Improvements in Triple Valves for Air Brakes.
Year: 1893

page_text: COMPLETE DIEVITRATION.
Improvements in Triple Valves for Air Brakes.
I, HENRY LAWRENCE HOWE of Canandaigua in the County of Ontario and
State of New York United States of America, Manufacturer, 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 generally to a triple valve for fluid pressure brakes adapted
by a variation of pressure in the train-pipe to cause the proper operation of the
brakes and to charge the auxiliary reservoir. And it has for its object to materially
simplify and improve the construction and operation of such valves to increase their
efficiency and to make their action more positive and more readily susceptible to the
variations of pressure.
To this end the present improvements reside broadly in means whereby the
auxiliary reservoir may be charged while the brakes are on; in the use of the co-
operating valves capable of being moved by a single device, the one to control the
putting on of the brakes by pressure from the auxiliary reservoir for ordinary
service stops, and the other to control the putting on of the brakes by pressure
from the auxiliary reservoir for ordinary service stops, and the other to control the
putting on of the brakes by pressure direct from the train-pipe, supplemented it
may be by that from the auxiliary reservoir for emergency stops. They also reside in
a check valve controlling the train-pipe opening to the triple valve and a projection
or arm adapted to prevent the check-valve from closing said opening at certain
times. They furthermore reside in a yielding stop for checking the movement of
the controlling valves, and for determining such movement in conjunction with
the variation of pressure; and in various other constructions hereinafter fully set
forth.
The improved triple valve is constructed and its operation is such that it controls
the connection between the train-pipe and the auxiliary reservoir, the connection
between said auxiliary reservoir and the brake-cylinder and the connection between
the train-pipe and the brake-cylinder direct. These connections are in the preferred
embodiment of the invention regulated by co-operating sliding valves which are
moved by a suitable piston, and the piston is adapted through the medium of
suitable connections between the train-pipe on one side and the train-pipe and
auxiliary reservoir on its opposite side, to be moved by variations in the pressure
in the train-pipe and by the rapidity with which these variations are effected.
For convenience, I will describe the movement of this piston as "forward" and
"backward," "forward" being toward the valves which it controls, and its
"forward limit" being a seat which is provided for it at one end of the cylinder;
and "backward" being in the opposite direction, and its "backward limit" being a
projecting spring somewhat shorter than the stroke of the piston which checks
backward movement of the piston according to the difference in pressure in front of
and pressure behind the piston and adapted to retard the backward movement of
the piston and to return the piston when relieved of pressure. Said piston is
capable of assuming four effective positions: First, it may be at the forward limit
of its stroke, at which time the co-operating valves occupy such position as to open
the brake-cylinder to exhaust and permit the charging of the auxiliary reservoir
from the train-pipe as in the ordinary running position. In the second place, the
piston may be drawn backward by a slight reduction of air pressure behind it,
so that it will come against the spring and slightly compress it, at which time the
co-operating valves will have changed their relative positions to bring their ports
into coincidence and thus open communication between the auxiliary reservoir and
brake cylinder and apply the brakes for a service stop; and at the same time have

page_text: closed the exhaust from the brake-cylinder, without either of said co-operating
valves disturbing the communication between the train-pipe and auxiliary reservoir.
In the third place, by equalizing the pressure on opposite sides of the piston
when the piston is in the position last mentioned, the spring will return it to a point
between the first and second positions, when communication between the auxiliary
reservoir, and the brake-cylinder will be entirely cut off by the co-operating valves,
the exhaust will not be opened, and the auxiliary reservoir may then be re-charged
without releasing the brakes. In the fourth place the operation first described may
be repeated by making a large reduction in the train-pipe pressure so that the piston
will now move backward to the backward limit of its stroke, at which time the co-
operating valves will move to such a position as to cut off direct communication between
the train-pipe and the auxiliary reservoir through the valve chamber and open direct
communication between the train-pipe and the brake-cylinder, and also if desired,
to open communication through a direct opening or through the co-operating valves
between the auxiliary reservoir and the brake cylinder. This last effect, however,
is not necessary, though preferable, because it permits the brakes to be applied
gently at first, as in service stops, and with heavy pressure immediately
afterwards.
