Improvements in Surface Contact Electric Railway Systems.
Year: 1897

page_text: Date of Application, 7th Sept., 1897-Accepted, 13th Nov., 1897
COMPLETE SPECIFICATION.
Improvements in Surface Contact Electric Railway Systems.
We, TILE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of this
invention (which has been communicated to us from abroad by William B. Potter,
of Schenectady, County of Schenectady, State of New York, United States of
America), and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:―
This invention relates to closed conduit systems of electric railways, or, as they
are otherwise called, surface contact systems, since a conduit in the proper sense
of the word need not form part of the system.
The supply system is arranged so that there will be the usual track rails and a
feeder constituting the line circuit, and surface contacts or studs which are
normally disconnected from the line circuit, also a series of automatically acting
electro-magnetic switches which serve to connect the contact studs with the feeder
in sequence as the car passes. A. small storage battery is provided upon the
travelling vehicle for closing the switches at times when the line current is not
available. The energizing coils for the switches are placed in the negative or
ground side of the system between the negative terminal of the motor and the
ground return. One coil is provided for each switch. The connections on the
positive side of the system from the feeder to the contact studs do not include
magnet coils and are of low resistance. The contact studs are arranged in two
series, one series is termed the high potential studs. These are connected between
the positive feeder and the positive terminal of the motors, and so receive
practically the full potential of the line. The second series is termed low potential
studs, since they form part of the circuit between the negative terminal of the
motor and the ground, and their potential is only slightly greater than that of
the ground. The high potential studs are in number a multiple of the low
potential studs, but the high potential studs are cross-connected in pairs or sets
so that the number of such sets is the same as that of the low potential studs.
The high potential studs are not connected as heretofore to the feeder one at a
time, but are connected in pairs or sets, and the interconnections between the
studs of each set are permanent. Of course, the different sets of high potential
studs are insulated from each other, and the high potential studs
thoroughly insulated from the low potential studs. In this way current cannot
leak from any of the high potential studs which happen to be alive through the
low potential studs so as to close the switches, nor will leakage current from
the high potential studs hold the switches closed after the car has passed by. In
describing the invention reference is made to the accompanying drawings in
which Figs. 1 to 3 are respectively diagrams of different modified systems embody-
ing the improvements; Figs. 4 and 5 are plans showing different arrangements of
the contact studs in the street.
are
In Fig. 1, A, A are the track rails, B, B¹, and so on are the high potential

page_text: in
studs on the positive side of the systein and C, C, and so on, are the low potential
studs on the negative side of the system. ,G, G, and so on are the switches_com-
prising, as is customary, an armature carrying a moving set of contacts, and also
comprising a single magnet coil in circuit between the low potential studs respec-
tively and ground. The moving switch contacts .close a circuit through the fixed 5
contacts g, g, so that the high potential studs are connected directly with the
feeder H on closure of the switches. The high potential studs are interconnected
permanently
shown
as
set
the diagram, and each is connected
It will
to the contacts of the line switch.
be observed that in the
arrangement shown in Fig. 1 the high potential studs are twice as many in I
number as the low potential studs, but are connected in pairs so that there is
one pair of high potential studs for each low potential stud. The different pairs
are separated by insulating material, shown at I, and of course the high potential
studs are all normally insulated from the low potential studs. The switch G
controls the circuit to studs B B, the switch G¹ to studs B' B', and so on.
are the car wheels, M M the motors, of which there may be one or more. The
positive terminal of the motors is connected to a shoe F running on the high
potential studs and the negative terminal of the motors to a second shoe F¹ running
on the low potential studs. A storage battery of moderate potential, for example 20
or 25 volts, is connected between the shoe F and ground. In the diagram the
second terminal of the battery is shown grounded through the wheels. This
arrangement is now well known in the art.
The operation of these parts is as follows:-
דיע D
The switches G1 G2 are shown closed, and current is furnished to the motors
through the switches, the corresponding high potential studs and collector F. :
The current returns to ground through the shoe F¹, the low potential studs and
magnet coils on the switches. The car may move in either direction. Assuming
that it advances toward the right, switch G¹ will open by gravity or a spring as
soon as the shoe F¹ leaves stud C₁, but this shoe will next strike low potential
stud so that the coils on switches G G³ are in multiple, and switch G³ will
close. The battery is available at any time to complete a circuit through the
switch magnets and close one or more of the switches when the line current is
not available.
In Fig. 2 a somewhat similar system is shown; in fact, the only difference is
in the arrangement of the high potential studs. Here the studs of adjacent pairs
or sets overlap, as shown. In this way the high potential studs may all be
arranged in a single row, but greater insulation distance be maintained between
the different pairs of studs. The operation of the system will be understood from
the previous description of the system of Fig. 1. It differs in no substantial
particular.
In Fig. 3 another modified system is shown differing more decidedly from what
has already been described. Here the high potential studs are not all arranged
in a single row as in the other figures and as has been customary in the art hereto-
fore, but they are separated in two rows at some distance apart, so that there is
a very considerable insulation distance between them. This necessitates a double
contact shoe for the positive studs, shown at F F, which are cross connected.
One set of high potential studs B B corresponds to switch G and lies in the path
of travel of shoe F. The next adjacent set of studs B B¹ lies on the path of travel
of shoe F and so on. The arrangement of the negative studs and the switch
magnets is not different from that already described, and the mode of operation
will be readily understood.
In Fig. 4 one arrangement of contact studs in the street surface is shown.
Here the high potential studs B B1, B2 and so on, are arranged in two rows out-
side of the track rails, while the low potential studs are laid in the centre of the
track. With this arrangement leakage current from the high potential studs
will be short circuited through the rails and will not pass through the pick-up
magnets,

page_text: In Fig. 5 the high potential studs are arranged in two rows between the track
rails and quite close to the rails. The low potential studs are arranged in the
centre of the track, and as far as possible from the high potential studs, so that
leakage current will, in this case also, naturally pass to the rails direct rather
than indirectly through the low potential studs and magnets.
Having now particularly described and ascertained the nature of the said inven-
tion (as communicated to us from abroad) and in what manner the same is to
be performed, we declare that what we claim is:-
1. The combination in a surface contact electric railway system, of a series of
high potential studs arranged alternately in a number of different parallel rows,
switches for connecting said studs with the line circuit, and electro-magnets for
closing automatically the switch contacts, as set forth.
2. The combination in a surface contact electric railway system, of a series of
high potential studs arranged alternately in a number of different parallel rows,
a series of low potential studs forming part of the circuit between the negative
terminal of the motor and the return conductor, and a series of switches com-
prising contacts through which the high potential studs are connected with the
feeder and magnet coils permanently connected between the low potential studs
and the return conductor, as set forth.