Improvements in Fluid Pressure Automatic Brake Mechanism.
Year: 1887

page_text: Improvements in Fluid Pressure Automatic Brake Mechanism.
I, GEORGE WESTINGHOUSE Jr. of Pittsburg in the County of Allegheny, State
of Pennsylvania, and United States of America, 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 statoment :-
In brake mechanism for railway trains arranged on what is known as the
Westinghouse automatic system, compressed air is transmitted from a Main reservoir
on the locomotive by a train pipe coupled from carriage to carriage to apparatus on
each brake vehicle. This apparatus consists of three parts, a brake cylinder in which the
air acts on a piston causing it to move rods and levers connected to the brake blocks,
an auxiliary reservoir which retains a local store of compressed air and a valve
arrangement known as the triple valve, by which are controlled the communications
between the train pipe the auxiliary reservoir and the brake cylinder so as to operate in
the following way. When the train pipe is charged with compressed air from the main
reservoir, the triple valve is in such a condition that the brake cylinder is open to the
atmosphere and therefore there is no action on its piston to put on the brakes, also tho
train pipe is in commuication with the auxiliary reservoir charging it with a store of
compressed air ready for use. When the brakes are to be put on, a valve or cock on
the train pipe is moved opening an escape by which the pressure in the train pipe is
more or less reduced. Immediately, owing to the change of pressure in the train pipe,
the condition of the triple valve is altered so as to close the communication from the
train pipe to the auxiliary reservoir, to close the discharge from the brake cylinder to
the atmosphere, and to open the communication from the auxiliary reservoir to the
cylinder whereupon the pressure acts on the brake piston so as to cause the brakes to be
put on. As the brakes are thus put on in consequence of reduction of pressure in the
train pipe, obviously the fracture of that pipe or its uncoupling by separation of the
train; or a serious leakage from it will have the effect of putting on the brakes_
automatically. By regulating the escape from the train pipe, the alteration of pressure
in it can be made greater or less so as to put on the brakes more or less suddenly and
forcibly as circumstances may require. For taking off the brakes, the pressure in the
train pipe is restored and this alters the condition of the triple valve so as again to

page_text: open communication from the train pipe to the auxiliary reservoir, to cut off the
auxiliary reservoir from the brake cylinder and to open discharge from the brake
cylinder, so that the brake piston is no longer pressed upon and the brakes are released.
In a similar way a triple valve with suitable invertions of its parts, is made to operate
when the brakes are worked by vacuum, the air in this case being exhausted from the
train pipe and from the auxiliary reservoir or local vacuum vessel when the brakes are
off, and the brakes being put on by admitting air to the train pipe so as to increase
the pressure therein. Such being generally the nature of the system and apparatus
of the Westinghouse automatic brake, my present invention relates to a modification
of and addition to the triple valve whereby the application of the brake is rendered
more rapid and effective, more particularly in trains of considerable length. Also,
when the brakes are worked by compressed air, the expenditure of compressed air is
economised by utilising part of the volume discharged from the train pipe for acting
in the brake cylinder, and when the brakes are worked by vacuum, a similar economy
is obtained by utilising part of the volume withdrawn from each brake cylinder to raise
pressure in the train pipe.
I will describe these improvements referring to the accompanying drawings.
Fig. 1 is a plan looking from below showing the general arrangement of the brake
apparatus on one brake carriage. The other figures, Figs. 2, 3, 4, 5 and 6 which are
drawn to an enlarged scale show the construction and arrangement of the triple valve
as modified and provided with additional devices according to my present invention,
that is to say,
Fig. 2 is a longitudinal Section on the line a. a. of Fig. 4.--Fig. 3 is a transverse
section on the line of Fig. 2, Fig. 4 is an elevation of the face of the drain cup
forming the cover of the triple valve; Fig. 5 is a longitudinal section at . Fig. 3
shewing the triple valve partly in elevation:-Fig. 6 is a part end view of the triple
valve, and Fig. 7, which is drawn to a smaller scale than Figs. 2 to 6 inclusive, is a
longitudinal section of the brake cylinder and auxiliary reservoir with elevation of the
triple valve attached to the end of the reservoir.
