Improvements in Brake Apparatus for Railways.
Year: 1891

page_text: Date of Application, 18th July, 1891
Complete Specification Left, 19th Apr., 1892-Accepted, 25th June, 1892
PROVISIONAL SPECIFICATION.
Improvements in Brake Apparatus for Railways.
I, CHARLES LUYERS, of No. 23 Nouveau Marché aux Grains, Brussels,
Belgium, do hereby declare the nature of this invention to be as follows:-
It is well understood that the theoretical requirements of a perfect brake
apparatus are, that it should effect the stopping of the train without jerks and in
the shortest possible time after the application thereof. It is also known that for
accomplishing this it is requisite that the brake should exercise, during the entire
duration of the stopping action, its maximum retarding force simultaneously and
uniformly on every brake carriage of the train. Now in order to cause a brake to
exercise on each pair of wheels its maximum retarding force it is necessary to
regulate the pressure of the brake blocks according to the speed and other possible
circumstances, so that the friction between the brake blocks and the wheels shall
not exceed that between the wheels and the rails, but shall always be just short of
that amount.
For realizing these conditions it is therefore necessary to be able to cause the
brake blocks to act with a constant pressure almost equal to that which would skid
the wheels, producing a constant coefficient of friction so as to keep the wheels
during the whole time of the application of the brakes, in a state near that of
skidding, in order that the brake may at every moment exert the maximum of
retarding force.
As is known, the coefficient of friction of the brake blocks on the wheels is not
constant, but diminishes, on the one hand, in proportion to the duration of applica-
tion; in consequence of the heating of the metal &c., while, on the other hand, it
increases as the speed of rotation diminishes, in particular during the period
immediately preceding the stoppage.
It would therefore be of the greatest importance to diminish as rapidly as possible
the speed of rotation from the moment when the brake blocks are applied, so as to
approach as quickly as possible to the period immediately preceding the stoppage,
and thus utilise the increase of the coefficient of friction in order to compensate for
the diminutions resulting from the duration of the application, and thus operate
during the whole time of stopping with a constant coefficient of friction which will
produce the maximum action preceding skidding. For this purpose it is also
necessary that the brake blocks shall be applied and act with the greatest precision
and regularity, for maintaining this maximum action until the train is stopped,
which will take place in a much shorter time than when the wheels are skidded and
slide on the rails.
These results are obtained in a manner which in practice approximates very
closely to the theoretical value, as regards the most essential part, that is to say,
the braking device of my improved brake apparatus, which I will proceed to
describe with reference to the accompanying drawings, in which
Fig. 1 is a side elevation of the braking device,
Fig. 2 a cross section of the brake cylinder with the distributing valve and
auxiliary reservoir,
Fig. 3 a vertical section of the discharge valve, and
Fig. 4 a cross section of the air pressure accumulator, with its compressor in
longitudinal section and the other parts in elevation.
Although the improved brake apparatus can be used in combination with all
known kinds of brakes, I have shewn the same by preference in combination with
the apparatus of an automatic fluid pressure brake of peculiar construction.
Referring to Fig. 1, it will be seen that the braking device consists of a disc or

page_text: drum M of a diameter much smaller than that of the wheels and which is fixed on
the axle, and is situated between two brake shoes or blocks S which embrace its
periphery to an extent proportionately much greater than in the case of the ordinary
brake blocks on the periphery of the wheels. The shoes are pivotted at their lower
ends to one and the same point of a suitable part of the framing, and their upper
parts terminate in lever arms which are moved in contrary directions by the looped
rod T of the brake cylinder C. The shoes S are provided with lining cheeks sof
cast steel, which are removeable and interchangeable after wear. The shoes with
their cheeks can always be held at a distance from the friction disc or drum M by
the adjustment of the nut e on the piston rod of the cylinder C.
It will be readily seen that the friction disc being of a diameter less than the
wheels its peripheral speed will decrease much faster than that of the wheels, and
the period preceding the skidding action will consequently begin much quicker for
the disc than for the wheels, relatively to the rails. In order therefore to keep the
friction disc at an action approaching the skidding, it suffices to exert on the shoes
a pressure sufficient for producing a braking action approximately equal to the
force of adhesion of the wheels and proportional to the speed, and to maintain this
pressure until the final stopping is effected, which will take place in a space of time
which will be all the shorter, the smaller is the diameter of the disc, because the
peripheral speed hereof diminishes more rapidly and thus leads quicker to the
period preceding skidding. The pressure of the shoes must however be increased
in proportion to the decrease of the diameter of the disc.
In the determination of the braking action on the disc, which should approximate
to the force of adhesion of the wheels on the rails, the force to be applied to the
shoes will therefore be proportionate to the diameter of the disc that is to say, the
product of these two factors must always be equal to the force of adhesion.
