Improvements in Thread Tension Devices for Sewing Machines.
Year: 1898

page_text: Date of Application, 24th Nov., 1898-Accepted, 14th Jan., 1899
די
COMPLETE SPECIFICATION.
[Communicated from abroad by JOSEPII ELI BERTRAND, of 23, Pinckney Street,
Boston, in the County of Suffolk and State of Massachusetts, United States
of America, Machinist.]
וי
Improvements in Thread Tension Devices for Sewing Machines.
1
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45, Southampton Buildings, in the County of Middlesex,, 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:
'
My invention relates to "thread tension for sewing machines" and it consists
in certain novel features of construction, arrangement, and combination of parts
which will be readily understood by reference to the following description and
the accompanying drawings in which:-
. Figure 1 is a side elevation of a sewing machine embodying my invention.
Figure 2 is an elevation of the tension wheel and its supporting stands viewed
from a standpoint opposite to that from which the same parts are seen in Figure 1,
and drawn to an enlarged scale...
Figure 3 is a plan of the parts shown in Figure 2 except the column.
Figure 4 is a partial section on line x, x of Figure 2.
Figure 5 is a sectional elevation of the ball carrying frictional washer with a
portion of one of its flanges broken away; and
Figure 6 is a section of the same.
In the drawings A is the frame of the head of the machine mounted upon
the column B, only a small portion of the upper end of which is shown in the
drawings.
The frame A is provided with two outwardly and upwardly projecting arms A¹
on opposite sides thereof, only one of which is shown.
The arms A have secured thereto the columns A2 in bearings in the upper
ends of which is mounted the cam-shaft C upon which are secured the several
cams for operating the feed slide, the needle, the looper and other operative parts
of the machine, mainly constructed, arranged and operating substantially as in
the machine shown and described in the Specification of a former Application
filed July 12, 1898, No. 15,309.
D is the needle operating lever connected at its front or movable end 'to one
end of the link E, the opposite end of which is pivoted to the needle segment a
in which is secured the curved barbed needle b in a well known manner.
The lever D is provided with the upwardly projecting arm D' carrying at its
upper end a cam truck e which engages with and is acted upon by the cam
path d formed in the inner face of a cam disc on the shaft C, said path, cam
truck, and the larger part of the lever D being shown only in dotted lines, but
are all constructed, arranged and operated substantially as shown and described
in the said former patent.
F is a portion of a bracket bolted to the flange of the column B, upon the outer
end of which is mounted the wax-pot (not shown) and G is a second bracket

page_text: Figures 2 and 4.
or stand, bolted to the bracket F, in the rear end of which is firmly secured the
spindle e upon which is loosely mounted the tension wheel H and the friction
hub I provided with the peripheral groove f, and is pressed hard against the
tension wheel H by the spring J, the tension of which may be regulated by
the thumb nut K fitted to the threaded end of the spindle e as shown in
L is an elbow lever, pivoted to the bracket F, the short arm of which is
forked and engages the groove f in the hub I, and the long arm of said lever
has connected thereto one end of the chain g, the other end of which is connected
to the short arm of the hand lever M, Figure 1, by means of which the pressure
of the hub I, upon the tension wheel H, may be removed at the will of the
operator.
So far the several parts of the machine not herein described are constructed,
arranged and operated substantially as shown and described in the above men-
tioned prior patent.
Thread tensions, as usually constructed, consist of a grooved wheel mounted
loosely upon a fixed spindle between a fixed abutment and a spring pressed
non-revoluble disc or collar, with washers of felt interposed between said fixed
abutment and wheel, and between said wheel and spring pressed collar, with
suitable means for regulating the amount of pressure applied to said wheel, and
thus vary the resistance to the rotation of said wheel.
This arrangement works well when new, but I have found by practical experi-
ence that, after a while the felt washers owing to the application of heat to
the tension devices become packed or hardened, and their surfaces become glazed,
so as to be practically inoperative, except by the application of excessive pressure
thereto, which of course necessitates frequent adjustments of the tension of the
spring pressure.
To overcome this objection is one object of my invention and to this end I
construct my improved tension wheel as illustrated in Figures 4, and 6 of the
accompanying drawings, which will be more fully described hereinafter.
Another object of my present invention is to relieve or diminish the tension
upon the thread while the needle is drawing the loop of thread through the
work, and increase said tension again while the stitch is being set, and to this
end I mount the lever N upon a suitable fixed fulcrum set in the frame A, and
I mount upon a stud set in one end of said lever a cam truck h upon which
the face cam O acts to intermittently vibrate said lever.
The lower end of the lever N has pivoted thereto the rod P, the rear end of
which extends through a bearing in the swivelling lug or ear i set in the lever L
and has adjustably fitted thereto the contact nut j and check nut j¹ as shown.
The location and length of the cam O is such, relative to the throws of the
needle operating cam path d, that said cam O will act upon the truck h to move
the upper end of the lever N towards the rear, and as a consequence, move the
rod P towards the front, causing the nut j to act upon the lug i, and thus move
the lever L about its pivot to a sufficient extend to relieve or diminish the pressure
with which the hub I is pressed against the tension wheel H, just as the needle
commences to draw the loop of thread through the work, and to hold said hub
in said retracted position until said loop is drawn through the work, when said
hub is again pressed, with the full force of the spring J, into contact with the
tension wheel H which pressure continues while the stitch is being set.
This relieving and applying of the pressure to the tension wheel takes place
once in each revolution of the cam shaft C and is of great advantage in that
the thread is relieved of the very heavy strain thereon, except when it is
needed in order to properly set the stitch.
The looper Figure 1 has imparted thereto a compound motion by means of
a cylinder cam and a face cam indicated by the dotted lines R in Figure 1,
substantially as in the before cited application.

