IMPROVEMENTS IN THE MEANS OF WORKING RAILWAY SIGNALS AND SWITCHES
Year: 1859

page_text: LETTERS PATENT to Josiah Latimer Clark, of Haverstock Hill, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN THE MEANS
OF WORKING RAILWAY SIGNALS AND SWITCHES."
Sealed the 26th July 1859, and dated the 14th February 1859.
PROVISIONAL SPECIFICATION left by the said Josiah Latimer Clark at
the Office of the Commissioners of Patents, with his Petition, on the
14th February 1859.
I, JOSIAH LATIMER CLARK, of Haverstock Hill, in the County of Middlesex,
do hereby declare the nature of the Invention for "IMPROVEMENTS IN THE
MEANS OF WORKING RAILWAY SIGNALS AND SWITCHES," to be as follows:-
This Invention has for its object improvements in the means of working
railway signals and switches. In order to work railway signals and switches I
arrange at or near the foot of the signal post or at or near the switch, two hydraulic
cylinders, each furnished with a pipe leading to the place from whence the
signal or switch is to be actuated, and at this place is a force pump (or pumps)
by means of which water may be forced through one or other of the pipes into
one or other of the hydraulic-cylinders. The pistons or plungers within theso
cylinders are connected with the signal or switch to be worked as is hereinafter
prescribed, or in any other convenient manner, and they are also.connected
together in such a manner that when the piston or plunger, or one of them, is
forced forward by water being injected into the cylinder, the plunger or
piston of the other cylinder is pushed back to its original position, and the
water which the cylinder contained is caused to flow back by the pipe to the

page_text: place where the force pump is situated, and there it is caused to flow into a
measuring vessel so that the person working the force pump may know by the
quantity of water returned by the pipe when the required amount of motion has
been produced. The employment of the returned water to give this indication
is the peculiar feature of my arrangement, which renders it superior to the
systems heretofore proposed for actuating signals and switches at a distance by
hydraulic power.
In place of the two bydraulic cylinders above described, one double-action
cylinder or other similar hydraulic apparatus may be employed, and in place of
obtaining the power directly by means of force pumps as described, it may be
obtained by allowing water to descend from an elevated cistern or to escape from
a reservoir it which it is contained under pressure. The mechanism by which
the hydraulic apparatus actuates the signal or switch I so arrange that,
however much the space passed through by the moving parts of hydraulic
apparatus may exceed that which is necessary, only just the amount of motion
required will be communicated to the signal or switch. For this purpose the
signal or switch is connected with an axis, on which a short arm having a
friction pulley at its end is mounted, in front of this arm and at right angles
to the length of the axis a bar, having a U-form notch in it, is caused by
the hydraulic apparatus to slide longitudinally in suitable guides as the notch
in the bar passes the friction pulley on the end of the arm, this is caused to
drop into the notch and the axis then rotates as the bar moves on until the
arm is brought into such a position that the friction pulley drops out of the
.notch, the bar can then slide on for any distance without producing any further
motion of the signal or switch. When the apparatus is employed to work a
signal which is required to give three distinct indications, as "all right,"
"caution," and "danger," then I mount two arms, such as I have described,
on the axis which works the signals, and make two notches in the sliding bar
with a sufficient distance between the two notches to allow for any variation
which may take place in the working of the hydraulic apparatus.
In some cases it is convenient to reverse the arrangement so that the
rotation of an axis through a greater or less angle may communicate a definite
amount of motion to a sliding bar, and in this case I employ apparatus to lock
the sliding bar after each motion, and to retain it until the next action of the
apparatus.
It will be readily understood that in place of actuating the sliding bar from
a distance by hydraulic apparatus it may be worked by a wire such as is now
employed for actuating distant signals. In some cases I work signals and
switches from a distance by means of two wires in place of the signal wire

page_text: now employed. I connect both of these wires at the distant end to the lever
or rod for actuating the signal or switch, and they are led back to the place
from whence the signal or switch is to be worked, and here they are each
passed over a pulley and heavy weights are attached to their ends. To give
motion to the signal or switch the wires are drawn up by suitable levers as
heretofore, and at each motion one of the weights at the ends of the wires
rises and the other falls, and this motion of the weight on the end of the
return wire furnishes a certain indication of the correct working of the
apparatus.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Josiah Latimer Clark in the Great Seal Patent Office on the
13th August 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSIAH
LATIMER CLARK, of Haverstock Hill, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of February, in the year of- our
Lord One thousand eight hundred and fifty-nine, in the twenty-second year of
Her reign, did, for Ierself, Her heirs and successors, give and grant
unto me, the said Josiah Latimer Clark, Her special licence that I, the said
Josiah Latimer Clark, my executors, administrators, and assigns, or such others
as I, the said Josiah Latimer Clark, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all times
thereafter during the term therein expressed, should and lawfully might make,
use, exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "Im-
PROVEMENTS IN THE MEANS OF WORKING RAILWAY SIGNALS AND SWITCHES,"
upon the condition (amongst others) that I, the said Josiah Latimer
Clark, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said Josiah Latimer Clark, do hereby
declare the nature of the said Invention, and in what mauner the same is to-