The result of this movement is to permit the rapid drawing off of the train pipe
pressure into the brake-cylinder and the subsequent direct expansion of the auxiliary
reservoir pressure into the brake cylinder, so that the brakes are suddenly and
forcibly applied as required in the case of an emergency stop. From the train
pipe communication is had with the front of the piston through the main passage
which leads to the valve chamber while communication is also had with the rear of
the piston through an independent passage. In the main passage from the train-
pipe opening to the valve chamber and piston-cylinder is located a two-seated
check-valve; while the piston carries a projection or arm which engages the two-
seated check valve and prevents the upward seating of said check valve when said
piston is at either limit of its stroke, so that train-pipe pressure may pass to the
auxiliary reservoir or to the brake-cylinder, as before explained. The co-operative
slide valves are so arranged that the outer one, to which the piston is connected,
has a limited movement over the other and completes its independent throw in
either direction during the ordinary operation of the triple valve in making service
stops before engaging the inner valve, and is adapted in such ordinary operation to
open communication between the valve chamber and the recess of the inner valve
by thus completing its throw in one direction; while said inner valve during
ordinary use in service stop remains stationary, without disturbing the communi-
cation between the train-pipe passage and the auxiliary reservoir through the valve
chamber and closing the communication between the brake-cylinder passage and the
train pipe, so that the mere movement of the outer valve upon the inner one may
serve to open communication between the valve chamber or the auxiliary reservoir
(with which said valve chamber is in constant communication), and the brake
cylinder, without cutting off communication between the train-pipe and auxiliary
reservoir through said chamber. These valves are also so constructed and pro-
portioned that a further movement of the outer one by the piston, after completing
its throw during use in ordinary service stop, may be made for the purpose of
throwing said inner valve and opening communication directly between the train-
pipe passage and the brake cylinder, in addition to opening communication between
the auxiliary reservoir and said brake-cylinder for use in emergency stop in which
case the outer valve serves as a connecting means between the piston and said
inner valve. Hence, it will be seen that the outer valve in its independent move-
ment serves only to effect the service stop and close the exhaust while the inner
valve in its movement serves for effecting the emergency stop; and to open the
exhaust from the brake-cylinder the return of both valves to their initial position
must occur. The double check-valve in the train-pipe passage is adapted to seat
upward or downward and permit the development of a pressure behind the piston
through the duct from the train-pipe opening, which pressure may be greater than

page_text: that in front of the piston and result in forcing the piston to its seat, or less than
the pressure in front of the piston and result in drawing the piston away from its
seat a greater or less distance according to the degree in reduction behind it. The
spring forms a check or stop for the piston. This check or stop, however, is a
yielding one and it is overcome to a greater or less extent according to the result
to be produced.
My invention will be fully understood upon reference to the accompanying
drawings, which show the triple valve in vertical longitudinal section, and in
which:
Figure 1 represents the parts in running position.
Figure 2 shows the parts in service-stop, and
Figure 3 represents the parts in emergency-stop position.
Figure 4 is a transverse section on the line 4, 4, Figure 3, showing the parts on
an enlarged scale and looking toward the piston.
Figures 5 and 6 are respectively top and bottom plans of the inner or recessed
valve.
Figures 7 and 8 are elevations of the respective ends of the upper slide valve.
Figures 9, 10, 11 and 12 are sectional elevations of a modified form of the triple
valve with additional features; Figures 13 and 14 are plan views of the two slide
valves of said modified form.
Figures 15 and 16 are sectional elevations of a modified form of the double seated
check valve of the train-pipe passage.
The improved triple-valve consists of a shell 1, having a valve chamber 2, and a
piston-cylinder 6, open to the valve chamber; and said valve-chamber is open to
an auxiliary reservoir as indicated in Figure 1, has a passage 3 supplemented, if
desired, by a passage 3ª, leading to the brake-cylinder opening 3, a passage 5,
leading to the train-pipe opening 4, and a passage leading to the exhaust port 7.
