Improvements in Electric Brakes.
Year: 1892

page_text: Date of Application, 27th Jan., 1892
Complete Specification Left, 6th Aug., 1892-Accepted, 31st Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements in Electric Brakes.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention (which has been com-
municated to me from abroad by Armand de Bovet of 47 Rue Taitbout Paris in
the Republic of France Engineer) to be as follows :-
This invention relates to brakes for railway and other purposes worked by
electricity. These brakes may be constructed for railway vehicles for example
according to either of two arrangements hereinafter described one of which is
relatively the opposite of the other but in both of which the brake acts upon a
drum or pulley fixed upon the axle and not directly upon the wheel of the
vehicle.
According to the first of these two arrangements there is fixed upon the axle a
magnetic wheel or pulley having a quantity of wire coiled in its interior in such a
manner that when a current is caused to flow in the wire the two rims or flanges of
the pulley act as the poles of an electro magnet.
A suitable number of wedge shaped iron blocks or shoes attached to a flexible.
band or strap engage with the groove formed between the rims or flanges of the
pulley and when the strap is contracted close the magnetic circuit formed in the
pulley by the action of the current.
The extremities of the strap are connected to the frame of the vehicle by a
combination of jointed rods or links so arranged as to compensate for the action of
the springs and enable the blocks to act upon the greater part of the periphery of
the pulley when the latter is rotating in either direction the blocks being caused to
press upon the pulley by the magnetic attraction of the latter with a force pro-
portionate to the intensity of the current circulating in the coils and the rigidity of
the encircling band or strap.
The brakes may be taken off when the current ceases by the elasticity of this
strap aided by the vibration of the vehicle or a reverse current may be momentarily
caused to pass in the coils with the same object. An alternative device for taking
off the brakes consists in an iron ring provided with a coil of wire and pole_pieces
which when excited by a current attract the shoes away from the pulley. In any
case it is advisable to surround the strap with an iron plate or guard in order to
steady it when out of action the shoes being required to move a very short distance
in order to place them in or out of action. The current is applied gradually and
the adjacent surfaces of the blocks and of the pulley are so arranged as to cause
of air
as little waste of energy as possible owing to the presence
spaces
these parts. The current caused to pass to the coils through brushes acting upon
copper or conducting rings insulated upon the axle.
between
According to another arrangement the shoes or brake blocks are magnetised in
place of magnetising the pulley. In this case the brake shoes act upon the
periphery of a disc bevelled at its circumference so as to present inclined surfaces
to the action of the shoes which may be in the form of an electro magnet whose
poles are arranged at an angle corresponding to the angle of the bevel on the disc.
These brake shoes are preferably provided with holes enabling them to be
threaded upon a couple of flexible straps by which they are supported in the
required position.
The supports for the brake shoes require to be maintained invariably in one
position relatively to the axle and consequently cannot be connected to the frame
as the latter is liable to move relatively to the axle owing to the action of the
springs. With this object either the existing supports connected to the axle boxes

page_text: or special supports may be provided such as a bar laid over the axle box and bent
downwards and curved or twisted so as to connect the two boxes transversoly.
In order to render the brakes automatic in their action the arrangements herein-
after described may be employed but my foreign correspondent considers it
necessary to be cautious in the employment of automatic arrangements which are
liable to render the brakesman less self reliant and engender habits of carelessness.
On this account it is considered preferable to arrange the apparatus in such a
manner as to be non-automatic in its action and to provide means for enabling the
engine driver to ascertain at any moment whether the brakes are in working order
or not by means of a signalling or indicating apparatus which can be worked by a
current too weak to apply the brakes but which is sufficient to show that the circuit
is in a state of efficiency. These arrangements are applicable whether the brakes
are arranged in derivation upon a main circuit or in series. The current may be
combined with suitable transformers if required and may be supplied with current
from a dynamo on the locomotive or from any other suitable source.
