IMPROVEMENTS IN ELECTRICAL APPARATUS FOR SIGNALLING BETWEEN RAILWAY TRAINS IN MOTION AND BETWEEN TRAINS AND STATIONS
Year: 1881

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS
IN ELECTRICAL APPARATUS FOR SIGNALLING BETWEEN RAILWAY TRAINS IN
MOTION AND BETWEEN TRAINS AND STATIONS.” A communication from
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 16th April 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN ELECTRICAL APPARATUS FOR
SIGNALLING BETWEEN RAILWAY TRAINS IN MOTION AND BETWEEN TRAINS AND
STATIONS." [A communication from abroad by Augustin d'Auriac, of St. Flour,
France.]
This Invention relates to electrical apparatus for establishing communication
between trains in motion and between trains and stations, whereby to prevent
collision between two trains running at different speeds upon the same line of rails
between two stations.
The apparatus is based on the principle that any good conductor of electricity,
when in contact with another body traversed by an electric current, will give
passage to the current at the instant of contact, and cause it to take another path
through a conducting wire suitably arranged.
The apparatus carried in a signalling van comprises a battery, a transmitter, and
a receiver, and the line conductor is a rail made of three bars of galvanized iron, as
hereinafter described.
Upon this rail runs a contact wheel of wood with a metal tyre, which receives
the currents traversing the rail and transmits them through a conducting wire to
the receiver, the wheel being kept in contact with the rail by a spring at all
speeds. Instead of a wheel any other suitable contact may be employed, such as
brushes, rubbers, &c.
,

page_text: The apparatus works only between one station and the next, the rail being
broken at each station, as it is sufficient to know at each station whether the line
is clear or not. The apparatus may be used constantly or at any moment, so that
from one station to the next the state of the line may be ascertained as often as
desired.
A signalling van should be placed next the tender of every train in order that
when stopping at a station the contact wheel shall rest upon the commencement of
the next section of the conducting rail to permit of communication with the next
station ahead before the train starts. The van being provided with batteries, and a
transmitter and receiver on the Breguet or other system, it is possible to correspond
by signal, and also to interchange messages between two trains on the same section
at once, stating their exact position, &c.
A train in distress may also call for assistance, as the end of every section of the
line rail may be connected with the telegraph instruments at the station, so that
On double
messages may at any time be sent from the train to the station ahead.
lines of railway the conducting rail should only connect with the station ahead,
but on single lines it should be capable of connection with the station at both
ends, a switch being employed in order that only the station ahead of the train
can communicate with it.
'
Having described the general working, I will proceed to describe the con-
struction of the apparatus with reference to the accompanying Drawings, in which
Figures 1 and 2 show two views of the contact wheel and apparatus in connection
therewith. Figure 3 is an elevation of a modification in which a contact brush is
used instead of a wheel; Figure 4 is a separate view of the brush; Figure 5 is a
cross section of the conducting rail.
Referring to Figures 1 and 2, an iron frame made of three parts a, a¹, a², bolted
together, is fixed at the middle of the floor 6 of the van. An iron spindle c forked
at its lower end is fitted to slide up and down on this frame, and has a collar d for
a spiral spring e to press upon. Its upper end f is screw threaded to receive a nut
in the boss of a hand wheel g, whereby to raise the contact off the rail, the spindle
being prevented from turning by the end of a screw i being received in a groove h
in the spindle. The fork k terminates in bearings 7 for the axle m of the contact
wheel n, which has a metal tyre o, and runs between the arms of the fork. When
the forked spindle is raised by turning the hand wheel g, the spiral spring e is
compressed between the collar d and the cross head of the frame, and when lowered,
until the contact wheel rests upon the conducting rail p, the wheel will be kept by
its own weight, and the pressure of the spring in constant contact with the rail at
all speeds, notwithstanding any inequalities in the level of the rail. The wheel n
is made of wood, and may either be solid or spoked. Its periphery has a groove
of proper width and depth turned in it for the tyre, and it is strengthened by
metal plates or rings q, Figure 2, one of which is fixed after placing in the
circumferential groove 3 iron hoops o galvanized at the sides, and united together
by 4 galvanized iron bolts. Thus constructed the rings form good conductors,
even when the tread is rusted. If the friction of the tyre on the rail is found
sufficient to keep it free from rust the tyre might be a single hoop. The axle m is
. hollow, and is provided with a stud r carried on an insulating discs, and electrically
connected to the tyre o by a wire passing through the axle. The stud r is
rounded, and is in constant contact with another rounded stud t pressed up by a
spiral spring u, and carried on an insulated arm v bolted to the fork k.
