Improvements in and relating to Surface Contact Electric Railways."
Year: 1897

page_text: Date of Application, 7th Sept., 1897-Accepted, 11th Dec., 1897
COMPLETE SPECIFICATION.
66 Improvements in and relating to Surface Contact Electric
Railways."
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 inven-
tion (which has been communicated to us from abroad by Lee H. Parker, of
Schenectady, county of Schenectady, State of New York, United States of America)
and in what mannner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
The present invention relates to surface contact electric railways, in which the
circuit to the contacts is normally interrupted, but is completed as the vehicle
advances by means controlled by the moving vehicle.
The invention relates particularly to that class of electric railways in which
the closing and opening of the circuit of the surface contacts is accomplished by
means of an electro-magnetic device carried by the moving vehicle. In
systems of this kind the greatest difficulty has been to maintain a constant air
gap between the magnet carried by the vehicle and the switch operating devices.
In theory it is accomplished by placing the switches and their operating mechanism
below the surface of the roadbed, and supporting the magnet from the car axle
which maintains it at a certain distance from the surface of the road; in practice
this fails to attain the object sought, for the switch boxes move slightly with respect
to the rails, caused by changes in the roadbed. However slight these changes
may be, they affect the working of the apparatus, as a very slight increase in the
air gap of the magnetic circuit will cause the failure of the switch to work. In
systems of this kind it has been proposed to make the operating magnet of sufficient
strength to operate the switches, without regard to changes in the air gap; this
is expensive, for it involves the use of a magnet many times the strength required
for normal operation to ensure the working of the few switching devices having an
increased air gap.
One object of the present invention is to provide a switch mechanism operated
by magnetic means controlled by the moving vehicle; the means being so
arranged that a constant air gap is maintained in the magnetic circuit irrespective
of any changes which may occur in the roadbed and tracks.
A further object of the invention is to provide a magnetically controlled switch-
ing device for closing and opening the circuit between the source of supply and the
contacts located at the surface of the roadbed, and one which is positively actuated
as the moving vehicle advances.
In carring out the invention two magnets are mounted on the moving vehicle
and are provided with shoes making contact with the track rails; these magnets
are energized by means of coils included in the motor circuit. Situated at suitable
intervals along the line of way are pole pieces bolted at their outer ends to the rails
and formed at their inner ends with enlarged faces between which is mounted an
armature for actuating the switch mechanism.
Mounted in suitable bearings is an aramature adapted to oscillate between the