The brakes may be worked automatically if desired by connecting one end of
the flexible strap to a sliding piece acted on by a spring and connected to a chain
so arranged that a pull on the chain compresses the spring and applies the brake
shoes. The other axle of the vehicle may be similarly provided with a brake
worked by another chain and both chains may be connected to one end of a lever
the other end of which is capable of being acted on by a cam on the axle so that
the reciprocating movement of the lever produced by the rotation of the cam
intermittently applies the brakes until the wheels cease to rotate.
..
In order to enable the cam to act upon the lever the arm of the latter may be
made flexible so as to admit of a slight lateral displacement. This arm of the lever
is normally held out of the path of the cam by an electro magnet excited by a
current which is automatically interrupted by the breakage of a coupling for
example and then allows the lever arm to be moved by the action of a spring or
otherwise into a position in which the cam is able to act upon it and cause the brakes
to be applied.
The automatic action may be suspended when required by fastening the lever
arm in the normal position by means of a chain for example. This lever may be
combined with a ratchet arrangement actuating a windlass and chains which
gradually force the brake shoes against the pulley. In either case it is necessary
to send a weak current along the train when in motion for the purpose of main-
taining the levers out of action. This involves the employment of a third wire
one of the two wires of the main current for working the brakes being common to
both circuits.
According to another arrangement a small dynamo is employed being capable
of oscillation on a vertical axis its weight having no influence on this movement.
On one extremity of the shaft of this dynamo there is a small pulley or friction
wheel constructed on the same principles as the brake pulley firstly hereinbefore
described being provided with a coil placed in the same circuit as the said brake
pulley. By the action of a spring this friction pulley is pressed either against a larger
driving pulley fixed on the axle, or against one of the travelling wheels or the flange
thereof. The friction starts the dynamo and generates a current which increases
the adhesion of the friction gear this being the same current as that which circulates
in the brake pulleys. When the brakes are off the dynamo is held out of action by
an electro magnet acting in opposition to the spring. According to this arrangement
the power required to apply the brakes is likewise derived from the motion of the
train. The dynamo may be enclosed in a casing covering all the parts except
the lugs by which the machine is attached and the end of the shaft carrying the
friction pulley and may be combined with means for maintaining it out of action
if necessary.
Dated this 27th day of Jan 1909

page_text: COMPLETE SPECIFICATION.
Improvements in Electric Brakes.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of
Middlesex Gentleman do hereby declare the nature of this invention (which has
been communicated to me from abroad by Armand de Bovet of 47 Rue Taitbout
Paris in the Republic of France Engineer 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 electric brake apparatus for railways and other like
purposes in which accumulators are preferably employed as the source of electricity.
According to this invention the brakes are connected in derivation on the main
circuit.
By these means automatic action is obtained as hereinafter explained under
conditions analogous to those existing in air brakes. The accumulators are charged
either periodically or continuously and a third wire thinner than the two others which
form the main conductor is added to the latter the whole being arranged to operate
in the manner hereinafter described.
And in order that my said invention may be fully understood I shall now proceed
more particularly to describe the same and for that purpose shall refer to the several
figures on the annexed sheet of drawings the same letters of reference indicating
corresponding parts in corresponding figures.
Figure 1 of the accompanying drawings represents in vertical section a magnet-
isable brake wheel or pulley employed according to this invention. Figures 2, 3
and 4 represents in side elevation, horizontal section, and plan respectively. the
arrangement of the wheel or pulley in combination with the brake shoes or blocks.
Figs. 5 and 6 illustrate modifications of these arrangements as hereinafter explained
and Figure 7 is a detail of the same drawn to a larger scale.
Figure 8 illustrates partly in section an arrangement in which magnetizable brake
blocks are employed. Figures 9 and 10 illustrate arrangements for supporting the
brake mechanism in a railway vehicle. Figures 11 and 12 illustrate electro magnetic
arrangements in which the power for applying the brakes is derived from the
momentum of the train. Figures 13 and 14 are diagrams illustrating the arrange-
ment of the electric conductors.