In the valve chamber 2 there is arranged a pair of valves adapted to control
these passages and their communication between the train-pipe and the auxiliary
reservoir through passage 5, the closing of the brake-cylinder from both the train-
pipe and the auxiliary reservoir, and the opening of the brake-cylinder to the
exhaust. Thus in said valve chamber is located a recessed slide valve 8 of such
size and proportions and with its lower openings so arranged, that when at its
forward limit or normal position it will uncover and its recess communicate with
passage 3 or passages 36, 3*. This valve 8 also has running through it, but not
communicating with its recess an exhaust duct 9, which, when said valve is at its
said forward limit, coincides in position with the exhaust port 7. In the chamber 2
and partially surrounding the valve 8 is another valve 10, which is connected with
and adapted to move the valve 8 by means of projections 11, 12. These projections
are, however, so spaced that valve 10 has a limited movement relatively to the
valve 8, and only moves the latter after first bringing one of the said projections
against it, which occurs after said valve 10 has completed its individual or
independent throw in either direction. The valve 10 is provided with a port, or
series of ports 10% and a recess 10%, the former of which coincides with a port
or series of ports 8, in the valve 8 when said valve 10 is at the backward limit of
its movement relatively to the valve 8, while the recess 10%, is adapted to open
communication between a port or series of ports 8, and the exhaust passage 9,
when said valve is at the forward limit of its movement relatively to the valve 8.
The valve 10 therefore co-operates with the valve 8 to open and close communica-
tion between the valve chamber and the brake-cylinder through the ports in said
valves. This valve 10 does not fill the entire cross-section of the valve chamber at
any point but is formed to provide a space for the free passage of the pressure
through the valve chamber 2, above the valves, as will appear upon reference to
Figures 4, 7 and 8.
In the passage 5, from the train pipe opening 4, to the valve-chamber 2, is
located a double-seated check valve 13, which has a lower seat 13ª, and an upper
seat 13. This double-seated check valve 13 works in an enlarged portion 5*,

page_text: between its seats in the passage 5 and in order to guide said valve accurately it
may be provided with vertical wings 13, secured at angles to each other and to the
valve 13. Communication is likewise established between the train-pipe opening 4
and the back end of the piston-cylinder 6, through the duct 14, and the annular
channel 14, and the perforations 14b. This communication is wholly independent
of the movement of the check valve 13 and is constantly open. It is, however,
restricted in size.
In my triple valve it should be noted that the train-pipe opening is in a
projection to one side of the piston and the air pressure is not communicated from
the train-pipe to the valve-chamber through the piston-cylinder, so that the
pressure is not cut off by the movement of said piston, and there being no flow of
air through said cylinder there is no deposit of dust or dirt in the cylinder which
would interfere with working of the piston.
In the piston-cylinder 6 is located the piston 15, having a stem 16, which is
connected to valve 10. A spring 17, behind the piston 15, is adapted to hold said
piston in a forward position, but the spring is of such length as to allow the piston
to assume a position a short distance from its forward seat without coming in
contact with said spring and also to move backward and slightly compress it.
When the piston is at its forward limit the rear projection 12 on the valve 10 is in
contact with the valve 8, and said valve 8 is pushed forward to the position shown
in Figure 1. When said piston is withdrawn or moved backward and the spring
slightly compressed the parts occupy the positions shown by full lines in Figure 2,
the exhaust duct 9, is closed and communication is established between the auxiliary
reservoir and the brake-cylinder through the chamber 2, and ports 10, 8, and
passage 3* or 3, which results in a gradual application of the brakes as for an
ordinary service-stop.
When the pressure is equalized on both sides of the piston and the spring is
permitted to project the piston to the spring's limit, the parts 10, 16, 15, 17, 18
and 18 occupy the positions shown by dotted lines in Figure 2 and communication
between the auxiliary reservoir and the brake-cylinder is cut off, but the exhaust
is not opened, so that the brakes will be held on, and the auxiliary reservoir may
be recharged.
This recharging of the auxiliary reservoir may be accomplished by a slight
increase in train-pipe pressure just sufficient to overcome the weight of the check
valve 13 without forcing it to its upper seat 13 so that such pressure may pass by
the thus floating check valve to the valve chamber 2 and thence to the auxiliary
reservoir.
