Improvements in Electric Train Control Systems.
Year: 1899

page_text: Date of Application, 30th Oct., 1899-Accepted, 27th Jan., 1900
COMPLETE SPECIFICATION.
Improvements in Electric Train Control Systems.
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 (which has been communicated to us from abroad by Charles E.
Barry, residing at Schenectady, in the County of Schenectady, State of New
York, United States of America, Electrical Engineer), 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 the electric control of trains on railways;.
and has for its object to obviate certain difficulties which arise with that form
of controlling device which consists of motor controllers upon each car, operated
in synchronism by one or more so-called
"master controllers. The general
features of this system of control are now well understood, and ordinarily each
motor controller regulates the motors of the car upon which it is placed. These
controllers are of well established form, usually of the series-parallel type,
though nothing in this invention, or in fact in the ordinary systems of train
control, limits the selection to this type of controller. In all motor controllers
there are certain defined positions in which the rotating switch may remain for
a greater or less length of time, some of which are known as "transition points,"
in which the switch should rest only for a short time. Other positions are known
as "running points," in which the controller may remain for an indefinite
time. In order to render certain the proper manipulation of the controller, so that
it will always rest at one or another of the selected positions certain devices
called step by step actuators are generally employed. A well known form of
this device consists of the so-called star-wheel or ratchet wheel, with which
a pawl engages, the spaces in the star wheel being so arranged as to register
with the proper positions of the cylindrical switch usually employed in the
controller.
"
"
In train control these motor controllers are operated by pilot motors, so called,
the operation of all the pilot motors being governed by the master controllers, so
that from any one of the latter all of the pilot motors are simultaneously operated
in either direction and to the extent desired. With this form of control, using
a step by step device, it may happen that the desired certainty of operation will
not be obtained. In these controlling schemes there is usually provided a so
called "throttle" or open circuiting contact for the pilot motor. This is operated
when the current rises to a predetermined value, so that the throttle may open
just before the controller reaches the desired position, the momentum of the con-
troller and motor serving to bring the former to just the point intended; but
it may happen that the star-wheel will be forced backward by its pawl overcoming
the momentum of the revolving parts, so that the controller does not complete
the intended steps, and a bad arc may result. The throttle is of course inde-

page_text: pendent of the rotation of the controller, except in so far as the latter effects
the current flow in the main motor circuit. In order to render the action just
spoken of certain, and to postpone the open-circuiting of the pilot motor until
the controller has certainly reached the desired position, there is arranged upon
the controller switch itself certain contacts by which the throttle is short-
circuited until the controller switch comes to just the point desires, at which
time the short-circuiting contacts are opened. By this means the actuation of
the controller to the extent desired is made to depend upon the rotation of the
controlling switch itself.
Another feature of this invention consists of means for varying the rate of
acceleration in a train control system. In its broadest aspect this branch of the
invention is of the scope just indicated. The particular arrangement which is
shown in this case consists of an auxiliary, coil upon the throttle, which of itself
is not sufficient to actuate the latter to open the pilot motor circuit, but which
assists another coil in circuit with the motors so that when the current in the
motor circuit reaches a certain determined limit the throttle will be opened until
the counter-electromotive force of the motors cuts down the current sufficiently
to permit the throttle to close again, when the controller will again take a step.
By including a regulable resistance in circuit with the first named coil, its effect
can be controlled and thereby the amount of current which may flow in the
motor circuit before the throttle will open. It is manifest that by increasing
the resistance, assuming it to be in series with the coil, the amount of current
flowing in the motor circuit and necessary to pull open the throttle would be
larger than where the effect of the first coil was not thus restricted. Of course
the resistance might be arranged in shunt or in series, the necessary modifications
being apparent to engineers.
In the operation of the invention, it is found desirable to entirely eliminate
the usual step by step devices; and for these is substituted a brake which acts to
check the rotation of the controller as soon as the pilot motor circuit is opened.
This is accomplished in the usual way by including a coil in the latter circuit
which will act to release the brake whenever current is flowing, a spring applying
a brake shoe of suitable form to a disk or drum affixed to the controller shaft,
whenever the current ceases. Furthermore the circuits are arranged so that
when the master controller is brought to the off position, the pilot motor will
be reversed and will run the motor controller backward until the off position is
reached, when certain contacts, to be described hereafter, open-circuit all the
pilot motors.
The accompanying drawing is a diagram which shows a convenient way of
applying the invention. The circuits of the apparatus are illustrated in full on
the left side of the drawing, while a conventional illustration of a motor con-
troller and a master controller are shown on the right, it being intended by this
to show a train of two cars. It is to be understood that the connections of the
apparatus on the right are the same as those on the left of the drawing, the
master controllers and motor controllers being in multiple; and by a consideration
of the circuits it will be manifest that the operation of the master controller
will be sufficient to ensure the operation of any number of motor controllers in
the desired manner.
In the drawing, A represents a master controller which may be of any con-
venient type, but which has been shown as a switch provided with a rotating
arm a and contacts 1 to 12. The throttle referred to in the statement of invention
is shown in diagram at D, and consists of the usual core provided with two
coils dd; the former of these is in series with the resistance R¹ controlled by
the contacts 5 to 12 of the master controller A; the latter is in circuit with one
of the motors, and would usually be connected between the final field terminal
and ground, though it is immaterial in what part of the circuit it is placed. The
resistance R¹is, as already described, regulable, and the effect of the coil d may
be changed in accordance with the amount of resistance in circuit.
As already

