Improvements in Electric Brakes.
Year: 1895

page_text: Date of Application, 1st Aug.. 1895-Accented. 23rd Nov., 1895
COMPLETE SPECIFICATION.
Improvements in Electric Brakes.
I, JOSEPH CRAWHALL CHAPMAN, Chartered Patent Agent, of 70, Chancery
Lane, in the County of London, (a communication to me from abroad from
William B. Potter, of Schenectady, in the State of New York, United States of
America, 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 electric braking apparatus, particularly as applied to
trains composed of a motor car and a number of trailers, or to a number of motor
cars and trailers combined; and has for its object to provide a safety appliance for
such a combination of apparatus, designed to prevent accident in case the train
breaks in two.
In the operation of long distance lines of any kind, it is imperative that the rear
portion of the train which is accidentally broken, shall be stopped or so materially
retarded as to avoid any danger of collision with the front part when that part is
brought to a standstill by the engineer. The ordinary air brake or other fluid
pressure brake in use upon a steam actuated railway train provides for this
emergency by exhausting the train pipe and turning on the pressure from the
auxiliary reservoirs, whenever the train is accidentally severed.
The forward part
of the train remaining under the engineer's control may be drawn away from the
part in the rear at any desirable rate of speed; but where the train is upon a down
grade, unless the rear part is checked, it may run away and collide with the front
portion; or if it be on the up grade, it may run away backwards. It is to prevent
sinular mishaps to electric trains and to provide analogous means of control, that
I have devised my invention, which consists, first in so coupling the cars that by
the rupture of the coupling a circuit will be completed through the brake-magnets
upon the portion of the train separated from the motors. To provide current for
this circuit, I equip each car which has no motors with a small generator the
armature of which is carried directly upon the axle; by preference I make the
field-magnets of this generator of hardened steel, so that considerable residual
magnetism will be retained even after the lapse of time and the ordinary shocks
and jars of railway travel. This generator may be, and preferably is, of small size,
inasmuch as it will be driven with considerable speed and its magnetismn, which
will be furnished by a series field, is carried to a high point. I also so arrange the
coupling of the generator in this connection that at the moment of rupture of the
coupling, the generator will be short circuited for an instant, and thus a very high
charge of current will pass through the field magnets and develop an initial field.
As a modification of this portion of my invention, I may also provide for an initial
excitation, by means of a small battery, primary or secondary. For the small
generator any suitable source of electro-motive force may be substituted, although
ordinarily the generator will be found most desirable commercially.
Another feature of my invention consists of means for notifying the engineer of
auy break in the train. This consists of a gong in the trolley circuit, or rather, in
a shunt from the trolley circuit to ground, the shuut being made of very high
resistance, so that the current is limited to a very small amount.
The bell is so
arranged that so long as the current is on, the hammer is held away from the gong,
but upon cessation of the current, the goug will ring.

page_text: the last car of the train; but, upon the breaking of the connections, the circuit
will be broken. It is of course to be understood that the circuit is from the
trolley to ground for which purpose the running gear on the last car will be
utilized.
My invention further consists in the details of the form of coupling which I
employ to carry out this purpose, and in other details and combinations which will
be fully pointed out hereinafter.
The accompanying drawings show embodiments of my invention,
Fig. 1 being a side elevation, partly in section, of the improved coupling which
I employ;
Fig. 2 a plan view of one member of the coupling ;
Fig. 3 is a detail showing the means for momentarily short-circuiting the
generator;
Fig. 4 is a modified form, partly diagrammatic and partly perspective, of the
arrangement shown in Fig. 3;
Fig. 5 is a diagrammatic plan view of a train equipped with my apparatus ;
Fig. 6 is a detail of the arrangement of gong in the alarm circuit, and
Fig. 7 shows an automatic reverse, more fully described hereafter.
Referring by letter, A is one of the parts of the coupling to which I have
referred, which I have designated as a whole by the letter ✗; B is another part,
each of the parts A and B being provided with means for attaching the cables C, D.
The two parts are insulated from each other by interposed sheets of hard rubber,
or other suitable insulation E, and are held together by screws G, only two of
which are shown in Fig. 1. The parts on the right of the coupling are identical
with those on the left, it being interchangeable, and are marked with the
letters A¹, G¹, &c. F, F1 are the projecting contacts of the metallic parts, A, A¹
respectively, designed to complete the circuit; it is understood that ordinarily the
circuit is completed from the cable D to the cable D', through the parts A, A¹, but
upon the interruption of the circuit contact is made between the parts A, B, A¹ B',
respectively, and the cables D, C, D', C', are connected.
The means for establishing this latter connection is shown in section in Fig. 1.
Therein His a cap enclosing a sliding bolt I carrying a bridge piece L, which
may be made of a single piece of metal, but which I prefer to make as illustrated,
in the form of an arch of several pieces of flexible metal, to ensure a good contact.
This bridge piece is held upon the bolt or stud by a lock nut P, and a spring K
acts to force it down into contact when the coupling is broken. Part of the metal
of the coupling is formed into a ring or flange O, best seen in Fig. 2, and provided
with a screw thread upon which the uut H is secured. N is a small projecting
portion of the part B₁ of the coupling, not protected by the insulation, and affording
contact with the bridging piece L. At M'I show a pin in one coupling registering
with a groove in the other. It is to be understood that the two parts of the
coupling are applied ordinarily at an angle and are then brought into alignment,
this action making the pin M engage with the groove. The shearing strength of
the pin M is less than the strength of the joint between the cables C, D, and the
parts A, B, respectively, s that in the event of a rupture of the train, the cables
will not be torn apart, but the pin M will be broken. The surfaces of the coupling
afford ample contact area for the transmission of any current which the cables are
sufficient to carry.
The parts shown in Fig. 2 are sufficiently described in connection with Fig. 1.
In Figs. 3 and 4 I show the arrangement by which an initial charge or excitation
is given to the small generator operating the brake on the part of the train
separated from the motor car.
Referring first to Fig. 3, X is as before, the main coupling illustrated in Fig. 1;
C', D' are cables extending therefrom, the right hand half of the coupling being
shown; E, E is a body of insulating material, carrying in it a small metallic
piece c, which forms a bridging contact between the flexible contacts, a, b, when the

