Improvements in Sewing Machines.
Year: 1890

page_text: Date of Application, 29th Apr., 1890-Accepted, 23th June, 1890
COMPLETE SPECIFICATION.
Improvements in Sewing Machines.
I RUSSEL GREEN WOODWARD of Waukegan, in the State of Illinois one of the United
States of America; Mechanic 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 :-
This invention has for its object to provide a sewing machine with a thread-
controller which shall have its position varied automatically to provide for variations
in thickness of the cloth or other material under the presser-foot, and thus give to the
needle and stitch forming devices sufficient slack thread to accord with the thickness
of the material.
In this invention the presser-bar has an attached rack which rises and falls in
unison with it, the teeth of the said rack engaging with teeth at the end of a
thread-controlling lever having a long arm which is extended from its fulcrum back-
wardly toward the tension device where it is provided with an eye to receive the
thread.
To make the thread-controlling lever light so that but little power is required to
move it, the said lever has been constructed of a plate and a wire.
My invention consists essentially in the combination with the work-support, presser-
foot, presser-bar, and rack attached thereto and rising and falling with the presser-bar,
of a thread-controlling lover having teeth at one end and an eye at the other end,
which acts upon the thread on its way to the eye of the needle and cause more slack
thread to be given to the needle as the thickness of the material under the presser-foot
increases, and vice-versa.
Fig. 1 in side elevation represents a sufficient portion of a sewing machine to
enable my invention to be understood, the needle-bar being partially broken out to shew
the presser-bar and rack attached thereto behind it, the thread-controlling lever being
shewn by dotted lines in the position it would occupy if the thickness of the material
should be increased as shown by dotted lines under the presser-foot, and Fig. 2 is a
detail to be referred to.
The bed-plate A, the over-hanging arm A' containing the usual bearings for the
needle and presser-bars, the needle actuating arm B, the link B' connected to a block
secured to the needle-bar B³, partially broken out in Fig. 1, the said needle-
bar, and the presser-bar C and presser-foot (2, are and may be all of usual
construction.
The presser-bar C has applied to it the collar Cx forming part of the rack (having
teeth 2, the said hub having a projection c, the collar being held in adjusted position
on the presser-bar by a set screw c¹.
The pin or projection c is in practice acted upon by a suitable strong spring c
attached at its opposite end to the over-hanging arm A, the said spring normally
acting to keep the presser-foot down upon the material under it.
The spring c is of common use in sewing machines.
The over-hanging aru A¹ has a stud screw D¹, which constitutes the fulcrum for
the thread-controlling lever D having at one end a series of teeth 3 to be engaged by
the teeth 2 of the rack C¹ which as described, is connected to and rises and falls
in unison with the presser-bar according to the thickness of the material under the
presser-foot.
The lever D, to make it light and yet sufficiently stiff, has a part of it composed of
wire, as at 4, the said wire being bent at its outer end to form a socket for the reception
of a stud screw 5, to secure to the end of the thread controller the eye 6 through
which the needle thread t is passed after leaving the usual tension device, the said
needle thread being represented as carried through an ordinary loop or eye b
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page_text: at the upper end of the needle-bar and thence through the eye of the usual eye-
pointed needle.
The tension device may and in practice generally will be substantially the same as
is described in the specification of Letters Patent granted to Lorenz Muther dated
the 29th day of June 1886 No. 8516.
In operation, as the material varies in thickness, say for instance as the material
increases in thickness, the presser-foot rises and causes the eye 6 to descend as
represented by dotted lines and effect the production of more slack in the needle-thread
so that when the needle descends, more slack will be given up to the formation of the
stitch than when the material under the presser-foot is thinner.
By extending the lever D well back toward the tension device, a slight movement of
the presser-bar gives considerable movement to the lever between the tension device
and its point of support on the needle-bar support A'.
Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed, I declare that what 1
claim is :-
1. The combination with the work-support, needle-bar, presser-foot, presser-bar,
rack plate connected to and rising and falling with the presser-bar, and a tension
device, of the pivoted thread controlling lever having teeth engaged by the said rack
and extended horizontally toward the tension device and acting on the needle-
thread between the tension device and needle-bar, to operate substantially as
described.
2. The presser-bar, its attached toothed rack, and the tension device, combined
with the overhanging arm, and the thread controlling lever D pivoted thereon
and extended back toward the said tension device, the said thread controlling
lever having teeth 3 at one end, and having one of its arms composed of wire like
material, as at 4, to operate substantially as described.
Dated the 28th of Anril 1890
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.