IMPROVEMENTS IN SEWING MACHINES
Year: 1884

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I SYDNEY PITT of Sutton in the County of Surrey Gentleman do hereby
declare the nature of my Invention for "IMPROVEMENTS IN SEWING MACHINES"
and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement :—
The improvements are especially adapted to be used in double thread chain
stitch sewing machines, and relate to the devices which actuate the looper or
needle, which carries the lower thread, to the feed movement, and to the mechanism
whereby the slack in the thread (formed by the looper in withdrawing from the
loop) is taken up.
It has been customary heretofore to give the looper a four sided motion, or a
transverse movement across the general direction of its longitudinal reciprocation,
and in most cases springs or their equivalents, have been employed to impart the
movement in one or more of the four directions.
In the present Invention the looper-actuating mechanism is much simplified, and
at the same time rendered positive, thus avoiding the uncertainty of action, and
the complication of the devices formerly used.
To attain these new results the looper is pivoted to a frame which is suspended
so as to oscillate upon an axis at right angles to the pivot of the loopor itself, and
both the looper and the frame are provided with driving. mechanisin whereby their
respective oscillations are effected.
The next feature of the Invention (which relates to the feed) consists in a
radially slotted disc mounted upon the outer or front end of the main shaft, a
crank pin adjustably secured in the slot, a rocking frame carrying the feed dog
and connected with said crank by means of an intermediate pivoted link. By
adjusting the crank in the slotted disc the length of the stitch is regulated at will
and without disturbing the relative timing of the feed and needle movements.
The remaining features of the Invention consist in the devices which control
the lower thread, and are specially applicable to machines used for sewing knit and
other elastic fabrics.

page_text: It has been customary heretofore to employ in this class of machines, a vibrating
spring arm to take up the slack in the lower thread caused by the receding move-
ment of the looper.
Such spring take up devices do not give the thread sufficient freedom for the
formation of the elastic stitch desired in elastic fabric work, nor do they act with
the rapidity sometimes requisite.
The present Invention consists in combining with the looper a rotating take-up
positively actuated and acting with certainty to engage the slack in the thread at
each vibration of the looper; also in combining with the looper and take up, an
intermittently acting stop, operating to prevent the feed of fresh thread during
the take-up movement, so that the take up is compelled to engage the slack already
existing.
Certain minor features of Invention which co-operate with theso main elements
to produce the desired results will be described in detail hereafter.
In the accompanying Drawings which form part of this Specification Figure I is
a perspective view of the machine, the usual cloth plate being removed; Figure II
is a vertical section at right angles to the main driving shaft and on a line passing
through the centre of the feed frame; Figures III and IV are respectively end and
side views of the adjustable crank mechanism, whereby the feed frame is actuated,
and Figures V and VI are sections through said crank mechanism the lines of
section being at right angles to one another; Figures VII and VIII are respectively
views in perspective and in side elevation of the tako up devices; Figure LX is a
cross section through the cam upon the main driving shaft, which oscillates the
looper frame; Figure X is a vertical section through the machine on the line x, x,
of Figure XII; Figure XI is a front elevation, and Figure XII is a top or plan
view of the machine the scale of representation being somewhat reduced, and the
cloth plate being in each instance removed.
The machine is mounted upon a bed-plate 1, and has the usual standard 2,
needle arm and bar 3, 4, presser foot 5, and other ordinary devices which need not
be described in detail, as they are well known to all persons skilled in the art of
constructing this class of machines.
The uprights 5, 6, support the cloth plate which is of the usual form, but has
been omitted from the Drawings to facilitate the view of the interior. These
uprights also afford bearings for the main driving shaft 7 upon one end of which
the driving pulley 8 is mounted.
The looper or lower needlo 9 receives its longitudinal oscillation from the lower
extension of the neodle arm 3, by means of the connecting pitman rod 10. The
looper 9 is pivoted at 11, upon a rocking frame 12 which is provided with bearings
in the uprights 5, 6, as shown. This frame 12, is oscillated at proper intervals by
a cam 13 upon the main shaft 7, working in the opening of a U shaped piece 14
fixed upon the end of the frame 12.
The connection 15 between the pitman rod 10 and the extension of the needlo
arm 3 should be by a ball and socket joint or of such a nature as to accomodato the
lateral oscillation of the frame 12.
The looper thus constructed has a positive motion in all directions.
The horizontal movements of the four motioned cloth feed 16 is obtained from the
front end of the main shaft 7 by means of a jointed crank secured to, but radially
adjustable upon said shaft.
Upon the outer or front end of the shaft 7 is mounted a disc 17, having on its
face a radial slot 18, whose cross section is T-shaped, so that the edges overhang
the slot. This slot receives the T-headed crank pin 19 the head of which slides
freely in the slot 18, whilst its projecting end is provided with a screw thread and
jam nut 20. A sleeve 21, surrounds the crank pin 19, and by the pressure of the
jain nut 20, and sleeve 21, the crank pin can be secured at any point in the slot,
thus affording a crank of any desired radius.
A link 22 embraces the sleeve 21, upon which it moves freely, and is also freely
pivoted at 23 to the arm 24 attached to the rocking frame 25, binged to the bed

