Improvements in Air Brakes for Railway Vehicles.
Year: 1895

page_text: Date of Application, 30th Sept., 1895-Accepted, 18th July, 1896
[Communicated from abroad by THE NEW YORK AIR BRAKE COMPANY, of
66, Broadway, New York, U.S.A., Manufacturers.]
Improvements in Air Brakes for Railway Vehicles.
I, REGINALD WALTER BARKER, of Monument Chambers, King William
Street, London, Patent Agent, do hereby declare the nature of my said invention,
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The object of my invention is to provide a quick action automatic brake
apparatus in which the quick braking power is obtained from the compressed air
stored in the auxiliary reservoir.
It consists of the ordinary automatic air brake composed of a train pipe, an
auxiliary reservoir, a brake cylinder and a triple valve controlling a passage from
the train pipe to the auxiliary reservoir, a passage from the auxiliary reservoir
to the brake cylinder and a passage from the brake cylinder to the atmosphere,
combined with local vents from the train pipe and suitable means for quickly
opening a second passage from the auxiliary reservoir, or one chamber thereof, to
the brake cylinder.
Figure 1 is a longitudinal section of the apparatus constructed. Fig. 2 is a cross
section of the same on line A A.
Fig. 3 is a modification of the structure in order to show all the moving parts
in one plane. It has the same moving parts, acting on each other in the same
way as the structure of Figs. 1 and 2. It differs only in the form of the passages
between the valves.
The various parts are numbered the same on all drawings, but the description
may be followed more easily by reference to Fig. 3.
In the drawings 1 is the ordinary triple valve piston one side of which has a
cylindrical recess in which piston 2 is fitted. 3 is a small opening through piston 2
through which air may pass to equalize the pressure upon its opposite sides.
4 is an exhaust valve controlling connection between port 5, which is open to the
brake cylinder, and port 6 which is open to the atmosphere. 7 is an application
valve controlling the port 8 between the auxiliary reservoir and the brake
cylinder. These valves are operated by the piston 1 in the usual way; that is,
when piston 1 is as shown, the brake cylinder is open to the atmosphere through
valve 4 and its ports while valve 7 is closed. When piston 1 is at the other end
of its stroke, valve 7 does not cover port 8 and the auxiliary reservoir is open to
the brake cylinder, while valve 4 has closed port 5 and cut off the opening from
the brake cylinder to the atmosphere.
9 is a large passage connecting the train pipe with chambers 10 and 12.
The valve 13 controls a vent 11 which leads to the open air when piston 14
has been moved to uncover passage 15. A spring 16 tends to bold valve 13 upou
its seat.
17 is an arm of valve 13 which fulcrums upon the shoulder 18 when valve 13 is
partly open.
19 is a pin passing through stem 20 of piston 2, which limits the motion of
piston 2 in a right hand direction to the position shown in the drawings.
21 is the space between the two pistons.
22 is a charging groove.
The auxiliary reservoir is divided into two chambers 23

