Improvements in Surface Contact Electric Railway Systems and in Apparatus for use therewith.
Year: 1897

page_text: Date of Application, 7th Sept., 1897-Accepted, 9th Oct., 1897
Improvements in Surface Contact Electric Railway Systems and in
Apparatus for use therewith.
We, THE BRITISH THOMSON-HOUSTON COMPANY, LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of this
invention (as 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:-
The present invention relates to electric railways operated by the well known
closed conduit or surface contact system and in apparatus for use therewith, and
has for its object to provide a system in which there will be a comparatively small
number of operating parts, with a simple and efficient arrangement of circuits,
ensuring the connection of the sectional working conductors with the feeder
during the passage of the car and permitting the switches to drop as soon as the car
has passed.
Other objects of the invention are herein fully set forth, and the novelty is
pointed out in the claims.
To attain the object of this invention a system of supply is employed with one
or more feeders, preferably buried (although they may be located any way con-
veniently adjacent to the road) with the usual contact studs or sectional rails
forming the working conductors. The latter are divided into two sets of contacts,
one series of high potential studs or contacts through which the working current
flows to the positive terminal of the motor or motors for the propulsion of the car,
the other of low potential studs on the negative side of the motor with which are con-
nected suitable devices for picking up the electro-magnetic switches. The terms.
high and low potential are used in this connection to distinguish conveniently
between those studs connected to the feeder and those connected to the return.
Two collecting devices in the form of sliding shoes are provided, spanning the gap
between the sectional conductors, so that one is always in circuit before the previous
one is cut out. The studs or sectional conductors are arranged in two rows and
'staggered" as it is termed; that is, they alternate in position in the two series,
and as it is preferred to place them, are in the roadway between the rails. Carried
by the car is a small storage battery of low potential, serving to "pick up" when
current is not flowing through the motors. At other times it may, if desired, be
cut out, or the arrangement may be such that the motor current acts to charge the
battery. Inasmuch as it is required to do but little work and through com-
paratively low resistance (it being connected between the track forming the ground
on one side and through the low potential studs and pick-up coils of the switches
to ground upon the other side,) it need be but of comparatively small capacity and
low electro-motive force, twenty or twenty-five volts being sufficient to overcome
with certainty the resistance in its circuit. The battery is connected in series
with the motor, but in multiple with the pick-up coils of the various switches, the
utility of this particular arrangement being pointed out hereafter,
"E

page_text: The switch devised for connecting the buried feeder with the working con-
ductors comprises a pick-up magnet having a coil connected to ground at one end,
the other being connected to one of the low potential studs, the coil being upon the
negative or ground side of the system. The usual switch contacts are provided, in
this case there being three of them. One of these is connected to the feeder, and
from each of the others connection is made to one of the studs in the roadway,
so that the closing of each of the switches energizes two of the high potential studs.
These latter connections are direct, including no holding-up coil or other device
tending to reduce potential, so that the full working potential is conveyed to each
of the contact studs in the roadway.
The accompanying drawings show the invention in some of its different aspects,
Fig. 1 illustrates in diagram the preferred arrangement of circuits; Fig. 2 the
sectional conductors in the form of rail with a collecting brush spanning the gap
between each two of them; Fig. 3 shows how the storage battery may be replaced
with another source of electro-motive force, and Fig. 4 is a detail of a modified
arrangement of the device shown in Fig. 3.
In Fig. 1, A, A are the track rails serving, as usual, for the ground return,
although this is not essential; B, B' are the high potential studs, C, C¹ the low
potential studs, G, G₁ the switches. Each of the these latter is provided with a
coil g, serving to pick up the switch and complete the circuit between the feedez
and the road contacts, the coil being in circuit between the studs C, C and ground.
Three contacts g¹ to g³ are provided for each switch. The contact g¹ is connected
to the feeder H; contacts g and g³ are connected respectively to the adjacent high
potential studs on each side of each switch, those for instance on the switch G¹
being connected to the studs B¹, B³. E is the storage battery or other source of
electro-motive force, connected between the axle 11 of the car and the sliding
contact or shoe F¹. M, M are the notors, of which there may be one or more
without varying from the invention.
