Improvements in Lock-stitch Sewing Machines.
Year: 1897

page_text: Date of Application, 4th May, 1897--Accepted, 17th July, 1897
[Communicated from abroad by THE SINGER MANUFACTURING COMPANY of New
York, United States of America, Sewing Machine Manufacturers.]
Improvements in Lock-stitch Sewing Machines.
I WILLIAM HARvey Inslee, Manager of the Singer Manufacturing Company,
Kilbowie, Dumbartonshire, do hereby declare the nature of this invention and in
what manner the same is to be performed as communicated to me, to be particu-
larly described and ascertained in and by the following statement:-
My Invention relates to lock-stitch sewing machines, and more particularly to
that class thereof in which a vibrating shuttle lever beneath the work-plate is
operated from a crank on a driving shaft journalled in the upper part of the arm
of the machine, although certain features of my invention are capable of use in
other forms of sewing machines.
In the drawings Fig. 1 is a sectional side elevation of a sewing machine embodying
my Invention. Figs. 12, 16 and 10 are detail views of certain parts shown in Fig. 1.
Fig. 2 is a section through the vertical portion of the bracket arın on line X-X,
Fig. 1. Figs. 3 and 4 are plan views of the front and rear part of the bed plate of the
machine, Fig. 3 being broken out to show a portion of the feeding mechanism
heneath the work-plate. Fig. 5 is a front view of the head of the machine with
the face plate removed, and Fig. 6 is a front view of the face plate. Fig. 7 is an
enlarged detail view of part of the presser foot lifting mechanism. Fig. 8 is a top
view of part of the thread controlling mechanism. Fig. 9 is a front side elevation
of the lower part of the machine to show a portion of the feeding mechanism
beneath the work-plate of the machine. Fig. 10 is a front end view of the work-
plate and the feeding mechanism below the same. Fig. 11 is a detail view showing
slight modification to be hereinafter referred to.
A denotes the bracket arm of the machine, and B the work-plate to which said
bracket arm is suitably secured. C is the driving shaft journalled in the upper
part of the bracket arm and provided with the fly and pulley wheel D, said shaft
having near its rear end the crank E from which the shuttle and feeding mechanisms
are operated, and having at its forward end a crank U provided with a crank pin
connected by a pitman U to the collar V attached to the needle-bar V carrying
the usual eye-pointed needle. The crank E is connected by a pitman lever F to a
link which is in turn connected to a crank arm a, on the rear end of a rotating
feed operating shaft J journalled in bearings afforded by hangers K, K, beneath
the work-plate, and having at its forward end a cam L which imparts upward and
forward movements to the feed-bar La carrying the feed-dog N and having an
arm L' to be engaged by said cam, the backward and downward movements of said
feed-bar being effected by a suitable spring, as L. The feed-bar L' is provided
with a depending arm or bracket L' having an inclined face which, in the backward
movement of said feed bar, under the influence of the said spring, abuts against
a stopping arm L³ attached a feed regulating shaft J journalled in
bearings K³, K, and having attached to its rear end a stitch regulating
arm Ja extending upward through a slotted block J attached to the work-plate,
and having a curved upper face against which a thumb nut J abuts to fix
the said arm and the feed regulating shaft J, to which it is attached, in any
desired position of adjustment. L is a link or bracket jointed loosely on
DB37
to

page_text: the forward end of the feed-regulating shaft J, and also jointed at its
upper end by means of a pin L³, to one end of the feed-bar L8 which is thus
supported at one end by said link or bracket. By varying the position of the
feed regulating shaft, by means of the stitch-adjusting arm J³, the position of the
stopping arm L on said shaft relative to the inclined lug or bracket L on the
feed-bar may be changed, to vary the backward throw of the feed-bar L under
the influence of the spring L³, and thus as the said feed bar, will always be moved
forward to a certain point by the cam L the length of the feed may be adjusted,
as may be desired, by limiting its backward movement..
The pitman-lever F is provided with a cap e secured in working position by
a clamping screw d, this construction facilitating the assembling of the parts.
