Improvements in Air-brakes.
Year: 1891

page_text: Date of Application, 29th July, 1891-Accepted, 10th Oct., 1891
COMPLETE SPECIFICATION.
Improvements in Air-brakes.
I, KONRAD TROBACH, of 20 Berlinerstrasse, Pankow near Berlin, Engineer, in
the Kingdom of Prussia, German Empire, 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 improvements in air-brakes of the two-chamber principle;
and the objects of my improvements are; first to employ the brake for reducing
the speed of the train while passing slopes, bridges, and the like without stopping
the same; secondly, when it is required to completely stop the train, to start the
brake with small pressure previous to applying full power; and thirdly to avoid
the great waste of high-pressure air met with in the air-brakes commonly in use.
1 attain these objects by providing a secondary cylinder behind the main-brake-
cylinder, the pistons of both cylinders having one common piston rod. A small
distribution-pipe runs alongside the main-train pipe and serves for opening a valve
by which air is let into the secondary cylinder at the will of the operator and also
serves for operating upon a second valve, which cuts off the high-pressure-air
feeding the chamber in front of the main-piston and at the same time allows the air
contained in this same chamber to expend itself into the open air.
When actuating the brake, which may be done from any part of the train, the
piston of the secondary cylinder will come first into action and quickly after this
also the main-piston is driven by the pressure-air, which may be said to merely
increase the force applied to the brake.
By this arrangement the consumption of air will be only about one third of the
amount consumed by the Carpenter-brake, because the train-pipe need not be opened
at all, and the distance the piston will move on, until the one side pressure comes
into action, is extremely small. The main-train-pipe is continuously charged with
high-pressure air, as is also the case in the Carpenter-brake, while the small distri-
bution-pipe running alongside of the same remains inactive, and is only charged
with pressure-air the moment the brake is to be set at work.
Experiments have proved that a 3″ piping 500 meter long may be charged with
air of 1, to 15 atmospheres in less than three seconds, and being opened when
charged with air of such a pressure, said air will escape in less than five seconds.
These experiments have also led to the conviction, that valves may be actuated
with great ease by the aid of the above mentioned long pipes.
This is the reason why I make use of the distribution pipe, by which all the
brake-cylinders may be set to work almost simultaneously and which in itself
cannot be the cause of any waste, since it is commonly not charged with air as is
the case with the main-train pipe. Neither does the application of this secondary
pipe cause any trouble, since the fastening or coupling of the same may be done by
the same grasp, which is necessary to couple the main-train-pipe, without requiring
greater skill or attention from the operator.
The above mentioned distribution pipe is connected to the high-pressure air
reservoir on the engine by a pressure-reducing valve which, when opened half way,
may feed this pipe with air up to 1 atmosphere. Immediately this is done the
brake will be started with a slight pressure by the aforesaid secondary piston.
Thereby the main-piston also moves on without performing any work, but merely
balancing the pressure of air in front and behind the piston by way of the train-
pipe, all ports leading thereto still being open. If it is required to make the brake
act with full pressure, the reducing valve can be opened to its full extent, whereby
the air in the distribution-pipe will gain a pressure of 15 atmospheres; this shuts
off the chamber in front of the main piston from the main train-pipe and opens an

page_text: exhaust port to allow the air enclosed in said chamber to pass out. Thus by the
one sided pressure on the main-piston the brake acts with full force. In case of
danger this increased effect may also be instantly arrived at by at once opening the
reducing-valve to its full extent. Morcover such sudden start of the brake may
also be effected from the inside of any carriage, by merely turning a handle, which
opens one of the cocks inserted between the main-train pipe and the distribution-
pipe and thus fill the latter with high-pressure air. Of such cocks there is one
under each passenger or brake-car. No matter in what manner the brake is set to
work, previous to working with full power, the brake will, at least for a short time,
merely be influenced by the smaller secondary piston, which at the same time causes
the main-piston to move on so as to consume only a small amount of air and yet
give a powerful effect when at work.
In order to make my invention more clear I refer to the accompanying
drawing, which illustrates a sectional view of the complete arrangement.
A is
the train-pipe, which is charged with high-pressure air from the engine in the
usual manner.
By way of the outlet-pipe L and the ports Ho and H
the pressure air enters the brake-cylinder behind the piston, that is to say the
chamber a, has to pass the forcing valve S, which only permits the passage of
air in this direction, and closes itself, when the pressure in B exceeds that of
the air in A, or when by chance the train-pipe A breaks and the air contained
therein escapes. The consequence of opening the train-pipe would be this: The
air contained in the chamber escapes, while the valve S closes itself and
prevents the air, in the chamber a, leaking therefrom. Thus the piston will be
driven to the front and will act on the brake-blocks in the same manner as in
the Carpenter brake.
A second smaller pipe E, which is herein called the distribution-pipe, runs along-
side of the train-pipe, and is connected to the pressure-air reservoir on the engine
by a reducing-valve. A branch-pipe L' connects the pipe E with the valve-box G
and the valve V. The valve V is screwed on to the brake cylinder and is furnished
with a double piston Rr, being integral with the piston-rod Q, which extends as far
as about of an inch away from the valve-seat v. The inside of the valve-casing
of V communicates with the outer atmospheric air by openings J and i.
When it is required to work the brake so as to merely reduce the speed of the
train, the distribution pipe E will be charged with air of atmosphere. This air
enters the valve V and causes the pistons Rr to approach the valve X.
As soon as the piston-rod Q knocks against the valve X the openings i will be
covered by the piston rod Q; the valve X will then open, overcoming the pressure
thereon from the inside of the chamber a. High-pressure air then enters the pipe
which conducts it behind the piston K' of the secondary cylinder C. The piston K'
as well as the main-piston K is firmly attached to the piston-rod D.
By the
pressure bearing against the back of the piston K', the brake will just be powerful
enough to reduce the speed of the train, without bringing the same to a stand-still.
The main-piston K has performed no work, but has merely distributed the pressure-
air inside of the brake-cylinder in such a manner, that the air in the chamber b
being in excess is forced into the chamber a by way of H', o, H, A. and S.
When it is required to release the brake again it is only necessary to open the
pipe E.
The pressure inside the pipe a will drive the piston r back into its former
position, thus opening the ports i. The pressure inside the brake-cylinder then
closes the valve X and the pressure behind the piston K' being withdrawn, the
spiral springs will now bring said piston back into its former position. If how-
ever, instead of releasing the brake, it is required to utilise the power of the same
to its full extent, it is only necessary to completely open the reducing-valve on the
engine and thereby increase the pressure in the distribution-pipe up to 1.5 atmo-
spheres. Of course the valve X will thereby be held open the more firmly, but
the piston inside the casing G will be driven by the air pressure entering the
chamber f. The piston is connected to the smaller piston U by the plunger P,
which slides in a stuffing-box M filled with metal- and leather-rings. While thus

