IMPROVEMENTS IN SEWING MACHINES
Year: 1875

page_text: LETTERS PATENT to George Browning, of the City and County of
Bristol, Machinist, for the Invention of "IMPROVEMENTS IN SEWING
MACHINES."
Sealed the 26th April 1876, and dated the 18th December 1875.
PROVISIONAL SPECIFICATION left by the said George Browning at
the Office of the Commissioners of Patents, with his Petition, on
the 18th December 1875.
I, GEORGE BROWNING, of the City and County of Bristol, Machinist,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN SEWING MACHINES," to be as follows:-
This Invention relates to improvements in sewing machines in which
a shuttle is used for carrying the locking thread, and more particularly
in that class of machines where crank action is used for working the
shuttle.

page_text: has been passed through a loop of the vertical needle thread, and
thereby ensuring a tight stitch.
Secondly. In means for adjusting the tension of the two threads
relatively to each other.
Below the bed of the machine and longitudinally thereof I mount a
rock shaft, the opposite ends of which are provided with short arms.
The arm at the forward end of this shaft projects upward through the
bed of the machine for the purpose of bearing against the tail end of a
slide that lies on a level with the throat plate and transversely of the
shuttle race.
The forward end of this slide is squared, and opposed to it
is a squared shoulder of the throat plate, or this shoulder may be formed
separate from the throat plate. At the throw of the shuttle the slide is
in its back position, and. a space is therefore open between it and the
fixed shoulder for the shuttle thread to enter as the throw of the shuttle
takes place. So soon as this-is- effected the longitudinal shaft before
mentioned is rocked, and its arm is thereby caused to press forward the
slide and nip the shuttle thread against the fixed shoulder. The needle
will then in its ascent instead of acting against, a; loose locking thread
as formerly, pull up the thread at a regulated tension and so form a
regular and tight stitch..
.
The rock shaft is set in action by a vertical sliding rod which passes
through the bracket arm, and bears upon the arm of the rock shaft at
the rear of the machine. Overlying the top of this rod is one end of a
horizontal spring carried by the bracket arm, the opposite end is also free
and serves to hold down the friction disc of the vertical needle thread to
prevent this spring which presses continuously on the arm of the rock
shaft from causing the rock shaft to hold the slide at all times up to the
shoulder. A cam on the vertical driving shaft is caused to act on the
under side of the arm, and thereby at the proper moment counteract the
pressure of the spring. The pressure spring which serves to put the nip
both upon the shuttle thread, and the vertical needle thread is inserted in
a trough-shaped guide which is made to receive a shifting fulcrum that
secures the spring in place; this shifting fulcrum may conveniently carry
an indicator to mark its position in its guides, which position determines
the relative amount of spring pressure to be put upon the two threads.
In order to increase the absolute amount of spring pressure the
fulcrum is formed by an excentric, the rocking of which on its pivot pin

page_text: will regulate the amount of depression of the spring. An arm extending
from this excentric works as an indicator over a graduated sector, and
thus shews the amount of pressure put upon the spring.
SPECIFICATION in pursuance of the conditions of the Letters Patent,.
filed by the said George Browning in the Great Scal Patent Offico
on the 17th June 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
BROWNING, of the Oity and County of Bristol, Machinist, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of December, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
'cessors, give and grant unto me, the said George Browning, Her
special licence that I, the said George Browning, my executors,
administrators, and assigns, or such others as I, the said George
Browning, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for " IMPROVEMENTS IN SEWING MACHINES," upon the condition
(amongst others) that I, the said George Browning, my executors
or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and
ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately
after the date of the said Letters Patent.
- NOW KNOW YE, that I, the said George Browning, do hereby
declare the nature of my said Invention, and in what manner. the
same is to be performed, to be particularly described and ascertained
.in. and by the following statement, reference being had to the Drawing

page_text: 4
་
My improvements consist,―
Firstly. In means for holding the locking thread immediately after it
has been passed through a loop of the vertical needle thread, and
thereby ensuring a tight stitch.
Secondly. In means for adjusting the tension of the two threads
relatively to each other. This tension is secured by the use of an elastic
bar or its equivalent, the extremities of which will press the one on the
friction discs of the needle thread to ensure the proper nip of the thread,
and the other end on mechanism that will nip the shuttle thread so soon
as it has passed through the loop of the needle thread and hold it tightly
against the pull of the ascending needle. The relative pressures of the
opposite ends of this elastic bar are determined by a shifting fulcrum,
the sliding of which in its fixed guides by the attendant will increase the
pressure on the end approached by the sliding fulcrum and proportionately
diminish the pressure of the opposite end of the bar. In my Provisional
Specification I described this presser bar as itself elastic, but experience
bas shewn that a rigid bar receiving pressure from a shifting fulcrum
spring is preferable, inasmuch as greater sensitiveness to adjustment is
thereby secured.
The manner in which I prefer to carry out my Invention is shewn in
the accompanying Drawing, where Fig. 1 is a side elevation of so much
of a sewing machine with my improvements applied thereto as will
serve to explain the nature of the Invention; Fig. 2 is an inverted plan
view of the same; Fig. 3 is an end section taken in the line 1, 2, of
Fig. 1; Fig. 4 is a partial plan view of the bed of the machine; Fig. 5
is a section taken in the line 3, 4, of Fig. 4; and Figures 6 and 7 are
detached sectional views of the presser bar, shifting fulcrum, and their
appendages.
Below the bed of the machine and longitudinally thereof (see

page_text: are provided with short arms a, a¹. The arm a at the forward end of
this shaft (see Figures 4 and 5) projects upwards through the bed of the
machine, and is jointed to the tail end of a slide 6 that lies on a level
with the throat plate and transversely of the shuttle race. The forward
end of this slide is squared, and opposed to it is a fixed bar b¹ terminating
in a similarly squared end which serves as a shoulder to receive the
pressure of the slide. At the throw of the shuttle the slide 6 is in its
back position, and a space is therefore open between it and the bar 61
for the shuttle thread to enter as the throw of the shuttle takes place.
So soon as this is effected the longitudinal shaft A is rocked, and its arm
is thereby caused to press forward the slide and nip the shuttle thread
against the fixed bar 6', as shewn at Fig. 5. The needle will then in
its ascent instead of acting against a loose locking thread as formerly
pull up the thread at a regulated tension, and so form a regular and

page_text: .
In order to increase the absolute amount of spring pressure the
adjusting screw e is provided, the turning of which will regulate the
amount of compression of the spring and the gripping force of the
pressure bar.
i
Having now set forth the nature of my Invention of "Improvements"
in Sewing Machines," and explained the manner of carrying the same
into effect, I wish it to be understood that under the above in part
recited Letters Patent I claim,-
.
First. The means above described for holding the locking or shuttle
thread against the pull of the vertical needle thread, and thereby
insuring tight stitches.
Second. Adjusting the relative tension or drag on the needle and
shuttle threads by means of a pressing bar and shifting fulcrum, as
described.
In witness. whereof, I, the said George Browning, have hereunto 1
set my hand and seal, the Sixteenth day of June, in the year
of our Lord One thousand eight hundred and seventy-six.