Whatever, therefore, may be the diameter of the disc, the coefficient of friction,
which diminishes on the one hand in consequence of the heating and increases on
the other hand in consequence of the diminution of speed, will remain constant
during the entire application of the shoes, which thus maintain the disc in a con-
dition near the skidding during the whole period of stopping. I have found in
practice that in assuming the diameter of the wheels to be one metre, the best
proportion for the disc is about one fourth the diameter of the wheels.
It will be readily seen that by means of this arrangement a much more precise
action of the brake device is obtained, not only on account of the reduction of the
dimensions, but also in consequence of the application of the shoes upon a more
uniform surface, which, as it does not run on the rails, is much less liable to
become unround than the wheels, and thus avoids the severe shocks and jerks
when applying the brakes, as the disc is prevented from biting at one part
of the revolution and running loose at another part, as is the case with the
wheels.
As the coefficient of friction must be dependent upon the degree of adhesion on
the rails of each vehicle, the pressure exercised on the shoes must not only be
proportionate to the speed, but also to the variable weight with which they are
loaded, which determines the degree of adhesion of each carriage; the pressure
exercised on the shoes must therefore not only be proportionate to the speed, but
also to the variable load of the vehicle. For fluid pressure brakes, the degree of
elasticity of the air acting in the brake cylinders should therefore be proportionate
to this weight, and in order to establish this proportion at every moment and for
each vehicle in a perfectly automatic manner, I employ the system of distribution
shewn diagrammatically at Fig. 2, the essential feature of which consists in the
combination of an auxiliary reservoir H with an admission valve, aud a regulating
valve.
The admission valve has for its object to allow the entrance of air pressure into
the brake cylinder C at the desired moment, on a decrease of pressure being
effected in the train pipe X and the regulating valve has the object of proportioning
the degree of elasticity of the air to the load of the vehicle.

page_text: For this purpose, it consists of two cylinders communicating with each other and
containing two pistons G formed of one piece, the one of large diameter being in
the lower cylinder, while the one of small diameter is in the upper cylinder. The
small cylinder is provided with diametrically opposite longitudinal grooves, passing
along part of its length to a sufficient extent for establishing a communication
between the large and the small cylinder. Into this grooved part opens, on the
one hand, the pipe t' branched on the train pipe X, and on the other hand the
pipe communicating at one end with the auxiliary reservoir H and at the other
end with the admission valve. Below the large piston G in the lower cylinder
is placed a spring R which bears with its lower end upon a disc on the other end
of a stem T' sliding through the cylinder, and to which are jointed one or more
levers that are subject to the action of the load of the vehicle.
The complete regulating valve is fixed at the upper end to the brake cylinder C,
and it is held at the lower end by suitable stays. The upward motion of the
spring R is limited by the upper end of the small piston which butts against the
upper end of the valve casing.
Under the above conditions it will be seen that when the carriage is empty, the
spring R is subject to the minimum pressure, as no pressure beyond that due to
the weight of the empty vehicle is transmitted by the before mentioned levers to
the stem T¹.
If then the air pressure coming from the train pipe ✗ and passing through t¹
into the valve apparatus produces a pressure above the piston G and in the
auxiliary reservoir H a pressure corresponding to the weight of the empty vehicle,
or, in other words, to the force of the spring R corresponding to that weight,
this spring will be compressed by the downward motion of the two pistons, the
upper one of which by such motion will close, by its ungrooved part, the admission
of air through t¹, so that the pressure in the auxiliary reservoir will not exceed the
degree corresponding to the dead weight of the carriage.
Assuming now that the vehicle carries a certain load. In this case the levers
acting on Twill lift the latter, thereby compressing and increasing the force of
the spring R to a proportionate extent, so that the air pressure admitted through t
will now require to be much greater for closing the admission of air pressure into H
by the descent of the piston valve and consequently the pressure in the auxiliary
reservoir will be correspondingly greater and proportionate to the load of the
carriage. The admission valve is composed of the outer cylinder c in which are
the pistons L and K fitting the one into the other, so as to leave an annular space
between them in which is a helical spring R bearing respectively against the
bottom of K and the head of L, which it thus keeps in position. The bottom of
the piston K is situated a certain distance from the bottom of the cylinder e, thus
leaving a space V. When the valve does not act, as in the drawing, the brake
cylinder C communicates by the tubular passage t³ with a groove d of the piston K
which opens into the open air; the latter is also made to pass to the joint between L
and K through a passage t, in order to prevent the adhesion of the two owing to
want of air between them. A space above the piston L communicates with a
grooved by the pipe t, and the pipe which admits air into the cylinder C opens
against the conical part of the piston L, which keeps that communication closed
when the valve is out of action. The pipe & coming from the auxiliary reservoir H
opens against the side surface of the piston K.
