Improvements in the Method of and Means for Stopping Electrically Propelled Cars.
Year: 1895

page_text: Date of Application, 23rd July, 1895-Accepted, 24th Aug., 1835
COMPLETE SPECIFICATION.
Improvements in the Method of and Means for Stopping Electrically
Propelled Cars.
I, ARTHUR KNOX BONTA of No. 200 Eleventh Street, Hoboken, in the County
of Hudson and State of New Jersey, United States of America, Electrical
Engineer, 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:-
This invention pertains to a means for stopping or arresting electrically
propelled cars or checking their speed by means of their propelling motors without
employing the electricity from the supply conductor or other source from which the
propelling current is derived.
In United States Patent to S. H. Short, dated May 3, 1892, No. 474,031, one
way of carrying out this method is described. It consists in disconnecting the
motors from the source of propelling current, reversing the relation of the armature
and fields, and connecting them in a closed local circuit in such a manner that
when they are rotated by the momentum of the car in a forward direction, the
electro-motive-force generated by each, opposes that of the other and tends to
produce a current in a direction to increase its own field magnetism, and cut down
that of the other. One motor (generator) therefore has the tendency to overpower
the other, which it does after an indefinite interval, depending upon the difference
of residual magnetism in the motors or upon the ability of one to build up or
become magnetized faster than the other. The weaker motor has its field polarity
reversed by the stronger and is thereafter operated as a motor in the direction to
run the car backward, by current supplied from the more powerful motor acting as
a generator. From this it follows that when the motors are first thrown together
in the local circuit their positive terminals are connected together and the negative
terminals together, or in other words the motors are connected together in
multiple.
This method of arresting the cars has been found to be very unreliable and
often too slow in action to prevent the accidents which it is designed to avoid.
The reason for this is that many times a pair of motors are so nearly alike or
balanced magnetically and electrically, that they will run a long time opposed to
each other before one will overcome the other. Instances have been known however,
where the motors are so unlike that one will reverse the other quickly but no
dependence can be placed upon them and the best and modern practice is to
construct the motors as near alike as possible.
In accordance with my invention, the motors are first disconnected from the feed
wire or source of propelling current and then a short local circuit is established in
which is connected one or more of the propelling motors; if only one motor is
included therein, its field and armature connections are simultaneously reversed
with respect to each other and if two or more motors are included in the circuit,
the field and armature connections of each are reversed with respect to each other
and the several motors are placed in series relations with each other, i.e., with the
positive pole of one motor connected with the negative pole of the next motor in
the next circuit.
With this method of connection the forward momentum of the car drives each
motor as a generator, and the currents generated by all of them will be in the
same direction through the circuit. Hence one motor instead of opposing another,

page_text: aids it, and the field magnetism of all motors is increased alike. Motors operated
as generators in this manner act instantly to retard the car because the attraction
between the fields and armatures which existed when the machines were operating
as motors has become reversed by the change of polarity between the fields and
armature and the momentum of the car is consumed by the attraction between
them tending to prevent the rotation of the armatures in the forward direction.
My method of stopping cars, is much more rapid than that heretofore practiced as
above described, because it becomes effective the moment the connections are
made, whereas by the old method it requires time for one machine to reverse the
other.
In carrying out my invention, I place upon the motorman's platform a switch
which I preferably combine with the regular car controller. If a "series parallel "
or other form of controller is used in which conductors from the several terminals
of the motors lead to the controller stand, I utilize the same set of conductors for
my closed local circuit and it therefore is only necessary to provide on or near the
controller stand, a suitable contact device to co-operate with the terminals of the
group of conductors found in the controller stand and with which the regular car
controlling contact devices also co-operate.
I will now describe my invention in detail with reference to the accompanying
drawing, in which
Fig. 1, is a plan in dotted lines of the track and lower framework of the car,
showing in full lines the cables extending from the motors to the controlling devices
on the platforms.
Fig. 2, is a plan of the top of one of the controller stands.
Fig. 3, is a diagram of circuits showing how the connections are made to propel
the car forward by its motors and also for arresting or stopping the car, in accordance
with my invention.
The
Electric cars are ordinarily controlled by a motorman who stands upon the
forward platform and manipulates an electric controller and a brake.
controller is operated by means of a lever attached to a cylinder adapted to be
rotated step by step thereby, and thus alter the connections to the motors for
stopping, starting and varying the speed of the car. It is common to provide a
second lever attached to a separate cylinder and having two running positions.
This second lever is called the reversing lever and when thrown into one of its
positions the car may be started and moved forward at any speed by means of the
controlling lever, and when said reversing lever is in the other position, the car may
be started and moved backward at any speed by the controlling lever. To accom-
plish this reversal the cylinder connected with the reversing lever is provided with
two rows of contacts which are thrown into contact with a stationary row of fingers.
The fingers are permanently connected by wires or otherwise with the brushes and
field magnet terminals of the two motors. When connection exists between the
fingers and one row of contacts on the cylinder, the circuits are such as to cause the
motors to rotate in a certain direction and when the fingers are in connection with
the second row of contacts certain reversals of current are accomplished, which
cause the motors to rotate in the opposite direction.
In carrying out my invention I prefer to add to the reversing cylinder a third
row of contacts which are adapted to be brought into connection with the fingers
and thereby establish a short closed circuit including the two motors in series.
Referring to the drawings, No. 1 and 2, respectively represent the two motors.
The conductors lead from the armature and field magnet terminals to the controller
stand terminals at the points a, b, c, d, e, f, g and h; whence branches lead to the
controlling and reversing cylinder hereinafter referred to. The wires from the
brushes of motor No. 1, lead respectively to the points b and c, while the field
terminals are represented by a and d. The wires from the brushes of motor No. 2,
lead respectively to the points f and g, while the field magnet terminals are
indicated by e and h.
In the plan of the top of the controller stand indicated in Fig. 2, A represents