The sliding contact or shoe F¹ completes the circuit for the negative side of the
motors, while the shoe F is connected to the positive side.
The operation of the devices just described is as follows: The switch G¹ is shown
closed, current therefore passing from the feeder H to the contact g¹ and by the
switch blade to contacts o³, g³. From the first of these current passes to the
stud B in the roadway; from the second to the stud B; these two studs being
both in engagement with the shoe F, the circuit is completed by the shoe to the
motors and thence to the shoe F1, then through the coil of the switch to ground
or the return circuit; the main line current thus passing through the coil holds up
the switch after it is brought to its attracted position.
As thus described it will be seen that so long as one of the switches G is closed,
the storage battery or other auxiliary source of electro-motive force has no
necessary function. Assuming however that all of the switches are down, as when
the car comes to a stop, and the motor current is interrupted; in this case, there
being no connection from any of the studs to ground through the motors, no current
would flow in the pick-up circuits; the storage battery E then acts to "pick-up,"
it being grounded at one end on the car axle, and through the various low
potential studs C', C having its circuit completed through the pick up coils to
ground. The battery may of course be again cut out as soon as current passes
through the motor, as will be manifest when the operation of the various switches
by the passage of the car is considered.
Assuming now that the car is moving to the right in the direction of the arrow
in Fig. 1, the next change in the circuits from the arrangement illustrated will
occur when the shoe F leaves the stud B¹; there being still a path for the current
of substantially equal resistance to the one broken, there is no objectionable
sparking in the roadway, the current still continuing to pass from the contact g³
to the stud B and to the motors as before. When the shoe F¹ reaches the stud C
(this being the next change in the connections), the switch C will pick up, the
main line current passing through the coil g' to ground. The circuits are thus

page_text: established for the high potential studs B, B³. The shoe F is in contact with the
stud B, and the shoe F1 with the studs C, C³. When the shoe leaves the stud C¹
the ground connection through that stud and its corresponding switch magnet
being broken, the switch G¹ drops; but as in the case of the high potential studs,
the stud C being in circuit before the contact with C'is broken, and offering an
alternative path of equal resistance for the current, there is but little sparking at
breaking contact. During the time that the shoe F¹ is in contact with both of
the low potential studs C¹, C³ the switches G1, G2 are both in their attracted
positions; but as soon as the shoes pass off the stud of either switch, the switch
blade drops. The paths for the current with the switch G2 attracted, are from the
contact to the stud B2, from the contact g³ to stud B³, the motor being
supplied through the stud B and grounded through the stud 0³, holding the
switch G attracted.
The next change in the connections is when the shoe F touches the stud B³, the
condition shown in Fig. 1 again existing, except that the switch
place of G
takes the
It is unnecessary to trace the connections when the car moves in the other
direction, as they are symmetrical with those already described.
Fig. 2 shows the same arrangement as that in Fig. 1, except that the sectional
contacts are shown as rails having an insulating space between them, and are
normally insulated from ground. In this case however the shoes or collectors are
simply long enough to span the gaps between the rails so that each of the sections
is cut in before the last preceding one is cut out.
Fig. 3 shows how another generator of electro-motive force might take the place
of the storage battery, it being under some circumstances undesirable to use the
latter. In such cases a small magneto-generator E¹ is provided geared to a
handle K, which might be the brake handle. The connections of this generator
are the same as those of the storage battery. At R is shown diagrammatically a
controlling device of any suitable form, while at R is a limiting resistance in shunt
to the motor circuit, it being thus connected between the shoes F, F¹. During
normal operation the motor current holds up the switches G, G¹ as the shoe touches
the stud C, C. When the car is brought to a stop, the current flowing in the
shunt circuit (which should be connected to the contact next to the off position
of the controller) would be sufficient (being limited by the resistance R) to hold
up the magnet until the car starts. If however stops of some length are to be
made, or if the car be run out from the depot for the first time, or under any other
circumstances when it is undesirable to leave the resistance in circuit and employ
the line current, the magneto-dynamo El may be operated to obtain the initial
impulse for the switches, the controller being brought to the position in which the
resistance R is cut in, the circuit from this resistance holding up the switch after
it has been brought to contact. At the first movement of the controller sending
current through the motors, the resistance R is cut out, and the motor current
operates the switch as before, sufficient overlap being provided, as is well under-
stood, to prevent the switch dropping.