The action of this apparatus will be as follows: Assuming that air is admitted
to the auxiliary reservoir to a pressure determined by the pressure of the spring R
regulated by the load of the vehicle, and that the piston G having cut off the
entrance of the air, is maintained in that position by the maximum pressure in the
train pipe, which pressure also exists in the space V, and thus keeps the admission
valve of the brake cylinder closed; then if air pressure be now discharged from
the train pipe to an extent corresponding to the brake pressure to be exerted pro-
portionate to the speed of the train, this will cause the pressure in V to be decreased,

page_text: groove
whereupon the piston K will descend until the pipe t' communicates with the
d' so that air pressure will now pass from the reservoir H through to over
the top of L, which will descend and allow the air pressure to pass through (6 into
the cylinder C, the pistons of which are then made to act on the brake shoes with
a pressure proportionate to the load and to the speed.
During this passage of air pressure from H to C, a check valve c' placed in the
communication t prevents the air from the reservoir H from returning through the
regulating valve and t. As soon as the pressure is re-established in the train pipe,
the parts resume their original positions, and the pistons of C, being drawn back
by their springs, will cause the air pressure to pass out through t³ d. The pressure
exerted by the spring R should always be sufficient to depress the piston K to
such an extent as to cause the pipe 2 to communicate with the groove d'; it must
therefore be greater than the pressure remaining in V after the decrease of pressure
in the train pipe.
For the purpose of insuring that the reduction of pressure in the train pipe X
shall always be proportionate to the speed of the train, 1 interpose in the said pipe
a regulator or reducing valve of the construction shewn at Figure 3, which
determines automatically the decrease in X when the driver has turned the pointer
T'he valve
of the valve into the position corresponding to the speed of the train.
apparatus consists of a cylinder Ci the bottom of which forms the seat of the
valve S₁ placed over the opening of the train pipe X. The valve has a hollow
stem Tinto which passes the solid stem Ts, to which is attached below the
collar the piston P working in the cylinder C. Between the piston P and the
valve S is a helical spring R coiled round T and T³, and which holds the valve
down on its seat so long as the pressure of the spring is greater than the air
pressure in X. The pressure of the spring is regulated by the compression thereof
by means of a toothed rack c formed on the stem Ts, and which can be raised or
lowered by the pinion fixed on the spindle of the hand wheel v, actuated by the
driver. Parallel to the rack is arranged a graduated scale over which travels a
pointer fixed to the rack, and the divisions of which correspond to different speeds
of the train.
P
When the pointer descends to zero on the scale, the spring R' compressed
between the piston and the valve S', exercises its maximum pressure, which then
balances the maximum pressure of the train pipe, and consequently prevents any
air from escaping therefrom. But when the rack is raised so as to cause the
pointer to point say, to a speed of 50 kilometres per hour, the pressure of the
spring R will be correspondingly diminished and will allow the valve S¹ to be
forced open by the excess of pressure in the train pipe, thus allowing such pressure
to escape until the equilibrium of pressure due to the above speed is attained,
whereupon the valve will be closed again.
It will be evident that at higher speeds the pressure of the spring will have to
be correspondingly further diminished, while if it is less, the pressure will have to
be increased, by the corresponding movement of the rack, allowing in the one case,
a further escape of pressure from the train pipe to take place and in the other case
allowing the pressure to accumulate again to a corresponding extent.
The reducing valve is placed on the engine and is interposed in the train pipe
which passes on the one hand to the brake cylinders and on the other hand to the
accumulator A fixed below the tender. The accumulator is a cylinder of sheet
iron of sufficient thickness, in which is arranged horizontally the compressor,
actuated directly by an axle of the vehicle. The compressor consists of two
cylinders of different diameters containing pistons P¹and P² fixed on the same
stem, and receiving simultaneous to and fro motion by means of a link M' jointed
on the one hand to a rod of the pistons and on the other hand to a lever L
suspended from the framing of the tender and actuated by an eccentric E' fixed
on the axle. This eccentric has an external ring which is in contact with the
lever L when the apparatus is in action; by this means the periphery of the

page_text: eccentric disc itself remains perfectly circular, which would not be the case
if it acted directly on the lever L, as a cam, always touching at the same
place. In the front cylinder, which is of smaller diameter is situated a
spring R confined between the cover and the piston P and which always tends to
bring the pistons towards the ends of the cylinders when the compressor is out of
action.
The two cylinders communicate with each other by means of the pipe t" which
communicates with the outer air by a branch to opening into a permeable casing,
which filters the air that passes into the cylinders.
