Improvements in Electric Railway Signals.
Year: 1893

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Railway Signals.
I, FRANK HAWTHORNE CLARKE, No. 47 Gotwald Building, Limestone Street,
Springfield, Clark County, State of Ohio, U.S.A., Engraver 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 statement :-
My invention relates to certain new and useful improvements in electric signals,
being especially adapted to railroad signalling, and it consists essentially of
electrical generators carried by the engines or trains and producing electric
currents, preferably constantly alternating, together with a series of electrical
conductors adjacent to the railway bed and forming a system of overlapping blocks,
so that should one train enter upon a given stretch of track already occupied by
another train, that fact will be audibly announced in both trains, or as many as
may enter or be upon such stretch,-the announcement being made in either or both
directions-forward or rearward; further peculiarities of construction and operation
will be hereinafter pointed out and claimed.
In the accompanying drawings on which like reference letters indicate corre-
sponding parts:
Fig. 1, represents a plan view of a portion of a railroad track and this system
applied thereto, approaching trains being indicated thereon by diagrams;
Fig. 2, a similar view illustrating the operation of this system when the trains
are moving in the same direction;
Fig. 3, a plan view of a portion of the main liue and of a side track, illustrating
the construction for signalling in connection with the latter;
and
Fig. 4, an enlarged plan view of the switch in Fig. 3, showing the construction;
Fig. 5, a cross section of the track, the electrical conductors, a generator carried
by an engine, and its connections with the said conductors.
The letters A, A, designate the rails of a railroad. The letter B designates a
strip of wood, or other insulating material parallel to and either along the inner or
outer side of each rail. Along each insulating strip or base, is laid a double line
of wires or other electrical conductors. Each line is formed in sections or lengths
of suitable distance, the ends of the sections being adjacent to, but not meeting
each other. On the same strip, one of the lines breaks joint, or alternates with the
other line, as shown in Figures 1 to 3 inclusive. That is to say, the matching ends
or break in one line, is about midway of the length or section of its companion line
on the same strip, whereby from every break or joint, of either line, the section of
the other line extends substantially half its length in both directions.
As before intimated, a double line is laid at each side of the track either on the
outside, or along the inside of each rail, as shown in the figures. The breaks of
the double line on one strip, correspond or match with the breaks of the double
line on the other strip. Thus a section on one side of the track, pairs with a
section on the other side of the track, and constitutes what will be termed a block;
and as each strip has a double line of overlapping conductors, a continuous series
of overlapping blocks is thus formed.
To illustrate the use of this arrangement and construction, diagram Figures, 1
to 3 inclusive, are shown. Referring to these figures, the letter C designates a
train or locomotive, approaching another train or locomotive D on the same track.
Each train carries an electric generator, E and F respectively, having connecting
wires to a pair of contact-devices or brushes E' F' respectively, of wire bristles,
adapted to be brought in electrical contact with conductors upon the strips B, as

page_text: indicated in Fig. 5. The generator is of any suitable form for producing a current
of electricity, and may be operated by hand or by machinery. In Fig. 5 the
pulley G of the generator is driven by an oscillating engine H, taking the steam
from the boiler; if desired, the generator may be driven by the use of a handle H³,
but it is preferred that it should be constantly operated, as will presently appear.
By operating one or both of such generators, a current of electricity is sent to the
brushes and into the electrical conductors along the track. Referring to Fig. 1
the two trains shown approaching each other, C and D, are in connection with the
same pair of sections or block No. 1, and the current of electricity will pass through
the brushes of each generator and complete a circuit, thereby causing an electric
bell in the engine cab, to sound. The generators are not described in detail, since
they form no part of this invention and any ordinary kind may be employed. The
alarm in both engines is given when this circuit is completed, as just described. If
the blocks are a mile long, for instance, the moment the engine enters a block
another engine is already on, an alarm is rung in each engine, thus notifying each
engineer that another train is within a mile of him. This notification_comes
through block No. 1; the currents of electricity pass out of the brushes E¹, into
block No. 2, on which engine C is located, and out of brushes F into block No. 3
which is in connection with the generator of engine D. Block No. 2, overlaps
No. 1, in one direction, and extends a suitable distance in the other direction
overlapping block No. 0. Any engine following engine C, as C' indicated by
dotted lines, will complete a circuit with engine C by means of a block No. 2, when
in the positions shown. If engine C were in the position of C' with regard to
engine D, no alarm would be sounded in either C or D; but one would be sounded
when both came within the same block.
Either alternating or coutinuous currents of electricity are used in signalling
approaching trains." When one train or engine follows another, however, as shown
in Fig. 2, it is necessary that the currents be alternating in order that the circuits
may be completed. Thus while either kind of current may be used when the
engines are approaching each other, alternating currents are preferred in this
invention. With an alternating current; engine M will be notified of the approach
of engine N, when the latter, reaches the same block, No. 10, for instance, on
which engine M is running. When M passes to block No. 11, the circuit is broken
between the two generators and remains so until engine N reaches block No. 12,
when it will again be completed if M is still in contact with block No. 12, as shown
in the dotted position, M¹.
Referring to Fig. 1 again, the engine D', is shown on block No. 4 which extends
up to block No. 1, and overlaps with block No. 3 which is charged with electricity
from engine D, which protects it from the rear. Thus no alarm is given between D
or D in their present positions; but as soon as D' moves upon block No. 3 it
completes the circuit and the alarm is given in both.
Thus it will be seen that wherever an engine with its generator is located on the
track, it is in contact, through its contact-devices or brushes, with two blocks,
which notify it of the approach of another train from either direction; and that
such other train cannot approach in either direction nearer than the terminus of
the adjacent blocks, without giving the alarm in both engines. Whether both
trains are running in the same direction or are approaching each other, an
alternating current produced by the constantly operating generators, will produce
an electric current in the electric conductors both in front and in rear, and when
both engines arrive in the same block the alarm is given. If one be stationary, and
the other be moving, the alarm is given. If both be stationary, the constantly
operating generators will maintain the alarm.
In order to protect a train from running into a switch set for a side track, the
arrangement illustrated by Figures 3 and 4, is employed. This consists in a double
loop of wires running out alongside the track to form part of the corresponding
block or blocks at the switch. Ordinarily this side track block is out of the circuit;
that is, when the main track is unbroken. When the switch is switched for the

