IMPROVEMENTS IN SEWING MACHINES
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by George Henry Smith at the
Office of the Commissioners of Patents, with his Petition, on the
14th November 1870.
I, GEORGE HENRY SMITH, Foreman, Britannia Sewing Machine
Works, Colchester, in the County of Essex, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN SEWING MACHINES," to be as
follows:-
My Invention relates first to improvements in that class of sewing
machines in which a circular revolving shuttle is employed, the im-
provements being in the construction and means of operating the said
circular revolving shuttle, by which I am enabled to use a spool carrying
a much larger quantity of thread than usual. The spool employed may,
moreover, be an ordinary flat bobbin or reel so that the necessity of
winding the thread from a bobbin or otherwise on to a specially con-
structed spool is avoided. I am also enabled to dispense with the
spool ring for retaining the spool in position in the circular revolving
hook.

page_text: In carrying out my Invention I employ a combined hook and cir-
cular shuttle case capable of receiving an ordinary flat reel or bobbin,
which I mount therein on a central pin or pivot, the reel or bobbin being
retained in place by the friction of an adjustable spring, which also
serves to apply the necessary tension in sewing. The hook is formed on
the edge of the circular shuttle case, and in sewing enters the loop
formed in the upper thread by the needle, but instead of casting off the
loop after passing the spool through it, as by the ordinary circular
revolving hook, the thread is allowed to pass behind the hook, the
combined hook and shuttle case (forming a circular rotary shuttle) with
the bobbin or spool contained therein being thus passed completely
through the loop. The thread on the bobbin passes out at the side of
the rotary shuttle, and by the passage of the latter through the loop a
lock stitch is formed by the two threads without twisting the looped
thread as usual.
In order to allow of the rotary shuttle passing through the loop I
attach it to the spindle, by which it is operated by moveable connections
which disconnect at the proper moment for the passage of the thread.
For this purpose I make the shuttle spindle terminate at the extremity
beneath the work plate in a disc of the same diameter as the rotary
shuttle. This disc carries two moveable pins which are caused by a
fixed cam surface to project from the face of the disc and enter corre-
sponding pin holes in the rotary shuttle. The shuttle rotates in a recess
in a circular aperture formed in a plate fixed beneath the work plate, in
which it is confined by a circular guard which also serves to carry a
sponge or other soft substance saturated with oil for lubricating said
shuttle with which it is in contact. The usual check brush is also attached
to the plate for retaining the thread on the shuttle, the moveable pins
being the only connection between the shuttle and the spindle by which
it is rotated. The pins pass through the disc in which they are carried,
each being furnished with a spring to withdraw or disconnect it from
the rotary shuttle when it arrives at a depression in the fixed cam
surface to allow of the thread passing between the shuttle and the disc,
one pin only being disconnected at a time.
.
My Invention relates, secondly, to improvements in that class of sewing
machines known as the shuttle machine in which two shafts are em-
ployed, the upper or needle shaft and the lower or reciprocating shuttle
carrier shaft. The improvements consist in an arrangement for

page_text: obtaining the four motion under feed. The feed bar is mounted in a
vertical position directly over the reciprocating or shuttle carrier shaft,
from which vertical motion is imparted to the feed bar by a cam on the
said shaft. The feed bar has a vertical slot at the upper part to permit
of its rise and fall, in which slot is received the end of a horizontal lever
pivoted at or near the centre, the other end of which lever is held by a
spring in contact with the rod which serves to connect the needle and
shuttle shafts for transmitting motion from one to the other. The
movement of this connecting rod oscillates the lever and imparts the
necessary to-and-fro motion to the feed bar. This motion is limited by
an adjustable stop.
•
In hand machines I mount the driving wheel so as to face the operator
and with its axis at right angles to the needle and shuttle shafts. I
drive one or other of these shafts by a crossed strap or cord from the
driving wheel. The strap runs direct to a pulley on the shaft to be
driven and returns round a guide wheel which leads it at right angles
to the pulley back to the driving wheel. Both driving wheel and pulley
have a (slightly) serpentine groove cut in their peripheries in which
the cord is received, the sinuous form of the groove preventing slip.