page_text: in motion the plunger P closes the ports between H and H¹ and thereby shuts off
the pressure-air from the chamber b. When the piston k arrives at the end of its
stroke, the openings O coincide with the port H and the air contained in the
chamber may escape by way of the port H₁ and the hollow pipe P¹. Now the
pressure upon the piston K in addition to that upon the piston K¹ amounts
to 3500 kilograms, which is fully transmitted to the brake-blocks by the rod z.
As soon as the operator partially closes the reducing valve, so as to reduce the
pressure inside the distribution-pipe to below 15 atmospheres the piston U will
overcome the force of the piston k, and bring the openings O into their former
position. In this way the operator may with great ease handle the brake and thus
have full power over the train.
In order to enable any passenger to make use of the brake in case of danger,
there is a cock arranged under each passenger-car connecting the distribution-
pipe E with the train-pipe A. Usually this cock will be closed, but by aid of
suitable levers the same may be opened from every compartment of the carriage.
When the cock is opened the distribution-pipe is filled with high-pressure air,
which quickly sets the valves to operate in such a manner, that the brake will
work with full force.
Finally the valve casings G and v are provided with small air-holes, J which
permit the air in front of the pistons k and R to escape and atmospheric air to
enter behind the piston U, or vice-versa, in order not to impede the motion of the
same.
The advantages of my new brake as compared to brakes of the older types are
as follows:
1. The ability to apply the brake with promptness, and with very little waste of
air, on any kind of train.
2. The ability to quickly reduce the speed when passing slopes, bridges etc..
without making use of the main piston.
3. The highly increased braking power by a very small consumption of air.
4. There need be no compensation-notch nor a loosely arranged piston in the
place of such notch. In my brake the air under pressure circulates in front of and
behind the piston at the same time, so that the piston cannot be easily worn
away.
In
5. In all air-brakes hitherto in use the pressure applied is reduced, when the
piston arrives at the end of the stroke, when the pressure should be greatest.
my air-brake the pressure will be of equal strength during the whole length of the
stroke, because air under pressure may enter the cylinder as the piston moves on,
and so said pressure will take effect with full power, when the pistons are at the
end of their stroke.
Any existing Carpenter brake may without difficulty be changed into a brake
according to my system, because all the necessary parts can be, attached to the
same.
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 an air-brake the combination of the train-pipe A and the main-brake
cylinder B with the secondary cylinder C, the pistons of both being connected by
the common piston rod D and the distribution-pipe E for distributing the air under
pressure inside of the cylinders as described.
2. In an air-brake the combination with the main-brake-cylinder A, of the
secondary cylinder C, the piston K', for applying the brake with minor force and
combined with the main piston K by a common piston-rod D, a pipe & connecting
the chamber behind the two pistons K and K', a distribution pipe E, running
alongside of the main-train pipe A and serving for actuating the valve X by aid of
the double piston R 1, the piston-rod of which extends so far as to be able to open

page_text: the valve X when the piston 7 moves on and closes the opening i as and for the
purpose set forth.
3. In an air-brake the combination of the main-brake-cylinder B and the main-
train-pipe A with a secondary cylinder C, the piston of which and the main-piston
having a common piston-rod D, a distribution pipe E running alongside of the
main-train pipe A serving for actuating the valve v and the piston k inside the
valve-casing G, the piston k being combined with the piston U by the plunger P,
which is provided with ports o and openings O, the first being adapted to allow the
access of air under pressure from the train-pipe A into the main-brake cylinder in
front of the piston and also to allow the air to escape from 6 to the chambers a by
way of the port H' and H, A and S the latter to allow the air contained in the
same chamber to escape into the open air as for the purpose set forth.
4. In an air-brake the main-brake-cylinder B communicating with the train-
pipe A by a forcing-valve S arranged so as to permit the access of air under
pressure into the brake-cylinder behind the piston and by the passages H, o and H¹
arranged so as to permit the access of air under pressure into the brake-cylinder
in front of the piston, in combination with a secondary cylinder C, communicating
with the main cylinder by the pipe, the admission of air into this pipe being
governed by the valve r, actuated by the double-piston R and the piston-rod Q,
the distribution pipe E serving for the admittance of pressure-air into the valve-
box V for operating upon said double pistou Ras and for the purpose herein set
forth.
Dated this 29th day of July 1891.
FREDK. WALKER,
11, Furnival Street, London, E.C., Agent for the Applicant.