Signalling on Railways.
Year: 1887

page_text: Date of Application, 18th July, 1887
Specification Accepted, 14th Oct., 1887
Signalling on Railways.
I, WALTER WALKER, of Dashwood House, New Broad Street, in the City of
London, Engineer, do hereby declare the nature of this invention, and in what manner
the same is to be performed to be particularly described and ascertained in and by
the following stateinent, reference being had to the accompanying drawings, and to the
letters and figures marked thereon, that is to say :-
In the specification of my British Patent dated 2nd November 1886, and numbered
14,105, I mentioned the use of contact apparatus, of any ordinary construction,
worked by a depressible bar or rail, for the purpose of controlling the earth connections
with the signals, so that when a train enters on a section of line of rails the earth
connections at that section are broken, and the signal is brought to "danger" by
gravity, and remains thereat, until the train, on passing off from that section of the
" safety" or
line, again causes the circuit to be completed and the signal to be set to
"line clear."
Now, the object of my present Invention is to describe and claim special constructions
and arrangements of contact apparatus, which I prefer to use in carrying out my
system of automatic electric signalling, and by means of which apparatus, I am
enabled to establish and maintain certain and perfect electrical contact, for the purpose
above set forth.
I proceed to describe my invention with reference to the accompanying drawings,
in which Fig. 1 is a central longitudinal section of one form of my improved contact
Fig. 3. is a vertical section, on an
apparatus, and Fig. 2, a plan, partly in section.
enlarged scale, of the contact proper. Fig. 4 refers to a modified form of the contact
apparatus.
In carrying out my invention I use for each signal two of either of the apparatus,
"contact maker," and the
hereinafter described, coupled together, one acting as a
other as a
"contact breaker," but for purposes of description, I describe only one of
each of such apparatus, it being understood that the other apparatus is of precisely
similar construction.

page_text: For some purposes, however, it may be found necessary to use only one apparatus
which may be either a "maker" or a breaker," as the occasion may require.
(
A, is an iron box in which the contact apparatus is placed; this box is fastened to
the rails, and extends, in the direction of its length, from one rail to the other, under-
neath the same, like a sleeper, and downwards in a hole dug in the earth. It is
constructed, as hereinafter fully described, so as to prevent moisture or water entering
therein, and attacking the working parts of the apparatus, and also to protect the same
from accident or interference.
B. B, are the lines of rail, and B¹ the depressible rail or bar, which, in this instance,
is placed on the inner side of the rail, and is operated by the flange of the wheels.
To the underside of this depressible rail is fixed a rod or stem b, passing through a
guide c in the top of the box, and jointed at its lower end to the lever C, having its
fulcrum in the bearing D. This lever extends along and within the box A, and carries
at its extremity the contact proper.
This contact proper consists of a cylindrical brass casing e, closed at top and
provided with a screw shank f, by means of which it is inserted into the socket g,
which is jointed to the extremity of the lever C. Within this casing is inserted a
lining of vulcanite 7, or other suitable insulating material, in which is screwed a brass
plug i, carrying at its lower and outer extremity, a platinum point ¹. This platinum
point is so arranged, as to make contact, on the descent of the casing (as explained
further on) with a platinum disc, plate, or strip, k, fixed to the upper and outermost
extremity of a brass plug 1, which is inserted in a block or sheath of vulcanite m,
fitted in a tubular brass piece or stem n, forming the rod of an inverted cup-shaped
piston o, capable of a movement within a cylinder p, bolted to the bottom of the
box A. Beneath this piston is a spiral spring r, for ensuring and maintaining
electrical contact, when established, by keeping the platinum disc or strip, on the
stem n, well up in its position ready to receive the point and yet be easily depressed,
so as to prevent any strain or breakage, in case the point should be forced down
further than is required to touch the platinum disc, plate, or strip k.
jand, are the terminals to which the wires are connected.
These wires are
screwed into the two brass plugs i and respectively. Both the terminals are
protected by vulcanite casings or caps J, J', respectively, the former being fitted
into the casing e, and lining h, and the latter into the tubular stem, n and vulcanite
sheath m.
Now, on the depressible rail or bar B₁ being depressed by the wheels of a passing train,
the lever C is consequently depressed, and the casing e, is caused to descend over
the tubular stem n, thus bringing the platinum point i, into contact with the platinum
strip k, and thereby completing the circuit and actuating the signals in the manner
set forth in the specification of my patent hereinbefore referred to.
In order to ensure the return of the lever C, to its normal position, after the train
has passed over the depressible rail, I connect to such lever, a rods provided with a
piston t, working in a cylinder T, bolted to the bottom of the box A. Beneath this
piston is a spiral spring v, which is compressed when the lever is depressed, so that
this spring may expand after the train has passed the depressible rail, and thus ensure
the return of the said lever. Above the piston is a rubber cushion a, to deaden the
shock or concussion of the piston against the cylinder cover.
The box A is provided with removeable end plates A', A", to render the contact.
accessible, when necessary.
To prevent water, or moisture, interfering with the contact, the box A, is cast with
rectangular ribs a, a', forming compartments in the length of the said box, so that
in the event of water collecting in the first compartment, it would take some time
before rising up to the upper surface of the rib a, and overflowing into the second
compartment where it would meet with further obstruction from the second rib a¹.
The plates A', A", are also fitted with rubber joints to further exclude, all moisture or
water.
If found desirable, the bottom of the box may be inclined from a¹, to A¹, in order
that any water may run towards the plate A', whence it could be drawn off by a tap,