The accumulators employed to work the apparatus are arranged in two groups
forming two equal batteries M and N Figure 13 one being placed at the front end
and the other at the tail end of the train. A third battery P of considerably
smaller size is arranged at one end of the train. The main circuit is formed by
the two large conductors a and b working electric brakes at e. A second circuit
supplied by the battery P is formed by the conductor and a fine wire c. This
second circuit is normally closed the passage of the current having the effect of
holding open the circuit ab by means of electro magnets 61 in such a manner that
the breaking of the circuit bc has the effect of closing the circuit a b.
These openings of the circuit bc may be produced by the engine driver who may
at the same time introduce resistances into the circuit in order to regulate the action
of the brakes. The circuit bc is also opened by the giving way of any of the
couplings and in this case the brakes on both portions of the train are applied by
the batteries at the ends of the train. It being possible that a coupling may give
way at any part of the train or even at the end carriage it is advisable that the two
batteries be of equal power and that each battery be capable of actuating all the
brakes in the train. The charge requires to be doubled but the batteries retain
their power for a correspondingly longer time.
It is evident that this arrangement may be modified if required and that the
vehicles may be arranged in groups containing a certain number in series each
group being in derivation. The modifications is this direction cannot be carried

page_text: .
beyond an arrangement with a local circuit in each vehicle and a main conductor
formed by two fine wires cc (Figure 14) operating as hereinbefore described.
The invention is not limited to the details of the arrangements described which
are given merely as examples but it is preferred to employ an arrangement such as
that illustrated in Figure 13 which does not require any special arrangement.except
with regard to the front and tail vans and enables the train to be made up in any
convenient manner and with any suitable number of vehicles. Nevertheless''the
time during which the accumulators will work with a given charge is influenced by
the number of vehicles composing the train.
Vehicles unprovided with brakes must of course be provided with the group of
the conductors which may be twisted together. In order to obviate mistakes in
coupling it is simply necessary to make the hooks or connections employed for
uniting the ends of the several conductors of distinctive forms so as to make it
practically impossible to connect the conductors together otherwise than in the
proper manner.
The brake mechanism which constitutes an important part of this invention is
illustrated in Figures 1 to 12 of the accompanying drawings.
According to the arrangement illustrated in Figures 1 to 4 a pulley C is keyed
upon the axle and is capable of being rendered magnetic being provided with a coil
of wire a so arranged that when an electric current circulates in the said coil two
magnetic poles are formed at the flanges b. Around this pulley is placed a flexible
band y provided with a suitable number of blocks or shoes as represented in
Figure 2 for example the said blocks being of such form in transverse section that
when the band is tightened they fit exactly into the groove of the pulley (as repre-
sented in Figure 3) and close in a short circuit the magnetic circuit developed by
the action of the current.
The extremities of the band or straps y are connected to the under frame of the
vehicle by iron rods hinged to the frame at a' and 6 (Figures 2 and 5) and hinged
to the brake strap at c and d. The centres c and a¹ are connected by a single rod
and the centres d and b are connected by two parallel rods so arranged that the rods
may cross one another as represented in the drawing without interfering with the
movement of the parts (Figure 4).
It will be readily understood on referring to the drawing that the magnetisation
of the pulley C causes the brake blocks to be drawn into the groove and tends to
carry them round with the pulley with a forco which depends upon the intensity of
the magnetisation (and consequently on the intensity of the current) and the
rigidity or resistance of the band or strap. With this arrangement of the con-
• nections the same result is obtained when the axle rotates in either direction.
The brakes may be taken off when the current ceases by the elasticity of the
encircling band or strap aided by the vibration of the vehicle. If necessary a
reversed current may be caused to pass for a short time immediately after the
current employed to apply the brakes ceases. According to another arrangement
an iron ring A provided with coils of wire may be arranged outside the strap and
provided with inwardly projecting pole pieces A¹ Figure 5. By causing the current
to act upon this ring directly it is cut off from the pulley the brake strap and shoes
are attracted towards the ring being so arranged as to be capable of oscillating
between the said ring and the pulley.
When the ring with the poles A is not employed it is necessary to surround the
strap with a plate or guard such as that represented at M N P Figure 6 preferably
of non-magnetic metal which serves to support and steady the strap which is pressed
against it by the effect of its elasticity and at the same time limits the movement
of the blocks.