Fig. 4 illustrates a modified form of the arrangement, in which the stud K¹
takes the place of the handle K, the magneto E' being belted to the fly-wheel K³.
The stud K is provided with a rack k¹, and a spring & for returning it to position
so that when the motorman presses down the stud, the fly-wheel K is rotated,
developing sufficient electro-motive force in the magneto E¹ to pull up the first
of the switches.
In the operation of a practical full-sized embodiment of the invention it is
found that several essential features are obtained by the combinations of apparatus
and circuits above described. Some of these are as follows: by employing a low
potential battery for the initial pick up and also to maintain connection with the
feeder the inherent advantages of this form of battery may be obtained, it being
in parallel to the pick-up coils, any flow of current producing a greater drop around
the coil than the electro-motive force of the battery, diverts a portion of the

page_text: current through it in opposition to its electro-motive force, and thus acts to
charge it; the battery being in series with the motors and not in multiple with
them, as it is sometimes arranged, may work with comparatively small current
and of moderate potential. After connection with the feeder has been established
by the closing of any of the switches, the full line potential is available to break
through or puncture dirt or other insulating material which might collect upon the
contact studs in the roadway, and tend to prevent proper electrical contact between
the shoes and the studs. By the staggering of the contacts in the preferred way
and by the disposition of the several circuits connected with the pick-up switclies,
cach contact-stud in advance of the car is connected to the feeder at a predeter-
mined interval before the contact is made by the motor shoe, this interval being
sufficient to allow for any sluggishness of the switches, so that an unfailing supply
of current is preserved for the motors. This is accomplished, not by the inter-
connection of the various switches with one another so that one switch being picked
up acts to pick up another switch in advance and thus energize the contacts
connected to that switch, but by connecting to each switch more than one of the
rcad contacts. Furthermore, an unfailing supply of current is ensured by a
fcature of the connection which will be apparent from the description and draw-
ings; that is, that each of the road contacts furnishing current to the motor is in
circuit with two of the switches, so that not only is sufficient time interval or
overlap," as it is called in the art, allowed, but should for any reason any one of
the switches fail to act, the car is not thereby immediately deprived of current, as
at least one of the studs with which it is in contact would still be supplied from
another switch. The path of the main current from the feeder to the high potential
studs is direct on the positive side, so that there is no drop of potential, and the
pick up coils could not be energized by a leakage current; this being accomplished
without interconnection of the magnet coils on the switches, if any of the ground
wires should break, it acts merely to disable the switch where the accident occurs,
and does not, as in some systems, pick up other switches and energize contacts not
covered by the car. The switch connections being also entirely symmetrical, the
system is applicable to running with equal facility in either direction. The
arrangement of the contacts entirely within the roadway, as an added feature of
security against leakage acting to hold up any of the switches.
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. A surface contact electric railway system, comprising a feeder, sectional
conductors, a track, and electro-magnetic switches for establishing temporary con-
nection between the feeder and the successive sectional conductors, each switch
provided with a single coil in circuit on the negative side of the system, and con-
tacts making direct connection between the feeder and the sectional conductors,
each switch furnishing current to more than one sectional conductor.
2. A surface contact electric railway system, comprising a feeder, sectional
conductors, and electro-magnetic switches for establishing temporary connection
between the feeder and the successive sectional conductors, each switch provided
with a single coil in circuit on the negative side of the system, and contacts
n aking direct connection between the feeder and the sectional conductors, each
switch furnishing current to more than one sectional conductor, and each section
taking current by permanent independent connections from more than one switch.
3. A surface contact electric railway, comprising a feeder, sectional conductors,
a source of electro-motive force of low potential upon the vehicle, and electro-
magnetic switches for making temporary connection between the feeder and the
sectional conductors, each switch provided with a coil forming a ground connec-
tion through which both the motors and the auxiliary source of electromotive
force are grounded, and contacts making direct connection between the feeder and
the sectional conductors, each switch energizing more than one sectional con-

page_text: ductor and each sectional conductor taking current by permanent independent
connections from a plurality of switches.