page_text: the starting, stopping and speed varying lever known in practice as the controlling
lever. It is attached to and rotates a cylinder inside of the case.. In the position
in which the lever is shown, the current is supposed to be cut off. Two stops a¹
and a, are provided to limit its movement. B represents the reversing lever.
When running in one direction this lever is against the stop b', as indicated in full
lines, and when running in the opposite direction the lever is against the stop b², as
indicated in dotted lines. For the purpose of my invention I make the stop 62
adjustable by embodying it in the form of a short arm or lever pivoted at the fixed
point 63 and thus capable of being lifted to permit the reversing lever to assume a
third position indicated by the dotted lines 6. In this third position the cylinder to
which the lever is attached and which is indicated by the dotted lines c, is at the
position to establish contact between the fingers referred to and the third row of
contact points. Referring now to Fig. 3, i and j, respectively represent the ordinary
two rows of contact points used heretofore in practice. k represents the stationary
row of fingers adapted to be brought into connection with the contacts on the
cylinder by rotating the latter. I represents the third row of contacts which I have
added to the cylinder and in it there are eight points corresponding respectively
with the eight fingers k. These contacts are lettered respectively m, n, o, p, q, r, s
and t.
The contacts m and o on the cylinder are permanently connected together by
wire 1. Contacts n and
and are
are connected together by wire 2. Contacts P
connected together by wire 3, and contacts and s are connected together by
wire 4. Branch wires from the eight terminals a, b, c, etc., of the motors lead
respectively to the eight fingers k while other branch wires indicated in dotted
lines lead to the car controlling devices.
In controllers of the class referred to wherein a controlling and a reversing
lever are used, it is customary to provide an interlocking device whereby the
reversing lever may be held at the cut off position. Such interlocking device by
a slight modification or addition, may be used in connection with the improvement
herein described, to prevent the third movement of the reversing lever until the
controlling lever is at the cut off position, and to prevent the movement of the
controlling lever until the reversing lever has been set to one of the running
positions.
$
run away
; or,
The operation is as follows: When the car is running forward under normal
conditions, the row of contacts i on the reversing cylinder is in contact with
fingers k; and assuming that the trolley current enters at a, and the ground
connection is at G, then the current will flow through the fields and armatures of
the motors in the directions indicated by the small arrows, the two motors operating
in parallel and each rotating in a direction to send the car forward. Now assume
the car to be under headway on a down grade and by accident or otherwise the
regular brake mechanism fails to work and the car starts to
assume that a collision with a vehicle or a person is imminent and the car cannot
be stopped quickly enough by ordinary means. In such instances and whenever
a quick stop is desirable the motorman would have recourse to my improvement.
He first throws the controlling lever to the "off" position, and thus severs the car
from the line entirely as indicated at w. He then lifts the adjustable stop b², and
swings the reversing lever to the third position bringing points 7, into contact
respectively with fingers k; thus establishing a short complete circuit including
the two car motors in series with each other and with the armature terminals of
each motor reversed.
The momentum of the car keeps the motors rotating in the same forward
direction and thus both machines are converted into generators and in as much as
their armature leads have been reversed, and they are connected in series with
each other, the current generated by each machine will leave its armature in the
opposite direction to which it did when the machines were running as motors, and
we trace the current as follows: Starting at brush 5, of No. 1 machine we have
current flowing from the armature by wire 6, contact o, wire 1, contact m, wire 7,