page_text: Or it could have a hole, or holes, in the bottom, with iron piping soldered to them
and connecting with another box, on a lower level, some distance away, also fitted
with a tap to let out any water.
It will be readily seen that by this contact apparatus, I require a very slight
deflection of the depressible rail or bar B¹, to procure the distance I desire, between
the contact points, of the contact proper, and that the box A, being fastened to the
rails, any sinking of the road bed and rails, would not alter the relative position of
these contact points. Furthermore, that the contact apparatus is thoroughly protected
from any injury, from accident or interference, and that as the only place where water
or moisture could possibly get into the box, is between the depressible rail B¹, and its
guide c, therefore the contact proper, at the other end of the box, will be protected
from any water or moisture, by reason of the construction of said box, in addition to
its own vulcanite and brass casings which protect the contact points from water, or
moisture, and act as guides from the upper to the lower half of the contact proper.
Fig. 4 is a modification of the contact apparatus just described. In this modification
the depressible bar or rail B' is of T, or other suitable shape, it is pivotted in the
stem or rod b, is placed outside the rail, and is operated by the tire of the wheels.
The object of this modified form of apparatus is to lessen the wear and tear on the
contact points, and for this purpose the lever C, instead of being a rigid one, as shewn
in figs. 1 and 2, is a jointed one, the joint acting as a substitute for the spiral spring r.
When this lever is depressed, the joint yields, and thus the constant impact of the
contact points is modified, or reduced. Fig. 4* shews, in plan, the arrangement of
joint of this lever.
Fig. 5 shews two of my contact apparatus, described with reference to fig. 4,
coupled together, the one being used as a "contact maker," and the other as a 'contact
breaker; the one called the "maker" is connected with the main circuit and the one
called the "breaker is connected with a local circuit from a local battery, and when
a train in passage completes the local circuit the current from it pulls over an armature
of a relay and breaks the main circuit, so that the terms "maker" and "breaker refer
to the making and breaking" of the main circuit. The depressible T shaped rail or
bar B¹ is here prolonged, and acts as a connecting rail, to couple the two rods or stems b
of the maker and breaker. This depressible bar is of such a length that the first wheel
of a train cannot leave it until the second wheel reaches it, and by this means a
constant contact is maintained in both maker and breaker, until the last wheel of a
train passes over the maker or breaker, and makes, or breaks, the electric circuit
respectively, in accordance with the relative position of the maker, or breaker, that is
say, whether the last contact apparatus, which is depressed by the last wheel of a
train, is a maker, or a breaker.
to
By this arrangement I obviate the intermittent making and breaking of the electric
circuit, and the consequent intermittent rise and fall of the signal, occasioned by every
wheel of a train, which would cause great wear and tear on the signals.
Fig. 6 shews a means of making a constant contact in either a maker or a breaker,
when either of these have to be used singly, and not coupled up, as shewn in fig. 4.
It will be seen that, owing to the length of the T shaped depressible and connecting
rail or bar, as shewn, the first wheel of a train cannot leave this rail until the second
wheel enters upon it, and that therefore a constant contact is maintained, and the wear
and tear on the contact points is saved.
In the arrangement shewn in fig. 5, the depressible and connecting rail or bar B¹
is connected to the rail, or to the sleeper, by means of forked rods q, q', one of which
has a right hand screw thread cut on it, and the other a left hand screw thread. These
rods are coupled by the tapped nut or piece q². The rod q is connected to the depres-
sible T shaped rail by a pin q, and the rod q', is, in like manner, coupled to a
bracket q, fastened to the rail, or to the sleeper. The object of this contrivance is to
receive the thrust of the train as it enters on the depressible rail, and thus relieve the
side strain and friction that would be otherwise allocated to the stem b.
In the arrangement shewn in fig. 6 this contrivance may be dispensed with, and

page_text: the ends of the depressible rail or bar B¹ slotted, and work over pins 2, z, fixed to the
web of the rail.
Having now described my Invention and in what manner the same may be performed,
I claim,
1. The improved contact apparatus, having its parts constructed, arranged, combined,
and operating, substantially, as herein described, and as shown with reference to
figs. 1 & 2 of the drawings, and for the purposes set forth.
2. The construction of the contact proper, as heroin described, and as shewn with
reference to fig. 3, of the drawings.
3. The construction of the box for the purpose of preventing moisture interfering
with the contact proper, as described, and as shewn with reference to figs. 1 and 2
of the drawings.
4. The modified construction and arrangement of the contact apparatus in which
the depressible rail or bar, is pivotted in the stem or rod b, and is placed on the outer
side of the rail, and the lever employed for effecting the contact proper is jointed, and
acts as a substitute for the spiral spring r, substantially as herein described, and as
shewn with reference to figs. 4, 5, and 6 of the drawings, and for the purposes set
forth.
5. The combination and employment of either two of the contact apparatus, herein
described, and shewn with reference to figs. 1 and 2, or with reference to figs. 4, and 5,
the same being coupled together by means of the depressible bar, or rail, placed either
on the outer, or on the inner, side of the line of rails, substantially as described, and
for the purposes set forth.