The piston P of the large cylinder contains two valves which allow the air to
pass through when the piston moves forward and this, on the return stroke, forces
that air through the large valve in the cylinder bottom into the accumulator A.
In the latter is arranged a pressure regulator consisting of a cylinder C³ containing
a piston P3 which is always pushed towards the interior of the accumulator by a
spring R³ while the accumulated air pressure tends to force it in the contrary
direction.
The cylinder C³ communicates on the one hand with the pipe and on the other
hand with the pipe which passes to a two way cock Fig. 3 on the engine
actuated by the driver. This piston Ps has a passage which establishes a com-
munication between the pipes to and when the pressure in the accumulator
arrives at the maximum.
It has been stated above that the pistons P1 P2 of the compressor are held at
the end of their strokes by the spring R² when the compressor is out of action.
When it is in action, the eccentric E forces the pistons backward and they are
forced forward again at the end of each stroke by the compressed air of the
accumulator introduced by the cock F which is turned so as to cause the pipe to to
communicate with the space a of the cylinder, so that this space is filled with the air
pressure of the accumulator which forces the pistons forward again till the pipe t
communicates with pipe and the outer air through the passage 1, thus allowing
the pressure in a to sink below that of the spring R, which keeps the pistons
at the end of their stroke, so that the eccentric E' then revolves without acting on
the lever L, and is consequently not subject to any wear. This condition continues
as long as the cock F keeps closed, and a out of cominunication with the
accumulator.
In order that the mechanism may be made to work also when the accumulator
is not charged with air pressure, a second cock F' worked by the driver is arranged
on the engine, by which a communication can be established between the boiler
and the space a so as to actuate the pistons in the first place by steam pressure.
The action of the above described brake apparatus is as follows.
Assuming the pressure in the accumulator A to be at the maximum, and that the
train requires to be stopped when running a 80 kilometers an hour, for example,
the driver effects a reduction of pressure corresponding to this speed in the train
pipe X by opening the valve S¹ to the requisite degree by the rack C²; the same
reduction then occurs in the spaces V of the admission valves of the_brake
cylinders, which then receive air pressure from the auxiliary reservoirs H at a
pressure proportional to the load of the vehicle, and consequently proportional to
the adhesiou between the rails and wheels. The brake shoes then brake the
friction disc M under the conditions which bring it quickly into a state bordering
on skidding, in order to stop the train without shocks in a minimum duration of
In order to replace in the accumulator the amount of compressed air
expended, the driver puts it in communication with the space a in order to bring
the compressor into action, which stops at the end of a few revolutions, the
quantity of air necessary for refilling the auxiliary reservoirs and for producing
the maximum pressure in the accumulator being very small. The driver then
closes the cock F and the brake is ready to be again applied.
time.
During the journey the brake can also be used repeatedly without recharging
the reservoir A, the quantity of air expended being only a few litres for each

page_text: applications of the brakes, so that although numerous applications of the brakes
may take place, the pressure in the accumulator will not be sensibly diminished.
Dated this 18th day of July 1891.
ABEL & IMKAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Brake Apparatus for Railways.
I, CHARLES LUYERS, of No. 23 Neuveau Marché aux Grains, Brussels, Belgium,
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 :-
It is well understood that the theoretical requirements of a perfect brake
apparatus are, that it should effect the stopping of the train without jerks and in
the shortest possible time after the application thereof. It is also known that for
accomplishing this it is requisite that the brake should exercise, during the entire
duration of the stopping action, its maximum retarding force simultaneously and
uniformly on every brake carriage of the train. Now in order to cause a brake
to exercise on each pair of wheels its maximum retarding force it is necessary to
regulate the pressure of the brake blocks according to the speed and other possible
circumstances, so that the friction between the brake blocks and the wheels shall
not exceed that between the wheels and the rails, but shall always be just short of
that amount.
For realizing these conditions it is therefore necessary to be able to cause the brake
blocks to act with a constant pressure almost equal to that which would skid the
wheels, producing a constant coefficient of friction so as to keep the wheels during
the whole time of the application of the brakes, in a state near that of skidding, in
order that the brake may at every moment exert the maximum of retarding force.
As is known, the coefficient of friction of the brake blocks on the wheels is not
constant, but diminishes, on the one hand, in proportion to the duration of applica-
tion; in consequence of the heating of the metal &c., while, on the other hand, it
increases as the speed of rotation diminishes, in particular during the period
immediately preceding the stoppage.
It would therefore be of the greatest importance to diminish as rapidly as
possible the speed of rotation from the moment when the brake blocks are applied,
so as to approach as quickly as possible to the period immediately preceding the
stoppage, and thus utilise the increase of the coefficient of friction in order to
compensate for the diminutions resulting from the duration of the application, and
thus operate during the whole time of stopping with a constant coefficient of friction
which will produce the maximum action preceding skidding. For this purpose it is
also necessary that the brake blocks shall be applied and act with the greatest
precision and regularity, for maintaining this maximum action until the train is
stopped, which will take place in a much shorter time than when the wheels are
skidded and slide on the rails.
