Improvements in Electric Locomotives.
Year: 1895

page_text: Date of Application, 10th Sept., 1895-Accepted, 12th Oct., 1895.
Improvements in Electric Locomotives.
I, JAMES DEVONSHIRE, Secretary of The British Thomson-Houston, Limited,
of 38 Parliament Street, Westminster, in the County of Middlesex, do hereby
declare the nature of this invention (a communication to me from abroad by Edwin
W. Rice, Jr., 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 object of the present invention is to provide an electric locomotive which
shall be self-contained and mounted on suitable trucks provided with motors for
propelling the same, and means for regulating their speed. Such a locomotive
can run on existing railway tracks without going to the expense of installing a
central station, and maintaining an outside line construction, either overhead or
underground.
In general, my invention consists in a self-contained electric locomotive carrying
a boiler capable of furnishing the desired amount of steam which is fed to a prime
mover of any desired character, preferably a compound condensing engine, or a
steam turbine, which drives a direct current generator supplying current to a rotary
transformer, which in turn supplies alternating currents to the motors, the motors
being suitably mounted on the car axles or geared thereto.
The regulation of these motors is obtained wholly or partly by varying the
periodicity of the current supplied thereto, and I accomplish this by varying the
amount of energy supplied to the prime mover, by varying the field excitation of
the generator, and consequently its potential, by varying the field excitation of
the transformer, or by other means of suitably controlling the speed of the rotary
transformer.
In the accompanying drawing, attached to and forming a part of this Specifica-
tion, is shown, partly in side view and partly in section, a locomotive embodying
my invention.
A is the base of the locomotive suitably mounted on trucks B, B', which are
provided with three-phase alternating induction motors mounted directly on the
car axles; but I do not limit myself to this exact construction, for any alternating
current motor can be used, and either geared to or mounted directly on the car
axle, the motors being as many in number as are advisable in any special case.
C is the boiler provided with a suitable fire box. It is of course understood that
the fuel and water may or may not be carried directly on the locomotive. K is
the cab enclosing the entire apparatus. From the steam dome C' on the boiler is
run the main steam pipe D, provided with a valve D', to vary the amount of steam
admitted to the steam turbine E, to which is directly coupled the exciter and the
direct current generator G. Mounted on the same base, but not mechanically
connected thereto, is a rotary converter H, wound in any well known manner,
which is adapted to transform the continuous current taken from the generator G
into alternating currents to supply the motors I, 11, 12, 13, which are mounted on
the axles of the trucks, B, B'.
The exciter F is of the usual shunt-wound variety, and supplies current to the
field of the generator G and transformer H, and these are independently controlled
by means of resistance boxes J, J
In starting the locomotive, steam would be admitted to the turbine E which
would cause the exciter F and generator G to generate current, and the current

page_text: from the generator G passes to the armature of the transformer H by means of
leads a., and thence, when transformed, to motors 1, 11, 12, [³. If, for example.
there is a difference of ten volts between a and b, and the field of the transformer H
has a certain excitation, the currents taken from the collecting rings c, d, e, will
have a certain frequency depending upon the speed of rotation of the armature and
the number of field poles, which will cause the motors to revolve at a certain speed.
Now, by varying the potential of the generator G, by causing the turbine to speel
up, I am enabled to raise the frequency of the currents in the transformer due to
the increased speed, thus increasing the speed of the motors I, 11, 12, 13.
Within certain limits the speed of the motors may be varied by varying the
excitation of either the field-magnet of the generator or the transformer or both;
as, for example, by lowering the field of the generator, the voltage would drop,
and in consequence the speed of the transformer, as would also the periodicity of
the current supplied to the motors; and the effert may be carried still farther by
properly regulating the field of the transformer H.
By supplying the motors with a heavy current at a low voltage and low
periodicity, I am enabled to get a maximum amount of torque at a very slow speed,
thus giving an easy start to the locomotive.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, what is claimed as
new is:
1. The combination in a self-contained electric locomotive, of a prime mover,
direct-current generator and separately excited rotary transformer, with alternating
motors mounted on or geared to the axles of the said locomotive, and means for
varying the periodicity of the current supplied to the motors from the rotary
transformer.
2. The combination in a self-contained electric locomotive, of a prime mover, a
generator and rotary transformer, both separately excited, with alternating current
motors mounted on the trucks of said locomotive, and means for regulating the fields
of both generator and transformer, and thus varying the periodicity of the supply
current.
3. The combination in a self-contained electric locomotive, of a prime mover and
separately excited generator and rotary transformer, with alternating current
motors mounted on the trucks of said locomotive, and means for varying the speed
of the prime mover, and regulating the field excitation of generator and
transformer.
4. The combination in a self-contained electric locomotive, of a prime mover, a
generator and rotary transformer, both separately excited, with an alternating
current motor mounted on the trucks of said locomotive, and means for regulating
by varying the field strength of the generator.
Dated this 10th day of September 1895.