The rail p is constructed, as shown full size in Figure 5, of 3 iron bars x
galvanised at their sides, and 2 outside bars y galvanised on their flat side only,
and all bolted together at intervals, the rail being spiked down on wood sleepers w
and fixed about 5 centimetres higher than the railway rails. If the friction of the
wheel is found sufficient to keep the rail free from rust, it also may be made of a
single bar, or at most of two bars, which would only require galvanising on their
adjacent surfaces. In order to allow for expansion an interval is left between the
ends of the rails, and they are connected by a galvanized iron wire z which is

page_text: slightly coiled and held at the ends by binding screws 2¹ screwing in holes tapped
in the rail ends and galvanized.
A rotary brush of whalebone may be applied to remove any dirt or obstructions
from the rail, said brush being driven by friction from an axle of the tender, or
preferably a blast nozzle rather narrower than the rail might be arranged just in
front of the contact wheel.
The electrical connections are as follows:-The positive wire (✗) connects the
transmitter with the hanger v, the current passing through the latter to contact t,
thence by the stud r and the wire and tyre o to the rail p. The negative wire (-)
connects with a copper shoe which rubs lightly against one of the wheels of the
van, the pressure being regulated by means of a small hand wheel.
This shoe would be placed at the right side of the van, and at the left side might
be placed a similar shoe in connection with the negative wire of the receiver.
A complete system of communication between two trains would require a return
line, and for this purpose two conducting rails would be employed as well as two
apparatus similar to that above described upon each van. If the earth through the
railway rails be insufficient, the pair of rails might be connected together by
galvanised iron wires or other good conductors, and it would also be well to
connect them with the earth at intervals of, say, 2 kilometres by conducting
wires X attached to a metallic plate X¹ buried in the ground, as shown in Figure 2.
The fish plates of the rails should be so made as to act as conductors, which, in
their ordinary rusty condition, they cannot be relied on to do so as to ensure the
efficient working of the apparatus. At branch lines and crossings the conducting
rail would be interrupted to allow the flanges of the wheels to pass, but the several
portions should be united by insulated conducting wires. As the oil and grease
dropping from the engines and carriages and mixing with the metallic dust
resulting from the wear of the rails might impede the passage of the current,
instead of a copper shoe before described as bearing on one of the wheels, a brush
may be applied to make contact with the rail, and thus ensure the passage of the
current.
The forked spindle and contact wheel may be made as light as possible, as the
wheel only bears with the pressure necessary to maintain the contact, and the
conducting rail might therefore be made much smaller than is represented. This
economy will admit of a return rail being employed, which is much preferable, and
although more costly at first would be soon repaid by the perfect immunity from
accident.
Figures 3 and 4 show a modification in which the contact wheel n is replaced by
a brush 1; it is jointed to an upright spindle 2 by means of a three armed lever 3
whose horizontal arms are connected to a horizontal lever 5 by rods 4 jointed to
each. The lever 5 has sliding weights 6 upon it, by shifting one or other of which
the brush 1 may be inclined in a reverse direction to the motion of the train, so as
to ensure its contact with the conducting rail. The brush is preferably made
double, as shown in Figure 4, and its metallic parts, which are insulated from the
rest of the apparatus, are connected electrically to the transmitter or receiver and
to a pole of the battery like the wheel m in Figures 1 and 2. The upright shaft 2
is screw threaded at 7, and is raised or lowered to regulate the position of brush 1
by means of a nut and hand wheel 8 toothed on its periphery and locked by a
latch 9. A pedal 10 jointed at 11 to a collar 12 on spindle 2 is for momentarily
raising the brush, the spindle being guided at its lower part in a frame 13 bolted
to the underside of the floor b of the carriage, and at its upper part in collars
carried by the upright rods 14. As in the contact wheel arrangement, a complete
system of communication is obtained by the employment of two brushes making
contact with two distinct conducting rails.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
15th October 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN ELECTRICAL APPARATUS FOR
SIGNALLING BETWEEN RAILWAY TRAINS IN MOTION AND BETWEEN TRAINS AND
STATIONS." A communication from abroad by Augustin d'Auriac, of St. Flour,
France.
