Improvements in and connected with Electro-locomotion on Railways.
Year: 1894

page_text: Date of Application, 12th Mar., 1894-Accepted, 14th Apr., 1894
[Communicated from abroad by JEAN JAQUES HEILMANN, of 19, Rue Cambon,
Paris, in the French Republic, Electrical Engineer.]
Improvements in and connected with Electro-locomotion on
Railways.
I, WILLIAM EDWIN HEYS, of 70 Market Street, Manchester, in the County of
Lancaster, Patent Agent, do hereby declare the nature of this invention, and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement ;-
This invention relates to that system of electric locomotion for railways described
in and by the Specification of Letters Patent granted to me No. 11,653 dated the
25th day of July A.D. 1890, according to which electro-motors driving some or all
the axles of the train derive their current from a generating dynamo or dynamos
carried by the train itself and driven by a suitable prime motor.
These improvements are equally applicable where the electro-motors drive only
the axles of the locomotive, and to the more general case where they are employed
to drive some or all the axles of the train. In each case the arrangements are
practically the same.
When a steam engine is employed in this system of electro-locomotion to drive
the dynamo, it is called upon to furnish a very variable amount of power, according
to the grade of the road and the state of the rails upon which the train is running.
At present, the means employed for controlling the variable amount of power
required consist in varying the admission of steam or in throttling it. But both
these means, for known reasons, are defective, and it is desirable to have a fixed
cut-off, since the efficiency of any particular steam engine is at its maximum with
one particular degree of expansion, and diminishes with either a greater or less
degree.
When, moreover, engines having dead centres are employed, to drive the
generators, difficulty is sometimes experienced in starting from a dead centre.
The object then of this invention is to permit the engine to work economically
with a constant cut-off under the most favourable conditions, or in other words, so
that the work done is always proportional to the speed of the engine irrespective of
the speed of the electro-locomotive and its train. A further object is to enable the
driving engine to be started when it has stopped upon a dead centre.
For the purposes of this invention, the generating dynamo is arranged to be
variably excited by means of a special exciting dynamo driven by a separate prime
motor. The variable excitation may be controlled by means of a rheostat inter-
calated in the field-magnet circuit.
If the excitation be diminished, the intensity of the magnetic field is also
diminished and the intensity in the armature increases until the torque has again
acquired its previous value. In consequence, the speed of the engine has auto-
matically increased, owing to the sole fact of the diminution of excitation, the work
The contrary
of the engine being augmented whilst the cut-off remains the same.
result follows if the excitation be increased.
For the purpose of starting the engine from a dead centre, the generating
dynamo may be temporarily employed as a motor at the moment of starting,
deriving its current from the exciting dynamo which is driven, as hereinbefore
described, by a separate engine.

page_text: The appended diagrams will enable this invention to be more readily understood.
In these diagrams :
:-
Figure 1 represents the scheme of connections, and
Figure 2, the arrangement of the apparatus.
G is the generating dynamo and E its exciting machine. The current from the
exciter E passes through the rheostat R and the ammeter a, on its way to the
generator field-magnet coils. is the local rheostat of the exciting machine
and its voltmeter. V is the voltmeter of the generating dynamo.
0
A is the principal ammeter, and A₁.. A.... are ammeters in the separate
motor circuits. ... I.... are switches in the separate motor circuits. C is a
commutator which is arranged to reverse the motion of the electro-motors by
inverting the connections of the motor magnet-coils ₁. . . with regard to their
armatures R₁.. Rg..
...
When the generating dynamo is employed as a motor. to start its driving, engine
from a dead centre, the exciting machine being driven by its separate engine, the
current from the exciter is passed temporarily into the generator armature by means
of the switch I.
In Figure 2, 6 6 are the terminals of the field coils of the generating dynamo,
and B B¹ those of the armature circuits.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an electro-locomotive system of the type set forth, the combination and
arrangement with the dynamo of an exciting dynamo driven by a separate engine
and means for varying the exciting current, substantially as and for the purpose
hereinbefore described.
2. In an electro-locomotive system of the type set forth, a separate exciting
dynamo driven by an independent prime motor, substantially as and for the
purposes herein before described.
'
3. In an electro-locomotive system of the type set forth, the combination and
arrangement with the generating dynamo, of an independently driven dynamo
which, when the principal engine has to start from a dead centre, is capable of
supplying current to the generating dynamo and thus operate it as a motor
temporarily to assist the starting of the principal engine, substantially as herein-
before described.
Dated this 10th day of March A D 1804
WILLIAM E. HEYS.