IMPROVEMENTS IN LOCK STITCH SEWING MACHINES
Year: 1881

page_text: LETTERS PATENT to Carl Pieper, Civil Engineer and Patent Agent, of 109/110,
Gneisenaustrasse, Berlin, S.W., Prussia, for an Invention of" IMPROVEMENTS
IN LOCK STITCH SEWING MACHINES." A communication from Ewald Brünckor,
of Cologne on the Rhine, Prussia.
PROVISIONAL SPECIFICATION left by the said Carl Pieper at the Office of
the Commissioners of Patents on the 7th June 1881.
CARL PIEPER, Civil Engineer and Patent Agent, of 109/110, Gneisenaustrasse,
Berlin, S.W., Prussia. IMPROVEMENTS IN LOCK STITCH SEWING-MACHINES."
[A communication from Ewald Brüncker, of Cologne on the Rhine, Prussia.]
This Invention relates to double-lock-stitch sewing-machines, and the improve-
ments consist, firstly, in placing the lower spool into a round shuttle, to which a
continuous rotative motion is imparted, while the spool does not rotate, and,
secondly, in providing for the upper thread a new kind of tension-device.
The spool for the under thread and a tension-device having slits and holes for
the thread to be passed through are so placed into the shuttle that the latter
may rotate while the thread prevents the spool and its tension from rotating.
The spool of course turns by as much as is necessary for the giving-out of thread
during the sewing-operation.
The shuttle, which has a projecting edge or rim in the middle of its periphery, is
placed in a bearing provided with a slit for the needle and the loop to pass through.
The shuttle is recessed on a part of its circumference, so that on one side of this
recess a hook for catching the loop of the upper thread is formed, and on the other
side a shoulder, against which acts a driver rotated by suitable gearing.
The bearing of the shuttle is fixed in an inclined position to the frame of the
machine, and so that the hook of the shuttle passes close to the needle, but the
shuttle may also be horizontal or vertical.
For the purpose of preventing the thread, which passes between the shuttle
and the driver, from encountering a resistance at the point where the latter is in
contact with the shuttle, a rotating finger at a certain moment enters into a recess
[Price Rd1

page_text: of the shuttle, and throws it forward sufficiently as to cause the driver edge of the
shuttle to become for a short time free of the operating edge of the driver.
On the top of the shuttle there is a tongue attached to the bearing of the shuttle
and reaching to the centre of the latter. This tongue retains part of the thread at
the end of every stitch. The lower surface of the shuttle is or may be fitted with
a small projection serving to enlarge the loop of the upper thread somewhat more
than would otherwise be the case.
The driver, instead of being arranged and acting as stated, may consist of a disk
with three or more driving-pins catching into holes in the bottom of the shuttle.
The said disk is placed at an angle to the latter, so that at least one of the
driving-pins will always be out of gear to let the loop pass completely around the
shuttle.
The tension-device for the upper thread consists of two oval plates connected by
screw-bolts, and between which two clamping plates are placed arranged to touch
each other with their middle part only. The pressure between the clamping-plates
can be regulated by a screw and a spring. The thread is drawn over the screw-bolts
and between the clamping-plates in the shape of the letter S.
The operation of the machine is in general as follows:-
The hook of the rotating shuttle catches the loop of the needle when ascending,
and draws it over the shuttle. When beginning to become slack the loop is partly
taken up by the redescending needle, whereas a part of it is retained by the afore-
said tongue. The latter part is thereupon taken up, and the stitch locked by the
following rotation of the shuttle.