This Invention relates to electrical apparatus for establishing communication
between trains in motion, and between trains and stations, whereby to prevent
collision between two trains running at different speeds upon the same line of rails
between two stations.
The apparatus is based in the fact that any good conductor of electricity, when in
contact with another body traversed by an electric current, will give passage to
the current at the instant of contact, and cause it to take another path through a
conducting wire suitably arranged.
The apparatus carried in a signalling van comprises a battery, a transmitter, and
a receiver, and the line conductor is a rail made of three bars of galvanized iron as
hereinafter described. Upon this rail runs a contact wheel of wood with a metal
tyre which receives the currents traversing the rail, and transmits them through a
conducting wire to the receiver, the wheel being kept in contact with the rail by a
spring. Instead of a wheel, any other suitable contact may be employed, such as
brushes, rubbers, etc.
The apparatus is used only between one station and the next, the rail being
broken at the stations as it is sufficient to know at whether the line is clear between
one station and the next. The apparatus may be used continuously or at any
moment in travelling between two stations, so that the state of the line may be
ascertained as often as desired, and collisions be thus entirely prevented.
The signalling van should be placed next the tender of the train, in order that
when stopping at a station, the contact wheel shall rest upon the commencement of
the following section of the conducting rail, to permit of communication with the
first station ahead, before the train starts.
The van being provided with batteries, and a transmitter and receiver on the
Breguet or other system, messages may be interchanged between one train and
A train in
another on the same section, and their exact position ascertained, &c.
distress can also call for assistance the end of every section of the conducting rail
being for this purpose connected with the telegraph instruments at the station, so
that messages may at any time be sent from the train to the station ahead. On
double lines of railway the conducting rail should only connect with the station
ahead, but on single lines it should be capable of connection with the station at
both ends, a switch being employed in order that only the station towards which
the train is advancing can communicate with it.
Having described the general working, I will proceed to describe the construction
of the apparatus with reference to the accompanying Drawings, in which Figures
1 and 2 show two views of the contact wheel and apparatus in connection therewith.
Figure 3 is an elevation of a modification in which a contact brush is used instead
of a wheel. Figure 4 is a separate view of the brush. Figure 5 is a cross section
of the conducting rail.
Referring to Figures 1 and 2, an iron frame made of three parts a, a¹, a², bolted
together, is fixed at the middle of the floor b of the van. An iron spindle c forked
at its lower end is fitted to slide up and down on this frame, and has a collar d

page_text: upon which spiral spring e presses. Its upper end is screw threaded to receive a
nut in the boss of hand wheel g, whereby to raise the contact off the rail, the
spindle being prevented from turning by screw i, the point of which is received in
a groove h in the spindle. The fork k terminates in bearings 1 for the axle m of
the contact wheel n, which has a metal tyre o, and turns between the arms of the
fork. When the forked spindle is raised by the hand wheel g, the spiral spring e
is compressed between the collar d and the head of the frame, and when lowered'
until the contact wheel rests upon the electrical conducting rail p, the wheel is kept
by its own weight, and the pressure of the spring in constant contact with the rail
at whatever speed the train may be travelling, notwithstanding any inequalities in
the level of the rail. The wheel n is made of wood, and may either be solid or
spoked; its periphery has a groove of proper width and depth turned in it for the
tyre, and it is strengthened at each side by metal plates or rings g, Figure 2. One
of these rings is attached after placing in the circumferential groove three iron
hoops o which form the tyre, galvanized at the sides and united together by four
galvanized iron bolts. Thus constructed, the rings form good conductors, even
when the tyre or tread of the wheel is rusted. If however the friction of the tyre
on the rail is found sufficient to keep it free from rust, the tyre might be a single
hoop. The axle m of the wheel is hollow, and is provided with a stud r carried on
an insulating disc 8, and clectrically connected to the tyre o by a wire passing
through the axle m, as indicated by the dotted lines, Figure 1. The stud ris
rounded, and is in constant contact with another rounded stud t pressed up by a
spiral spring u, and carried on an insulated hanger V bolted to the fork k. The
rail p is constructed (as shown full size in Figure 5) of three iron bars galvanized
at their sides, and two outside bars y galvanized on their flat side only, and all
bolted together at intervals, the rail being spiked down on wood blocks w nailed to
the sleepers, the rail p being fixed about five centimetres higher than the railway
rails. If the friction of the wheel is found sufficient to keep the rail free from
rust, it also may be made of a single bar, or at most of two bars which would only
require galvanizing on their adjacent surfaces. In order to allow for expansion, an
interval is left between the ends of the rails, and they are connected by a galvanized
iron wire Z, which is slightly coiled and held at the ends by binding screws Z¹,
screwing in holes tapped in the rail ends, and also galvanized. A rotary brush of
whalebone may be employed to remove any dirt or obstruction from the rail, said
brush being driven by friction from an axle of the tender, or in lieu of this, a blast
nozzle rather narrower than the rail might be arranged just in front of the contact
wheel.