page_text: side track, however, the currents will flow up along the loops. This is accomplished
by means of a construction shown in Fig. 4, consisting of a common plate of copper,.
or other electrical conductor O, for each side of the track, connected by a link P,
insulated, and both operated by an insulated connection P with the switch rails,
from the switch stand Q. By the usual operation of the switch from the main track
to the side track and vice versa, the pivoted plates O are operated from their dotted
positions to their full line positions and vice versa. When in the position shown by
dotted lines, these plates connect the double line of conductors for the main track;.
when in the position shown by full lines, however, these plates are swung over into
contact with the conductors of the side track, as shown in Fig. 4, so as to bring
these loops into the blocks of the main line and thus notifying a train approaching
the switch, that the switch is open. If a train be ou the side track and passing off
to the main track, the alarm will also be sounded if another train be within half a
block of the switch in either direction on the main track. It is not necessary that
the conductors for the side track extend down far along said track, except for the
additional safety to both trains in notifying them of the presence of each other before
the train on the side track enters the main track.
As before mentioned, these blocks may be of any convenient length, according to
circumstances; broad claim is made, however, to overlapping blocks of whatever
length and arrangement, together with either alternating or continuous currents of
electricity. In carrying out this invention, it is not intended to limit the same to
the particular forms and arrangements herein shown and described, the same being.
but one way in which the end sought is attained.
Either a chemical or a mechanical electric generator may of course be used..
When an alternating current is employed then the preferred generator is that
mechanical generator known as the Seiemens.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :
1st. In electric signals for railroads, the combination with a double set of
electrical conductors located in parallel lines and overlapping each other in each
set, and corresponding with each other, to form a double series of overlapping pairs
of conductors to constitute overlapping blocks, and an audible signal, of generators
producing alternating currents, carried by the trains, and electrical connections from
cach generator to each set of conductors respectively, said signal being in the
circuit so formed, whereby signals are sounded and a circuit is completed from one.
set to the other, when the generators of two trains are in electrical connection with
the same block.
2nd. In electrical signals for railroads, the combination with a pair of insulated
electric conductors mounted at one side of the track, of another pair of said con-
ductors at the other side, matching with the first pair and insulated therefrom, and
so on successively, whereby a double series of overlapping blocks is formed, of
generators producing an alternating current of electricity, carried by trains, and
electrical connections and contacts between said generators and cach double line of
conductors, respectively, and an audible signal in each train, each in the circuit so
formed.
3rd. In electric signals for railroads, the combination with a double set of over-
lapping electric conductors forming blocks, of an auxiliary line of conductors
forming a loop extending out into a side track and means to electrically connect and
disconnect such side track loop with the conductors of the main line.
4th. In electrical signals for railroads, the combination with overlapping electric
conductors forming a double line at each side of the track and constituting blocks; of a
double loop of electric conductors extending out along a side track, the ends of the
loops being adjacent to each set of conductors on the main line, respectively, and an
electric switch consisting of a movable plate for each set of the main line conductors,
and adapted to be brought into and out of electric engagement with the ends of the

page_text: side track loops by the operation of the switch in setting the switch-rails for the side
track and main line, respectively.
5th. The herein described system of automatic signalling, the same consisting of
electrical generators carried by some part of trains, clectrical connections and
contact pieces proceeding from the respective generators, audible signals also
carried by the trains and in the generator circuits, and electric conductors adjacent
to the railway bed with which said contact pieces are in electrical engagement, such
line conductors consisting of a double set of lengths or sections, the lengths or
sections of one set overlapping those of the same set, and the lengths or sections of
each set terminating opposite to the corresponding lengths or sections of the other
set, whereby electrical communication may be established between a plurality of
trains occupying at the same time corresponding lengths of the opposite sets and
overlapping adjacent lengths.
6th. The herein described system of automatic signalling, the same consisting of
alternating-current electrical generators carried by some part of trains, electrical
connections and contact pieces proceeding from such generators, audible signals
also carried by the trains and in the generator circuits, and electrical conductors
adjacent to the road bed and composed of lengths or sections arranged in pairs at
either side, the lengths or sections of one pair overlapping those of another pair
and the lengths or sections of the same pairs terminating opposite to one another,
whereby an audible signal will be sounded in a plurality of trains moving in the
same direction and occupying the same section of the respective sets.
Dated this 14th day of February 1893
S. S. BROMHEAD,
97, Newgate Street, London, E.C., Patent Agent.
S. S. BROMHEAD,
97, Newgate Street, London, E.C., Patent Agent.