IMPROVEMENTS IN SEWING MACHINES
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by George Slater at the Office
of the Commissioners of Patents, with his Petition, on the 20th May
1871.
I, GEORGE SLATER, of Lamb's Passage, Chiswell Street, in the County
of Middlesex, Engineer, do hereby declare the nature of the said In-
vention for "IMPROVEMENTS IN SEWING MACHINES," to be as follows:-
:-
My Invention relates to the class of sewing machines known as
shuttle machines. It is well known to those familiar with the con-
struction and working of sewing machines that the shuttle has to be
thrown across the path of the needle so that the two threads may be
interlocked in forming the stitches. The shuttle is moved to and fro
by a carrier or driver, and many different methods of constructing and
operating the same have been devised.

page_text: The ordinary way of operating the shuttle carrier or driver has been
to give it a reciprocating or to-and-fro motion along its race or bed,
either in a straight line or in the arc of a circle.
It is obvious, however, to those familiar with the science of mechanics
that a reciprocating movement involves a stoppage at the end of each
stroke of the shuttle, and although this stoppage is imperceptible from
the rapid action of the machine, yet its effects are observed in the
wearing of the parts and the noise produced by their working.
I obviate these difficulties by a peculiar combination and arrangement
of devices whereby I impart to the shuttle carrier a continuous rotary
motion around the centre of a shaft, but without allowing the said carrier
to turn over, that is to say, the said carrier is not fixed to a revolving
arm which would be carried around with the shaft, but is guided and
controlled so that the point of the shuttle is always kept towards
one side of the machine. For this purpose I place a crank on the end
of a revolving shaft which is geared in connection with the driving
wheel of the machine, and extends to the front thereof under the cloth
plate. The extremity of this crank is fitted on a pin or stud projecting
from the back of the shuttle carrier. The carrier has a tail piece
extending downward and connected by a pin or stud to a link which
is fitted to vibrate on a fulcrum pin fixed in the stand or bed of the
machine.
It will be understood from this description that the carrier while
free to follow the rotations of the revolving crank is yet prevented
from turning over upon its centre by the connection of the vibrating
link to the tail piece. The carrier is arranged behind or against a flat
plate extending across the front of the machine, and of such a depth
that the shuttle in its revolutions will be always guided and kept in
place by the said plate. The pin which connects the crank with the
carrier passes through the crank, and is provided with a nut whereby
the carrier may be adjusted in relation to the aforesaid plate. The
said pin is surrounded by a small spring which serves to keep the
carrier properly up to the guide plate.
I prefer to cast the crank in one piece with the ordinary cam which
operates the feed bar, and I form a weight on one side of this cam to
counterbalance the weight of the shuttle, and thereby equalize the action
of the parts during the revolution of the carrier.

page_text: The mechanism for carrying and operating the needle, the presser
foot, the tension devices, the feed mechanism, and other parts, except
those above described, may be constructed in any ordinary and convenient
manner.