page_text: be performed, to be particularly described and ascertained in and by the
.following statement thereof, that is to say:-
This Invention has for its object improvements in the means of working
Tailway signals and switches. In order to work railway signals and switches,
I arrange at or near the foot of the signal post or at or near the switch two
hydraulic cylinders, each furnished with a pipe leading to the place from
whence the signal or switch is to be actuated, and at this place is a force
pump (or pumps) by means of which water may be forced through one or
other of the pipes into one or other of the hydraulic cylinders. The pistons
or plungers within these cylinders are connected with the signal or switch to
be worked as is herein-after described, or in any other convenient manner, and
they are also connected together in such a manner that when the piston or
plunger of one of them is forced forward by water being injected into the
cylinder, the plunger or piston of the other cylinder is pushed back to its
original position and the water which the cylinder contained is caused to flow
back by the pipe to the place where the force pump is situated, and there it
is caused to flow into a measuring vessel, so that the person working the
force pumps may know by the quantity of water returned by the pipe when
the required amount of motion has been produced. The employment of the
return. water. to give this indication is the peculiar feature of my arrangement,
which renders it superior to the systems heretofore proposed for actuating
signals and switches at a distance by hydraulic power.
The arrangement of apparatus above described is clearly shown at Figure 1.
a, a, are two hydraulic cylinders placed at or near the foot of the signal post
or switch, they each contain a piston, and the two pistons are connected
together by a rod, as is shown; b, b, are pipes leading from the cylinders a, a,
to the place from which the signal or switch is to be actuated; c, c, are force
pumps, which are each furnished with a lever handle by which they may be
worked, by the side of each of the pumps a measuring vessel or reservoir dis
placed; c, e, are pipes connecting the measuring vessels with the pumps and
with, the pipes b, b, and these pipes are also connected by other pipes f, f, with
the pumps; 9, 9, are cocks for opening and closing the passages between the
pipes b, b, and the pumps, and between the same pipes and the measuring
vessels; the two cocks are connected together by the arms h, h, and connecting
rod, and they are both worked at the same time by the hand lever j, the
lower end of which is jointed to the connecting rod. The action of the
apparatus is as follows:-When it is desired to move the rod connecting the
pistons of the hydraulic cylinders towards the right, the hand lever j is brought
into the position shown in the Drawing, and the force pump on the left-hand

page_text: side is worked, it draws water from its measuring vessel d, and forces it into
the left-hand cylinder a, this moves the pistons with their rod in the desired
direction. The water expelled from the hydraulic cylinder on the right hand
side passes into its measuring vessel d, and when the person working the
apparatus perceives that the water has risen up to a mark previously placed
within it, he knows that the apparatus at a distance has moved through the
desired space and he stops pumping. The rod connecting the two pistons of
the cylinders a may be made to actuate the signals or switch in any convenient
manner, but the arrangement shown in the Drawing is preferred; this arrange-
ment will be herein-after described.
In place of the two hydraulic cylinders above described, one double-action
cylinder or other similar hydraulic apparatus may be employed, and in place of
obtaining the power directly by means of force pumps, as described, it may be
obtained by allowing water to descend from an elevated cistern, or to escape
from a reservoir in which it is contained under pressure.
When this arrange-
ment is adopted to work the signal or switch, it is necessary only to open the
cocks to allow the water under pressure to pass into one of the cylinders a,
and to allow the water already in the other cylinder to return to the mea-
suring vessel, and as the water in this case is used but once; the measuring
vessel has a small aperture in it at the bottom, by which the water after
having shown itself gradually runs away.
The mechanism by which the hydraulic apparatus actuates the signal or
switch I so arrange that however much the space passed through by the
moving parts of hydraulic apparatus may exceed that which is necessary, 'only
just the amount of motion required will be cominunicated to the signal or
switch. For this purpose the signal or switch is connected with an axis, on
which a short arm having a friction pulley at its end is mounted. In front of
this arm, and at right angles to the length of the axis, a bar having a U-form
notch in it is caused by the hydraulic apparatus' to slide longitudinally in
suitable guides; as the notch in the bar passes the friction pulley on the end
of the arm, this is caused to drop into the notch, and the axis then rotates as
the bar moves on until the arm is brought into such a position that the friction
pulley drops out of the notch, the bar can then slide on for any distance
without producing any further motion of the signal or switch. This arrange-
ment is also shown at Figure 1. k is an axis with which the signal or switch
is connected by levers and rods, or in other convenient manner; is a short
arm on the axis k, having a friction pulley at its end; m is a U-form
bend on the rod connecting together the pistons in the cylinders a, a, as
already described.
As the U-formed bend m passes over the pulley 1,

