WITH ROTARY HOOK "IMPROVEMENTS IN SEWING-MACHINES
Year: 1883

page_text: "
LETTERS PATENT to Carl Pieper, Civil Engineer and Patent Agent, resident
at 109-110. Gneisenaustrasse, Berlin S.W., Prussia, for an Invention of
a
WITH ROTARY HOOK
"IMPROVEMENTS IN SEWING-MACHINES
nication to me from Rudolf Gritzner of Dürlach, grand-duchy of Baden,
German Empire.
commu-
PROVISIONAL SPECIFICATION left by the said Carl Pieper at the Office
of the Commissioners of Patents on the 4th October 1883.
CARL PIEPER, Civil Engineer and Patent-Agent, resident at 109/110 Gneisenau-
Strasse, Berlin S.W. Prussia, "IMPROVEMENTS IN SEWING-MACHINES WITH ROTARY
HOOK (a communication to me from Rudolf Gritzner of Durlach, grand-duchy of
Baden, German Empire)
»
This invention relates to improvements in sewing-machines with rotary hook and
has reference firstly to the arrangement of the spool for the under thread, secondly
to the feeding device and thirdly to the take-up of the upper thread.
According to the first part of my invention I construct the said machines in such
a manner that the spool for the under thread can be made of considerably larger
dimensions than hitherto and that the casing of the spool rests only upon a point
whereby the passage of the loop of the upper thread is facilitated and rupture of
the thread is obviated. For this purpose the casing with the spool is loosely
inserted in a suitable holder attached to the bed-plate of the machine. It is
provided at the top with a projection having a hole in it through which the thread
of the spool is passed, and at the bottom it has a projecting lip. Both, the
projection and the lip enter into recesses in the holder, thereby maintaining the
casing in an upright position. The whole weight of the casing and the spool is
carried on the extreme end of the lip. The line of gravity passing through the
bearing point does not coïncide with the vertical centre line of the spool and casing,
but lies before the same. The loop, therefore, falling off the rotary hook before the
central position is reached, will with certainty be drawn around the casing. To
allow the loop to fall of previous to reaching the vertical centre line, the end of
the rotary hook is bent slightly towards the centre of the disc on which it is
formed.
In order to permit the loop of the upper thread to pass the bearing point or tip
of the casing, the latter must be lifted. This is effected by adjusting the tension of

page_text: the under thread in such a manner that it overcomes the weight of the casing and
the spool or, in other words, that during the time the thread necessary for
completing the stitch is drawn up, the casing will be lifted and held in a suspended
position by the under thread so that the loop may easily pass the said tip. Then
the loop is drawn up rapidly; but it cannot yet pass the projection hereinbefore
mentioned which bears against a surface adapted to limit the lift of the casing. It
is necessary therefor to bring the said caising down again into its normal position.
To this end the main shaft, or preferably the feed bar of the machine, is provided
with suitable means as, for instance, a lever which either operates upon the
projection or directly upon the thread, thereby pulling out the latter and causing
the casing to drop so that the loop is then free to pass the projection.
By the arrangement of a loop guiding device it is prevented that both halves of
the loop pass on the same side of the casing, and thus any failure of stitches is
obviated. Moreover, a part of the casing is cut away on one side in order to permit
the loop to be pulled up rapidly.
The projection which maintains the casing in an upright position has also for its
object to hold out of the path of the rotary hook the under thread passing through
it and thus to prevent rupture or other accidents.
A flat spring or the like pivoted to the casing may be provided for in order to
hold the spool in its position.
The rotary hook is bent and shaped in such a manner that, when the loop has
been seized and is carried around, the part thereof next to the needle will move
out of the way while the other or distant part will be retained at the bottom of a
guiding piece by which the loop is prevented from becoming entangled in the
rotating hook.
When the loop is fully opened, which in consequence of the peculiar form of the
rotary hook is effected with rapidity, and the guide piece by its rotation arrives at
a certain lower position, the loop falls off and is drawn around the casing of the
spool.
The second part of my invention has for its object to provide means whereby the
feed bar, after having moved the fabric the requisite distance for an other stitch, is
always returned to the same starting point in proximity to the needle, however
long its stroke for spacing the stitches may be. In order to effect this I put in
operation the feed bar by a vibrating lever the free end of which bears against and
is acted upon by a conical sleeve mounted eccentrically on the shaft and arranged
to rotate with the same. This sleeve or cone is capable of adjustment longitudinally,
so that by varying its position with regard to the vibrating lever I am enabled to
regulate the movements of the feed bar according to the length of the stitches to
be formed. Moreover, one side of the cone is parallel to the axis of rotation.
When this parallel side comes into contact with the vibrating lever, the feed bar
having completed its stroke, reaches its starting position and is again ready for
feeding the fabric by another step forward.-Now, as the said contact takes place
once at each revolution of the sleeve and as a complete revolution is required for
the formation of a short stitch as well as of a longer one, it follows, that the feed
bar, whether it have moved the fabric a short or a long distance, always returns to
its starting position close to the needle.