As shown in Fig. 1, the underframing 1 of carriage of the train is provided with
an air pipe 2, having stop cocks 3 near each end of it and having flexible connections
and couplings 4 and 5 by which it is connected to the corresponding pipes of the
carriages before and behind it. On some convenient part of the underframing
of each brake carriage are fixed the auxiliary reservoir 6 and the brake cylinder 7
which are connected together and to the train pipe 2 by passages governed by the
triple valve 10. In the brake cylinder 7, as shewn in Fig. 7, is fitted a piston 8 which
is pressed back by a spring and which is connected by a set of levers and rods,
constituting the brake rigging to the brake blocks 9. When the piston 8 is pressed
forward by compressed air admitted to the cylinder behind it, the brake blocks 9 are
pushed against the wheels with more or less force according as there is greater or less
pressure of air acting on the piston. When the air is discharged from the brake
cylinder 7, the spring pushes back the piston 8, and the brakes are taken off.
The triple valve box 10 is attached to the end of the auxiliary reservoir 6 with
which the space 23 of the valve box directly communicates. There is also a
communication 10 from the valve box by a pipe 41 to the brake cylinder 7, a communi-
cation 17 from the valve box to the train pipe 2 and a communication from a space 38
in the valve box, by passagess 39 and 40 and the pipe 41 passing through the auxiliary
reservoir to the brake cylinder 7. Usually a four-way cock 21 is employed to alter
the communications 16 and 17 with passage 22 and 18 in such a way that the brake
piston can be worked non-automatically by turning the cock so as to put 17 from the
train pipe in direct communication with 16 to the brake cylinder, or that the
communication with the brake cylinder can be entirely cut off. For automatic
working the cock 21 is in the condition shewn in Fig. 2, putting 16 in communication
with a port 22, and 17 in communication with the interior of the drain cup 19. and
thence by holes 20, with the cylindrical space 11 which is fitted with a piston 12. This
piston 12, when it is in the position shewn in Fig. 2, uncovers grooves 43 and 44
forming a small passage between the space 11 and 23 and thus putting the train pipe 2

page_text: in communication with the auxiliary reservoir 6, maintaining equality of pressure in
the pipe and the reservoir except when a rapid change of pressure takes place in the
pipe. Between two enlarged parts or collars 24 and 25 on the stem 13 of the
piston 12 is placed a slide valve 14 pressed by a spring against a facing which has
through it the port 22 and another port 31 communicating with a discharge opening
15 to the outer air. In the body of the slide valve 14 there is formed a passage 28
and a side passage 29 with the valve 26 interposed between them. The stem of the
valve 26 is loosely connected by a pin to the stem 13, and its head 27 projects a little
beyond the end of the slide valve 14 which has certain freedom of movement between
the collars 24 and 25. Near the end of the slido valve 14 there is a passage 32. So
far the construction is substantially the same as that of the triple valves now in use for
Westinghouse automatic brake apparatus. These valves and their operation has
been described in the Specifications of previous Patents but in order that the farther
operations effected by the present improvements may be the more clearly understood,
I will explain the operation of the parts which I have already described as they usually
work. When the parts are in the condition shewn in Fig. 2, the brake Cylinder is,
by the passage 41 and 16 the port 22, the cavity of the slide valve 14, the port 31 and
the opening 15, in communication with the open air, and therefore the brake piston 8
is held back by the spring and the brakes are off. At the same time the trainpipe
being in communication, by the passages 17 and 18, the cavity 19, the holes 20, the
space 11 the grooves 43 and 44 and the cavity 23, with the auxiliary reservoir 6, the
pressure in the pipe and reservoir is the same or nearly so.
When the brakes are to
be applied with moderate force the pressure in the pipe is reduced by allowing a
portion of the compressed air to escape from it, the piston 12 is then pressed forwards
by the higher pressure existing in the auxiliary reservoir first passing beyond the
groove 43, then opening the valve 26 and moving the slide valve 14, until it cuts off
the port 31 from 22, and brings 28 into communication with 22. The compressed air
now passes from the auxiliary reservoir by 29, 28, 22, 16, and 41 to the brake
cylinder 7 causing the brake piston 8 to advance and the brakes to be put on.