page_text: when the rod moves back or towards the left, the pin n' on the rod
comes against the projecting lever o, which forms part of the arm 7, and
strikes up the pulley into the U-formed bend, and then by the con-
tinued motion of the rod the axis k is caused to rotate until the pulley
falls below the. U-formed bend, and when this is the case the axis k
will have moved through a sufficient angular space, and no further motion will
be produced whatever be the distance through which the pistons in the
cylinders a, a, may move; the action is precisely similar when the motion is in
the opposite direction. It is obvious that for the arm 7 and the rod with the
U-formed bend, there may be substituted a toothed segment mounted on the
axis k, working with a rack on the rod connecting the pistons..
When the apparatus is employed to work a signal which is required to give
three distinct indications, as "all right," "caution," and ", danger," then
I mount two arms such as I have described on the axis which works the
signals, and make two notches in the sliding bar with a sufficient distance
between the two notches to allow for any variation which may take place in
working the hydraulic apparatus. This. arrangement is shown at Figure 2, its
action being similar to that of the arrangement already described no detailed
description of it is necessary. It will be readily understood that in place of
actuating the sliding bar from a distance by hydraulic apparatus, it may be
worked by a wire such as is now employed for actuating distance signals. In
some cases it is convenient to reverse the arrangement so that the rotation of
an axis through a greater or less angle may communicate a definite amount of
motion to a sliding bar, and in this case I employ apparatus to lock the
sliding bar after each motion, and to retain it until the next action of the
apparatus.
Figure 3 shows apparatus arranged in this manner and applied to a switch.
a is a drum, mounted on an axis; and b is a cord, passing from the point from
whence the signal or switch is to be worked to the drum; c is a weight,
tending constantly to cause the drum to revolve and wind up a portion of the
cord On the axis of the drum is a projection 6, which when the drum
revolves, acts so as to move the sliding bar é through a certain definite distance;
e is a U-formed bend in the bar e, and this bar, as shown in the Drawing, is
in its extréme position towards the right hand. When the cord bis drawn up
from the point from whence the signal or switch is worked, the drum a
-partially revolves, carrying the projection d with it; this acts: first to raise the
catch f, and then to give the bar the desired amount of motion; when this is
dònė, the catch again locks the bar e, and no further motion of the bar takes
place, although the druin. may still continue its motion. When the cord is

page_text: slacked off, the weight causes the drum to revolve in the opposite direction,
and the bar is moved back, the unlocking and relocking by the catch f taking
place as before.
In some cases I work signals and switches from a distance by means of two
wires in place of the single wire now usually employed. I connect both of
these wires at the distant end to the lever or rod for actuating the signal or
switch, and they are led back to the place from whence the signal or switch is
to be worked, and here they are each passed over a pulley, and heavy weights
are attached to their ends. To give motion to the signal or switch, the wires
are drawn up by suitable levers, as heretofore, and at each motion one of the
weights at the ends of the wires rises and the other falls, and this motion of
the weight on the end of the return wire furnishes a certain indication of the
correct working of the apparatus.
This arrangement is shown in side view in Figure 4, and in plan at Figure 5,
applied to work a signal. a is a vertical axis, on which the signals are
mounted. On the axis is a pulley b, to which the two wires or cords c, c, are
attached, so that when one of the wires or cords is drawn up, the axis a is
caused to revolve in one direction, and when the other wire or cord is drawn
up, it is caused to revolve in the other direction. The angular motion of the
axis a is limited by stops as may be required. d, d, are pullies, over which
the wires or cords c, c, pass; and e, c, are weights attached to their ends.
The apparatus is worked by means of hand levers f, f, one attached to each
wire. When it is desired to move the signal, one of these hand levers is
moved so as to raise the weight on the wire to which it is attached; the other
weight then, if the apparatus is in working order, gives the desired motion to
the signal; and if the apparatus is not in working order, then the second
hand lever f, and the corresponding weight, by remaining stationary, at once
show that something is wrong. Suitable catches may be provided to lock the
hand levers ff, if desired.
In witness whereof, I, the said Josiah Latimer Clark, have hereunto set
my hand and seal, this Thirteenth day of August, in the year of our
Lord One thousand eight hundred and fifty-nine.
JOSIAH LATIMER CLARK. (L.S.)