To the said pitman lever is pivoted, at f, the upper arm of a bell-crank lever G
the lower end of which is provided with a ball embraced by a yoke on the rear
end of the shuttle-operating lever H, said bell-crank lever being pivoted on centre
screws, one of which is provided with a lock-nut g³. The shuttle-lever H is
pivoted on a stud or bolt provided with a lock-nut H which prevents said stud
from becoming loose from the work-plate into which it is screwed, said nut also
serving as an adjustable cone-bearing for the pivot of the shuttle lever.
To
The presser bar, W, carrying the presser-foot which is yieldingly forced against
the work in the usual manner by a coil spring surrounding said presser bar, is
preferably automatically lifted at each stitch. while the needle is in the work so
as to facilitate turning of the latter on the needle in sewing curved seams.
effect this result I have provided the driving shaft C with a cam X against which
rests the lower end of the vertically movable sliding rod X to which a gripping
arm Y is pivotally attached by the pin Y, said arm preferably loosely embracing
the presser-bar so that in the operation of the machine, when the rod X is lifted
by said cam, the said arm will be caused to grip the presser-bar and lift the same,
and when the said rod X is not lifted by the said cam the presser bar will be free
to move vertically through the gripping arm Y to adjust itself to varying thickness
of the material beneath the presser foot. The adjusting screw Y³ limits the down-
ward movement of the arm Y and causes the latter to be unclutched from the
presser-bar. If it be found desirable to attach the lifting arm rigidly to the
presser-bar this can be done by means of the clamping screw 7 passing through
the slotted forward end of said arm; and in such case it may be desirable to attach
the said arm rigidly to the bar X by screwing the latter into the arm, as shown
in Fig. 5.
Tis the pull-off and take-up lever provided with a pin or roller stud T entering
a grooved cam on the shaft C, said lever being pivoted at and having an upwardly
extending pull off arm T provided near its upper end with a slotted or open thread
сус P, P³ are the tension discs mounted on a stud S by which it may be secured
in any desired position of adjustment. Beneath the lower tension disc P' is a
lever P3 pivoted forward of the stud S and pressed upward, so as to force the said
tension dises into yielding contact with each other, by a coil spring P seated in a
recess in the top of the bracket arm and bearing against the underside of the said
lever, the pressure of said, spring being regulated by a screw S. The driving
shaft is provided with an eccentric R2 surrounded by a strap R³ having an
upward extension R which impinges against the forward end of the lever P³, of
against the leather washer interposed between a shoulder near the upper end
of said extension and the underside of said lever; said extension R being preferably
constructed with a reduced part at its extreme upper end formning a stud n loosely
entering a hole in the said lever. From this construction it will be obvious that
when the machine is in operation the lever P³ will be vibrated so that, at times the
tension discs will be relieved from the pressure of the spring P, thus providing
an intermittent or automatic tension which will clamp the thread at the proper
intervals and then release it, so that the said tension will properly co-operate with
the take-up and with the pull-off afforded by the arm T of the take-up lever.
The tension may be released by the operator when the, work is to be removed

page_text: simply by pressing with the finger against the rearwardly extended end of the said
lever P3, thus removing the pressure of said lever from the tension discs.
The thread passes from the thread spool forward through the eye of the pull-off
arm T, thence backward between the tension discs P, Pa, thence forward through
the thread eye b, thence downward through the thread guide on the face-plate A³,
thence upward into the hook at the forward end of the take-up, and thenco
downward to the needle. The pull-off action of the arm T and the take-up action
of the take-up lever in tightening the stitches and in drawing slack for the next
succeeding stitch, will occur alternately, so that the thread will be clamped by
the tension discs P, P, when the take-up arm is drawing thread from the spool,
but will be released therefrom during a portion of the time when the take-up is
operating, so that the slack can pass freely forward as may be required in the
formation of stitches.
The needle-bar is provided with a downwardly and backwardly inclined
groove near its lower end to carry any superfluous oil backward away from the
needle thread.