page_text: and 24, between which are an always open passage 25 and a check valve 26 which
will permit air to flow freely from chamber 24 to chamber 23.
Valve 27 and check valve 28 are located in a passage 29-30 joining chamber 24
and the brake cylinder. Check valve 28 permits air to flow from 30 to the brake
cylinder, but prevents flow in the opposite direction.
31 is a spring that tends to keep valve 27 on its seat. Valve 27 is opened by
the stem of piston 14.
When in service compressed air from the train pipe passes through passage 9,
chamber 10, chamber 12, and charging groove 22 into the auxiliary reservoir,
also from chamber 12 through passage 3 to 21, the space between the two pistons,
and the pressure in all the above mentioned chambers and the auxiliary reservoir
becomes equal.
The passage
is made of such size that when the piston 1 is moved slowly to
the left, the air in space 21 will be pressed through passage 3 without making
sufficient pressure on piston 2 to overcome the resistance of the spring 16 and the
air pressure tending to keep valve 13 on its seat. Therefore the piston 1 may
move its whole stroke to the left slowly without opening the vent covered by
valve 13. When piston 1 is moved quickly to the left, the air confined in space 21
cannot flow through passage 3 fast enough, and it therefore forces piston 2 to the
left with sufficient force to push valve 13 from its seat and vent the train pipe to
the passage 11. As the passage 3 is always open the confined air in 21 will
gradually pass through the passage from the pressure of the spring 16 on valve 13
and stem 20 until piston 2 has entered its cylinder far enough to allow valve 13 to
close the vent. On the return of piston 1 to the position shown in the drawings,
the pin 19 prevents the piston 2 from returning farther than the position shown,
and air passes through passage 3 to fill space 21 to the same pressure as in
chamber 12.
In the process of applying brakes in the ordinary automatic brake systems, the
operator reduces the pressure in the train pipe slowly if he wishes a moderate
application, and very quickly if he wishes a quick application. When in the
normal condition the pressure in the auxiliary reservoir and in chamber 12 is the
same as in the train pipe, to which chamber 12 is open, and consequently
the pressure on both sides of piston 1 is equal. Upon a reduction of pressure in
the train pipe the preponderance of pressure on the reservoir side of piston 1
moves it to the left. In the traverse of piston 1 it first closes charging groove 22;
second, closes exhaust valve 4, and, third, opens port 8 between the auxiliary
reservoir and the brake cylinder. If the reduction in the train pipe is slow, the
air confined in space 21 will have time to flow through passage 3 and there will be
no motion to piston 2. The action above described is called a service stop and
occasions a moderate application of the brakes. If the pressure in the train pipe
15 quickly reduced, the preponderance of pressure on the reservoir side of piston 1
moves it quickly to the left carrying with it piston 2 (because the confined air in
space 21 cannot flow through passage 3 fast enough) which opens valve 13 and
vents the train pipe into passage 11. The fluid pressure in passage 11 moves
piston 14 to the right and allows the vented air from the train pipe to pass to the
atmosphere through 15. The movement of piston 14 to the right opens valve 27
and allows air to pass from chamber 24 of the auxiliary reservoir through 29-30
and check valve 28 to the brake cylinder. At the same time port 8 will be
open and air will flow from chamber 23 of the auxiliary reservoir to the brake
cylinder. As the passage 29-30 is many times larger than the passage 8 the
pressure in chamber 24 of the auxiliary reservoir will equalize with that in the
brake cylinder before much air has passed from chamber 23 through passage 8.
Under normal conditions this equalization would be forty-five to fifty pounds
pressure in the brake cylinder. The air flowing from chamber 23 through port 8
would gradually increase this pressure about ten pounds more. The check
valve 28 prevents this additional pressure from reaching chamber 24 through
passage 29-30. As passage 25 is always open there will be a gradual reduction

page_text: of pressure in the brake cylinder by this passage until the pressure in
chambers 23-24 and the brake cylinder are equal. This is a desirable feature
in a brake as it is important to get a high braking pressure instantly when the
speed is great and to reduce that pressure as the speed slackens in order to prevent
skidding the wheels. An increase of pressure in the train pipe forces piston 1 to
the right, thus closing port 8 and opening the brake cylinder to the atmosphere
through ports 5 and 6 and in valve 4.
It is obvious that this device would operate in the same manner if attached to
an ordinary auxiliary reservoir without any division. In this case when by a
quick reduction of train pipe pressure vent valve 13 was opened, the escaping air
would move piston 14 to the right and open valve 27, thus opening a large passage
from the auxiliary reservoir to the brake cylinder in addition to the small
passage 8. The pressure in the brake cylinder would be raised to the full point
of equalization almost instantaneously. The apparatus can therefore be attached
to the auxiliary reservoirs now in service, although the extreme pressure obtained
with a divided reservoir would not be reached.
Having now particularly described and ascertained the nature of my said inveu-
tion und in what manner the same is to be performed, I declare that what I
claim is':-
1. In an automatic brake system normally operated by a triple valve, the com-
bination with a vent valve between the train pipe and the atmosphere, of a piston
located in the line of flow from the vent valve to the atmosphere, so as to be
actuated by a quick discharge of fluid from the vent valve to cause opening
movement to a valve controlling a passage from the auxiliary reservoir, or a
portion thereof, to the brake cylinder, substantially as set forth.
2. In an automatic brake system normally operated by a triple valve, which
controls a passage from the auxiliary reservoir to the brake cylinder, an auxiliary
reservoir divided into two parts with an always open passage between them and a
check valve opening in one direction combined with a valve controlling a separate
passage from one portion of the auxiliary reservoir to the brake cylinder,
substantially as set forth.
3. In an automatic brake system normally operated by a triple valve, the com-
bination with the triple valve piston and a vent valve from the train pipe of
a cylindrical chamber forming part of the triple valve piston, a second piston
in said cylindrical chamber and an air space closed by the second piston and
a small passage between the two sides of the second piston so that the motion of
the triple valve piston may actuate the second piston to open the vent valve or
not depending on the speed with which the triple valve piston is moved,
substantially as set forth.
Dated this 30th day of September 1895.