improvements in and relating to Electric Motors and Dynamo Electric Machines.
Year: 1897

page_text: Date of Application, 18th Feb., 1897 -Accepted, 1st May, 1897
[Communicated from abroad by ELMER AMBROSE SPERRY, of Cleveland, County
of Cuyahoga, State of Ohio, United States of America, Engineer.]
improvements in and relating to Electric Motors and Dynamo
Electric Machines.
1, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent
Agents, 45 Southampton Buildings, in the County of Middlesex, 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:-
The present invention relates to controllers and a system of control for an electric
motor or motors, particularly when used for propelling vehicles either on street or
other kinds of railways, where the motors are used for propelling the vehicle, and
when it is desired to stop, the motors are converted into generators and the energy
thus produced is supplied to a system of electric brakes.
In running a car or train it often happens that it will, with the source of power
cut off, run on its own momentum for some little time, as on a slight grade or a
level. The power being shut off, and the circuits through the motor or motors
open, the magnetization of the field dies down, the amount remaining depending
upon the residual magnetism of the pole-pieces, which varies according to the
style of motor and the kind of iron used in its field.
It is desirable to always maintain a certain amount of field magnetization; so
that the motors, when converted into generators by suitable connecting devices,
may be instantly responsive to any demand for energy. Especially is this the case
where there are poor contacts between parts of the system which would require
considerable energy to burn them out, and in consequence of the high resistance
of the circuit the machine would build up slowly, thus taking a certain interval of
time, which, as will readily be seen, would be a serious objection were it necessary
to stop instantly on account of danger.
To overcome this objection I wind a separate field coil on the pole pieces of the
motor, which may or may not form a part of the main field winding of the motor;
in this application however I have shown it separate from the main winding and
only in circuit at certain intervals, namely, when the power circuit is interrupted
and the controller in what is known as the "off" position. The brushes and
contacts of the controller are so arranged with respect to each other that when the
power handle is thrown to the off position, the armature connections are reversed,
and the circuit is completed through the extra or auxiliary field coil. This coil,
being in circuit with the armature, will always maintain a certain amount of field-
magnetization so long as the car is running under the conditions above described,
and if it be desired to stop, the generator will be instantly responsive to any
demand for energy.
An essential difference between this controller and other existing types is that
a field is maintained for the motor or generator after the power circuit has been
interrupted; while the circuit from other controllers to the motor or generator is
interrupted when in the off position, in the present case there is always a circuit
between the controller and motor or generator.
In a system as above described, it has been found that the current generated by

page_text: the motors when converted into generators is too great at the start, and to take
care of this excess of current, more resistance is inserted on the brake side than
on the power side of the controller, the extra resistance being divided into any
suitable number of sections and cut out step by step when the brake cylinder is
operated; this extra resistance is idle except when the brake circuit is completed.
The current for the brake circuit flows through both main and extra resistance,
while the current from the power system flows through the main alone.
An automatic limit switch is provided for cutting down the current of the
generator, if at any time the current flowing through the brake circuit is excessive,
due to the fact that the motorman cuts out resistance too fast, or for any other
reason, and the apparatus is thereby endangered. The switch consists of a magnet
with an energizing coil in series with the brakes, having its armature pivoted at
the centre of gravity, thereby greatly lessening the vibration, due to the jolting of
the vehicle, and adapted to close a pair of contacts putting a shunt of more or less
resistance around the field coils of the generator, weakening them and causing the
current generated to be decreased. Upon a predetermined drop in the current
supplied by the generator, the shunt circuit around the fields is automatically
broken, and the switch is ready to operate again immediately upon an excess of
current.
When operating electric brakes used in connection with motor and trail cars, it
sometimes occurs that the contact with the rail or ground is better at the trail car
than at the motor car, and if the brakes are connected in multiple, with the ground
forming one side, this will lead to difficulties, because when the power is supplied
to the motors in the usual way by a circuit groundel on the axle, the current
instead of going through the wheel of the motor car to ground, will go through
the coil on the brake magnet of the motor car, which is grounded on the axle,
thence through the brake magnet coils on the trailer or trailers to ground, thus
setting the brakes on both motor and trail cars. Where the train is only lightly
loaded this is not so serious a matter, for the motor can overcome the effect of its
brakes and drag the train with the set brakes to a point where the ground contact
of the motor is good, then the brakes will free themselves and the train will proceed
as before; but if the train is heavily loaded it cannot start until good contact is
made at the motor car.