The driving shaft C is preferably journalled at its forward end in a bushing or
sleeve T secured in a recess in the forward part of the arm by means of a set
screw T6, the opening in the arm A in which said bushing or sleeve is inserted
being of sufficient size to permit of the passage therethrough of the crank E and
also the take-up cam T on said driving shaft: so that in assembling the parts of
the machine together, the said shaft, with said cam and crank, can be placed in
position by being inserted from the front end of the bracket-arm through said
opening.
From the foregoing it will be seen that I provide a lock-stitch sewing machine
in which all of the necessary mechanisms for actuating the needle, shuttle, feed
and take-up, as well as mechanisms for operating a pull-off, an intermittent or
automatic tension and an automatic presser-foot lifting device, are all operated
from a main or driving shaft located in the upper part of the arm of the machine;
thereby simplifying the construction of a lock-stitch machine having all of these
desirable features.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what I
claim is:-
1. The combination with the feed bar L8 provided with the feed dog N, the
arm L' and the depending arm or bracket L, said arm or bracket being rigid with
said feed bar and having an inclined face, of a rotating shaft, provided with a cam
for imparting upward and forward movements to said feed-bar, a spring for
effecting the downward and return movements of said feed bar, the feed regulating
shaft extending lengthwise of the machine and provided with the stopping
arm L³ which may be moved to different positions relative to, the inclined face on
the said arm or bracket LP, to limit the backward movements of the said feed bar
under the influence of said spring and thus regulate the feed.
2. In a sewing machine, the combination with the main shaft thereof, of take-up
and pull-off devices operated from said main shaft and having an alternate action
so that the pull-off performs its function when the take-up relaxes the needla
thread and the take-up performs its function of tightening the stitches when the
said pull-off is moving idly, and an intermittent or automatic tension co-operating
with said take-up and pull-off devices, and arranged to act on the thread between
the take-up and pull-off and the spool or thread supply, substantially as set forth.
3. The combination with the tension discs and the stud on which the said disces
are mounted, of the lever P³, a spring independent of said Jever for pressing the
latter against one of said discs, and means for operating said lever, whereby said
discs are intermittingly relieved from the pressure of said spring, substantially
as set forth.
4. The combination with the tension discs and the stud on which the said discs

page_text: are mounted, of the lever P³, an independent coil spring P acting to press said
lever against one of said discs, the driving shaft C provided with the eccentric R
a strap surrounding the said eccentric and having an upward extension for
operating said lever to cause the pressure of said spring to be, at times, removed
from the said tension discs, substantially as set forth.
5. The combination with the driving shaft C provided with the cam T and with
the eccentric R, of the take-up and pull-off lever operated by said cam, the tension
discs P and P¹, a stud on which said dises are mounted, the lever P3, the spring P
for forcing said tension discs into yielding contact with each other, and the
eccentric strap R³ provided with an upward extension R for operating said lever
to relieve the tension discs, at times, from the pressure of said spring, substantially
as set forth.
6. The combination with the driving shaft C provided with the cam X, of the
presser bar W, the vertically movable sliding rod X operated by said cam, the
horizontal gripping arm or lever Y pivotally attached at one end of said rod X'
and having at its opposite end an opening for loosely receiving the presser bar:
whereby when the said rod X is lifted the said arm will be caused to grip the said
presser bar and lift the samo, but will permit the said presser bar to move
vertically through the said opening when the said arm or lever Y is not in gripping
or clutching connection with said presser bar, so that the presser foot may freely
rise and fall to accommodate itself to different thicknesses of work, but will have
n uniform vertical movement whatever may be the thickness of the work.
7. In a sewing machine, a needle bar provided with an oil groove A8 inclined
downwardly toward and extending to the rear side of said bar, for the purpose
of carrying surplus oil backward away from the needle thread, substantially as
set forth.
WALLACE FAIRWEATHER.
Of the Firm of Cruikshank & Fairweather, Chartered Patent Agents,
62 Saint Vincent Street, Glasgow, Agent for the Applicant.