The groove in the pulley and the blocks are made of a form such as that illus-
trated in Figure 7 so that when the brake blocks are tightened they fill the groove
in order to prevent waste of magnetic force through an air space at m and n.
The centres a¹ and 6 Figures 2, 5, and 6, being attached to the frame of the
"vehicle partake of the displacements resulting from the action of the springs but

page_text: the brake straps and blocks require to be retained in one position relatively to the
pulley and it is consequently necessary for their supports such as A B Figure 5
or M. N. P. Figure 6 to be likewise secured in a fixed position relatively to the
axle and consequently they cannot be connected to the frame. Arrangements of
the supports enabling these conditions to be complied with are hereinafter described
the combination of jointed rods or links by which the brake strap is connected
to the frame being so arranged as to compensate for the action of the springs and
enable the blocks to act upon the greater part of the periphery of the pulley. By
making the brake strap sufficiently flexible and of suitable length the links at c
and may be dispensed with. In the case of apparatus arranged as hereinbefore
described the current is caused to pass to the coils in the pulleys through brushes
acting upon insulated rings carried by the axle.
According to another arrangement the shoes or brake blocks are magnetised in
place of magnetising the pulley. In this case the brake shoes act upon the
periphery of a disc Figure 8 keyed upon the axle and bevelled at its circumference
as represented in the drawing so as to present inclined surfaces to the action of the
brake shoes. These shoes constitute an electro magnet provided with a coil of
wire a and presenting polar surfaces arranged at an angle corresponding to the
periphery of the disc. These brake shoes are provided with holes through which a
couple of flexible straps s are passed in order to support the shoes in the required
position. An external guard plate w is provided for the protection of the coil a.
With this arrangement the electrical connections may be of any ordinary or suitable
construction.
To enable the brake shoes to be maintained in the required position relatively to
the axle they must be supported upon the bearings or grease boxes in the case of
railway vehicles of ordinary construction. The parts which require to be supported
in this way are light and are not exposed to great strain. In vehicles provided with
an iron bar connecting the two grease boxes and employed for supporting certain
parts of the ordinary brakes it is simply necessary to attach to these bars two
transverse pieces to which the longitudinal bars or plates supporting the brake
straps may be connected. When this arrangement cannot be employed special
supports must be provided. Figure 9 illustrates an arrangement in which a bar v
is employed being placed upon the axle boxes and extending round the wheels from
one side of the vehicle to the other. This bar is bent and twisted so as to stand on
edge at the front and back of the wheels in a suitable position for supporting the
brake mechanism.
Figure 10 illustrates another arrangement which may be employed when
sufficient space exists between the inner side of the horn plate and the wheel for
introducing a supporting bar v such as that herein before referred to the said bar
being bent so as to fit over the grease box and pass around the wheels in such a
manner as to provide suitable points of support for the flexible brake strap.
The brake apparatus constructed and arranged as hereinbefore set forth are
automatic in their action. Figures 11 and 12 illustrate two other arrangements
which may be employed in order to obtain perfectly automatic action. According
to the arrangement illustrated in Figure 11 one end of the flexible strap is con-
nected at a to a sliding block a acted on by a springs and connected by a rod t
attached to a chain c so arranged that a pull on this chain has the effect of com-
pressing the springs and applying the brakes. The other axle of the vehicle may
be similarly provided with a brake worked by a chain c. The chains c and c¹ are
connected at m to one extremity of a lever oscillating upon a centre p attached to
the frame. The other extremity of this lever is acted upon by a cam fixed upon
the axle. This mechanism may be adjusted in such a manner that the action
of the cam tightens the brake strap but not necessarily with sufficient force to skid
the wheels. With this object the lever may be arranged to possess a certain
amount of elasticity. Under these conditions the speed is gradually reduced by
the intermittent application of the brakes occurring at each revolution of the
wheel. A small number of revolutions is sufficient to stop the vehicle as the

page_text: brakes are applied with the same amount of force at each revolution although
the speed gradually decreases. The lever working on a horizontal axis at p is
capable of being displaced laterally so as to be normally maintained out of contact
with the cam by the action of an electro magnet excited by an electric current.