page_text: indicated, the resistance might be placed in shunt to the coil, and the corresponding
difference in circuits and effect will be understood by engineers, so that it has
not been considered necessary to illustrate it. Switches similar in construction
to the throttle 1) are illustrated at 1¹ D², D³ 12, and 13 form in conjunction a
reversing switch for the pilot motor, the armature of which is shown at E geared.
to the controller B, its field being illustrated at E³. It is a series motor of
ordinary construction. The switch D is provided with two coils dd', the upper
one d of which is in circuit between the trolley and ground, the lead from the
trolley T passing to the switch blade of the master controller. As the blade
passes over the contact 2, the coil d is energized, and draws up its core so that
the contacts illustrated are bridged. The switch blade at this time also touches
the contact 1, so that the coil is energized, as are the coils of the switches D³, D",
thus completing the upper set of contacts of the reversing switch.
The con-
troller B has contacts 13, etc. the upper three of which control the action of the.
pilot motor, as presently to be described. The lower contacts beginning with
number 18 regulate the motors M, M by the well known system of series
parallel control, the motors being first connected in series, and as the controller
rotates the resistance R being cut out step by step until finally one motor is
shunted round the other, the circuit is opened and the two are reconnected in
multiple, this being a well known system of control the particular steps of which
it is unnecessary to trace. A series of contacts H are also provided registering
with the brushes of fixed contacts 16, 17. Brake C is also used, consisting of the
drum C upon the shaft of the controller, a brake-shoe C2 having a spring
which applied it to the drum, and a coil C in the circuit of the pilot motor.
With the parts in the position illustrated, the operation is as follows: Assuming
that the switches D, D2, D3 are drawn up to close the upper sets of contacts and
that the throttle D is in its illustrated position, current passes from the trolley
to the switch arm a, contact 3 and thus to the contact 13 of the motor controller,
to contact 14, across the contacts of the throttle D, by the upper contacts of
switch to the armature. E' of the pilot motor, thence through the coil C³
across the upper contacts of switch D through the field E to ground. The pilot
motor then starts in the direction of the arrow, rotating the controller B until
the contact 13 passes off the corresponding contact 13. This, as will be seen
by inspection, is the "full series position of the motors, at this point the
resistance R being all cut out and the motors M, M connected in series. Depend-
ing upon the position of the switch arm a, the acceleration will be greater or
less, as may be desired, and as already pointed out in connection with the
operation of the throttle D. If the arm « for instance, be on the contact 7 and
full resistance R is in circuit, the acceleration will be very considerable..it'
requiring a large current in the motors to open the throttle D, and this effect
will be still further increased if the arm a touches the open-circuiting contact 8,
which entirely cuts out the coil d thus throwing upon the coil all of the work
of opening the switch. The arm
a being between the contacts 3 and 4, the
circuit of the pilot motor will be opened and the motor controller will be, as
already explained, in the full series position. When the arm touches contact 4,
however, the circuit will be again closed passing from that contact to contact 15
on the motor controller and then through the pilot motor as before.
In this case the controller B will be operated until it comes to the full multiple
position, and here also the acceleration may be regulated as may be desired by
the regulation of the resistance R'. In both cases the contacts 16 and 17, when
touching any one of the contacts H on the motor controller, short circuit the
throttle D until the motor controller has opened the contacts 16 and 17 so that
the latter controller will only stop in one of the defined positions at which it
is designed to operate.
Should the current fail for any reason, the motorman would bring the master
controller A to its off position: the motor controller would remain where--it
happened to be until the current came on again, but as soon as this occurred,

