Improvements in and relating to Automatic Fluid Pressure Train Brakes.
Year: 1899

page_text: Date of Application, 31st Oot., 1899-Accepted, 6th Jan., 1900
COMPLETE SPECIFICATION.
Improvements in and relating to Automatic Fluid Pressure
Train Brakes.
I, WILLIAM HENRY CLARKE, of 177, Times Building, New York, in the State
of New York, 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 statement.-
This invention relates to automatic fluid pressure train brakes Its object 18
to furnish means by which a high breaking force may be utilised when desued
without injurious effects, such for instance as the locking on sliding of wheels,
which frequently takes place at moderate speeds when excessive pressure is
applied to the brake shoes
Experiment in the art has demonstrated that when a train is at full speed a
higher pressure may be safely applied to the brake-shoes without locking and
sliding the wheels, than when the momentum of the train has been nearly checked
It is therefore evident that the maximum efficiency of the brakes will be obtained
if an excessive pressure is used at high speed and gradually reduced as the tiain
approaches a full stop
În automatic air biake systems, such as the Westinghouse, it is the practice in
making an emergency application of brakes, to vent both the auxiliary reservon
and the train pipe into the brake cylinder in order that an extra pressure may be
obtained This venting of the train-pipe into cylinders not only hastens the
stop by furnishing extia pressures, but incidentally accelerates the response of
the triple valves throughout the tiain
In the practice of my invention, I utilise the standard (Westinghouse) capacity
relation between the auxiliary reservoir and the bake cylinder and limit the
pressure which shall enter the brake cylinder, in either service or emergency
application of biakes to a predetermined amount in each. and then, by increasing
the leverage of the biake rigging, I am able to secure the desired maximum
brake stress in emergencies
My invention not only serves to automatically limit the service pressure in the
brake cylinder to say 40 pounds per square inch (the altered leverage in the
biake rigging giving the desued results with this pressure) but it also provides
means for automatically reducing to a predetermined proportion to the pressure
remaining in the auxiliary reservoir any pressure which may enter the biake
cylinder in excess of the maximum desired Further, the use of diaphragms
instead of pistons precludes the possibility of leakage which might render the
device inoperative.
My invention is illustrated in the accompanying drawing which represents a
section of a standard Westinghouse tuple valve with my improved valve fitted
thereto.
Refening to the diawing by letter, A represents the triple valve of ordinary
construction and operation, B the port leading to the brake cylinder (not shown)
tarough a suitable pipe b, C the auxiliary reservoir and the port leading from
the auxiliary reservoir to the triple valve. D is the casing of my improved valve,
preferably accured between the fiiple valve and the reservoir or cylinder to which

page_text: the tuple valve is usually attached It contains two diaphragms d and don
a common stem d carrying two valves, one designated herein as the intercepting
valve controlling the passage from the auxiliary to the triple, and the other
the discharge valve d' governing the escape port a leading to the atmosphere,
for brake cylinder pressure Both valves are rubber seated The area of the
diaphragm is about one-thnd larger than that of d but the proportion may,
of course, be varied as desired. The stem of the intercepting valve projects
loosely through a yoke and carries a head which engages with the voke.
The discharge valve which is hollow, callies an end cap through which the
stem passes, the stem terminating in a head d with which the cap may engage
The valve contains a spring hearing against the head d through which the
valve is seated on the movement of the diaphragms to the left The head d
and the cap dª are both provided with au passages (shown in dotted lines) and
the valve is pierced laterally to connect port a with its interior chamber. The
poit a by which ain from the brake cylinder passes to the discharge valve a¹
and larger diaphragm is restricted as shown In the usual service applications
of the biakes auxiliary reservoir pressure is admitted by the triple valve com-
paratively slowly into the brake cylinder passage and passes slowly to the larger
diaphragm d by reason of the restriction of the port a Should the amount of
pressure expanded thus into the brake cylinder by the tiple valve exceed three-
fourths of the remaining auxiliary reservon pressure upon the smaller dia-
phragm d, it will be seen that the laigei diaphragm will over balance the other
by reason of the relative sizes of the diaphragms, and both will be forced to the
night carrying with them both valves, closing communications between the
auxiliary reservoir and the triple valve and opening the escape port a¹ for a com-
paratively slow release of brake cylinder pressure
This depletion of cylinder pressure will continue until the relative pressures
in reservoir and cylinder are again established, when a further depletion will
cause the slightly preponderating pressure on the smaller diaphragm d to slowly
move both diaphragms to the left, seating the discharge valve ³ Further motion
to the left will then be arrested by the resistance of the spring d and of the
intercepting valve as at this point the yoke will come into contact with the
head of the intercepting valve stem and said valve will be held to its seat by
reason of the slight excess of pressure on its left side, the area of that side being
somewhat larger than that of its right side These combined resistances to
further movement to the left at this time will accordingly serve to check further
escape of brake cylinder pressure while retaining in the auxiliary reservon all
of its remaining pressure When, however, the brake cylinder pressule is
hnally released through the usual movement of the triple valve, pressure on the
larger diaphragm will also be released through the same port a by which it
entered and auxiliary pressure will force all parts to then normal positions, as
shown in the diawing, where the discharge valve is closed and the poit a and the
intercepting valve are open. In an emergency application pressure from the
auxiliai y resci vol 18 admitted suddenly and in large volume to the brake
cylinder and attains the maximum degree therein before it has time to actuate
the larger diaphragm because of the restriction of the passage a thereto, as
heretofore described It is thus evident that full emergency pressure will be
obtained in the brake cylinder and will be immediately thereafter slowly reduced
in the manner before described, thongh ports a and a¹ and valve until the
stated proportion to remaining auxiliary piessure 18 leached, when further escape
will be checked and pressure held in both cylinder and reservoir until brakes
are released in the usual manne It is evident also that this operation will be
the same whenever a full or nearly full expansion of the auxiliary into the brake
cylinder takes place, whether in emergency or service applications and the
highest braking efficiency will thus be obtained. Further, the increased brake
pressure available by this device without injurious effects requires a less amount
of air in making ordinary stops and allows a greater number of applications