These results are obtained in a manner which in practice approximates very
closely to the theoretical value, as regards the most essential part, that is to say,
the braking device of my improved brake apparatus, which I will proceed to
describe with reference to the drawings accompanying my Provisional Specification,
in which
Fig. 1 is a side elevation of the braking device,
Fig. 2 a cross section of the brake cylinder with the distributing valve and
auxiliary reservoir,
Fig. 3 a vertical section of the discharge valve, and
Fig. 4 a cross section of the air pressure accumulator, with its compressor in
longitudinal section and the other part in elevation.

page_text: Figs. 1ª, 13 and 1° of the accompanying drawings shew respectively an elevation,
plan and part side view of a modified arrangement of the brake block and parts
connected therewith.
Although the improved brake apparatus can be used in combination with all
known kinds of brakes, I have shewn the same by preference in combination with
the apparatus of an automatic fluid pressure brake of peculiar construction.
Referring to Fig. 1, it will be seen that the braking device consists of a disc or
drun M of a diameter much smaller than that of the wheels and which is fixed on
the axle, and is situated between two brake shoes or blocks S which embrace its
periphery to an extent proportionately much greater than in the case of the
ordinary brake blocks on the periphery of the wheels. The shoes are pivotted at
their lower ends to one and the same point of a suitable part of the framing, and
their upper parts terminate in lever arms which are moved in contrary directions
by the looped rod T of the brake cylinder C. The shoes S are provided with lining
cheeks of cast steel, which are removeable and interchangeable after wear.
shoes with their checks can always be held at a distance from the friction disc or
drum M by the adjustment of the nut on the piston rod of the cylinder C.
8
The
In the modification shown in Figs. 1^, 1 and 1° the rod 1 is pivotted to the rod 2
and to the sway beam 3, which has its fulcrum on a pivot on the end of the bar 4
which at its middle has a screwed adjustment 5 by means of which the brake
blocks n n' can be brought nearer to the friction disc or drum d when they wear
away. The friction disc d has a diameter about equal to th that of the running
wheels D of the vehicle and such a width that the work produced by the ion
shall produce on each unit of contact surfaces a quantity of calories such that the
diminution of the coefficient of friction due thereto shall be compensated for by
the increase of friction resulting from the slower speed due to the proportions
between the diameters as before explained. This friction disc or drum d is con-
structed of two semi discs secured together round the axle E by means of screw
bolts. Round the friction disc is arranged a system of rods and beams 6, 8, 15
pivotted together at 7, 11, 13, 16 and to the fixed pivot at 17. This pivot 17 is
maintained fixed and independent of the movements of the framing by connecting
it to links 18 which are pivotted at their upper ends to the trough shaped cross
beam 19 rigidly fixed to the upper faces of the axle boxes of E. The said beam 19
is steadied laterally by side cheeks not shown fixed to the under-framing, and
passing down in contact with either side of 19, while having freedom to move
independently thereof in following the oscillations of the under frame upon the
springs. The pivot 17 is also stayed laterally by means of two horizontal rods 20
pivotted at 21 to the bracket 22, 23 fixed to the under framing.
It will be readily seen that the friction disc being of a diameter less than the
wheel its peripheral speed will decrease much faster than that of the wheels, and
the period preceding the skidding action will consequently begin much quicker for
the disc than for the wheels, relatively to the rails. In order therefore to keep the
friction disc at an action approaching the skidding, it suffices to exert on the shoes
a pressure sufficient for producing a braking action approximately equal to the force
of adhesion of the wheel and proportional to the speed, and to maintain this
pressure until the final stoppage is effected, which will take place in a space of
time which will be all the shorter, the smaller is the diameter of the disc, because
the peripheral speed hereof diminishes more rapidly and thus leads quicker to the
period preceding skidding. The pressure of the shoes must however be increased
in proportion to the decrease of the diameter of the disc.
In the determination of the braking action on the disc, which should approximate
to the force of adhesion of the wheels on the rails the force to be applied to the
shoes will then be proportionate to the diameter of the disc that is to say, the
product of these two factors must always be equal to the force of adhesion.
Whatever, therefore, may be the diameter of the disc, the coefficient of friction,
which diminishes on the one hand in consequence of the heating and increases on the
other hand in consequence of the diminution of speed, will remain constant during

page_text: the entire application of the shocs, which thus maintain the disc in a condition
near the skidding during the whole period of stopping. I have found in practice
that in assuming the diameter of the wheels to be one meter, the best proportion
for the disc is about one fourth the diameter of the wheels.