The batteries would be placed in a box specially arranged to protect them from
shocks, and the Breguet Morse or other transmitter and receiver would be placed
on a convenient table.
The electrical connections are as follows:-The positive wire (+) connects the
transmitter with the hanger V, the current passing through the latter to the
contact t, thence by the stud r and the wire and tyre o to the rail p. The negative
wire (-) is connected with a copper shoe which rubs lightly against one of the
wheels of the van, the pressure being regulated by means of a small hand wheel.
This shoe would be placed at the right side of the van, and at the left side might
be placed a similar shoe in connection with the negative wire of the receiver.
A complete system of communication between two trains would require a return
line, and for this purpose two conducting rails would be employed, as well as two
apparatus similar to that above described upon each van. If the earth through the
railway rails be insufficient, the pair of rails might be connected together by
galvanized iron wires or other good conductors, and it would also be well to connect
them with the earth at intervals of, say, two kilometres, by conducting wires X
attached to metallic plates ✗¹ buried in the ground, as shown in Figure 2.
The fish plates of the rails should be so made as to act as conductors, which in
their ordinary rusty condition, they cannot be relied on to do, in order to ensure
the efficient working of the apparatus. At branch lines and crossings the con-

page_text: ducting rail would be interrupted to allow the flanges of the wheels to pass, but
the several portions should be united by insulating conducting wires. As the oil
and grease dropping from the engines and carriages and mixing with the metallic
dust resulting from the wear of the rails might impede the passage of the current,
instead of a copper shoe, before described as bearing on one of the wheels, a brush
may be applied to make contact with the rail, and thus offer a certain passage to
the current.
The forked spindle and contact wheel should be made as light as possible, as the
wheel only bears with the pressure necessary to maintain the rolling contact, and
the conducting rail might therefore be made much smaller than is represented.
This economy will admit of a return rail being employed, which is much to be
preferred, and although more costly at first would be soon repaid by the perfect
immunity from accident.
Figures 3 and 4 show a modification in which the contact wheel n is replaced
by the brush 1, as above mentioned; it is jointed to an upright spindle 2 by means
of a three armed lever 3, whose horizontal arms are connected to a horizontal
lever 5 by rods 4 jointed to each. The lever 5 has sliding weights 6 upon it by
shifting one or other of which, the brush 1 may be inclined in a reverse direction
to the motion of the train, so as to ensure its contact with the conducting
rail. The brush is preferably made double, as shown in Figure 4, and its
metallic parts, which are insulated from the rest of the apparatus, are connected
electrically to the transmitter or receiver and to a pole of the battery, as in
the case of the wheel n, shown in Figures 1 and 2. The upright spindle 2
is screw threaded at 7, and is raised or lowered to regulate the position of
brush 1 by means of a nut and hand wheel 8 toothed on its periphery, and
locked by a latch 9. A pedal 10 jointed at 11 to a collar 12 on spindle 2 is
for momentarily raising the brush, the spindle being guided at its lower part in a
frame 13 bolted to the underside of the floor b of the carriage, and at its upper
part in collars carried by the upright rods 14. As in the contact wheel arrange-
ment, a complete system of communication is obtained by the employment of two
brushes making contact with two distinct conducting rails.
The dimensions and details of construction may be varied according to
circumstances.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
herein before in part recited Letters Patent is,―
1. The system of electrical conducting and contact making apparatus combined,
arranged, and applied in connection with a railway carriage and railroad
substantially in the manner herein specified, whereby to establish telegraphic
communication between two trains, or between a train and the station towards
which it is proceeding in the manner described.
2. The combination and arrangement of parts of the wheel contact arrangement,
substantially as herein described and represented in Figures 1 and 2.
3. The combination and arrangement of parts of the brush contact arrangement,
substantially as herein described and represented in Figure 3.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Fifteenth day of October, in the year of our Lord
One thousand eight hundred and eighty one.
A. M. CLARK. (L.S.)