IMPROVEMENTS IN RAILWAY SWITCH AND SIGNAL APPARATUS
Year: 1856

page_text: application for Letters Patent was not given within the time prescribed
by the Act.)
PROVISIONAL SPECIFICATION left by William Lawrence Mitchell at tho
Office of the Commissioners of Patents, with his Petition, [on the
26th December. 1856.
I WILLIAM LAWRENCE MITCHELL, of 34, Albert Terrace, London Road;
Southwark, do hereby declare the nature of the Invention for "IMPROVEMENTS
IN RAILWAY SWITCH AND SIGNAL APPARATUS," to be as follows:-
This Invention has for its object improvements in railway switch and signal:
apparatus. For these purposes, in constructing railway switch apparatus, the
two moveable tongues of the main line and siding or branch are connected:
together by. a link or rod, which is pin-jointed to each tongue. In the middle.
of the link which connects the two tongues is a slotted opening, in which a
crank pin of a crank on an upright axis works, and by which the position of
the tongues may be altered. On the upper part of the upright axis is a cross-
head having curved sides, against which a projecting bolt or instrument on the
locomotive engine comes when it is desired to change the position of the
tongues. The projecting bolt or instrument on the locomotive "engine is
moveable, so that the engine man may in passing cause the switch apparatus
to be acted on or not, as the case may require. And in order that the tongues
may be put over by band, as heretofore, and be retained in either position, a
lever, carried by a suitable axis on a standard (fixed at the side of the road)
:
:

page_text: is used. The lever is weighted at its upper end, and by a projecting pin at its
lower end, which works in a slot in a rocking lever below (to which the switch
rod is attached), the tongues can be put into either position, and they will
remain till the weighted lever is reversed. And in order to give notice at a
station or at a point forward of a coming train, the following combined
apparatus is used:-An axis at right angles to the line is employed, moving in
suitable bearings. On this axis is an arm having an incline thereon, and so
arranged that a passing train or locomotive engine may depress it, and thereby
give motion to its axis, on which there is a second arm, which by its move-
ment acts (by a friction roller) on a lever near its axis, and this lever, by a
wire or wire cord, gives motion to a lever at a station or place at a distance
forward of the passing train, and by so doing either sets up a signal or acts on
a bell. On the second arm on the axis (put in motion by a passing train or
locomotive) is a link, which at its other end is attached to a bell-crank lever,
which is attached by its other end to an upright connecting rod, which at its
other end is attached to a box, which at the middle of its length moves on
necks or axes. The bottom of the box is formed with a zig-zag incline, in
which a heavy ball moves, so that when a train is passing, the bell crank and
connecting rod being acted on, give motion to and raise one end of the box;
the ball then runs down the zig-zag incline till it comes to the other end of the
box, where it strikes a catch and actuates mechanism, so that the end of the
box is released, and the box descends to its original position by reason of one
end of the box being heavier than the other. The ball returns to its original
position, and so do the other parts of the mechanism. In order to act on the
signals of railways by the hand or pull-over levers, the chain, in place of being
made fast to the pulley, passes freely through the pulley, and is kept tight by
means of a weight; hence, when the pulley is moved to wind on the chain
and to give motion to the wire communicating with the signal, there will be
no slack chain to take up, but the chain and wire in connection therewith will
be at the proper tension, notwithstanding expansion, or contraction, or stretch,
and the extent of movement of the pulley will be constant.