To overcome this difficulty, I propose to connect the brakes in multiple as before,
but instead of grounding each individual brake coil on its own axle, the ground
ends of the magnet coils are connected to a separate wire which extends through
the train and is grounded on the motor car; if now the contact of the wheels on
the motor car be poor, it will only affect the passage of the current through the
motor or motors, and will have no effect on the brakes.
When a train is composed of a motor car and a trailer or a number of trailers,
it is necessary to provide some means for adjusting the flow of current through the
brake magnets; this adjustment may be effected to conform to differences in weight
of the cars, to compensate for the difference in the total retardation of mechanism
upon the trail cars, or the combined effect of the retarding action of the brakes
upon the motor car, and lastly, to compensate for the difference in electrical
resistance in the brake magnet coils or groups. This is accomplished by inserting
suitable resistances in circuit with the various brakes, in such a manner as to give to
each car just enough braking effect to handle its own load independent of the
other cars on the train. For example, the brakes of the motor car may be
connected in simple multiple, and those on the trailers in multiple with each other,
but in series with the source of supply, with a suitable regulating device between
the source and the brakes for varying the current supplied thereto.
In Patent No. 569,305, Oct. 13, 1896, I have shown an auxiliary field coil which
is adapted to energize the field-magnets of the motor at the interval between the
shutting off of the source of power supplied to drive the car, and the completion of
the brake circuit, the motor being connected in such a manner as to act as a
generator and supply current thereto. The auxiliary field is normally in circuit

page_text: with the main source of supply, but on failure of the supply due to the trolley
coming off or for any other reason, the terminals of the auxiliary field coil are
automatically shifted to the armature of the motor, and continue to be in circuit
therewith for any predetermined length of time.
The application above referred to, while embodying some of the features of the
present invention, is not intended to broadly cover the features herein contained, but
is specific to the arrangement shown. The present application includes in its scope
the one referred to and contemplates in its broad aspect the use of any auxiliary
field coil which is used to energize the field magnets of a motor or motors at the
time when they shall be receiving no power from the main source of supply and
before they are coupled in circuit with the brakes. It is also within the scope of
this invention to keep the auxiliary field coil in circuit with the armature while
supplying current to the brakes.
Fig. 1 is a diagrammatic view of the controller showing the circuit connections
through a motor and exhibiting two sets of contacts which are mounted on the
same insulating cylinder and separated from each other by an intervening space,
and a third set adapted to receive connections from the outside circuit.
Fig. 2 is a diagrammatic view of a motor and an automatic shunting device for
the field thereof.
Figs. 3 and 4 illustrate a diagrammatic view of the motor and circuit
connections to the source of electrical supply when the motor is operating in two
directions.
Figs. 5 and 6 indicate automatic circuit connections with the controller in the
"off" position, and the motor is acting as a generator while traveling in either
direction, and the auxiliary field coil is connected to the armature terminals.
Figs. 7 and 8 show the motor operating as a generator running in the two
directions when the controller is so positioned that the armature current is
compelled to flow through the main field coils of the motor or motors, but otherwise
they are the same as Figs. 5 and 6.
Fig. 9 represents the circuit connections of the brake magnets between the
controller and the said magnets located upon both the motor car and trailer, and
illustrating means for adjusting the current flowing to the brake magnets of one car
in relation to those of the other.
Fig. 10 is a detail view of the reversing switch.
Fig. 11 is a detail view of the shunting device.
Like letters and numerals of reference indicate like parts throughout the
several views.
The brushes or contacts are mounted in a vertical line with the contacts for
controlling the motor mounted on the left, and those for controlling the brake on
the right. The brushes are now in the off position, and unlike controllers hereto-
fore are in engagement with certain of the contact plates on the brake side of the
controller. With the brushes in this position, the auxiliary high resistance field
coil or coils are connected to the armature terminals which have been reversed by
means of the cross connections on the cylinder, and the motor is now a generator
feeding current through this field coil.