It will be readily seen that by means of this arrangement a much more precise
action of the brake device is obtained, not only on account of the reduction of the
dimensions, but also in consequence of the application of the shoes upon a more
uniform surface which, as it does not run on the rails, is much less liable to become
unround than the wheels, and thus avoids the severe shocks and jerks when applying
the brakes, as the disc is prevented from biting at one part of the revolution and
running loose at another part, as is the case with the wheels.
As the coefficient of friction must be dependent upon the degree of adhesion on
the rails of each vehicle, the pressure exercised on the shoes must not only be
proportionate to the speed, but also to the variable weight with which they are
loaded, which determines the degree of adhesion of each carriage; the pressure
exercised on the shoes must therefore not only be proportionate to the speed, but
also to the variable load of the vehicle. For fluid pressure brakes, the degree of
elasticity of the air acting in the brake cylinders should therefore be proportionate
to this weight, and in order to establish this proportion at every moment and for
each vehicle in a perfectly automatic manner, I employ the system of distribution
shewn diagrammatically at Fig. 2, the essential feature of which consists in the
combination of an auxiliary reservoir H with an admission valve, and a regulating
valve. The admission valve has for its object to allow the entrance of air pressure
into the brake cylinder C at the desired moment, on a decrease of pressure being
effected in the train pipe X and the regulating valve has the object of proportioning
the degree of elasticity of the air to the load of the vehicle.
For this purpose, it consists of two cylinders communicating with each other and
containing two pistons G formed of one piece, the one of large diameter being
in the lower cylinder, while the one of small diameter is in the upper cylinder.
The small cylinder is provided with diametrically opposite longitudinal grooves
passing along part of its length to a sufficient extent for establishing a communi-
cation between the large and the small cylinder. Into this grooved part opens, on
the one hand, the pipe t' branched on the train pipe X, and on the other hand the
pipe t³ communicating at one end with the auxiliary reservoir H and at the other end
with the admission valve. Below the large piston G in the lower cylinder is placed
a spring R which bears with its lower end upon a disc on the other end of a stem T¹
sliding through the cylinder, and to which are jointed one or more levers that are
subject to the action of the load of the vehicle.
The complete regulating valve is fixed at the upper end to the brake cylinder C,
and it is held at the lower end by suitable stays. The upward motion of the
spring R is limited by the upper end of the small piston which butts against the
upper end of the valve casing.
Under the above conditions it will be seen that when the carriage is empty, the
spring R is subject to the minimum pressure as no pressure beyond that due to
the weight of the empty vehicle is transmitted by the before mentioned levers to
the stem T. If then the air pressure coming from the train pipe X and passing
through into the valve apparatus produces a pressure above the piston G and in
the auxiliary reservoir H a pressure corresponding to the weight of the empty
vehicle, or, in other words, to the force of the spring R corresponding to that
weight, this spring will be compressed by the downward motion of the two pistons,
the upper one of which by such motion will close, by its ungrooved part, the
admission of air through t', so that the pressure in the auxiliary reservoir will not
exceed the degree corresponding to the dead weight of the carriage.
Assuming now that the vehicle carries a certain load. In this case the levers
acting on Twill lift the latter, thereby compressing and increasing the force of
the spring R to a proportionate extent so that the air pressure admitted through t¹
will now require to be much greater for closing the admission of air pressure into H

page_text: arranged on the engine, by which a communication can be established between
the boiler and the space a so as to actuate the pistons in the first place by steam
pressure.
The action of the above described brake apparatus is as follows.
Assuming the pressure in the accumulator A to be at the maximum, and that the
train required to be stopped when running at 80 kilometres an hour, for example,
the driver effects a reduction of pressure corresponding to the speed in the train
pipe X by opening the valve S' to the requisite degree by the rack C'; the same
reduction then occurs in the spaces V of the admission valves of the brake
cylinders which then receive air pressure from the auxiliary reservoirs H at a
pressure proportional to the load of the vehicle, and consequently proportional to
the adhesion between the rails and wheels. The brake shoes then brake the
friction disc M under the conditions which bring it quickly into a state bordering
on skidding, in order to stop the train without shocks in a minimum duration of
time. In order to replace in the accumulator the amount of compressed air
expended, the driver puts it in communication with the space a in order to bring
the compressor into action, which stops at the end of a few revolutions, the
quantity of air necessary for refilling the auxiliary reservoirs and for producing
the maximum pressure in the accumulator being very small. The driver then
closes the cock and the brake is ready to be again applied.
