Electro Magnetic Car Brake and Traction Device.
Year: 1894

page_text: Date of Application, 4th Sept., 1894-Accepted, 13th Oct.,
1894
CODIT LEIE DI MOLTIVATION.
Electro Magnetic Car Brake and Traction Device.
We ROBERT THOMAS MURRAY of 1516 Railroad Avenue, Alameda, County
of Alameda, Plumber, and CHARLES MILTON ALLEN, of 2203 Larkin Street,
City and County of San Francisco, Electrician, all in the State of California U.S.A.
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 :-
Our invention relates to improvements in car brakes and tractile devices for
electric or other roads; and it consists in the employment of a powerful electro
magnet or magnets through which a direct attraction and frictional resistance may
be had with the surface of the track over which the car is passing, or by which the
tractile power of a motor may be increased.
It also consists in certain details of construction which will be more fully
explained by reference to the accompanying drawings, on which-
Figure 1 is a side elevation of a car showing our device in its proper position.
Figure 2 is a diagram of the switch mechanism.
Figures 3 and 4 are modifications of our device.
The object of our invention is to provide a brake in which the armature of the
electro magnet is attracted with any desired degree of force, to the rails over
which the car is passing whereby the friction of the brake upon the rail may be
increased to any desired degree independent of the weight of the car.
The device is also useful in the case of motors when starting, or when climbing
steep grades, to increase the tractile force of the wheels by the employment of a
strong electro magnet, the armature of which is retained a short distance above the
rail but near enough so that the attraction will act to hold the wheels more firmly
in contact with the rails than could be effected by the weight of the motor alone.
In the drawings illustrating our invention we have shown electro magnets A A
mounted upon the car truck B, which we have in the present case shown for the
purpose of illustrating the operation of our invention.
These electro magnets are made of any suitable or desired power.
We prefer to
wind them with wires in independent series, so that the current may pass through
one, two, or more of the series, thus increasing the power of the magnet to any
desired degree.
In the
These magnets are mounted upon frames C, and have suitable guides upon which
they are movable up and down. Each magnet is set over the line of the rails upon
which the car passes, at any suitable or convenient point upon the car.
present case we have shown them mounted between the truck wheels, and they are
connected with springs E E which normally support the magnets, so that the brake
shoes which are secured to the lower ends of the magnets, are at a sufficient
distance above the surface of the track, where they remain when no current of
electricity is passing through the coils.
When, however, a current of electricity passes through the coils, the magnet is
energized and the attraction between the magnets and the surface of the track
draws the brake shoes downward until they are diawn into strong frictional contact
with the track.
It will be manifest that this friction may be increased to any desired degree by
the strength of the current and by the addition of more coils in the series. This
may be effected in various ways. In the present case we have shown these coils of
the magnet connected with insulated plates G, G', G' by connecting wires H.
I is a switch lever fulcrumed between these plates which are arranged in series