Assuming that the brushes are on the line 2-2 at the left of the central position,
the current will be supplied to the motor in a manner suitable to propel the car,
and the circuits would be as follows:
From the source of current C to the brush T, contact plate 10 cross connected
to plate 11, to brush 13, through resistance R to brush 15, cross connected to
brush 16, to contact 17, cross connected to contact 18, to brush 21, through the
flexible connection 22 to the armature A of the motor, through the flexible lead 23
to the brush 20, to the plate 24, cross connected to plate 25, to brush 26, wire 28,
to field F, wire 27, to ground. By moving the brushes farther towards the left, it
will be seen that one section after the other of the resistance is short-circuited,
until finally the motor is connected directly to the source of power with no
resistance in circuit. This is indicated in Fig. 3. Fig. 4 indicates the same

page_text: condition of circuits except that the relation of the field and armature has been
reversed by means of the reversing switch and the motor is rotating in the opposite
direction.
Assuming that the brushes are in the position shown in Fig. 1; the motor has
been converted into a generator by means of the cross connections between the
plates on the brake side which are opposite to those on the power side, and the
direction of current flowing through the armature is reversed relative to that of
the field.
Assuming now that the car is running on momentum, a cui rent will be generated
and the circuit is as follows:
From the armature A. to the flexible lead 22, the brush 21, plate 35, cross
connected to plate 34, through the relatively high resistance field coil f, to
ground G, thence by way of the dotted line 36 to the shunting device S, to
contact 30, cross connected to contact 29, to brush 20, through the armature in
the direction indicated by the dotted arrow, to the point of starting; thus it will
be seen that the shunting device S shunts the brake coil B' in this position.
It will be seen from the above that the generator is supplying current to the
auxiliary field coilf and that the field F is open-circuited, and that the brake
coil B is shunted by means of the shunting device S, as shown in Figs. 5 and 6,
the former indicating the position when running forward, the latter backward.
Assuming that the cylinder is now rotated so that the brushes rest on the line 1-1
to the right of the off position, the circuit will be as follows:
From the armature A, through the flexible lead 22, to the brush 21, the
plate 35, cross connected to the plate 45, the brush 26, wire 28, field F, wire 27,
to ground G¹, thence to ground G, through the coil M on the liinit switch, brake
coil B', to brush B, contact 32, cross connected to plate 31, to brush 31, to
resistance R, to brush 15, by cross connection to brush 16, to contact plate 30,
cross connection to plate 29, brush 20, to armature A, as indicated by dotted arrow,
to point of starting.
This condition of circuits corresponds to that shown in Fig. 7, and it will be
noted that the auxiliary field is short-circuited. This is not essential to the
invention however, for it would work as well were it open-circuited, as shown in
dotted lines, and I aim to embrace that feature in the claims. Further rotation of
the cylinder merely cuts out more resistance, so further description is unnecessary.
Fig. 8 indicates the same condition as above, except that the generator is rotating
in the opposite direction. It will be seen by reference to the above, that the brake
circuit includes more resistance than the power side, for it includes both resistances R
and R¹, whereas the power circuit only includes resistance R.
Referring now to Fig. 10, a detail view of the reversing switch is shown. The
brushes 20 and 21 are mounted on a suitable insulating piece which is connected
with a lever 50 pivoted in any suitable manner, and adapted to move the brushes up
or down to give the required connections to the armature leads. The armature A
is connected by flexible leads with the brushes 20 and 21, which are adapted to
engage plates 29 and 35 or 29 and 60, which are mounted on a suitable cylinder or
support. By tracing out the connections it will be seen that the current is reversed
whenever the brushes are shifted from one position to the other. This reversing
switch is adapted to shift the armature connection when the motor is used to
propel the car forward or backward.
It has been found in practical operation that in the hands of some motormen
upon applying the brake the current is turned on too suddenly, and it runs up to a
point dangerous to the apparatus. In Figs. 1 and 2 is shown what I term a
"limit switch" for preventing this undue increase of current, which consists in
a shunt wire 42 including any suitable resistance, as R³, and the contacts D
and D¹, the former being mounted on the armature M¹ pivoted preferably at the
center of gravity g, the shunt being completed through the magnet frame and the
wire 43. The coil M being in series circuit relation with the brake magnets, an
excess of current will cause the armature M' to be attracted, and the contacts D

page_text: and D¹ will momentarily be closed, thus shunting a portion of the current around
the fields through the resistance R³ and wire 42. It is preferable to support this
armature at or about its center of gravity, for the purpose of reducing to a
minimum the amount of vibration which a lever of this kind would be subjected to,
caused by the jolting of the vehicle. A suitable spring and adjusting nut are
provided to regulate its action.