During the journey the brake can also be used repeatedly without recharging the
reservoir A, the quantity of air expelled being only a few litres for each application
of the brakes, so that although numerous applications of the brakes may take place,
the pressure in the accumulator will not be sensibly diminished.
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 :-
1. In railway brake apparatus constructing the braking device in the form of a
friction disc or drum of a diameter less than that of the wheels for the purpose of
accelerating the diminution of the speed of rotation with reference to the speed of
travel, and of utilising the increase of the co-efficient of friction obtained by such
retardation for compensating for the diminution of the co-efficient of friction
resulting from heating &c. of the parts of the braking device, and of producing
thus a constant co-efficient of friction which, with a constant pressure approxi-
mately equal to the force of adhesion, will exert on the axles an action always near
the skidding, without ever reaching this, and thus reducing to a minimum the time
required for stopping the train substantially as described.
2. The distributing valve for the brake cylinders consisting essentially of the
combination with the auxiliary reservoir H of a valve for regulating the pressure
proportional to the load on the vehicle, and an admission valve of special con-
struction, the regulating valve being characterized by a double piston G* controlled
by a spring R subject to the load of the vehicle and allowing the auxiliary
reservoir only to be charged with a pressure proportional to the load, while the
admission valve consists of two pistons L and K fitting one within the other and
having between them a spring Rª which keeps L closed while it presses K down-
wards when a decrease of pressure occurs in the train pipe X and consequently in
the space V for allowing the compressed air of the reservoir H to pass through tº d¹
and t to above L, which is thereby depressed and thus gives access to the cylinder
hrough to substantially as described with reference to the drawings.
4. The combination with the accumulator A, of the compressor with two
pistons P P which are always maintained at the end of their instroke by a
spring R' but are moved forward by means of the air pressure in the accumu-
lator A, which is put in communication with the space a either by the cock F or,
when first starting the space a is supplied with steam through the cock F, the
compression of the air being effected by the piston P' forced backward by the
eccentric E on the wheel axle, until the maximum pressure is attained in

page_text: the accumulator, such pressure being then made to act on the piston P³ of the
pressure regulator so as to compress the spring R³ sufficiently for putting the
space a in communication with the atmosphere through the passage l, and pipe to t³,
so as to allow the pistons to be held back by the spring again, substantially as
described with reference to the drawings.
5. The improved construction of brake apparatus combined and operating as
herein described with reference to the drawings.
Dated this 19th day of Anril 1892.
ABEL & IMRAY,
Agents for the Applicant.

page_text: by descent of the piston valve and consequently the pressure in the auxiliary
reservoir will be correspondingly greater and proportionate to the load of the
carriage. The admission valve is composed of the outer cylinder e in which are
the pistons L and K fitting the one into the other, so as to leave an annular space
between them in which is a helical spring Ra bearing respectively against the
bottom of K and the head of L, which it thus keeps in position. The bottom of
the piston K is situated a certain distance from the bottom of the cylinder e thus
leaving a space V. When the valve does not act, as in the drawing, the brake
cylinder C communicates by the tubular passage t³ with a groove d of the piston K
which opens into the open air; the latter is also made to pass to the joint between L
and K through a passage t, in order to prevent the adhesion of the two owing to
want of air between them. A space above the piston L communicates with a
grooved by the pipe t', and the pipe to which admits air into the cylinder C, opens
against the conical part of the piston L, which keeps that communication closed
when the valve is out of action. The pipe coming from the auxiliary reservoir H
opens against the side surface of the piston K. The action of this apparatus will
be as follows: Assuming that air is admitted to the auxiliary reservoir to a pressure
determined by the pressure of the spring R regulated by the load of the vehicle
and that the piston G having cut off the entrance of the air is maintained in that
position by the maximum pressure in the train pipe, which pressure also exists in
the space V, and thus keeps the admission valve of the brake cylinder closed; then
if air pressure be now discharged from the train pipe to an extent corresponding to
the brake pressure to be exerted proportioned to the speed of the train, this will
cause the pressure in V to be decreased, whereupon the piston K will descend until
the pipe communicates with the groove d' so that air pressure will now pass from
the reservoir H through to over the top of L, which will descend and allow the air
pressure to pass through into the cylinder C, the pistons of which are then
made to act on the brake shoes with a pressure proportionate to the load and to
the speed.
During this passage of air pressure from H to C, a check valve c¹ placed in the
communication prevents the air from the reservoir H from returning through the
regulating valve and t. As soon as the pressure is re-established in the train pipe
the parts resume their original positions, and the pistons of C being drawn back by
their springs, will cause the air pressure to pass out through td. The pressure
exerted by the spring R* should always be sufficient to depress the piston K to
such an extent as to cause the pipe t' to communicate with the groove d'; it must
therefore be greater than the pressure remaining in V after the decrease of pressure
in the train pipe.