page_text: a circuit would be completed from the intermediate point in the resistance R,
passing across the lower contacts of the switch D3, through the coil C, releasing
the brake, through the armature E' in the reverse direction, and then through
the lower contacts of the switch D, through the field E' in the same direction as
before, to ground; reversing the connection of armature and field and rotating
the controller in the opposite direction until it is brought to the off position.
It of course may happen that the controller will be in any one of these positions,
even the full multiple, when the current fails. In order to prevent damage to
the motors by the current coming on while they are stationary and without
resistance. The switch D is introduced. This it will be observed, is connected
between the end of the resistance and the main motor lead at the contacts 23, 24,
of the controller B. It is in the same circuit with the other automatic switches,
and when the first switch is picked up by turning the master controller,
the circuit of D' is completed from the contact 1 of the master controller, so
that the motors are again brought in circuit. The action of this switch is inde-
pendent of the reversing circuit for the pilot motor just described, as will be
manifest by tracing the connections. It will thus be impossible to throw the main
current on the motors until the controller B has been brought to the off position,
unless indeed it be the intention of the motorman to do so, when it may be
accomplished by manipulation of the controller AN
Having now particularly described, and ascertained the nature of our said
invention (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 train control system, automatic means for varying the rate of
acceleration.
2-In a train control system, motors and a motor switch, means controlled by
the current flow in the train motors for opening the pilot motor circuit, and
means under the control of the motorman for retarding or accelerating the opening
of the circuit so as to increase or decrease, as may be desired, the permitted
main current, and thus correspondingly change the acceleration of the train.
3 The combination with motors and a motor switch a pilot motor actuating
the switch, and a master controller for the pilot motor, of an open-circuiting
device for the pilot motor, and means controlled by the master controller for
medifying the action of the open circuiting device.
4 The combination of motors and a motor switch, a pilot motor, and a master
controller, with a throttle for the pilot motor circuit comprising a coil, means
for varying the ampere turns of the coil, and a part movable under the influence
of the coil, actuating the switch controlling the pilot motor circuit.
5-In an open-circuiting device for the pilot motor of a train control system,
the combination of a coil the effect of which is regulated by the master controller,
with another coil in series in the motor circuit, a part movable under the
influence of the coils, and a switch operated by the moving part.
6 In a throttle or open-circuiting device for the pilot motor of a train control
system, the combination of a coil, a regulable resistance in circuit with the coil,
means on the master controller for varying the regulating resistance a second
coil in circuit with the motors, and a switch controlled by the coils.
7 The combination with motors and a motor controller, of a pilot motor operat-
ing the controller, a throttle or open circuiting device for the pilot motor, and
means upon the controller for bridging the throttle contacts until the controller
reaches certain predetermined positions.
8-The combination of motors and a motor controller, with a pilot motor
actuating the controller, an open circuiting device or throttle in the circuit of
the pilot motor and controlled by the current flow in the motor circuit, and
bridging contacts operated by the controller, maintaining the circuit of the pilot
motor until the controller reaches certain definite positions.
9 The combination with the throttle or open circuiting device for the pilot

page_text: motor of a train control system, of fixed contacts in the motor controller con-
nected to those of the throttle, and moving contacts carried by the main motor
switch for bridging the fixed contacts at desired times.
Dated this 25th day of October 1899.
THE BRITISH THOMSON-HOUSTON CO. LTD.,
J. J. MANHEIM,
A. R. MONKS,
Directors.
ALFRED CLEMENTS,
Assistant Secretary.