When the piston is at its backward limit the parts occupy the position shown in
Figure 3, at which time the valve 10 has completed its throw and also completed
the throw of inner valve 8 by engagement therewith by projection 11, so that now
direct communication between train-pipe and auxiliary reservoir is cut off and
direct communication is established from chamber 2 to the brake cylinder opening 3,
through openings 3*, 10, 8ª, and 3b, and from the train-pipe directly to the brake-
cylinder through port 5, the recess of valve 8 and opening 3b, and the pressure in
the brake-cylinder is thus suddenly raised by the drawing off of pressure from the
train-pipe through the large passages shown and is furthermore supplemented by
pressure from the auxiliary reservoir so that the brakes are suddenly and forcibly
applied as is desired in the case of an emergency stop. In order to prevent the
seating of the double check-valve 13 against its upper seat 13 when the piston is
at the backward limit of its movement, and thus prevent the air rushing in from
the train-pipe and communicating pressure to the brake-cylinder or to prevent
seating of the valve when the piston is at its forward limit and the reservoir is
being charged, there is provided a stop which in this instance is carried by the
piston in the form of an arm 18, adapted to engage a projection 18*, on the end of
the double check-valve 13 when said piston reaches the positions named. Said
arm 18, however, is cut away at intermediate points on its lower edge, so as to
permit the double check valve 13 to reach its seat and close the passage to the

page_text: auxiliary reservoir, and permit the development of pressure behind the piston, to
bring the parts from the position of Figure 2 to that of Figure 1. This arm 18,
engages the projection 18" when the piston is at its forward limit by reason of the
downward inclination of the lower edge while it engages said projection when the
piston is at its backward limit, through the medium of a finger 18" on its end. In
order to accommodate the spring 17, the cylinder head 19 has a box 20 of proper
size, and in order to regulate the tension of said spring 17 a set screw 21 having a
pressure disk 22 is passed through the end of the box 20 and secured against
turning by a lock-nut 23.
The operation of the device is as follows:-
In the normal position of the parts or in ordinary running position, the compressed
air enters at the train-pipe opening 4 and passes through passage 5 to the valve
chamber 2 to the front of the piston 15, and through said chamber to auxiliary
reservoir, it also passes to the rear side of the piston 15, by the way of the smaller
passage 14. During this passage of the air the check valve 13, is kept from its
seat as indicated in Figure 1, which shows the positions the parts occupy while the
train is running and the charging of the auxiliary reservoir is going on. Any
desired pressure may be developed in the auxiliary reservoir. When it is desired
to make a service stop, at which time the brakes are to be applied easily, a small
reduction of about five pounds pressure is made in the train-pipe whereupon the
double check valve 13 will move to its lower scat 13" holding the pressure above it,
at the same time the pressure behind the piston 15 will be correspondingly
reduced, and being less than that in front of it, said piston will be caused to move
backward into contact with and slightly compress its spring 17, but no further, as
the difference in pressure is not sufficient to further compress said spring. This
backward movement of the piston effects the relative movement between the slide
valves which is positive and exact, and moves the co-operating valve 10 to close
the exhaust duct 9, and to bring the ports 8ª, 10%, into coincidence and thus
establishes communication through a restricted passage 8, 10, 3*, between the
auxiliary reservoir and the brake-cylinder which results in the gradual application
of the brakes. The parts now occupy the positions shown by full lines in
Figure 2.
If it is desired now to release the brakes the pressure is suddenly raised in the
train pipe when the double check valve 13 will move to its upper seat 13" thereby
temporarily cutting off communication between the train-pipe and the auxiliary
reservoir, pressure will be developed behind the piston and the latter will be forced
to its seat, thereby returning the parts 10, 16, 15, 17, 13, and 18 to the positions
shown in Figure 1, and causing the incline of the finger 18 to move the check
valve 13 from its upper seat and again establishing direct communication between the
train-pipe and the auxiliary reservoir, so that the train pipe pressure may pass on
to the auxiliary reservoir.