page_text: A portion of the spindle e is made square in cross section to receive the
hub I and prevent the rotation of said hub thereon, as shown in Figure 4.
The outer end of the spindle e is threaded and has fitted thereon the adjusting
nut K, and between said nut and the hub of the collar H said spindle is
surrounded by the spiral spring J by the tension of which said collar is pressed
hard against the wheel H.
M³ is an elbow lever mounted loosely upon and movable about the spindle e,
upon the side of the stud G opposite to the wheel H and carrying at its upper
end the thread guiding sheave m and normally held in the position shown in
Figure 2, by the tension of the spring O.
I form in the side of the grooved tension wheel H an annular chamber H¹, in
which is placed the two steel plate-like washers or discs 7 and 1, and between
said washers is mounted the circumferentially grooved ball carrying washer or
ring R¹ having mounted in suitable sockets or bearings therein a series of steel
balls S, said ring and balls being so fitted to said chamber as to be revoluble
about the axis of the spindle e, with said balls in contact with the inner surfaces
of the steel washers and .
The steel washers and , and the ball carrying ring R and balls S, are used
in lieu of the two felt washers heretofore in common use and completely over-
come the objections found to exist in the use of the felt washers, the frictional
contacts being all metal, and not affected by the heat applied to the tension
devices, to keep the waxed thread at the desired working temperature, and as
a consequence, the tension is more uniform and therefore requires less frequent
attention, which is of great advantage.
The balls S are preferably arranged in series of three, the balls in each series
having their centres in a line tangent to a circle concentric to the axis of a
motion of the tension wheel H, and in a different tangential line to any other
series, whereby said balls bear upon the steel washers in two or more circular
paths, or at different distances from the axis of revolution of the tension wheel.
The stand G has set therein the stop-pin T, to limit the movement of the
lever M in one direction, in a well known manner.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, as communicated to
me by my foreign correspondent, I declare that what I claim is :-
-
1st. In a sewing machine the combination of a tension wheel; means for
applying a yielding pressure thereto to produce tension upon the thread carried
thereby; and means for intermittently and automatically removing or diminish-
ing said pressure to relieve the tension on said thread.
2nd. The combination in a sewing machine of a stitch forming mechanism;
the tension wheel H; the hub I; the spring J; the elbow lever L provided with
the lug ; the lever N; the cam truck h; the cam O; the rod P pivoted to the
lever H and having a bearing in the lug i; and the adjustable contact nut j
all constructed, arranged and operating substantially as described.
3rd. The combination in a sewing machine of a stitch forming mechanism;
a tension wheel; means for applying a yielding pressure thereto to produce a
tension upon the thread carried thereby; mechanism for controlling said pressure
constructed and arranged to intermittently apply and relieve said pressure,
whereby the tension upon said thread is diminished while the needle is drawing
the loop of thread through the work and increased while the stitch is being set.
4th. In a sewing machine the combination of the needle segment a; the
needle b; the looper k; the lever D; link E; the cam path d for vibrating said
lever D and operating said needle; the cam R for operating the looper; the
tension wheel H; the hub I; the spring J; the elbow-lever L; the lever N;
the rod P pivoted to said lever and provided with the contact nut or shoulder j
constructed and arranged to act upon said lever L to relieve the pressure of the

page_text: hub I upon the tension wheel when said rod is moved towards the front of the
machine; and the cam O for vibrating said lever N.
5th. A thread tension device for sewing machines, in which the friction upon
the grooved thread carrying wheel is produced through ball bearing surfaces.
6th. In a tension device for sewing machines, the combination of a grooves
thread carrying wheel mounted loosely upon a fixed spindle; 'series of balls;
a suitable annular ring for carrying said balls; and means for pressing said
wheel into firm contact with said balls to regulate the resistance to the rotation
of said wheel.
7th. In a thread tension device for sewing machines, the combination of a
thread carrying wheel provided with an annular chamber in its side, and mounted
upon a fixed spindle; a pair of steel disc like washers fitted within said chamber;
a grooved annular ring or frame between said steel washers; a series of steel
balls carried by said ring; and means for pressing said wheel, steel washers,
and balls into firm contact, with greater or less pressure, to regulate the friction
upon said wheel.
8th. In a thread tension device for sewing machines, the combination of a
thread carrying wheel provided with an annular récess in its side, and loosely
mounted upon and revoluble about a fixed spindle; a pair of steel disc-like
washers fitted within said recess; a circumferentially grooved annular ring or
frame between said steel washers; a series of steel balls mounted in separate
bearings in said annular ring with their centres at different distances from the
axis of rotation of said ring; a spring for pressing said wheel, washers, and balls
into close contact; and means for regulating the tension of said spring to
increase or diminish the friction upon said wheel.
541
1
1000
HASELTINE, LAKE & Co.
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.