page_text: Figs. 12, 13, and 14. Moreover the bearing D may be formed of a series of anti-
friction rollers of suitable shape. The shuttle is recessed on a part of its circum-
ference in the manner_shown by Figs. 1 and 2, and so that on the left hand side
(with regard to these Figures) a hook o and on the opposite side a shoulder o² are
forined, the object of the hook being to catch the loop of the upper thread, whereas
the shoulder o³ is the point against which the driver y, Fig. 8, acts by its edge ².
This driver consists of a disk fixed on a shaft c', Fig. 11, rotating in bearings 6s
and b, and provided with a projecting part ³, 12, forming a skew surface. The
said part,, fits in such a manner into the recessed part of the shuttle that the
edge (which is vertical to the disk of the driver) will lie in the throat of the
hook o, whereas the edge is in contact with the shoulder o' as already stated
(see also Figs. 7 and 10).
The bed D of the shuttle is by preference fitted in an inclined position to the
bed-plate of the machine, as shown by Figs. 11 and 15, and so that the needle will
pass through the slit q of the bed and along the lower conical side of the shuttle.
But the shuttle may also be arranged in a vertical or a horizontal position if
desired. When placed horizontally the needle should however make a stop during
its upward motion, so as to allow the shuttle to pass freely through the loop.
The driver is rotated by the bevel-wheels 22 and q² (Figs. 3, 11, 15, and 16) the
wheel q² being keyed on the main-shaft u.
Between the shuttle and the driver there is sufficient play for allowing the upper
thread to pass except at the point where the driver by its edge bears against
the shoulder o² of the shuttle. An arrangement is therefore required which acts
instead of the driver y at the moment the thread has to pass between k² and o",
and which separates these points from each other during such passage. The
mechanism serving for this purpose is represented in Fig. 3. It consists of a
finger attached to the shaft u, and so timed with regard to the rotation of the
shuttle that it will at every rotation enter into the recess n² of the shuttle. The
radius of the finger being moreover somewhat larger than the radius drawn
from the axis of A to the recess n², the said finger will during its action accelerate
the rotative speed of A by so much as to cause the required separation of the
points o and . As soon as ' leaves the recess n the driver y again resumes its
operation. If preferred the speed of the end of the finger and the recess n² may
be equal; but in this case the arrangement must be so made that upon entering
into 2 will cause the shuttle to be advanced by as much as is required for causing
the necessary play between. 2 and o².
The loop of the upper thread when passing around the shuttle is operated upon
in the manner to be described hereafter by a tongue ?, Figs. 7, 9, 10, and 11, aud
by a projection e' with which the shuttle may be provided on its lower face. The
tongue r is jointed at s to the shuttle-bed D, and a spring serves to keep it in
its place, while it may be turned aside by the knob t when the spool is to be
exchanged. The point of the tongue reaches to the centre of the shuttle and just
leaves sufficient room between it and the tension B for the passage of the thread.
A modification of the driver is shown by Fig. 18. It consists in this case of a
disky with three or more driving-pins, and it is placed at a certain angle to the
shuttle, so that at least one of the driving-pins will always be out of engagement
to let the loop pass around the shuttle.
The Figures 15 and 16 show the general arrangement of the improved machine.
The needle-bar is worked from the shaft u by an eccentric, eccentric-rod v, rocking-
shaft, and rocker-arm z, coupled by a connecting-link to the bar a'; but any
other known and suitable arrangement may be applied for this purpose.
For imparting to the upper thread the requisite tension, and for allowing this
tension to be regulated with facility the device &', Fig. 16, and shown in Fig. 17
in section may be used. It consists of two disks or plates secured together by the
screws n¹ and o¹, and between which the clamping-plates 7 and 8 and a springing-
plate gare placed. The said plates and are bent so as to allow of being
brought in contact with each other at the middle, and they may be pressed

page_text: together more or less by the screw p'. The thread is drawn in the manner shown
by Fig. 16 over the screw-bolts n and o¹, or the washers with which these are
provided. It will thereby pass between the plates and a', where its friction cau
be increased or diminished by turning the screw p¹.
The operation of the machine is as follows:-
The motion of the needle and of the shuttle are so timed with respect to each
other that the hook o of the shuttle will be close to the needle when the latter after
having descended begins to rise. The hook consequently enters into the loop
formed by the needle and enlarges the same, and when the loop has slipped into
the throat of the hook it will be drawn over the shuttle. The under part of the
loop passes into the space between the driver and the bottom surface of the shuttle,
and here meets the projection «¹ which causes a further oxtension of the loop, sec
Fig. 10. (The said projection e¹ may however be omitted if preferred, as in fact
the machine will also work without it). The throat of the hook o having arrived
at its lowest point, the upper part of the loop slips on the tongue r, as is also
shown in Fig. 10. The loop is now stretched to its greatest extent, so that the
further motion of the shuttle causes it to become slack. This slack is still increased
on account of the leading-edge of the projection e (which tapers out into the
bottom of the shuttle), passing at this period under the lower loop-part and allowing
it to slip off. A part of the slack thus produced is taken up by the needle which
is descending again, whereas a part is retained by the tonguo r in the manner
shown by Fig. 7. Meanwhile the finger h¹ has accelerated the motion of the
shuttle, or thrown it forward by so much as to cause it to become free of the
propelling edge of the driver, in consequence whereof the neodle proceeding in its
descent draws the under part of the loop through the space thus produced. The
entire loop which has now encircled the under thread is thereby brought to the
top of the shuttle, and is there retained by the tongue 7, but it is not taken up
any further by the needle which has finished its down-stroke.
The second rotation of the shuttle now begins. Its hook o again enters into
the loop of the needle, but the tension-apparatus of the upper thread presenting
resistance, the shuttle first of all pulls the spare thread, i.c., the remaining portion
of the first loop off the tongue, and locks the stitch, as represented in Fig. 11.
The following stitches are formed by a repetition of the same process.
If it should be preferred the stitch may be completed at the end of every single
rotation of the shuttle by means of a take-up provided for this purpose.
Having thus described the nature and object of this Invention, and the manner
in which it is to be carried out in practice as communicated to me by my
correspondent, I hereby claim as new and important features of the same,-
1. In a double-lock-stitch sewing-machine the rotating shuttle A, containing the
under-thread spool C together with a suitable tension device, and provided with
a hook o in combination with a bed or bearing D and a driver which causes the
rotation of the shuttle, substantially as and for the purpose described.
2. The combination with the shuttle A rotating within the bed or bearing D of
the tongue r, as herein before specified.
3. The tension-device for the upper thread consisting of the clamping-plates 7³,
and s¹, screw-bolts n' and o¹, springing-plate q' and adjusting-screw p³, as and for
the purpose described.
-
In witness whereof, I, the said Carl Pieper, have hereunto set my hand and
seal, this Twenty first day of November, in the year of our Lord One
CARL PIEPER. (L.S.)