If, on the other hand, it is desired to retain the brakes for a length of time, as in
case of a grade and to replenish the pressure in the auxiliary reservoir without
releasing them, the pressure is slowly raised in the train-pipe until equalized on
opposite sides of the piston, when the spring 17 will press the piston forward as far
as the spring can reach, closing ports 8, 10%, as indicated by dotted lines in
Figure 2. The brake-cylinder is now cut off from the auxiliary reservoir but not
opened to exhaust and while the brakes are held on, the auxiliary reservoir may be
recharged by slowly raising the pressure in the train-pipe and avoiding the forcing
of the double check valve 13 to its upper seat; the flow of the air not being
sufficient to throw said valve to said upper seat. After recharging the auxiliary
reservoir, the piston may again be moved backward by a slight reduction in train-
pipe pressure and the brake-cylinder be again opened to the auxiliary reservoir
pressure. This operation may be kept up indefinitely, so that the brakes need
never be released on a grade for recharging the auxiliary reservoir. The brakes
are released finally by a sudden raising of pressure in the train-pipe. If it is
desired to make an emergency stop, the parts being in the position shown in

page_text: Figure 1, or in those shown in Figure 2, while the train is running and the auxiliary
reservoir is, therefore, charged, a large reduction in pressure is made in the train-
pipe, such as fifteen or twenty pounds. This acts as before to seat the double
check valve 13 on its lower seat 13, and to force back the piston but this time the
piston projecting spring will be compressed and the piston will move to its backward
limit so that the slide valves in the chamber 2 will be drawn back to the position
shown in Figure 3. This position of the parts affords direct communication between
the recess of valve 8 and the large brake-cylinder port 3b and also between said
recess and the train-pipe passage 5. Two very important results are obtained by
this last mentioned movement of the inner and co-operating valves: first, the train-
pipe pressure is drawn off very quickly into the brake-cylinder and the brakes
applied and held there without materially relieving the surplus pressure in the
auxiliary reservoir and therefore not permitting the piston to return the inner and
co-operating valves to service stop position; and, second, a gentle pressure had
been previously applied to the brakes by pressure from the auxiliary reservoir
through the valve openings 10" and 8", as in the service stop, and said pressure from
the train-pipe is then further supplemented by the direct pressure from the auxiliary
reservoir through the said openings. Furthermore it will be seen that in this
position of the parts, the pressure in the train-pipe may be gently raised and
transmitted directly to the brake-cylinder through valve 8, thus causing the
triple valve to work "straight air on an emergency stop. When the pressure
becomes equalized on both sides of the piston and in the brake cylinder, the
spring gradually returns the piston to the position shown by dotted lines in
Figure 2.
"
From the foregoing description it will be seen that the triple valve has several
advantages over other practised forms, in that the communication between the
train-pipe and auxiliary reservoir and the brake cylinder is not had through the
piston cylinder, hence there being no flow of air through said piston cylinder, no
dirt can accumulate in the same to interfere with the movement of the piston 15;
again, the air is never cut off from the train-pipe to the auxiliary reservoir by any
movement of the piston 15, or of the valves 10 and 8 at any time; in service stop
the air passes over the valve 10 to the auxiliary reservoir (as in Figures 1 and 2)
and in emergency stop through the recess of valve 8 and passage 3 and 3* to said
reservoir (as in Figure 3)-hence the check valve 13 serves as an equalizing device
for the pressure from the train-pipe under the valve and that above said valve, and
always permitting the pressure to be maintained or renewed while the brakes are
on either in a service stop or in an emergency stop, and also when the brakes are
off. When communication between the train-pipe and the auxiliary reservoir is
cut off in a triple valve, the brakes are liable to be released and cause serious
trouble, by the train pipe pressure becoming more than that in the auxiliary
reservoir. In my triple valve this can never happen, because of the equalizing
action of said check valve 13. It will also be seen that the two seated check
valve 13 is always operated positively by air pressure on one side or the other, it is
not dependent upon the action of any spring, and means are provided for absolutely
preventing it from cutting off the air pressure, flowing through from train pipe when
the piston is at either end of its throw or stroke. Should anything ever happen to
the only spring employed in the device, the brakes can nevertheless be applied and
even the energency stop pressure be applied without difficulty.
There is no loss in pressure in the auxiliary reservoir occasioned by leakage into
the train-pipe when the pressure is drawn down in said pipe for the purpose of
applying the brakes, because the two-seated check-valve immediately seats itself on
its lower scat 13" and closes the train-pipe passage. In triple valves which have
an open charging slot or port, considerable leakage occurs until the piston has
effected a sufficient movement to close the charging slot. The value of this
improvement is obvious.
It will be observed, in conclusion, that as the force of the air pressure from the
train pipe to the auxiliary or directly to the brake cylinder is on one side of the

page_text: piston cylinder and not through said cylinder, as in many other forms of valves, and
also that as the outer or rear side of the piston is open to the train pipe through a
small passage, and that as the check valve is smaller in area than the piston, I am
enabled to constantly and gently supply pressure to the train pipe, and thence to
the auxiliary reservoir or direct to the brake cylinder without any tendency of
moving said piston while so doing, and thereby avoid the inadvertent movement
of the valves 8 and 10 to release position.