The third part of my invention comprises an arrangement by which the take up
for the upper thread may have imparted to it the requisite irregular motion in a
more convenient manner than hitherto practicable. It consists in the employment
of a stud fixed to the face of a rotating disc or the like or to an eccentric strap so
as to move in a circle or in an ellipse and working within a slot of the take up
lever, this slot being so shaped, that by the motions of the stud the said lever is
caused to take up or give out thread in exact accordance with the requirements for
the formation of perfect stitches.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Carl Pieper in the Patent Office on the 31st March 1884.
"
CARL PIEPER, Civil-Engineer and Patent-Agent resident at 109/110 Gneisenau-
Strasse, Berlin S W., Prussia IMPROVEMENTS IN SEWING-MACHINES WITH ROTARY
HOOK a communication to me from Rudolf Gritzner of Durlach, Grand-Duchy of
Baden, German Empire
"
This invention relates to improvements in sewing-machines with .rotary hook,
and more particularly to the arrangement of the spool-case for the under thread, to
the feeding-device and to the take-up of the upper thread.
The invention is représented on the annexed sheet of drawings. Fig. 1 is a
front-view of the holder of the spool-case with the case in it. Fig. 2 is a side-view
of the parts shown in Fig. 1 and of the rotary-hook. Fig. 3 represents in front
view the holder without the case, a portion of the part b being broken away.
Fig. 4 is a vertical transverse section of the holder, the case and the spool. Fig. 5 is
a front-view of the disk carrying the rotary hook. Fig. 6 shows the 'spool-case and
certain parts acting upon the same. Fig. 7 is a back-view of the case with the
spool in it, and Fig. 8 a side-view thereof from the right-hand side of Fig. 7.
Fig. 9 is a view of the feed-regulating device from below. Fig. 10 shows a
modification thereof. Figs. 11 and 12 show two alternative arrangements of the
improved take-up motion.
The object of the first part of the invention consists in so constructing and
combining the spool-case, the holder thereof and other parts that the loop of the
upper thread will pass around the case with certainty and facility, though the case
be of a size as to contain a comparatively large spool.
The spool-case 8 is loosely inserted in the holder a attached to the bed-plate of
the machine. It is made of dish-like form so as to be adapted to receive a large-
spool. At the top it is provided with a projection c having a hole in it through
which the thread of the spool is passed, and at the bottom it has a projecting lip 1,
while the holder is fitted with the recesses c¹ and l¹ for the said projection and lip
to enter into, and with an arm b extending around the case. The case is thus
maintained in an upright position and prevented from turning. The weight of the
case and the spool is so distributed that the extreme end of the lip, or bearing-
point of the case, will be in the vertical line z zpassing through the centre of
gravity of the case and the spool. The line z 2, however, does not coincide with
the vertical center-line of the case and spool, but lies before the same, so that the
hook in its rotation will first pass the said bearing-point and subsequently the
center-line xx. Moreover, the end of the rotating hook e is bent by so much
towards the centre of the disk g on which it is formed, that the loop of the upper
thread guided by the hook, will slip off the hook immediately after it has passed
the point of the lip and before it has reached the center-line xx. The loop is
then carried fully over the case by the action of the take-up. This arrangement
by which the loop is caused to leave the hook sooner than otherwise, while never-
theless it is with certainty carried around the spool-case, presents the advantage to
allow, for drawing up the loop, more than half the time required for one rotation
of the hook.
In order to permit the loop to freely pass the bearing-point of the case, the latter
must be lifted. This is effected by so adjusting the tension of the under thread as
that the force required for drawing off thread from the spool, will be greater than
the weight of the case and the spool together. A. pull-being then brought to bear
upon the thread as the portion thereof required for completing the stitch is drawn

page_text: off the spool, the casing will first be lifted and held in suspended position by the
thread, so that the loop is then free to pass the bearing-point. According to the
drawing the requisite tension of the thread is obtained by a spring f operating to
press the spool against the back of the casing; but any other suitable tension-
device may be employed with the same effect.
For the purpose of limiting the lift of the case, a surface or stop must be
provided for, adapted to act against the thread-guiding projection c. But as the
loop, which is drawn up rapidly, would be checked in its passage across the end
of the said projection while the latter is in contact with the stop, the case must be
depressed again into its normal position soon after the loop has passed the lip 1.
According to Fig. 6 the said stop is formed by one arm of a lever h whose other
arm is connected with the feed-bar of the machine, so that the lever will be
operated as required to depress the case in proper time for the loop to pass the
projection c. The lever h or other device may, however, also be operated directly
from the main shaft by a cam or otherwise, and instead of pressing on the case it
may be made to act on the thread, so as to pull it out and thereby cause the case
to drop and to allow the loop to pass over the projection c.
In order to prevent failure of stitches by a passage of both halves or parts of a
loop on the same side of the case, a loop-guide is provided for, consisting in a
plate projecting from the edge of the case and adapted to open the loop and to
guide it upon the case. For allowing the loop to be taken up with greater facility,
a part of the edge of the case opposite to the guide r is cut away, as may be seen
from Figs. 7 and 8.