Referring now to Fig. 9, C' indicates the motor car and C" the trailer. The
controller E is coupled to the motor, as shown in Fig. 1, and to the brake
magnets B and B in simple multiple arc by means of wires e and 36. This
however is not the case with the brake magnets B³, B and B³. These are placed
in multiple between the wires 36 and 37, and in series with an adjusting coil J
inserted between wire e and 37, and consisting of any suitable resistance, with means
for varying it by means of which the current flowing to the group of magnets on
the trail car C may be adjusted with reference to the group upon the motor
car C. The circuit between the brakes is a metallic one aut the return circuit is
grounded by wire el on the axle of the motor car.
Fig. 11 is a detail view showing the cylinder in cross section, and the relation
which the brushes bear to the shunting device S. This shunting device S consists
of two brushes mounted on the back of the controller in any suitable manner,
connected together and adapted to engage with contact plate 30 and 32 when in
the position shown in Fig. 1. As soon as the cylinder is rotated in the direction of
the arrow, the brushes 16 and B, which are connected to the external circuit,
break contact with the contacts 30 and 32, and the shunting device S remains idle,
there being no current in the circuit. If the controller is revolved in the opposite
direction, one of the brushes of the shunting device S engages with contact 17 and
the other brush is open-circuited. Thus it will be seen that the shunt S is only in
circuit when the controller stands as in Fig. 1.
Having now particularly described and ascertained the nature of the said iuven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :
1. In an electric brake system, the combination of a dynamo electric machine
having a series and shunt field coil and adapted for propelling and braking the
vehicle, with means for maintaining a field magnetization at the time the dynamo
electric machine is not affecting the motion of the vehicle.
2. In an electric brake system, the combination of a motor for propelling and
braking the vehicle, with an auxiliary field coil for energizing the field magnets at
the time the motor is not affecting the propulsion of the vehicle.
3. The combination with an electric motor, of an auxiliary field coil, and means
for automatically connecting the coil in circuit with the motor when the source of
supply is interrupted.
4. The combination of an electric motor having main and auxiliary field coils,
means for reversing the relation between the armature and fields, and means for
connecting the auxiliary field coil to the armature at a time when the motor is not
affecting the propulsion of the car.
5. In a controller for electric motors, the combination of contacts and connections
for regulating the supply of energy to the power side and to the brake side of the
system, an auxiliary field coil, and brushes and connections for establishing various
combinations in the circuit relations, certain of the brushes engaging with the
contacts when the power and brake circuits are interrupted, for purpose of energizing
the auxiliary field coil.
6. In an electric controller, the combination of contacts for regulating the supply
of current to the motor or motors, contacts for regulating the supply of energy to
the brake circuit, brushes for establishing connection between the motor circuit and
the contacts, and a field coil for energizing the field of the motor in the off position
of the controller.

page_text: 7. The combination with an electric motor, of an auxiliary field coil of relatively
high resistance, and brushes and contacts for including the said coil in circuit with
the motor armature at the off position of the controller.
8. In a controller for electric motors, the combination of contacts for establishing
circuit connections with the motors when propelling the vehicle, other contacts for
regulating the supply of current to the brakes when the motors are converted into
generators and supplying current to the brakes, and means for establishing a
connection between the armature and an auxiliary field coil between the times
when the power circuit is broken and the brake circuit established.
9. In combination, an electric motor, main and auxiliary field coils, contacts and
brushes for establishing connection between the main field and the armature of the
motor, and other contacts for establishing circuit relation between the armature
and the auxiliary field coil.
10. In combination, an electric motor provided with main and auxiliary field
coils, a controller for regulating the current flowing through the motor, means for
reversing the relation between armature and field coils, and contacts and brushes
for connecting the auxiliary field coil in circuit with the armature.
11. In an electric brake system, the combination of means for placing the motor
in operative connection with a source of electrical supply so as to be driven as a
motor, means for reversing the relation of the armature and field of the motor and
operative connecting the armature circuit to an auxiliary field coil or coils on the
motor, and means for coupling the armature to a low resistance field circuit of
the motor.
12. The combination, with a series electric machine having an auxiliary field
coil, of means for disconnecting either one or the other of such field coils from the
armature circuit, and a reversing switch for the armature circuit.
13. The combination, with a series electric machine having an auxiliary field
coil, of means for disconnecting either one or the other of such field coils from the
armature circuit, a reversing switch for the armature circuit, a plurality of exterior
circuits, and means for coupling them successively to the said motor.
