Improvements in and relating to Tension Devices for Sewing Machines.
Year: 1899

page_text: Date of Application, 7th Sept., 1899-Accepted, 25th Nov., 1899
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COMPLETE SPECIFICATION.
Improvements in and relating to Tension Devices for Sewing
Machines.
communication from abroad by the INTERNATIONAL GOODYEAR SHOW
MACHINERY COMPANY, of 100 to 104, Bedford Street, Boston, State of
Massachusetts, United States of America.
J. ALFRED GEORGE BROOKES, of 55 and 56, Chancery Lane, in the County of
London, Chartered Patent Agent, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:―
The present invention relates generally to tension devices for sewing machines,
and more particularly to tension devices for the several types of waxed thread
sewing machines.
As provided with any of the tension devices of the prior art, insofar as I am
advised of the same, any material increase of the speed of operation of a waxed
thread machine will produce an increase in the tension under which the thread
is drawn from the supply, so that if the speed of a machine, carrying a sufficient
tension to sew a tight seam at a relatively low speed, be materially increased,
the machine will break thread and will not operate successfully, and on the other
hand, if the speed of a machine adjusted to run rapidly be materially decreased,
a loose and insecure seam will result.
The mode of operation above suggested has been found to be objectionable in
many uses of waxed thread machines, and particularly so when such machines
are used to secure the welt to the upper and insole of a' boot or shoe, or to secure
the outsole to the welt, or the outsole to the upper and insole either in the McKay
sewed or turned shoe, since it results in a loose seam around the toe, when the
speed of the machine is slacked to enable the operator to properly present the
work, and in a loose seam at both sides of the back of the shank where the seam
commences and ends.
The object of the present invention is to obviate the difficulty above stated and
to provide a tension device, which will enable a machine when running at high
speed to carry sufficient tension to sew a tight seam when operated at a rela-
tively low speed.
A preferred form of my present invention as applied to a shoe sewing machine
of the usual type, such for example as the Goodyear machine, is illustrated in the
accompanying drawing, in which,
Figure 1 is a perspective view,
Figure 2 is a side elevation,
Figure 3 is a plan,
Figure 4 is a transverse section, and
Figure 5 is an end elevation.
Like letters of reference designate like parts throughout the several views.
In my improved tension device means are provided whereby the thread as it leads

page_text: the tension thereon has reached a predetermined amount, and when such pre-
determined tension has been reached, is released and allowed to run freely from
the supply, the device however being so arranged that the release of the thread
as above stated, as soon as the tension falls below said predetermined amount,
effects a locking of the thread controlling devices, and prevents a further running
of the thread from the supply; the result being that the pull or tension upon the
thread can never exceed a predetermined amount, and the thread is drawn off
by successive increments as required by the stitch forming devices, the pull
required to draw off any increment, after the thread has been released as above
stated, being only that required to overcome the resistance of the passage of
the thread through the wax pot.
In the specific embodiment of my invention illustrated in the drawings the
thread holder consists of a thread truck A, around which the thread T passes
as it leads from the wax pot C to the stitch forming devices.
The thread truck A is rotated by the thread T, when it is being drawn from
the supply, and means are provided for locking the truck A from rotation and
thus holding the thread against any pull of less than a predetermined force,
and the devices controlling the rotation of the truck A are so constructed and
arranged that when such predetermined pull or tension is reached the truck A
will be released, so that the thread will be released and will run freely from
the wax pot, said devices being, however, further so arranged that when the
truck A is released and tension reduced, the truck will be immediately locked
again from rotation and the running of the thread stopped after an increment
thereof has been drawn off.
To secure the above arrangement in the machine of the drawings, the thread
truck A is mounted and free to rotate upon a short shaft a, which is fixedly
secured at its opposite ends to the arms b, b, of a yoke B, which embraces the
truck A.
For the purpose of locking and unlocking the truck A its supporting yoke B
is arranged to have a swinging movement in a vertical plane. As shown, the
body of the yoke B is hollow, and has a bearing on a short shaft or cylindrical
stud d, about which the yoke B is free to swing, and which is projected hori-
zontally from a bracket D, which is bolted or otherwise suitably secured to the
column E, which is the usual supporting column of this class of machines.
In one of the lateral faces of the truck A is formed a recess f, which forms the
female member of a conical frictional clutch, the male member f¹ of which is
formed upon a disk f2 fixedly, secured to the shaft a.
In addition to its motion of rotation about the shaft a, the truck A is arranged
to have a limited lateral movement sufficient to effect an engagement and dis-
engagement of the clutch as hereinafter described.
The truck A carries upon its opposite lateral face an annular disk h, the outer
face of which is conical or wedge shaped, said disk being secured to the
truck A so as to move laterally and rotate therewith. Projected horizontally
from the bracket D is a stud h2, upon the inner end of which is mounted a disk h³,
the inner lateral face + of which is conical or wedge shaped and which, when the
yoke B is swung back, that is to say in a direction opposite to that of the pull
of the thread, is arranged to engage the conical face h¹ of the disk h, and to
move the truck A laterally to engage the clutch members f, f', and hold the
truck A from rotation.
A suitable placed spring is provided which tends to impart a backward move-
ment to the yoke B, and normally holds the conical face h of the disk h³ in
engagement with the conical face h¹ of the disk h, and the clutch members f, f',
in engagement to prevent rotation of the truck A. As shown the spring above
referred to consists of a coiled spring L, one end of which is secured to a fixed
support i, and the other to a bridle attached to the yoke B at or near the
upper ends of the arms b. Means are provided whereby the tension of the
spring L may be regulated conveniently by an adjustment of the support