page_text: pole pieces which are secured to the rails; to this armature is secured a suitable
switch arm for completing the circuit between the source of supply and the sur-
face contact.
As the vehicle advances, the magnet at the front causes a magnetic flux to pass
through the pole pieces and armature; at the same time a current passes through
the armature coil to ground and the armature having its upper and lower parts
oppositely polarised is moved to the left or right, depending upon the direction
of the flux. At the rear end of the vehicle is a second magnet wound oppositely
to the first, for reversing the magnetism and opening the switch.
In the accompanying drawing, Fig. 1 is a diagrammatic illustration of the inven-
tion; Fig. 2 is a sectional view of a switch box; and Fig. 3 is an enlarged view
of the switch armature.
At A, A are indicated the traffic rails upon which the vehicle B is arranged
to travel. Mounted on the front and rear of the vehicle are electro-magnets C
and C¹; these are energized oppositely as indicated at N, S, N¹, S', the object of
which will be hereafter explained.
Located at suitable intervals along the line of way are switch boxes D, made of
cast iron and provided with removable covers D¹; in the centre of these covers
but insulated therefrom are contacts D adapted to be connected to the source of
supply. The boxes D are of sufficient size to enclose the switch-operating
mechanism, thereby protecting it from moisture and injury.
The contact shoe E is carried by the moving vehicle, and is preferably sup-
ported from the axle of the car; it is long enough to expand at least two contacts
and is usually provided wih springs to compensate for irregularities, but as the
support forms no part of the invention, it is not illustrated
Motors F are provided for propelling the vehicle; these are controlled by means
of the controller G.
When it is desired to reverse the polarity of the magnets C and C³, the switch H
is thrown; this changes the direction of current through both of the magnets
simultaneously.
In Fig. 2 is shown a section through one of the switch boxes. The pole pieces I
are bolted to the traffic rails and extend into the switch box D), where they are
provided with enlarged faces between which the armature revolves. The
armature J is mounted in suitable bearings and as it oscillates it opens and closes
switch M.
Protected by means of a suitable covering is the feeder K; extending therefrom
is a wire secured to the positive terminal of the switch.
Fig. 3 shows an enlarged detail view of the switch operating mechanism. The
armature J is provided with a coil or coils P having one end connected with the
contact D, the other to the box D), which is grounded. The switch M is shown in
its closed position, and current is supposed to be passing from the contact D³,
through the armature coils to ground so polarizing the upper part of the magnetic
armature oppositely to the lower part and at the same time a
passing through the pole pieces I from the shoes forming a part of the magnet C.
magnetic flux is
The air gan between the armature J and the pole pieces I always remains the
same; the latter being secured together at the bottom by the non-magnetic plate L
which holds them in alignment and prevents their separating. The magnets C
and Care provided with shoes which make contact with the tracks and are so
supported that they follow all irregularities of the track; this may be accomplished
by the use of vertical guides which allow the weight of the magnets to press the
shoes upon the tracks.
The operation of the invention is as follows:-
When the contact shoe E reaches a contact D³, a shunt circuit is formed through
the coils on the armature J to ground; at the same time a magnetic flux passes
from the magnet C through the shoes and traffic rails to the armature J and the
direction is such that the upper part of the armature is attracted by
the right hand pole piece which at the same time repels the lower part: Similarly

page_text: the left hand pole piece attracts the lower part of the armature and repels the
upper part, the effect being a right-handed rotation of the armature, which closes
the circuit between the feeder K and the contact D2; this action is repeated
at each switch as the vehicle progresses. To open the switches the magnet C¹,
is energized oppositely to the magnet C, which causes the armature J of the rear
switch to revolve left-handedly and open the circuit, and this while the vehicle
is over the contacts, preventing accidents to persons crossing the tracks near the
vehicle.
In going in the opposite direction, the switch H is thrown to the left; this
simultaneously reverses the polarity of the magnets C and C, and the operation is
as before. The magnets C and C, are in a shunt circuit from the contact shoe E
to the ground and under normal operation are permanently included in circuit.
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. In a surface contact electric railway, the combination of a vehicle, stationary
contacts, switch mechanism for including the contacts in circuit with the source
of supply, coils permanently connected between each contact and the ground,
a contact shoe mounted on the vehicle and supplying current to the coil as it
advances, a magnet mounted at the front of the vehicle co-operating with the coils
to close the switches, and a second magnet mounted on the rear of the vehicle
co-operating with the coils to open the switches.
2. In a surface contact electric railway, the combination of a moving vehicle,
contacts located along the line of travel, switches for closing the circuit between
the source of supply and the contacts, armatures for operating the switches, a coil
mounted on each armature forming a permanent connection between the contact
and the ground, fixed pole pieces for the armature, and a magnet carried by the
vehicle supplying a magnetic flux to the pole-pieces.
3. In a surface contact electric railway, the combination of a vehicle, a magnet
mounted thereon and making sliding contact with the rails, a coil for energizing
the magnet, pole-pieces secured to the tracks at intervals, armatures mounted for
movement between the pole-pieces, switch mechanism operated thereby, and a coil C
on each armature permanently connected between each surface contact and ground.
4. In a surface contact electric railway, the combination of a vehicle, magnets
of opposite polarity located in advance and rear of the vehicle, shoes for each
magnet, making sliding contact with the rails, energizing coils for the magnets
a source of supply, and a switch for simultaneously reversing the polarity of the
magnets when it is desired to reverse the direction of movement of the vehicle.
Dated the 7th. day of September, 1897.
Dated the 7th. day of September, 1897.
For the Applicants.
J. C. CHAPMAN.
Chartered Patent Agent, 70, Chancery Lane, London, W.C.