page_text: plate 1 at 26. An arm 27 carrying the feed surface 16 is pivoted at one end to
the upper portion of the frame 25 and rests at the other end upon the cam 28 of
the driving shaft 7. A downwardly depending piece 29, also secured to the arm 27
embraces the lower side of the cam 28. The vertical movements of the feed aro
effected by means of the cam 28, and the horizontal movements by means of the
jointed crank attachment and rocking frame 25, and as the adjustment of the
crank pin 19 is radial to the driving shaft 7, the commencement and conclusion of
the feed movement must occur in precisely the same relation to the needle move-
ment, whatever be the length of feed, since the oscillations of the frame 25,
whether great or small will always correspond in duration to the same arc of
rotation of the driving shaft.
In order to compensate the wear upon the link 22 it is constructed, as shown,
with an opening or slot between the projecting ends 30, through which a tightning
screw 31 passes.
The ordinary tension device 32, may be used for controlling the supply of the
upper thread 33.
The take up devices for the lower thread are arranged with reference to the
looper and thread supply as follows.
The lower thread 34 may be used either with tension exerting devices in
connection with the novel devices hereinafter set forth for controlling it or the
latter devices may be alone relied on.
After passing from the spool 35 and such tension devices as may be used, the
thread 34 descends and passes through the stop device, thence to the take up
mechanism and finally to the looper 9.
The stop device is composed of an upper spring 36, and lower spring 37, which
are normally open, but are closed together at proper intervals to grip the thread
passing between them by means of the projection 38 (see Figure X) upon tho
rocking frame 12, which at each oscillation of the frame presses against the lower
spring 37 and raises it into close contact with the upper one.
In order that the pressure of the springs upon the thread may be regulated, a.
screw 39 is insorted in the projection 38, in such manner that the end of the screw
is the actual bearing point of the projection which is thus rendered adjustable.
On the withdrawal of pressure by the retreat of the projection 38, the springs
automatically open and free tho thread, which can then be drawn by the looper
without resistance.
The take up consists of two rotating cam shaped discs 40, secured upon the
main shaft 7, and provided with an intermediate throw off arm 41, the thread
being compelled to ride over and in close contact with the straight cam faces of the
discs by means of the guides 42, placed on either side thereof the eyes of said
guides being well within the circle described by the straight portions of said cam
in rotating.
In the operation of the take up, the straight edges of the cam catch the thread
between the guides and carry it towards the throw off arm, until it reaches the
lutter, whereupon it is compelled to ride very rapidly up the cam surface (thus
taking up the slack between that point and the looper). The circular portions of
the cams then run freely beneath the thread until the looper is about to take
another forward impulse, whereupon the straight portions of the cams being again
presented beneath the thread it rides down them and the looper draws out tho
slack previously taken up as well as a quantity of fresh thread sufficient for the
new stitch.
A single disc 40 may be used in place of the two, if desired, but two are
deemed preferable, as the point of the throw off arm 41, is prevented from
entanglement with the thread.
The guides 42 are pivoted at 43, to the standard 44, so that they may be raised
for convenience in threading as indicated by dotted lines in Figure VIII, and they
are held down to their work by means of a spring 45, which bears against the flat
edge of the pivot.

page_text: A hinged cap 46 is employed to cover some of the moving parts at the front end
of the machine, said cap being held up by means of a spring 47.
The operation of the stitch forming mechanism is similar to that of other well
known machines, save in so far as it is modified and improved by means of the
'soveral devices hereinbefore described and which are now claimed as follows:
First. The combination with the needle, and the feeding mechanism, of a pivoted
looper frame, whose axis of oscillation is substantially at right angles to the line of
foed, a looper pivoted to said frame and having an axis of oscillation substantially
at right angles to the axis of the frame, and means for oscillating said frame and
said looper respectively, the whole operating substantially in the manner specified.
Second. In a sewing machine having an eye pointed needle, the combination
'with said needle, of the oscillating looper frame 9, the looper pivoted thereto upon
an axis at right angles to the axis of the frame, and the pitman 10, connected
with the looper by means of a ball and socket joint, whereby the oscillation of the
looper frame at right angles to the movement of the pitman is permitted.
Third. The combination of the rocking frame, having the feed dog mounted
'thereon, the driving shaft provided with a lifting cam beneath said feed dog, and
also provided on its outer end with a radially adjustable crank pin, and the freely
pivoted link connecting said crank pin and said frame whereby the length of feed
may be altered without varying the time of feed movement, substantially as sot
forth.
Fourth. In a double chain stitch sewing machine the combination with the
stitch forming mechanism, a tension device acting upon the upper thread, and an
intermittently operating stop and take up acting upon the lower thread,
substantially as specified.
Fifth. As an improvement in take up devices for sewing machines, the
. combination of a cam disc arranged with its periphery in contact with the thread,
mechanism whereby said cam is rotated in proper relation to the action of the
stitch forming mechanism, and a throw off arm extending within the line of
rotation of the cams periphery, the whole operating substantially as set forth.
Sixth. As an improvement in take up devices for sewing machines, the
combination of a cam disc and mechanism for rotating the same, with thread
guides arranged on each side of said cam, and having eyes for the passage of the
thread, said eyes being located within the outer periphery of the cam, substantially
as and for the purposes set forth.
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