IMPROVEMENTS IN SEWING MACHINES
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents on the 9th November 1880.
A com-
munication from abroad by George Franklin Newell, of Greenfield, in the
County of Franklin, State of Massachusetts, United States of America.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN SEWING MACHINES." [A coin-
munication from abroad by George Franklin Newell, of Greenfield, in the County
of Franklin, State of Massachusetts, United States of America.]
These improvements relate, first, to a noiseless mechanical device having an even
and positive motion for operating the needle lever and shuttle driver of sewing
machines; secondly, to the construction and arrangement of the feed devices;
thirdly, to the construction of the needle bar in connection with devices for
clamping the needle; fourthly, to the tension device for the upper thread; and,
fifthly, to the combination of a spooler or bobbin winder with the driving wheel
and a clutch, whereby the driving wheel is disconnected from the working
mechanism by the same movement which brings the friction disc of the spooling
device into contact with the wheel to be rotated thereby, all as hereinafter more
fully described.
The transverse driving shaft carrying the driving wheel and pulley extends about
balf way across the work plate, and carries at its inner end two discs connected by
a crank pin, by which motion is transmitted to the lever driving the needle bar
through a driving bar which projects upwards through the standard of the sewing
machine and is connected with the needle lever pivoted in the standard arm by a
link, the said driving bar having its upper end forked to straddle the end of the
needle lever and link when the device is in operation. A radius link pivoted at
one end to the standard and at the other in a slot in the driving bar, regulates the
time of the needle by giving direction to the driving bar, which moves forward and
rearward while the needle lever is at rest at its extreme upward and downward
movement. In the outer face of one of the two dises between which the crank pin
is fixed is a socket diametrically opposite the crank pin to receive the ball shaped
end of an arm whose other end is pivoted in a slot made in the pivoted end of the
shuttle-driving arm. As the driving shaft is revolved, a revolving motion is given

page_text: The feed
to the ball end of this arm and the other end of the said arm being pivoted on a
pin so that it may have a slight vertical motion in the slot of the shuttle driving
arm, which itself is pivoted on a vertical pivot to the work plate so that it may
move in a horizontal plane, the combined movements cause the shuttle end of said
driving arm to reciprocate horizontally with a proper operating motion. This part
of the improved device does away with cams and gear wheels and all unnecessary
friction of running parts and substitutes therefor a direct crank motion.
motion consists of a rod receiving reciprocating motion from an eccentric on the
driving shaft, and extending longitudinally beneath the work plate to the other
end of the same. The end of this eccentric rod receives a perforated ball loosely in
a socket in which it is retained by a detachable section of the rod. Through the
opening in this ball extends an arm that is connected to and works on the same
centre with another arm like an elbow lever. These two arms are not however
rigidly connected, but are connected by pins and slots, so that there is a slight play
between the two, but when the first arm is oscillated about the centre by the
eccentric rod it oscillates the other arm, which has its extremity seated in a notch
in the feed bar which is thereby caused to reciprocate. This feed bar is held in
suitable guides in order to elevate its roughened face when moved forward, and
depress it on the backward move. The outer end of the eccentric rod where it
crosses the feed bar is slotted obliquely, and the feed bar has a horn which projects
through said slot, whose inclination is such that when the eccentric rod is
advancing the feed bar, the inclined slot in passing over the horn of the feed bar
raises it, while for the alternate movement the reverse action takes place. This
result is also assisted by the leverage movement of the eccentric rod in vibrating
about the arm of the elbow lever as a centre. To vary the length of the feed, the
outer end of the eccentric rod is adjusted on the said arm nearer to or further from
its centre of oscillation for lengthening or shortening the stitch. This is effected
as follows: A sliding bar is arranged transversely in guides in the end of the
work plate and has a fork which embraces the end of the eccentric rod. One end
of this bar is jointed to an adjusting lever extending nearly the whole length of
the work plate and provided with a set screw that passes through a slot in the
work plate. The needle bar has at its lower end a longitudinal hole for the needle
and a narrow slot leading sideways into said needle socket. At the top of the
socket also there is a hole extending transversely through the bar, whilo tho
exterior surface of the lower end of said needle bar is screwthreaded and receives a
corresponding screwthreaded collar baving a tapering or bevelled inner edge. Into
the recess or slot in the lower end of the needle bar is fitted a loose jaw having at
its top a right angular bend which enters the transverse hole in the bar, and
having at the bottom an outwardly projecting bevelled toe against which the
bevelled end of the screw collar bears when it is screwed down, thereby forcing
the jaw inward and clamping the needle in the socket.
For the upper thread tension I apply to the top of the arm of the machine a
spring plate, one end of which rests loosely in a seat upon a projection from the
arm, and the other end of which rests loosely upon the flat face of a rocking
support whose lower end is stepped in a recess formed in another projection from
the arm, and which support rocks freely in all directions. This spring plate has an
eye to which the thread is led laterally by a slot, and near its middle it is strained
downwardly with more or less tension upon the thread by means of a central stem
and screw nut, so that the thread as it passes between the face of the rocking
support and the flat spring is held with more or less tension. By the employment
of a rocking support its face follows the spring in a latitudinal as well as
longitudinal direction, and keeps in parallel position therewith for the different
degree of curvature of the said spring plate involved in the adjustment of the
tension.
The Invention also consists in means for winding the bobbin and disconnecting
the driving wheel from the working parts of the machine by the same movement
which throws the bobbin winder shaft into engagement with the driving wheel.

page_text: For this purpose the hand wheel and driving pulley are made to revolve loosely on
the main shaft and are geared to revolve rigidly with it by means of a clutch.
In a groove in this clutch rests the lower end of a lever fulcrumed to the work
plate and extending above the saine and having a swivelling connection with the
Lobbin winder shaft. This shaft has a friction disc on one end which may bo
brought into frictional engagement with the hand wheel to cause the bobbin winder
shaft to revolve. This shaft is carried at one end by a bearing aud passes through
the standard, and has between these two points a spiral spring whose tension holds
the said shaft and the friction disc away from the driving wheel. The other end
of this shaft is provided with a centre bearing, and between this and a bearing the
bobbin is inserted, and when the shaft is pushed back longitudinally to admit of
the insertion of the bobbin, the saine movement both throws its disc into contact with
the hand wheel to cause the rotation of the bobbin, and also through the lever
and clutch disconnects the said wheel from the other working parts of the machine,
80 that there is no wear and tear on the machine while the bobbin is being wound.