For the purpose of insuring that the reduction of pressure in the train pipe X
shall always be proportionate to the speed of the train, I interpose in the said pipe
a regulator or reducing valve of the construction shown at Fig. 3, which determines
automatically the decrease in X when the driver has turned the pointer of the
valve into the position corresponding to the speed of the train. The valve
apparatus consists of a cylinder C¹ the bottom of which forms the seat of the
valve S' placed over the opening of the train pipe X. The valve has a hollow
stem Tinto which passes the solid stem Ts to which is attached below the collar r
the piston P working in the cylinder C¹. Between the piston P and the valve S'
is a helical spring R coiled round T2 and T and which holds the valve down on
its seat so long as the pressure of the spring is greater than the air pressure in X.
The pressure of the spring is regulated by the compression thereof by means of a
toothed rack formed on the stem Ts, and which can be raised or lowered by the
pinion p fixed on the spindle of the hand wheel v, actuated by the driver. Parallel
to the rack is arranged a graduated scale over which travels a pointer fixed to
the rack, and the divisions of which correspond to different speeds of the train.
When the pointer descends to zero on the scale, the spring R' compressed
between the piston and the valve S' exercises its maximum pressure, which then
balances the maximum pressure of the train pipe, and consequently prevents any
13

page_text: air from escaping therefrom. But when the rack is raised so as to cause the
pointer to point say, to a speed of 50 kilometres per hour, the pressure of the
spring R will be correspondingly diminished and will allow the valve S' to be
forced open by the excess of pressure in the train pipe, thus allowing such pressure
to escape until the equilibrium of pressure due to the above speed is attained
whereupon the valve will be closed again.
It will be evident that at higher speeds the pressure of the spring will have to be
correspondingly further diminished while if it is less, the pressure will have to be
increased, by the corresponding movement of the rack, allowing in the one case, a
further escape of pressure from the train pipe to take place and in the other case
allowing the pressure to accumulate again to a corresponding extent.
The reducing valve is placed on the engine and is interposed in the train pipe
which passes on the one hand to the brake cylinders and on the other hand to the
accumulator A fixed below the tender. The accumulator is a cylinder of sheet
iron of sufficient thickness in which is arranged horizontally the compressor,
actuated directly by an axle of the vehicle. The compressor consists of two
cylinders of different diameters containing pistons P' and P' fixed on the same
stem and receiving simultaneous to and fro motion by means of a link M¹ jointed
on the one hand to a rod of the piston and on the other hand to a lever L
suspended from the framing of the tender and actuated by an eccentric E¹ fixed on
the axle. This eccentric has an external ring which is in contact with the lever L
when the apparatus is in action; by this means the periphery of the eccentric disc
itself remains perfectly circular, which would not be the case if it acted directly
on the lever as a cam always touching at the same place. In the front cylinder
which is of smaller diameter is situated a spring R₁ confined between the cover
and the piston P¹ and which always tends to bring the pistons towards the ends of
the cylinders when the compressor is out of action.
The two cylinders communicate with each other by means of the pipe t' which
communicates with the outer air by a branch t³ opening into a permeable casing
which filters the air that passes into the cylinders.
The piston P of the large cylinder contains two valves which allow the air to
pass through when the piston moves forward and this on the return stroke, forces
that air through the large valve in the cylinder bottom into the accumulator A.
In the latter is arranged a pressure regulator consisting of a cylinder C containing
a piston P which is always pushed towards the interior of the accumulator by a
spring R while the accumulated air pressure tends to force it in the contrary
direction.
The cylinder C³ communicates on the one hand with the pipe to and on the other
hand with the pipe to, which passes to a two way cock F Fig. 3 on the engine
actuated by the driver. This piston P³ has a passage which establishes a com-
munication between the pipes to and t when the pressure in the accumulator arrives
at the maximum.
It has been stated above that the pistons P1 P2 of the compressor are held at
the end of their strokes by the spring R³ when the compressor is out of action.
When it is in action, the eccentric E forces the pistons backward and they are
forced forward again at the end of each stroke by the compressed air of the
accumulator introduced by the cock F which is turned so as to cause the pipe to to
communicate with the space of the cylinder so that the space is filled with the air
pressure of the accumulator which forces the pistons forward again till the pipe t
communicates with pipe 8 and the outer air through the passage 1, thus allowing
the pressure in a to sink below that of the spring R, which keeps the pistons
at the end of their stroke so that the eccentric E¹ then revolves without acting on
the lever Land is consequently not subject to any wear. This condition continues
as long as the cock F keeps t' closed and a out of communication with the
accumulator.
In order that the mechanism may be made to work also when the accumulator
is not charged with air pressure, a second cock F¹ worked by the driver is