page_text: coupling is ruptured. In the tube d is mounted a tumbler e slightly bevelled at its
top end and engaging with the bridging portion el of the insulating piece E, E; fis
the field of the generator Q' carried upon the axle of the truck. At UI provide
a stop which prevents the destruction of the auxiliary coupling. The office of the
tumbler e is to prevent the insulating slide carrying the contact from being drawn
with any little strain which may happen to occur, it taking considerable force to
pull the slide, but after the part et has passed the tumbler, the slide cannot be
pushed in accidentally.
The operation of the device just described is as follows: When the coupling X is
ruptured, the pull of the cable D¹ pulls out the slide E carrying the contact c and
the part el passes the tumbler e, which then locks it in position. The contacts a,
are thus momentarily short-circuited by the contact, and the initial charge is
passed through the field-magnet f. The magnetism rapidly runs up and current is
sent out to the brake magnets on the car, as will be more fully described in referring
to Fig. 5. It is of course to be observed that the generator Q' is normally open-
circuited, so as to prevent the operation of the brake in ordinary handling of
the car.
Referring now to Fig. 4, I illustrate substantially the same combination of parts
except that I provide also auxiliary contacts a', 6', which are connected by an
auxiliary movable contact c'; the field of the generator Q¹ is divided, for purposes
of illustration. A few cells of storage battery or other source of electro-motive
force are coupled to the auxiliary contacts, and the portion f of the field is placed
in circuit by connecting these contacts. The operation of this device is the same as
that described with reference to Fig. 3. It is of course possible, however, and
would ordinarily be preferable, to connect the storage battery directly to the series
field of the generator.
In Fig. 6 I show the automatic alarm. This consists of a single stroke gong Y.
The hammer y is pivoted at y', and held in place by a pawl y*. This pawl acts
as the armature to an electro-magnet y which attracts the pawl against the pull of
the spring y, a similar spring y engaging the hammer when the paul is released.
A handle y is provided, by which the hammer may be restored to place after its
stroke. The operation of these parts will be described in referring to Fig. 5, which
is a general view of the system.
In Fig. 5, S is the controller; Q, Q &c. are the motors W, W the wheels of the
cars; R. Rare the brake magnets; Z is a resistance in the shunt circuit of the
bell Y designed to limit the current. This shunt circuit is carried ordinarily to
the rear of the train and grounded upon one of the axles of the rear coach. The
current passes from the trolley T through the shunt and through the bell and energizes
the electio-magnet y' to hold the pawl y in place. In the event of the coupling
between the cars breaking, the shunt is also broken and the circuit interrupted.
The current in the electro-magnet falls off, the pawl is drawn back by the spring y
and the hammer y strikes the bell. Upon the circuit being again made, the
handle is pulled and the hammer drawn back to place. When the train is
broken by the rupture of the coupling the electrical coupling X is also broken, the
coupling shown in Fig. 3 or that shown in Fig. 4 (indicated at X in Fig. 5) is
operated, the generator Q' is momentarily short-circuited, the current passing
along the line 1 to the coupling X thence through the short-circuiting contacts
upon that coupling to the lead 2 and back to the generator. The contact c,
however, immediately passes off the contact b and the circuit is then to the
cable D (Fig. 3), thence to the cable C and to ground, the circuit from the other
side of the generator passing through the coupling X to the brake magnets and to
ground at the rear of the car in Fig. 5. The operation in the same relation of the
parts shown in Fig. 4 will be understood without further description.
As thus far described and illustrated, my improved apparatus would operate only
when running on one direction; that is, forward, or to the left in Fig. 5; as this
would, however, prevent its operation in case the rear end of the train shoud break
off when running up grade, so that the car would first come to a stop and then run