When this current is interrupted (which would necessarily occur on the breakage
of a coupling) the lever is moved by the action of a spring into a position in
which it is acted on by the cam. The automatic action may be suspended when
required by fastening the lever arm in the normal position by means of a chain
extending to the sides of the vehicle.
According to a modification of this arrangement the lever may he provided with
a pawl or driver combined with a ratchet wheel on a shaft provided with an electro
magnetic clutch arrangement enabling it to work a windlass, as in the Achard
brake described in the Specification annexed to Letters Patent No. 3006 A.D. 1864,
thereby winding up the two chains cc and tightening the brakes gradually or until
the wheels begin to skid. With this arrangement the automatic action cau likewise "
be suspended when required, as herein before described.
According to another arrangement illustrated in Figure 12 a small dynamo 1 is
connected to the frame in such a manner as to be capable of moving upon a vertical
axis so that its weight has no influence on its lateral displacement. On one
extremity of the shaft of this dynamo there is a small pulley or friction wheel 3 of
from about 3 to 4 inches diameter constructed on the same principles as the pulley
illustrated in Figure 1 and provided with a coil placed in the same circuit as the
coil in the said brake pulley. By the action of a spring 4 this friction pulley is
pressed either against a pulley of larger diameter fixed upon the axle of the
travelling wheels or against one of the said wheels or the flange thereof as repre-
sented at 6 Figure 12. The friction starts the dynamo and generates a weak
current which increases adhesion of the friction gear and consequently gradually
acquires more power. This current circulates in the brake pulley or in the two
brake pulleys of the same vehicle when each axle is provided with a brake.
When the brakes are taken off the dynamo is maintained out of action by means
of the electro magnet 5 which compresses the spring 4 and prevents the pulley 3
from coming in contact with the wheel 6. With the arrangements illustrated in
Figures 11 and 12 the power required to apply the brakes is derived from the
momentum of the train. The dynamo 1 is preferably enclosed in a casing covering
all the parts except the lugs by which the machine is supported and the end of the
shaft carrying the pulley 3. This brake mechanism may be provided with means
for holding it out of action in the same way as the mechanism hereinbefore
described.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In an electric railway brake the combination of three wires or conductors
for supplying the current in the manner and for the purpose substantially as
herein before described with reference to Figures 13 and 14 of the accompanying
drawings.
2. In an electric brake the combination of a wheel or pulley with brake blocks
carried by a flexible support in close proximity to the periphery of the pulley so
that when an electric current is supplied to the pulley or to the brake blocks these
parts are caused to adhere together and are separated by the effect of the elasticity
or resilience of the support of the blocks when the current ceases substantially as
herein before described with reference to Figures 1 to 8 of the accompanying
drawings.
3. In an electric brake the combination of a magnetisable wheel or pulley fixed
upon the axle and a number of metallic blocks attached 'to a flexible strap or band
surrounding the pulley the said blocks being caused to adhere to the pulley when
the latter is magnetised by the passage of an electric current in the coils with

page_text: which it is provided substantially as hereinbefore described with reference to
Figures 1 to 7 of the accompanying drawings.
4. In an electric brake the combination of an iron disc fixed upon the axle and
a number of brake blocks provided with coils so as to be capable of acting as
electro magnets being arranged at the periphery of the said disc and adhering
to the latter when excited by the passage of an electric current in their coils sub-
stanially as hereinbefore described with reference to Figure 8 of the accompanying
drawings.
5. An automatic electric railway brake in which the power required to apply the
brakes is derived from the momentum of the train by means of electro magnetic
mechanism combined and operating substantially as hereinbefore described with
reference to Figures 11 and 12 of the accompanying drawings.
6. The arrangements and combinations of parts constituting improvements in
electric brakes substantially as hereinbefore described with reference to the accom-
panying drawings.
J. H. JOHNSON & Co.,
Agents.