When in this operation the pressure in the auxiliary reservoir is reduced by
expansion of its contents into the brake Cylinder until it is slightly below the pressure
in the trainpipe, the piston 12 moves back, closing the valve 206, and thus arresting the
further flow of air from the auxiliary reservoir to the brake cylinder so that the brakes.
are held with a force proportionate to the reduction of pressure in the train-pipe.
The brakes are taken off by restoring the pressure in the train pipe, and thereby
causing the piston 12 to move farther back. This by moving the slide valve 14,
puts 22 in communication with 31 so that the air escapes from the brake cylinder, and
the brake piston is pushed back by the spring taking off the brakes. Also the
piston 12 on returning to the end of its stroke again uncovers the groove 43 putting
the train pipe into communication with the auxiliary reservoir so that the pressure in
the latter is restored.
When it is desired to apply the brakes with full force, the pressure in the train pipe
is largely reduced. The piston 12 is thus caused to move so far forward that the slido
valve 14 opens free communication by the port 22, from the auxiliary reservoir to the
brake cylinder, thus allowing the compressed air in the reservoir to expand freely into
the brake cylinder and to act with the maximum available pressure on the brake
piston.
Such being the Action of the apparatus in the form in which it is commonly used,
I will now describe the improvements which form the subject of my present invention
and the mode in which these improvements serve to increase efficiency and economy in
the use of the apparatus.
In the drip cup 19 I provide a central boss bored to guide the collar of a stem 33
which is pressed by a spring 35. Between the collar of the stem 33 is fitted a slide
valve 36 with a spring pressing it against the facing in 34 in which there is a port 37.
From this port there is communication by the passages 39 and 40, past the stop
cock 21, and by the pipe 41 passing through the auxiliary reservoir C to the brake
cylinder.

page_text: In the passage 39 there is a spring check valve 12 preventing return of air from the
cylinder.
Between the stem of the piston 12 and the end of the stem 33 there is a free space
allowing the piston 12 to move without meeting 33, sufficiently to work the brakes
as described above, when there is a moderate reduction of the pressure in the train
pipe. If however it is desired to apply all the brakes of the train rapidly and with.
full force, the pressure in the train pipe is suddenly and considerably reduced, so much
so that the piston 12 is by the superior pressure in the auxiliary reservoir forced beyond
its usual stroke, so as to bear against and push the stem 33 in opposition to the
spring 35. By the movement thus given to the slide valve 36, the port 37, is
uncovered and air from the space 11 passes to the brake cylinder which is thus partly
supplied from the train pipe communicating with the space 11, and partly from the
auxiliary reservoir first by the passage 28, in the slide 14, and finally by the
passage 32, coming in communication with the port 22. This action has a twofold
effect. In the first place, as a portion of the compressed air is discharged from the
train pipe not only at the escape which is purposely opened at one end of the train,
but also by the port 42 at every triple valve throughout the whole length of the train,
the reduction of pressure throughout the pipe is rendered very rapid, and all the brakes
- are consequently put on practically simultaneously. And secondly, the volume of
compressed air which thus passes from the train pipe to each brake cylinder is utilised
in aiding the movement of the brake piston, instead of being wasted as it would be if
it escaped directly to the atmosphere. Thus there is effected a considerable economy
of the air under pressure, only a moderate escape being necessary to put on all the
brakes of the train simultaneously and with full force.
In case of an accidental escape from the train pipe, by the separation of the
train or by rupture of the pipe, the action described ensures great rapidity and
force in putting on the brakes and thus providing against subsequent damage.
Instead of having a free space between the stems 13 and 33 as shewn in Fig. 2, the
two stems might be rigidly connected together, the slide valve 36 being in that case
lengthened so as not to uncover the port 37 until the piston 12 makes its full stroke as
above described.
In cases where the brakes are worked by vacuum, that is to say the brake blocks are
kept off the wheels as long as the pressure in the train pipe and the auxiliary reservoir
is kept considerably below that of the atmosphere, but the brakes are put on when the
pressure in the train pipe is increased by admission of air to it, so as to exceed that in
the auxiliary reservoir, a similar arrangement of the triple valve with suitable inversions
of its parts is applicable as will be understood by reference to Fig. 8, in which all the
parts corresponding with those in Fig. 2 are marked by similar reference numerals.