The rotary hook is provided with a recess t, which, while the loop is being
carried around the spool-case, allows the part of the loop next to the needle to
give way, while the other or distant part is retained at the bottom of the guiding
piece by which the loop is prevented from becoming entangled in the hook, and
which facilitates the slipping off of the loop from the hook at the required point of
rotation of the latter.
->
The second part of the invention has for its object to provide means whereby
the feed-bar after having moved the fabric the required distance for another
stitch, is always returned to the same starting-point in proximity to the needle,
however long ita stroke for spacing the stitches may be. The device serving for
this purpose is shown by Fig. 9. The feed-bar i is put in operation by a
vibrating lever j, pivoted at 11, and the free end of which bears against and is
acted upon by a conical sleeve n mounted eccentrically on the shaft m and
arranged to rotate with the same. This sleeve or cone is capable of adjustment
longitudinally by means of the bell-crank lever o and a clamping-screw q passing
through a slit p in the bed-plate of the machine. According as the position of the
said sleeve is varied and portions of greater or less excentricity are thereby
brought opposite to the end of the lever j, the stroke of the feed-bar and
consequently the stitches will be longer or shorter. Moreover, one side of the
cone n is parallel to its axis of rotation, and this side is arranged to be in contact
with the vibrating lever when the feed-bar is in its starting-position for feeding
the fabric forward. Now, as the said contact takes place once at each revolution
of the sleeve, and as a complete revolution is required for a short stitch as well as
for a long one, it follows that the feed-bar, whether it have moved the fabric a
short or a long distance, always returns to its starting-position close to the needle.
Fig. 10 shows a modification of the arrangement of the adjusting-lever o, which
is in this case a straight lever pivoted at o² and having a lateral arm with a pin
to engage with the groove in the cone n.
The third part of the invention comprises an arrangement by which the take-up
for the upper thread may have imparted to it the requisite irregular motion in a
more advantageous manner than heretofore. In order that in machines with large
shuttles or under-thread spools the upper thread be given out and taken up in the
manner required for forming and closing the loop of the under thread, the take-up
lever must be operated in a special manner so that its speed for equal parts of the

page_text: course of the needle when descending, will be materially different from its speed
for the like course-parts of the ascending needle. For producing this particular
kind of motion it has hitherto been the usual practice to operate the take-up by a
cam-groove cut into a thick part of the main shaft. This arrangement, however,
presents the disadvantage of requiring very steep portions in the said groove, or a
very considerable difference in the length of the two arms of the take up lever.
According to the present improvement the take-up is operated by means of a stud
moving in a circle or an ellipse and working in a slot of the take-up lever or of an
arm attached thereto. As shown by Fig. 11, the said stud, v¹, is fixed to the face
of the pinion w¹, driven by the pinion won the main shaft m, the two pinions
being of the same size, and it engages with the cam-slot in the arm v fixed to the
take-up lever u. In Fig. 12 the pin v¹ is shown secured to an arm on the strap y¹
of the eccentric y, which is fixed on the shaft m and serves to operate the needle-
bar. The pin in this case moves in a line resembling an ellipse. The cam-slot in
the lever-arm vis in either case so shaped that, by the motion of the stud, the
lever u is caused to take up and give out thread in exact accordance with the
requirements for the formation of the stitches.
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 sewing-machines with rotary hook, a spool-case maintained stationary in
a holder and having a dish-like shape so as to be adapted to contain a large
under-thread spool, and which is supported in but one point, in combination with
means for alternately lifting the case from its support and of depressing it, for the
purpose of facilitating the passage of the loop of the upper thread around
the case.
2., The spool-case 8 having a projection c serving as thread-guide and lying in a
recess of the case-holder a so as to prevent the case from turning, the said
projection and the bearing-point of the case being arranged in the vertical line z z
passing through the centre of gravity of the case and the spool, and the case
having a portion of one side removed to facilitate the drawing-up of the loop of
the upper thread.
3., The spool-case 8 and spool & provided with means for so regulating the
tension of the under thread that, when the thread is drawn upon in the formation
of a stitch, its tension will be in excess of the weight of the case and the spool,
in combination with means for depressing the spool-case after having been lifted.
4., The stitch regulating device consisting in the cone n placed on the shaft m
so as to be parallel thereto on one side and to rotate with the same, and which is
adjustable lengthwise on the shaft by a lever o, in combination with the lever j
operated by the cone and acting upon the feed-bar i, substantially as and for the
purpose described.
5., The combination with the take-up lever u of an arm v having a cam-slot in
which engages a stud v fixed to the face of a pinion w' actuated by the pinion w
on the main shaft m, or to an arm on the strap y¹ of the eccentric y on the shaft m,
substantially as and for the purpose specified.
In Witness whereof I, the said Carl Pieper have hereunto set my hand and
seal this twenty-second day of March in the year of our Lord one thousand
eight hundred and eighty-four.
CARL PIEPER (L.S.)