page_text: and to this end said support is adjustably secured to a bracket D, so that it may
be set nearer to or further away from the yoke B.
As shown the shank of the support is threaded, and is projected through a
sleeve, on the bracket D, a spline connection being provided leaving the
shank of the support / free to slide but not to rotate in the sleeve d³. A threaded
nut d³ engaging the threaded shank of the support at the outer end of the
sleeve da, serves to adjust the support, and hold it in its adjusted position. I
also find it convenient in practice to provide upon the shaft an annular disk or
washer P, which serves to take up the end thrust when the disks h and h³ are
in engagement.
I have also provided means for limiting the forward movement of the yoke B,
i.e. its movement in the direction of the pull of the thread, which means may
consist of any suitable device, conveniently, of the stop n, which projects into
the path of movement of the yoke B. As shown the stop n is excentrically
mounted upon a cylindrical supporting block n', which is mounted to to rotate in
suitable bearings in the bracket B, and provision is made to clamp it in any
desired position, the arrangement being such that by turning the block n' the
position of the stop n may be varied to vary the amplitude of oscillation of the
yoke B. In the device of the drawings the limitation of the forward move-
ment of the yoke B as above described is of considerable importance, in that,
when my improved tension is applied to a rapidly running machine, it prevents
the yoke B being carried too far forward to be returned at the proper time to
lock the truck A to prevent the drawing off of more thread than is required. I
do not however desire it to be understood that such arrangement is an essential
feature of the present invention.
To release the truck A at the will of the operator, and allow the thread to be
drawn freely from the wax pot, I have provided in the device of the drawings
a bridge m which is secured to the arms b, b, of the yoke B, and to which is
attached a cord or other suitable connection, connecting the same with a con-
veniently placed lever (not shown), whereby the yoke B may be drawn forward
against the tension of the spring Ĺ to unlock the truck A.
I desire to say in this connection that in this specification I have used the term
lock in its broadest sense to include a frictional holding as illustrated and also
a positively locking means.
It is also to be noted that the conical clutch members f and f' are made
slightly tapering to increase their holding capacity, and that although the yoke B
is actuated by the spring L to close the clutch members when closed the action
of the clutch members to hold the truck from rotation is not effected by variations
in the tension of spring L.
To prevent the cooling of the thread while passing over the truck A, suitable
heating means are provided which leads from the wax pot heating pipe R to the
yoke supporting shaft or stud d which is made hollow to permit the passage of
steam, and thence to other parts of the machine.
It is to be further noted that the arrangement of the spring L is such that any
sudden pull of the thread, such for example as occurs in the illustrated type of
sewing machine as the stitch is set, is taken up by the spring, so that the stitch
is set under a uniform tension and the strain on the thread occurring when other
forms of tension are used is prevented.
The operation of the device of the drawings is described as follows:-
The spring L having been adjusted so that the tension thereof will hold yoke B
in position to keep the disks h and h³ in engagement and the clutch closed against
any pull on the thread less than the required tension, if a tension be exerted on
the thread equal to the required tension, the yoke B will be drawn forward
against the tension of the spring L disengaging the disks and h³, and allowing
the clutch to open to permit a free rotation of the truck A, which allows the
thread to run freely from the supply. The release of the thread as above stated
releases the yoke B and the spring L acts to restore it to its original position,

page_text: and the clutch is again closed locking the truck A, and preventing the drawing
off of the thread from the supply until the required tension is again brought 'on
the..thread.
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It is to be noted with regard to the above stated operation, that no thread can
be drawn from the supply until the truck-A is released; that the truck A will
be released only when the pull. on the thread reaches the predetermined tension,
and, as a consequence, that a uniform pull on the thread will draw off thread
from the supply in a series of small increments and that while each of such incre-
ments is being drawn off there is no resistance against the pull of the thread
except the resistance offered in its passage through the wax pot and its strippers.
I desire to say that I consider myself to be the first to ever produce any form
of tension which with a uniform pull of the thread would release the thread
in successive increments.
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. In a tension device, the combination with a thread holder having nieans to
positively hold the thread at all times against any tension thereon less than a
predetermined tension, of means controlled by the pull of the thread 'to release
an increment of thread when said predetermined tension is reached, substantially
as described.
2. In a tension device the combination with a thread truck arranged to be
rotated by the thread, of mechanism for positively restraining said truck from
rotation, and releasing means operated by the pull of the thread, said restraining
mechanism acting at all times to hold the truck from rotation until released by
the releasing means, substantially as described.
3. In a tension device, the combination with a thread holder movable bodily
in the direction of the pull of the thread, of a spring controlling the movement
of the holder arranged to offer a yielding resistance to the pull of the thread,
substantially as described.
4. In a tension device, the combination with a thread truck arranged to be
rotated by drawing off the thread, of restraining and releasing mechanisms con-
trolled by the pull of the thread and controlling the rotation of said truck, and
means for adjusting the releasing mechanism to vary the pull required to operate
said mechanism without materially affecting the action of the restraining
mechanism, substantially as described.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.