page_text: away backwards, I provide means for ensuring a supply of current from the
auxiliary generator Q in whichever way the train may be moving; and the means
preferred is illustrated in Fig. 7. Briefly, the arrangement consists in mounting
the field-magnets of the generator upon the axle by a bearing of slight friction,
just sufficient to ensure their being turned in the direction in which the axle is
turning until arrested by a suitable stop on the frame. I thus provide for
reversing the relation of the armature and field, by shifting the field in relation to
the commutator brushes, and in whichever direction the armature shall revolve, it
will generate current. In Fig. 7 Q is, as before, the generator as a whole, Q' its
field-magnets, illustrated as of the four-pole type; Q³ is the brush-holder yoke
attached to any suitable fixed support, and Q' is a stop also attached to a fixed
support, as any part of the truck frame; q, q' are lugs upon the outer frame of the
field-magnets, designed to co-operate with the fixed part or stop Q;, are the
brushes bearing upon the commutator; q' is a counterbalance for the lugs 7, 7' and
Qis a suitable yoke supported by bearings not illustrated, but of any suitable form,
upon the axle.
It is manifest that any suitable means may be adopted for so adjusting the
relation of armature and field as to render the apparatus operative, in whichever
direction the car may move.
Having now particularly described and ascertained
the nature of this
invention and in what manner the same is to be performed I declare that what I
claim is :
1. In combination, an electric motor car, a trailer attached thereto, braking
apparatus upon both cars normally actuated by the motors upon the motor car
when operated as generators, an auxiliary normally idle source of electro-motive
force carried upon the trailer, and means whereby the auxiliary generator is thrown
into closed circuit with the braking magnets upon the trailer by the accidental
separation of the trailer from the motor car.
2. In combination, an electric motor car, a trailer, braking apparatus upon the
two cars normally operated by the motors upon the motor car when operating as
generators, an auxiliary normally idle dynamo-electric generator carried upon or
driven by the axle of the trailer, and suitable couplings and connections between
the braking apparatus and the auxiliary generator whereby the accidental separation
of the connection between the motor car and trailer acts to set the brake upon the
trailer.
3. In combination, an electric motor car, a trailer, an auxiliary normally idle
dynamo-electric machine upon the trailer car, and means whereby the accidental
separation of the two cars will close the auxiliary generator upon a local circuit
acting to stop the trailer car.
4. In combination, an electric motor car, a trailer, braking apparatus upon the
two cars normally operated by the motors upon the motor car when acting as
generators, an auxiliary normally ille dynamo-electric machine upon the trailer
car, and means whereby the accidental separation of the two cars will first
momentarily short-circuit the auxiliary machine and then throw it upon a local
circuit including the brake magnets.
5. In combination, an electric motor car, a trailer, braking apparatus upon the
two cars normally operated by the motors upon the motor car when acting as
generators, an auxiliary normally idle dynamo-electric machine upon the trailer,
and means for causing the accidental separation of the two cars to impart an initial
excitation to the field-magnets of the auxiliary machine, and then throw it upon a
local circuit including the braking apparatus of the trailer.
6. In combination, an electric motor car, a trailer, braking apparatus upon the
two cars normally actuated by the motors upon the motor car when operating as
generators, an auxiliary normally idle dynamo-electric machine upon the trailer,
contacts and connections whereby the auxiliary machine is first momentarily
short-circuited to obtain an initial field-magnetization and is then thrown upon a

page_text: local circuit including the braking apparatus upon the trailer, and means for
preventing the accidental displacement of the contacts and connections.
7. As a means for arresting a moving vehicle, a normally idle dynamo-electric
generator thereon, braking apparatus, means for imparting an initial magnetization
to the generator, a local circuit, and means for including the generator in the local
circuit with the braking apparatus.
8. In an electric braking apparatus, a dynamo-electric generator composed of an
armature mounted upon the axle of the vehicle, a field-magnet also rotatably
mounted upon such axle, and a stop limiting the motion of the field-magnet in
either direction; whereby the relation of the field-magnet and armature may be
reversed to correspond to the direction of motion of the car.
9. As a means for arresting a moving vehicle, a normally idle dynamo-electric
generator thereon, braking apparatus, means for throwing the generator into a local
circuit including the braking apparatus, and means for adjusting the relation of
armature and field in accordance with the direction of motion of the vehicle.
Dated this 1st day of August 1895.
J. C. CHAPMAN.