page_text: field magnet of No. 1 machine, wire 8, contact p, wire 3, contact r, wire 9, brush 10
of No. 2 machine, armature, brush 11, wire 12, contact s, wire 4, contact q, wire 13,
field magnet of No. 2 machine, wire 14, contact t, wire 2, contact n and finally by
wire 15, to brush 16, and into the armature and brush 5. It will thus be seen that
the current generated by each machine traverses the fields of both, in the same
direction that the propelling current formerly did and builds up or strengthens
them, but in the armatures the current is reversed, as indicated by the heavy
This results in an attraction between the armature and field magnets of
each machine, in a direction to hold back or stop the car. The current generated
in this closed circuit is immediately very great and a car moving at a very high
speed will be stopped within a few feet if on a level, and if on a grade will slow
down to a creeping pace.
arrows.
The primary use for which this invention is designed is to prevent accidents on
grades. Many instances are recorded of brakes giving out on down grades and the
high speed or vibration of the car throwing the trolley off, thus rendering
ineffective the practice which motormen are instructed to resort to, to wit-reversing
the motors. When the trolley is off the wire, the main current is not available
as a power to stop the car, but by my invention the retarding power is generated
automatically by, and in direct proportion to, the speed of the car. In this
connection it should be pointed out that by my invention, if the efficiency of the
motor was 100% and the traction was perfect, the car would be stopped instantly,
but as such conditions do not exist in practice, the car will be stopped in the
quickest possible time.
It is obvious that the third row 1, of contacts on the reversing cylinder may be
placed upon a separate cylinder and operated by means of an independent handle.
It is also obvious that my switching apparatus is not confined to a combination
with the particular type of controller herein referred to. It will be observed that
the type of controller herein referred to, operates to vary the speed by altering
the connections of the field coils of the motors and this is the most modern and
approved form of controller. It however, necessarily involves running a large
number of wires between the controller stand and the motors. In applying my
invention to this particular controller, I utilize these extra wires for the short
circuit which it involves, and do not find it necessary to add any apparatus whatever
beyond the row of contacts 1, the adjustable stop not being essential, although
useful. In consequence of this I am able to equip a car with my invention at a
very small expense.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is :
1. In an electric car, the combination of a propelling motor or motors, a
controller stand located on the motorman's platform and containing a car controlling
switch and a separate reversing switch the latter consisting of a cylinder having
three sets of contact points thereon and a set of stationary fingers or terminals
with which said sets of contact points are adapted to engage; one set establishing
connections to send the car forward, another set to send the car backward, and the
third set to reverse the relation of the field magnet and armature connections and
establish a closed local circuit in which the terminals of the motor or motors will
be connected in series, substantially as described.
2. In an electric car, the combination of a propelling motor or motors, a controller
stand located on the motorman's platform and containing a car controlling switch
and a separate car reversing switch, the latter consisting of a cylinder having three
sets of contact points thereon and a set of stationary fingers or terminals with
which said sets of contact points are adapted to engage; one set establishing
connections to send the car forward, another set to send the car backward, and the
third set to establish a closed local circuit in which the terminals of the motor or
motors will be connected together for the purpose set forth.

page_text: 3. In an electric car, the combination of two propelling motors, a controller
stand located on the motorman's platform, said controller stand containing two
circuit changing cylinders; one for reversing, and one for varying the speed, a
short circuit including both motors, a circuit controller for said short circuit located
upou said reversing cylinder, and a lever for operating said reversing cylinder, the
lever having two stops one of which is adjustable.
4. In an electric car, two propelling motors, a controller stand located on the
motorman's platform, a controller located in said stand and conductors leading from
the motors to terminals on said stand whereby the speed of the motors may be
changed, all in combination with a reversing switch located in said stand and
controlling the course of the current over said conductors, the reversing switch
having extra contacts by means of which the motors may be thrown into a closed
local circuit, substantially as described.
5. In an electric car, two propelling motors, a controller stand located on the
motorman's platform, a controller located in said stand and conductors leading
from the motors to terminals on said stand whereby the speed of the motors may
be changed, all in combination with a reversing switch located in said stand and
controlling the course of the current over said conductors, the reversing switch
having extra contacts by means of which the motors may be thrown into series in
a closed local circuit which local circuit includes the said conductors leading from
the motors to the controlling stand.
Dated this 22nd de- of Tal- 100=
W. E. HEYS & SON,
Agents for the Applicant.