14. In an electric controller, the combination of a plurality of circuits, certain
of which are for regulating the current supplied to the motors, certain others
for regulating the energy supplied to the brakes, resistance included in the first
named circuit, and the said resistance plus other resistance included in the brake
circuit.
15. The combination of a dynamo electric machine for propelling and braking
purposes, means for including the machine in circuit with the source of supply when
it is desired for propelling purposes, and for disconnecting it from the supply and
converting it into a generator for braking purposes, and an automatic switch for
opening and closing a shunt circuit around the field coils of the dynamo electric
machine when acting as a generator for preventing an increase of current over a
predetermined amount.
16. The combination of a dynamo electric machine mounted on a vehicle for
propelling and braking purposes, a controller for including the machine in circuit
with the source of supply and regulating the energy supplied thereto, and for
disconnecting the machine from the supply, converting it into a generator and
regulating the energy supplied thereby to the brake circuit, and an automatic
device for shunting a part of the current around the machine when it is acting as
a generator.
17. The combination of a dynamo electric machine for propelling and braking
purposes, a controller for regulating the machine when employed for propelling and
braking purposes, and an automatic switch controlled by the current in the brake
circuit for closing a shunt around the field coils of the machine when it is acting as
a generator.
18. The combination of an electric motor, a controller provided with means for
converting it into a generator, an auxiliary field coil, means for establishing

page_text: connection between the field coil and the armature, and an automatic shunting
device for the generator.
19. In combination with a series electric motor, a plurality of exterior circuits,.
means for changing the circuit connection of said motor from one to the other f
the said exterior circuits, a device for converting the motor into a generator,
operated by such means, and means for automatically weakening the fiel!
magnetization of the generator without directly altering the current in the
armature, said means responsive to current produced by the generator when such
current rises or tends to rise above a predetermined amount.
20. In combination with a series electric motor, a plurality of exterior circuits,
means for changing the circuit connection of the said motor from one to the other
of the said exterior circuits, a device for converting the motor into a generator
operated by such means, and an automatic shunt for the field magnet coil of such
generator, the said shunt being responsive to the current in one of said exterior
circuits.
21. The combination of an electric motor, a controller for regulating the sa:ne
a plurality of circuits extending therefrom, more resistance include: in one circuit
than in the others, main and auxiliary field coils for the motor, and means for
connecting them in any desired relation with the armature.
22. The combination of a series wound dynamo electric machine for propelling
and braking purposes, means for including it in circuit with the source of supply
when it is desired to propel the vehicle, and for disconnecting it from the supply
and converting it into a generator, and an automatic limit switch for shunting the
same when it is used for braking.
23. The combination of a vehicle, a dynamo electric machine for propelling and
braking purposes mounted thereon, means for including the machine in circuit
with the source of supply when employed for driving the load and for disconnecting
it from the supply and converting it into a generator for braking purposes, and for
regulating the braking energy when so connected, and automatic means controlled
by the current in the brake circuit for preventing the locking of the vehicle wheels
by means of the brake magnets.
24. The combination of a dynamo electric machine for propelling and braking
a vehicle, with means for maintaining a field magnetization at all times when the
vehicle is in motion.
25. The combination in an electric brake system, of brakes on the motor car
connected in parallel, brakes on the trailer connected in a group, and a resistance
for regulating the supply of energy to the group.
26. The combination in an electric brake system, of brakes on the motor car
connected in parallel, brakes on the trailer connected in a group, the members of
the group connected in parallel with each other, and the group as a whole connected
in series with the source of supply.
27. In an electric railway system, the combination of means for placing the
motor in operative connection with a source of electrical supply so as to be driven
as a motor, means for reversing the relation of the field and armature of the motor
and operatively connecting the armature circuit to an auxiliary field coil or coils
on the motor, circuits for establishing connection between the motor and the
brakes, means for closing a shunt around the brakes, and means for simultaneously
coupling the armature circuit with a low resistance field coil and opening said
shunt.
28. In an electric brake system, the combination of a dynamo electric machine
for propelling and braking the car, a controller provided with contacts and
brushes for establishing desired circuit relations, and a shunting device for the
brake magnets.
29. In an electric brake system, the combination of a dynamo electric machine
for propelling and braking the car, a controller provided with contacts and brushes
for establishing connections between the dynamo electric machine and the brake.

page_text: magnet coils, and a mechanical shunting device for shunting the brake magnet
coils at a predetermined time.
Dated this Civtoonth dasi of Wah1907
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.