IMPROVEMENTS. IN OVER-EDGE SEWING MACHINES
Year: 1885

page_text: I, THOMAS ROBERTSON, of 8 Forfar Road, Dundee, in the County of Forfar,
North Britain, Engineer, do hereby declare the nature of my said invention for
"IMPROVEMENTS. IN OVER-EDGE SEWING MACHINES," to be as follows, that is
to say:
My said Invention relates to sewing machines of the kind used for sewing sacks
with a helical stitch produced by means of a helical or arc-shaped needle working
in combination with a thread barrel. In machines of the kind referred to as
hitherto commonly made there has been within the thread barrel and projecting
from the back end of that barrel, a spindle having a screw thread formed on it
over a considerable portion of its length. This screwed spindle produces a longi-
tudinal movement of the thread barrel by working in gear with a segment of a nut
or internally screwed block, such block being segmental to admit of its being easily
disengaged from the spindle when the spindle and thread barrel have to be moved
forwards for commencing a fresh seam. This combination of the long screwed
spindle and segmental screwed block is found to be unsatisfactory in practice, and
my Invention comprises an improved combination of parts to be substituted
therefor.
In carrying out my Invention the spindle of the thread barrel is made plain but
with a longitudinal groove and it passes through a hollow boss having a worm or
screw formed on the outside of it, to which it imparts rotation by a key engaging
in the groove. The worm boss is held between the gable or end frame of the
machine and a small bracket fixed thereto, and to a part of it there is applied
a small frictional brake for regulating the tension, this brake consisting of a pair
of levers embracing the boss and centered on a fixed pin, their ends being connected
by a thumb screw and interposed spring by means of which the degree of gripping
action is easily adjusted.
The worm of the boss gears with a worm wheel having fixed to it a pinion
gearing with a spurwheel on a separate stud. The spurwheel has formed on one
side of it clutch teeth to engage with similar teeth on a small wheel constructed
for driving a pitch chain, and a spring and hand lever are provided for engaging

page_text: and disengaging the clutch parts. The pitch chain is connected by a length of
plain chain or cord passing round a guide pulley to the small crosshead at the back
end of the thread-barrel spindle; and the parts are arranged so that the chain or
cord pulls back the spindle and thread barrel when the clutch parts are in gear and
the machine is operating. Then when a seam has been finished the clutch parts
are disengaged and the weight and cords provided for the purpose as heretofore
move the barrel and its spindle forward again. This forward movement is limited
by a ring or collar fixed at any required part of the spindle by means of a pinching
screw and small key, a helical spring being placed in front of the ring or collar to
act as a buffer,

page_text: Improvements in Over-edge Sewing Machines.
I, THOMAS ROBERTSON, of 8 Forfar Road, Dundee, in the County of Forfar,
North Britain, Engineer, 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, that is to say :-
I
לי
My said Invention relates to sewing machines of the kind used for sewing sacks
with a helical stitch produced by means of a helical or arc-shaped needle worked
in combination with a thread barrel. In machines of the kind referred to as
hitherto commonly made there has been within the thread barrel and projecting
from the back end of that barrel, a spindle having a screw thread formed on it
over a considerable portion of its length. This screwed spindle produces a longi-
tudinal movement of the thread barrel by working in gearing with a segment of
a nut or internally screwed block, such block being segmental to admit of its
being easily disengaged from the spindle when the spindle and thread barrel have
to be moved forwards for commencing a fresh seam. This combination of the long
screwed spindle and segmental screwed block is found to be unsatisfactory in
practice, and my Invention comprises an improved combination of parts to be
substituted therefor.
And in order that my said Invention and the manner of performing the same
may be properly understood I hereunto append a sheet of explanatory drawings
to be hereinafter referred to and showing part of an over-edge sewing machine
with my improvements applied thereto.
Figure, 1, is a plan; figure, 2, a side elevation partly in section; and figure, 3,
an end elevation with the end frame or gable of the machine shown in dotted lines.
In these drawings the same reference numerals are used to mark the same or like
parts wherever they are repeated.
In carrying out my Invention the spindle, 4, of the thread barrel (not shown) is
made plain but with a longitudinal groove, 5, by preference on its upper surface,
and it passes through a hollow boss, 6, having a worm or screw, 7, formed on the
outside of it, to which it imparts rotation by a key engaging in the groove, 5. The
worm boss, 6, is held between the gable or end frame, 8, of the machine and a small
bracket, 9, fixed thereto, and to a part of it there is applied a small frictional brake
for regulating the tension, this brake consisting of a pair of levers, 10, embracing
the boss, 6, and centered on a fixed pin, 11, their ends being connected by a thumb
screw, 12; and interposed spring, 13, by means of which the degree of gripping action
of the levers, 10, is easily adjusted.
The worm, 7, of the boss, 6, gears with a worm wheel, 14, on a stud, 15, and has
fixed to it a pinion, 16, gearing with a spurwheel, 17, on a separate stud, 18. The
spurwheel, 17, has formed on one side of it clutch teeth, 19, to engage with similar
teeth on a small toothed wheel, 20, constructed for driving a pitch chain, 21.
A spring, 22, interposed between a collar, 23, on the spurwheel boss and a head, 24,
formed on one end of the stud, 18, engages the clutch parts which are disengaged
when desired by the hand lever, 25. The pitch chain, 21, is connected by a length
of plain chain, 26, or it might be a cord, passing round a guide pulley, 27, to the

page_text: small crosshead, 28, at the back end of the thread barrel spindle, 4. The guide
pulley, 27, is centered at the outer end of a long bracket, 29, and the parts are
arranged so that the chain, 26, with the assistance of the weight, 30, pulls back
the spindle, 4, and thread barrel when the clutch parts are in gear and the machine
is operating. Then when a seam has been finished the clutch parts are disengaged
by means of the hand lever, 25, and the weight and cords, 31, provided for the
purpose as heretofore move the barrel and its spindle, 4, forward again. This
forward movement is limited by a ring or collar, 32, fixed at any required part of
the spindle, 4, by means of a pinching screw, 33, and small key, a helical spring, 34,
being placed in front of the ring or collar, 32, to act as a buffer.
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 over-edge sewing machines the combination of parts constituting my.
improvements substantially as hereinbefore described.
"
2. The construction and arrangement of the spindle of the thread barrel in
combination with the hollow boss having a worm on the outside of it substantially"
as and for the purposes hereinbefore described.
3. The construction and arrangement of the frictional brake for regulating
the tension substantially as hereinbefore described.
4. The combination and arrangement of parts for effecting the backward
movement of the spindle when the machine is in operation substantially as
hereinbefore described.