain, which otherwise would be brought upon it, when the take-
up is setting or tightening the stitch, but it also has the added function of a
measurer.
The position occupied by the loop-keeper with relation to the needle is clearly
illustrated in the drawings and their relative movements will be readily understood
from the table in Figure 6 taken in connection with Figures 2-5 inclusive.
In Figure 2 the needle is shewn as having nearly completed its up stroke in
drawing out a loop; and the loop-keeper A is shewn in its lowermost position.
During the remainder of the up stroke of the needle (see right hand end of the
table in Figure 6) the keeper makes its up stroke, entering and engaging the loop.
Now following the table from the left-hand end it will be seen that the keeper
holds the loop in this position a short time while the needle commences its descent.
In Figure 3 the needle is shewn as having moved down a short distance. The
loop keeper commences its descent also, and continues to desceud until about half-
way down, when it rests. During this movement of the loop keeper the take-up
comes into operation taking up about of the loop formed by the said loop keeper,
and giving the final strain requisite to set or tighten the stitch when the loop
keepor comes to rest.
The needle having completed its down stroke, takes a fresh loop and theu recedes
on its up stroke until its hook reaches the work (the parts being represented in this
position in Figure 4) the loop keeper having held back so much of the old loop, as
will be equal in length to about one half of the new loop now in process of being
drawn out by the needle.
The needle continuing its up stroke, pulls this new loop through the work and
the loop keeper moves towards the work as seen in Figure 5, thereby supplying the
needle with thread for one leg of the loop, in quantity sufficient to prevent drag of
the thread through the hook-the thread for the other leg of the loop being drawn
from the spool or other main source of thread supply. This movement continues
until the loop keeper has give up all of its thread, at which time the needle will
have nearly completed its up stroke the parts at this time resuming the position
shewn in Figure 2.
The loop keeper A is represented in Figure 1 as being operated by a rock shaft
oscillated by a cam through a connecting rod, but it is obvious that these details
may be widely varied without departing from this invention. The form of loop
keeper may also be varied so long as it will act to engage the loop drawn out by
the hooked needle, hold back or retain such length of the loop as is needed for one
leg of the next succeeding loop, and then give up this length of the old loop to form
part of the fresh loop drawn out by the needle.
The invention is shewn as applied to that class of hook-needle sewing machines
in which the stitch is tightened by the take up, but it is equally applicable to
machines in which ordinarily the needle tightens the stitch by a final pull on the
loop, the thread leading from the spool or source of supply being then held.
When the invention is embodied in machines of the latter class, the final pull
upon the loop to tighten the stitch will best be given by the loop keeper instead of
the needle the keeper having substantially the same sequence of movements as in
the other case, so far as its "measuring" function is concerned; but the device
which in the one class of machines would act as a take up, would, in the other class
act simply to draw back the surplus or slack of the loop given up by the loop-
keeper in moving from its highest to its middle position, that is the position repre-
sented in Figure 4.

page_text: The stroke of the loop keeper can be adjusted so as to cause it to pull the loop to
tighten the stitch; and it is obvious that it is a matter of adjustment of the range
of movement of the take up, whether it shall merely take up the slack or surplus
thread given up by the loop keeper, in moving down to the position shewn in
Figure 4, or whether in addition to taking up this slack, it shall exercise the further
pull needed to set or tighten the stitch.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. The combination with the booked needle and looper, of a loop keeper, situated
on that side of the work to which the loop is pulled by the needle, and having a
movement to and from the work with an intermediate period of rest during its loop
releasing movement, and actuating mechanism therefor, timed in their movements
relatively to, and operating in connection with, the needle, substantially as des-
cribed, and means by which the slack, or surplus thread of the old loop supplied by
the loop keeper before it attains its intermediate position of rest, is drawn back to
the side of the work on which the needle takes its loop, before the needle pulls the
new loop through the work, all substantially as hereinbefore described.
2. The combination with the hooked needle and its looper and the take up for
tightening the stitch, of a loop-keeper, situated on that side of the work to which
the loop is pulled by the needle, having a movement to and from the work with an
intermediate period of rest during its loop releasing movement, and actuating
mechanism therefor, timed in their movements relatively to the needle and take up
substantially as described, whereby the loop keeper retains that portion of the old
loop needed to furnish the requisite supply of thread to one leg of the new loop, and
at the same time takes the strain occasioned by the action of the take up in setting
or tightening the stitch, substantially as herein before described.
Dated this 24th day
1000
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C., Agents.