4. The combination in an electric railway system, of a row of high potential
studs or sectional conductors insulated from each other and from the line, when
electrically inactive, switches having contacts by which said studs are connected
to the line circuit in pairs or sets when the switches are closed, and a second row of
low potential studs or sectional conductors connected with the negative branch
of the supply circuit through magnet coils upon the switches, said high and low
Lotential studs respectively forming part of a series circuit through the car motor
or motors when the system is in operation.
5. The combination in a surface contact electric railway system, of a row of high
potential studs or sectional conductors disconnected from each other and from the
line, when electrically inactive, and automatically acting electro-magnetic
'switches, each of which forms when closed a direct connection between the line
circuit and a pair of said studs.
6. The combination in a surface contact electric railway system, of a row of
high potential studs or sectional conductors, a row of low potential studs, switches
comprising a magnet coil between the low potential studs and the line circuit,
electrical connections from each high potential stud to two of the switches, and
separate normally insulated contacts at each switch connected to adjacent studs,
whereby, when the system is in operation each switch in closing connects a new
stud to the line and establishes a new connection to a second stud already alive.
7. The combination in a surface contact electric railway system, of a series of
studs or sectional conductors insulated from each other when electrically inactive,
three-point switches which on closing connect the line conductor with a pair of
adjacent studs through the several switch contacts, and magnet coils on the
switches the circuit of which is completed by collector shoes on the cars.
8. In a surface contact electric railway system, the combination of a row of
high potential studs forming one side of the motor circuit, a second row of low
potential studs completing the circuit so that the two sets of studs and the motor
are in series, line switches, each having a magnet coil coupled permanently, and
independently of the magnet winding of any other switch, in a separate branch
connection between one of the low potential studs and the line circuit; whereby
each switch may be energized independently of any other switch, and electrical
connections between the switches and high potential studs, such that one of the
high potential studs is always connected to line before the collector shoe makes
contact with it in either direction of travel of the car.
9. The combinaion in a surface contact electric railway system, of a row of high
potential studs or sectional conductors, switches, electrical connections between
contacts at each switch and a pair of said studs such that when the system is in
operation any given stud is connected to line, first through one switch and then
through a second switch, and the two connections are then opened successively in
the order in which they are made, a row of low potential studs, and magnet coils
Or the switches connected permanently between the low potential studs and the
negative side of the line circuit.
10. The combination in an electric railway system, with the three-point line
switches G, the high potential studs or sectional conductors B each connected with
contacts at a pair of switches and in pairs to each switch, the row of low potential
studs C staggered with reference to the high potential studs, and magnet coils on
the switches permanently connected between the low potential studs and the
return conductor forming part of the line circuit, as set forth.
11. A controlling device for a surface contact railway, comprising contacts and
connections for regulating the motors from rest to full speed, and a contact or
contacts shunting a part of the line current through the electro-magnetic switches
during the time the motor current is interrupted, thereby preserving the live
circuit of the car.

page_text: 12. A controlling device for a surface contact railway, provided with contacts
for regulating the motors from rest to full speed and a contact or contacts com-
pleting a shunt circuit through a limiting resistance and the automatic switches
of the system, thus shunting a part of the line current through the switches during
the time the motor current is interrupted and keeping alive the contact over which
the car may be.
13. A controller for a surface contact electric railway, provided with contacts
for regulating the motor from rest to full speed, a contact or contacts connected in
such manner as to energize at least one of the automatic electro-magnetic switches
of the system during the time that the motor current is interrupted and thus keep
alive the contact or contacts over which the car may be, thereby preserving the
lighting system and the capacity for starting the motors.
14. In a surface contact railway system, a magneto-generator connected between
the sliding contacts of the car, actuated by a stud, and a rack and pinion so
arranged that the foot of the motorman may rotate the magneto to pick up the
switch contacts at starting substantially as herein set forth.