page_text: upon opposite sides of the centre about which the lever turns, and they are
arranged in such a manner with relation to each other that when the switch lever
is turned so that the two plates G G, upon opposite sides are coupled together,
the coils a will be connected, and the current passing through these will be of a
certain strength.
By moving the lever so that either plates G', G¹, or G³, G² are connected, the
strength of the magnet will be increased at will, while by turning it to the first of
the series of plates 9 upon opposite sides of the centre, the current will be cut off
from the magnet altogether. When this occurs the springs E which support the
magnet-carrying frame, will act to raise the brake shoes from the track and leave
the car free to run without resistance.
L represents a resistance coil through which the current passes before entering
the magnets, and which reduces the current to the proper tension for use in the
magnet coils."
The switch lever I is actuated by a rod M connecting it with the foot lever N
by which the motor man can operate it by pressing the lever against a collar M¹
upon the rod M, so as to force the latter back, and turn the switch lever.
This rod M is also moved by a hinged swinging guard O at the front of the car
so as to throw the switch lever into proper position to give the necessary amount
of power to the magnet for the stop, whenever the guard strikes an obstruction, and
the guard is held in this position by a pawl O. This pawl may be released by
the action of the foot lever N which when pressed down releases the pawl, and
allows the spring P to force the guard O back to its original position, when the
pressure upon the lever N is relieved. This is done gradually and the switch
lever moves correspondingly to cut off the current from the magnet coils.
When the brake is to be put on by hand, it is done by means of the connecting
rod Q extending from the ordinary rotary brake shaft Q' back to the knee
levers R, and these levers acting upon the brake shoes force them down upon the
track so as to make the usual frictional brake which depends upon the weight of
the car for its efficiency. This brake may thus be used eutirely independent of the
electro magnetic device.
When the power of the magnets is to be used to increase the tractile power of
the wheels, in ascending gradients, a stop is employed, which consists of a bar m
movable horizontally upon supporting guides and connected by a 1od n with an
actuating foot lever o within reach of the motor man. The bar m has openings p
made vertically through it and when the bar is in its norinal position, these
openings will stand beneath the adjustable screws q which pass through the top
bar of the frame C in which the inagnets are fixed. In this position the magnets
are free to move downward to apply the brakes when the magnets are energized.
If it is desired to increase the tractile force upon the wheels, the bar m is moved
until the openings p are out of line with the screws g. Now when the magnets are
energized, they are drawn down toward the tracks, but the screws strike the
bar m, and prevent actual contact, between the brake shoes and the rails, so that
while there is a powerful attraction between the magnets and the rails, there is no
actual frictional contact. The screws q may be so adjusted as to stop the magnets
and brake shoes at any desired distance from the rails, but the construction shown
in Figure 3 is preferable for this purpose.
In Figure 3, I have shown the magnet frame as having projecting lugs D upon
each side which travel upon inclined planes F. These inclined planes are fixed to
a plate F which slides upon a guide plate 1. The plate F' is slotted and pins J
extend up through these slots from the plate I and thus limit the movement of the
inclined planes, which move beneath the lugs D, and are connected by a rod G¹
with a lever E¹ or other mechanism within convenient reach of the operator
whereby he may move the inclines so as to raise the magnets a considerable
distance above the track.
When released, the inclined planes are drawn back by action of a spring H.
When constructed, as shown in Figure 4, the curved planes F' are rotated a part

page_text: of a revolution by levers or by chains L' passing around them as shown, the
movement acting upon the pins D to raise the magnets in the same manner as
described for the straight incline*.
The inclined planes travel upon a supporting horizontal guide-plate I', and act
as before described to elevate or depress the magnets through the projecting lugs,
and at whatever point the magnets are arrested with relation to the track, they
will, whenever a current of electricity is passed through the coils surrounding
them, be attracted with a corresponding force, and this will add to the weight
upon the wheels in proportion to the magnetic force developed.
When the motor car or locomotive is to be started upon a level track, and it is
desired to increase its tractile force, the magnets will be lowered to a point very
near to the surface of the track, and the electrical current being passed through
the coils, will develop a strong attractive force in the magnet which will be
equivalent to the addition of that much weight, and thus increases the adhesion of
the wheels to the rails.
The same operation is employed when the motor is climbing grades where the
adhesive force of the wheels must be increased, the magnets may be raised from
the rails either to decrease the force of attraction, or when passing over curved
or rough places of the track where it is necessary to raise them to prevent
contact.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is-
1st. A brake for railway cars consisting of vertically moving brake shoes
adapted to form contact with the line of rails, and an electro magnet which carries
the brake shoes and moves with them, independent coils surrounding the core of
the magnet, said coils being connected in series, and with switch plates arranged
about a centre, a lever pivoted at this centre and movable to make connection
between the various pairs of plates whereby the power of the magnet is increased,
diminished or destroyed, substantially as herein described.
2nd. A brake for railway cars consisting of vertically moving shoes adapted to
form contact with the rails, an electro magnet which carries the brake shoes and
moves with them, a switch mechanism by which an electric current is caused to
pass through the coils of the magnet or is cut off therefrom, a connecting rod and
lever whereby the switch is actuated at will, and a movable guard extending down
in front of the car and connected with the switch actuating mechanism, and
locking devices whereby the magnet is energized and the brake applied auto-
matically by contact with any obstruction, substantially as described.
3rd. A means for increasing the tractile power of motors, consisting of an
electro magnet or magnets vertically movable with relation to the rails, a
mechanism by which the magnets are raised or depressed, and retained at any
desired distance from the rails, whereby the attraction of the magnets towards the
rails is varied by their distance therefrom, substantially as herein described.
Dated this Fourth day of September 1894.