page_text: of biakes without recharge of auxiliaries It will also be seen that when holding
brakes on grades with auxiliary and cylinder pressures nearly or fully equalised,
the tiple valve piston being in its full application position, if, as frequently
happens, the biake cylinder pressure becomes depleted by leakage this valve
will, in the performance of its regular functions as described herein, automatic-
ally admit additional pressure into the brake cylinder from the auxiliary resei-
von, thus obviating a dangerous reduction of baking pressure.
I am aware that an increase in the leverage of the brake 11gging means an
increased length of stroke for the brake cylinder piston, but this increase will
be slight and of no more consequence than ordinary "slack adjustment" pro-
vides for
My invention contemplates a differential diaphragm actuated by auxiliary
eservoir and brake cylinder pressures through a noimally restricted passage,
first, to control the port leading from the auxiliary reserven through the tiple
valve to the cylinder; second, to automatically reduce any excessive pressure
which may, for any cause, enter the brake cylinder, and third, to automatically
reduce to a predetermined percentage of the remaining auxiliary reseivon pies-
sule, any pressure in excess of such percentage which may be vented from said
esei von to said cylinder in any application of the brakes
It is evident that two diaphragms of any deaned areas may be employed m my
improved apparatus without departing from the spint of my invention and I
do not limit myself in this respect, noi as to any special standard of either
emergency or service brake pressuies In standard systems, such as the Westing-
house, auxiliary lesei voi piessure 18 at all times practically free to pass to the
triple valve casing, which latter, on account of its construction and parts, presents
many opportunities for leakage. It will be seen that my improved valve retains
auxiliary pressure therein at times when such leakages become most dangerous,
as, for instance, when brakes are being held with considerable force on grades.
Further, as by the action of my improved valve the pressure in the triple valve
casing, above its piston, being at such times somewhat less than auxiliary reset-
you pressure, it is evident that when the train pipe pressure is increased in order
to release the brakes, the tiple valve piston will be more quickly and readily
moved to the release position than if it was then exposed to auxiliary reservoir
pressure above its piston These also constitute important features of my
invention
The two diaphragms of different areas on a common stem, may be properly
designated as a differential diaphragm oi piston
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 18
-
1. In an air brake system, the combination of a brake cylinder and auxiliary
reservo, a tuple valve, a port between the iesei von and tiple valve and an
intercepting valve controlling said port, an escape port for brake cylinder pressure
and a discharge valve controlling the same and fixed on the same stem as the in-
tercepting valve, and means whereby the pressure in the brake cylinder will serve
to close the intercepting valve and open the discharge valve, all constructed and
alanged substantially as herein before described and as illustiated by the accom-
panying drawings
2 In an an biake system, the combination of a brake cylinder and auxiliary
reservon, a tuple valve, a port between the reservoir and triple valve and an
intercepting valve controlling said port, an escape port for brake cylinder pressure
and a discharge valve controlling the same, and means whereby the pressure
in the brake cylinder will serve to close the intercepting valve and open the
discharge valve, and the auxiliary reservoir pressure thereafter close the dis-
charge valve, all constructed and arranged substantially as herembefore described
and as illustrated by the accompanying diawings.
3. In an air brake system, the combination of a brake cylinder and auxiliary

page_text: reservon, a tiple valve, a port between the reservon and tuple valve and an
intercepting valve controlling said port, an escape port for brake cylinder pressure
and a discharge valve controlling the same and means whereby the pressure in the
brake cylinder will serve to close the intercepting valve and open the discharge
valve, and the auxiliary resei von pressure thereafter close the discharge valve
and open the intercepting valve, all constructed and ananged substantially as
herein before described and as illustrated by the accompanying drawing
4. In an an biake avstem, the combination of a bake cylinder and auxiliary
reservon, a triple valve, a port between the reservou and triple valve and an
intercepting valve controlling said port, an escape port for brake cylinder pies-
sure and a discharge valve controlling the same, and two diaphragms of different
areas acting together to control the intercepting and discharge valves, said
diaphragms being respectively subjected to pressures from the auxiliary reservou
and the brake cylinder, all constructed and arranged substantially as heiem-
before described and as illustrated by the accompanying diawing
5 In an au biake system, the combination of an auxiliary reseivou, a tuple
valve, a brake cylinder, a port connecting the same, an escape port for the brake
cylinder pressure, valves controlling said ports and a differential diaphragm
actuating said valves, said diaphragms being subjected on one side to auxiliary
reservou pressure and on the other side to biake cylinder pressure, all constructed
and arranged substantially as hetembefore described and as illustrated by the
accompanying drawing.
6 In an air brake system, the combination of an auxiliary reservon and triple
valve, a port connecting the same, a valve controlling said poit and a differential
diaphragm actuating said valve, said diaphragm being subjected to auxiliary
1csei voir pressure on one side and to biake cylinder pressure on the other side,
all constructed and arranged substantially as herein before described and as
illustrated by the accompanying diawing
7 In an air brake system, the combination of an auxiliary reservon, a brake
cylinder, a passage connecting the same, and a valve device exposed to auxiliary
reservou and brake cylinder pressures and adapted to automatically produce, and
maintain a predetermined ratio between said pressures, all constructed and ar-
langed substantially as herembefore desciibed and as illustrated by the accompany-
ing drawing.
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