Improvements in Brakes for Electric Motor Vehicles.
Year: 1899

page_text: Date of Application, 1st July, 1899
Complete Specification Left, 2nd Apr., 1900-Accepted, 5th May, 1900
PROVISIONAL SPECIFICATION.
Improvements in Brakes for Electric Motor Vehicles.
I, HENRY LEITNER, of 207, Piccadilly, in the County of London, Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
-
My invention relates to brakes for vehicles propelled by electric motors which
are provided with controlling mechanism so arranged that the motors are stopped
by short circuiting the armatures and keeping the fields excited, the motors
generating a back EMF which rapidly brings them to rest.
According to my present invention, I utilise this back EMF for applying the
brake which is of the following construction. Two solenoids, preferably of the
kind which have their coils within an iron casing, are provided with an armature
consisting of an iron bar bent to U form so as to have two limbs extending as
cores into the solenoids.
The coils of the solenoids are connected in series with the field coils of the
motor and serve to weaken them, so that the back current in the armature is
developed less violently than is the case when the field is fully excited. The
armature bar of the brake solenoids is wound with a coil which is connected in
series to the coil of the motor armature and serves not only to render the arma-
ture bar itself a magnet, but also to act as a resistance in the circuit of the
motor armature coils, preventing them from overheating.
The armature bar is connected to a brake block or strap which may also be
connected to a hand lever or pedal.
As the armature bar is itself an electromagnet, it operates with great force in
applying the brake when its limbs are attracted into the solenoids.
Deted this 1st day of July 1899.
3
ADEL & IMRAY,
Agents for the Applicant.
UUUI I DI
Improvements in Brakes for Electric Motor Vehicles.
I, HENRY LEITNER, of 207, Piccadilly, in the County of London, Electrical
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:
My invention relates to brakes for vehicles propelled by electric motors which
are provided with controlling mechanism so arranged that the motors are stopped
by closing the armature circuit and keeping the fields excited, the motors
generating a back E.M.F. which rapidly brings them to rest.
According to my present invention I utilise the motor current for applying
the brake and the apparatus is of the following construction. Two solenoids,

page_text: preferably of the kind which have their coils within an iron casing are provided
with an armature consisting of an iron bar of Ụ shape having two limbs extend-
ing as cores into the solenoids. The coils of the solenoids are connected in
series with the field coils of the motor and serve to weaken them, so that the
back current in the armature is developed less violently than in the case when
the field is fully excited.
The armature bar is connected to a brake block, or strap which may also be
connected to a hand lever or pedal.
In order that the invention may be more readily understood, 'reference is
had to the accompanying drawing which illustrates the construction of my
improved brake.
JAZ0217GHT
The two solenoids A and A' are enclosed in the iron casing B and B¹ to form
ironclad electromagnets. As above described these solenoids are connected to
the field coils of the motor and are in series with them and the exciting generator,
and the solenoids are also oppositely wound to have their poles in reversed
position the north pole of one solenoid being at the bottom and that of the
other at the top. The solenoids leave. a free central passage a extending..com-
pletely through them and the casing is perforated at 6 to continue this passage.
In connection with these electromagnets I employ an armature C consisting
of a U shaped bar the two limbs c of which are adapted to extend into the sole-
noids as cores.
When the solenoids are excited a powerful pull is obtained, the cores, which
complete the magnetic circuit, being drawn into the solenoids with great force
applying any well known form of mechanical brake to the vehicle. The sole-
noids are excited only when brought into circuit with the motor, which occurs
when the vehicle is to be stopped, the controlling apparatus used with such
vehicles being adapted to cut the motor armature out of circuit with the battery
and to place in the field magnet circuit the electromagnet coils described..
The armature C may also be separately excited by coils placed upon it and
put into the motor circuit. The poles of the armature are opposite to those of
the solenoids increasing the pull of the latter upon the armature.
:' ' }'
The connections between the armature bar and the brake are of any suitable
description and the parts are fixed to the body of the vehicle in a direction which
when the notion of the vehicle is arrested utilizes the momentum of the armature
in assisting the attractive pull of the solenoids.
10
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare, that what
I claim is:
2%
(1) An improved means for applying brakes on electric motor vehicles, con-
sisting of two electromagnets of opposite polarity, an armature having limbs
extending as cores into the magnet coils, and connections to the brake, the coils
being placed in the motor circuit to stop the vehicle, substantially as described
and for the purposes specified.
(2) The improved apparatus for applying brakes on electric motor vehicles,
comprising the two fixed ironclad electromagnets of opposite polarity, parallel
to each other, a U shaped armature bar having two limbs extending as cores into
the coils of the said magnets and connections from the bar to the brake, the
two magnet coils when the vehicle is to be stopped being placed in the field
circuit of the motor, substantially as described and shown and for the purposes
specified.
GEO. H. RAYNER,
37, Chancery Lane, London, Agent for the Applicant.