Here the piston 12 in its position of rest, when the brakes are off, remains at the
farther end of the cylinder 11. When air is admitted to the train pipe so as to
increase the pressure therein above that in the auxiliary reservoir, the piston 12 moves
backward, first opening the valve 26 and allowing air to pass by the port 22 from the
brake cylinder to the auxiliary reservoir, and then, as it makes its full stroke, opening
the port 37 and allowing air to pass from the cylinder to the train pipe.
Although I have described the stem 33 which carries the slide valve 36 as being
moved by the piston 12 of the triple valve, it is obvious that it might be worked as
described by a separate piston in a cylindrical cavity communicating on the one side
of the piston with the auxiliary reservoir and on the other side with the train pipe.
As however the piston 12 is necessary to perform its ordinary function by working
the slide valve 14, it is more simple to utilize the movement of this same piston to
work also the slide 36 than it would be to introduce a separate piston for that purpose.
In many triple valves flexible diaphragms are employed in lieu of pistons such as 12
and simple shut off valves instead of slide valves such as 14 and 36.
Fig. is a vertical section of a valve arranged to operate in this manner for
automatic vacuum brake apparatus.
The passages 15, 16, 17 and 24 communicate respectively with the open air, the brake
cylinder, the train pipe and the vacuum vessel which serves as auxiliary reservoir.

page_text: While exhaustion is maintained in the brake pipe the flexible diaphragm 12 remains in
the position shewn, uncovering a small aperture 43 by which the train pipe through 17,
communicates with the reservoir through 23, so that the reduced pressure in both the
pipe and the reservoir is the same or nearly so. At the same time the valve 14 being
closed and 30 open, there is communication from the brake cylinder through 16 with
the open air through 15 and the brakes are off. For putting on the brakes, air is
admitted to the train pipe increasing the pressure therein, whereupon the diaphragm 12
moves first covering the aperture 43 and allowing the valve 30 to close and then
opening the valve 14 whereby the brake cylinder through 16 is put in communication
with the auxiliary reservoir by 23, and the excess of the atmospheric pressure on the
one side of the brake piston over that of the partial vacuum on its other side
causes the brake piston to move putting on the brakes. When, in this operation,
the pressure in the train pipe is rapidly and considerably increased, the diaphragm 12
moves to a greater extent opening not only the valve 14 but also the valve 36 thus for
a time, making communication from the brake cylinder through 16 past the Valve 36
and the check valve 42 to the train pipe through 17. By the passage of the volume of
air from the brake cylinder to the train pipe, effects are produced corresponding to
those resulting from the action on the slide valve 36 in Figs. 2 and 8, that is to say ;
in the first place, air enters the brake pipe not only at the end of the train where the
pipe is purposely opened, but also at every triple valve throughout the train, and
consequently the increase of pressure throughout the whole length of the pipe is
rendered very rapid, and all the brakes are put on practically simultaneously; and,
secondly the volume of air that thus passes from each brake cylinder aids in effecting
that reduction of the pressure in the cylinder which is required for putting on the
brakes.
Having now particularly described and ascertained the nature of this invention and
in what manner the same is to be performed, I declare that what I claim is:-
1. In fluid pressure automatic brake mechanism, wherein the communication of the
train pipe, the auxiliary reservoir and the brake cylinder are controlled by a triple
valve, in combination with the triple valve, a secondary valve worked by a piston or
diaphragm subject on its one side to the pressure in the train pipe and on its other sido
to the pressure in the auxiliary reservoir, in such a manner that when by rapid change
of pressure in the train pipe the piston or diaphragm is caused to make a considerable
stroke, communication is opened from the train pipe to the brake cylinder, substantially
as and for the purposes herein set forth.
2. In fluid pressure brake mechanism, wherein the communication of the train pipe,
the auxiliary reservoir and the brake cylinder are controlled by a triple valve, the
construction and arrangement of the said valve and the combination therewith
of a secondary valve in such a manner that a moderate movement of the valve piston
or diaphragm puts the reservoir in communication with the brake cylinder, and that
its farther movement puts the train pipe as well as the reservoir in communication
with the brake cylinder, substantially as and for the purposes herein set forth.
ABEL & IMRAY,
Agents for the Applicant.