Improvements in Electric Brakes for Railway and Tramway Vehicles.
Year: 1899

page_text: Date of Application, 23rd Mar., 1899-Accepted, 13th May, 1899
Improvements in Electric Brakes for Railway and Tramway
Vehicles.
A communication from abroad by THE ACTIEN-GESELLSCHAFT ELEKTRICI-
TÄTSWERKE (vorm. O. L. KUMMER & Co.), of Niedersedlitz, near Dresden,
Germany.
I, WILLIAM LLOYD WISE, of 46, Lincoln's Inn Fields, in the County of
London, Consulting Engineer and Chartered 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 ascertained in and by the following statement:―
Electric railway and tramway vehicles (hereinafter called trailers) that are
to be drawn by motor or other vehicles, do not always carry attendants, and it
is therefore very important that they should, especially when intended for use in
mountainous districts, be provided with brakes that will stop them automatically if
the connexion be broken between them and their motor vehicles.
Now this invention has for object the provision of such a brake that is adapted
also for ordinary use, the same brake bands or blocks being used in each case.
With a brake according to this invention, ordinary braking can be effected
either mechanically by a person on the trailer, or electrically from the motor
vehicle, or in both ways; the emergency brake will also come automatically
into action immediately on the separation of the trailer from the motor vehicle.
In order that the nature of this invention and the manner in which it is to be
performed may be clearly understood, reference will be had in the following
description to the accompanying drawing, which illustrates diagrammatically
an example of apparatus constructed according thereto.
The brake bands a (for which brake blocks can be easily substituted if desired)
of each pair of wheels are attached to two three-armed levers b and c, which are
mounted on shafts & and e suitably supported in the truck of the vehicle and
which apply the brake bands by moving in the directions indicated by the arrows
in the drawing.
The lever b can be operated either by means of a chain f attached to the shaft
of the brake handle or by attracting an iron core (or cores) y into a magnetic
coil (or coils) h, or in both ways. The coil can be most conveniently excited
by the short-circuit current of the motor or motors when running as a generator
or generators; arrangements may be made such that the lever b will be acted
upon simultaneously with the cutting out and braking of the motor vehicle, so
that the trailer will be braked at the proper time.
In emergencies, the brake is brought into action quite independently by means
of the levers c, one of which is provided for each pair of wheels. The two
levers of the two pairs of wheels of a vehicle may be connected by sliding con-
nexions, as by means of pins engaging in slots p, to a three-armed lever i, which
is carried by an axle k mounted in the truck of the vehicle.
C
The lever is arranged to form (or it may be connected with) the armature of

page_text: the electromagnet 7, which, when excited, attracts the armature lever i, against
the action of a tension spring m. The magnet may be excited in any suitable
manner as by the motor current or by a battery carried on the motor vehicle
so that if the trailer should become separated from the motor vehicle, the electric
connexion would be broken and the current of the magnet interrupted. The
tension spring m would then cause the lever i to turn in the direction indicated
by the arrow, and thereby bring the levers into the positions indicated by
dotted lines n, with the result that the brake bands would be drawn tight against
their pulleys and the vehicle be brought to a standstill. As will be seen from
the drawing, the arrangement is such that when the armature is drawn up
against the magnet, the leverage of the spring m, which is attached to an arm
of the three-armed lever i, is a minimum, so that the magnet 7 need not exert
much attractive force; and that whilst the lever i is travelling from the position
shown, the leverage of the spring m continually increases and that when the
brake bands are applied it acts, through the pins of the lever i, with approxi-
mately maximum leverage. The brake bands can be released in any suitable
manner for example, by moving, in the direction indicated by the arrow, a hand
lever o secured to the shaft k.
It is obvious that in lieu of the spring m a weight may be provided so con-
nected to the lever i as to act thereon similarly to the spring m.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:--
1. An electric brake for electric railway and tramway trailers, in which the
brake bands or blocks, are applied, for ordinary braking, by means of one or
more electro-magnets energized by the short-circuit current of the motor or
motors or in a mechanical manuer, or in both ways, whilst for emergency brak-
ing, the same brake bands or blocks are applied by spring or weight force which
is caused to act by the breaking of the circuit of another electro-magnet that
is effected by the separation of the trailer from the motor vehicle.
2. An electric trailer brake according to the preceding claim, in which the
brake bands of each pair of wheels are stretched between two three-arm levers,
one of which, intended for ordinary use, applies the brake bands on being rotated
mechanically, or by energizing an electro-magnet, or in both ways, whilst the
other, intended for emergency braking, applies the brake bands on being rotated
by means of the spring which is liberated automatically on the separation of
the trailer from the motor vehicle.
3. An electric trailer brake according to Claim 1, in which the armature of
the electro-magnet that causes the emergency braking, is located between the
two axes of the vehicle and is formed as a multiple-armi lever, with which the
brake levers have sliding connexions, and the spring or weight power is applied
to the said lever in such a manner that, when the armature is drawn up to the
electro-magnet, the said force acts on the said lever at a small leverage and
consequently with small power in order to allow of the use of an electro-magnet
of small attractive force, whilst the leverage at which the force acts upon the
said lever continually increases during the rotation of the lever away from the
electro-magnet till the brake bands or blocks are applied.
4. The improved electric trailer brake constructed, arranged, and operating as
hereinbefore described with reference to and shown diagrammatically in the
accompanying drawing.
n..1 L
a 1 1