Improved Means for Stopping or Controlling Electrical Railway and Tramway Engines or Carriages.
Year: 1892

page_text: Date of Application, 30th Apr., 1892
Complete Specification Left, 25th Jan., 1893-Accepted, 1st Apr., 1893
PROVISIONAL SPECIFICATION.
Improved Means for Stopping or Controlling Electrical Railway and
Tramway Engines or Carriages.
We, MICHAEL HOLROYD SMITH of 161 Trinity Road, Upper Tooting in the
County of Surrey, Engineer, and THOMAS PERCEVAL WILSON, of 3 Whitehall
Place, London, S.W. Engineer, do hereby declare the nature of this invention to
be as follows:-
5 This invention relates to improved means for stopping or controlling electrically
operated engines or carriages when on a descending gradient or otherwise running
free from contact with the electrical source of supply.
When applied to a car or engine carrying but a single motor the invention
consists in an arrangement of parts whereby such motor forms part of a closed
O circuit. With this arrangement if the switch be so set that if the current from
the source of supply were on, the motor would be driving in reverse direction to
the travel of the car, then as the car travels the current generated by the motor
in the closed circuit will increase in proportion to the increased speed of the car
and will almost immediately become sufficient to stop the motor temporarily and
consequently the car or engine. In other words the action of the current
generated will become sufficient to temporarily stop or control the motor
generating it.
When two driving motors are employed they may be connected in closed circuit
say by coupling in parallel so that under the conditions above described the current
generated by each will act upon the other and similar arrangements may be made
where more than two motors are employed.
Dated this 30th day of April 1892.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, W.C., Agent for the Applicants.
COMPLETE SPECIFICATION.
Improved Means for Stopping or Controlling Electrical Railway and
Tramway Engines or Carriages.
We, MICHAEL HOLROYD SMITH of 161 Trinity Road, Upper Tooting in the
County of Surrey, Engineer, and THOMAS PERCEVAL WILSON of 3 Whitehall
Place, London, S.W. 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 relates to improved means for stopping or controlling electrically
operated engines or carriages or machinery when on a descending gradient or
otherwise running free from contact with the electrical source of supply.
To clearly explain the invention reference is made to the drawings which form
part of this Specification and in which :-
Fig. 1 represents diagrammatically two electric driving motors coupled in
parallel, and
Fig. 2 represents the arrangement when a single motor is employed.
For the purpose of explanation let it be assumed that the car or engine carrying
two motors AA, as indicated in Fig. 1, is on a descending gradient and it is desired
to stop the car otherwise than by or in conjunction with the ordinary hand or
mechanical brakes, and without resorting to the usual electrical source of supply
which may be shut off by opening switch B. If now the ordinary reversing

page_text: switch (not shown) be so set that if the current through B were on, the motors
would be driving in reverse direction to the travel of the car say as indicated by
dotted lines which as will be seen by the arrows change the internal coupling then
the current generated by each motor in the then closed circuit will act through the
other motor and will increase in proportion to any increased speed of travel of
the car, and the current so generated will almost immediately become sufficient to
stop the motors temporarily, and cousequently the car. In other words the motors
become dynamos generating a current sufficient to temporarily stop or control their
motion.
When a single motor is employed as indicated in Fig. 2 the action is the same
but it is necessary to form a circuit which can be closed when switch B is open.
This may be done by means of a separate switch C which will be normally open
when the motor is running in connection with the usual source of electric supply,
but will be closed when switch B is open and it is desired to run the motor A in a
closed circuit for the purpose of controlling or stopping the movement of the car.
The invention may be utilized with motors either series, shunt or compound wound,
but when sudden or impulsive action is to be avoided it will be found preferable to
employ it in conjunction with a compound motor either alone or with at least one
compound motor in each set of two or more motors as the number which may be
used is not limited, it being only essential that those motors which are to stop or
control the travel of the car when free from the usual source of electricity should
be in or be readily capable of being put in a closed reverse circuit with regard to
the current to be generated by them.
It will be evident that this invention may be also employed in conjunction with
machinery actuated by electric motors and in which brake power is necessary, as
for example in colliery haulage, cranes and lifts and the like.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is :-
The improved means for stopping or controlling electrical engines or carriages
consisting of so closing and coupling the circuit that the motors generate a current
which tends to move them in a reverse direction to that in which they are being
driven.
Dated this - 1002
PHILIP M. JUSTICE, Fel. Chart. Inst. P.A.,
55 & 56, Chancery Lane, London, Agent for the Applicants.