In the modification shown in Figs. 9 to 14, one of the changes over the
construction before described relates to the form of the upper one of the slide
valves which is formed of two independent parts 10 and 10 the part 10 containing
the duct 10* being held in a recess in a yoke 11* directly connected to the
piston 15 so as to move in unison therewith, and the part 10° containing the
recess 10 being mounted loosely in said yoke 11 so as to have periods of rest
irrespective of the other part 10 and thus provide lost motion between the piston
and said part 10. This construction permits a slightly longer travel of piston 15
to effect the service stop in moving from Fig. 9 position to Fig. 10, holding the
brake cylinder open to the atmosphere until just before the ducts 10 and 8"
register which allows the auxiliary reservoir pressure to pass into the brake
cylinder, and thereby rendering the piston 15 more sensitive and more easily
started in its movement to Fig. 10 position upon a slight reduction in train pipe
pressure in that it has less weight to move in the first instance, the part 10 being
of small size. This sensitive movement of the piston 15 also saves the pressure,
it not requiring so much of a reduction to effect its movement and also avoids
in a long train, heretofore requiring considerable reduction in pressure to effect
the service stop, any tendency of the valve nearest the engine moving further than
needed to make the service stop. The same lost motion between the two parts 10
and 10° also renders the piston 15 more delicate, when, after a service stop an
equilibrium of air pressure is established on both sides of said piston to permit
the spring 17 to move the piston back slightly into Fig. 11 position to close
communication between the auxiliary reservoir and the brake-cylinder to hold
the air pressure in said cylinder while, for instance, the engineer is recharging
the auxiliary reservoir. The train pipe opening 5 in this construction is divided
into two ports, and the slide valve 8 is provided with a cross bridge 8° and a
flange 8 which overlie the ports of said opening 5, the flange having the ports 8d
through it to permit the pressure to pass from the train pipe into the valve
chamber and thence to the auxiliary reservoir. This construction enables the
further stroke of the piston 15 from service stop position, Fig. 10, to emergency
position, Fig. 12, to be shortened and thus effect the emergency stop more
rapidly. The port 3* leading to the brake cylinder is dispensed with as before
suggested.
In lieu of the arm 18 rigid with the operating piston in the other construction,
there is employed an independent piston 18 fitting a perforation 184 in the casing
between the train-pipe opening 5 and the cylinder 6, the piston 18° thus being
exposed on one side to auxiliary reservoir pressure and on the other side to train
pipe pressure. The rod 18 of this piston carries a collar 18b which forms the stop
against which the end 18ª of the check valve 13 abuts when the parts are in
emergency position as in Fig. 12; a spring 18e surrounding said rod holding the
piston and its stop in the normal position shown in Fig 9, the stop being out of
line with the end of the check valve so as not to obstruct its seating against its
upper seat 13. On the emergency stop the pressure above the check valve on the
train pipe side of the piston 18 has been so much reduced by having expanded into
the brake cylinder through the recess of the valve 8 that the auxiliary reservoir
pressure on the opposite side of said piston is sufficient to more its stop into
Fig. 12 position to obstruct the scating of the check valve 13 and hold it from its
seat and thus enable the train pipe pressure below the check valve to also pass into
the cylinder. This piston 18 also serves to uncover a passage 19 so that when in
the emergency position the auxiliary reservoir pressure may pass from the

page_text: cylinder o and opening 5 into the brake cylinder independent of any movement
of the slide valves.
This modified construction also includes means for ensuring the positive
movement of the triple valve to exhaust position, and so that the entire variation
in train pipe pressure is utilized to accomplish the movement of the triple valve
without liability of such variation being modified by additional air or by a loss of
air; and thus enable all the triple valves in a long train of cars to move to
exhaust position substantially simultaneously; and so that only that variation of
train pipe pressure need be made which is absolutely necessary to produce the
desired movement of the parts, thereby lessening the extent of variation needed
and also making the parts respond without delay. This is accomplished by
providing a bye-passage leading from the train pipe to some portion of the
triple valve structure or connection, and providing a valve arranged to control
such passage to hold the pressure in the train pipe until the brake cylinder
has been opened to the exhaust. The structure is provided with a bye-passage Fl
opening at its lower end by a passage 34 into the train pipe passage 4 below
the check valve 13 and its upper end past a small check valve 40 into the
same passage above the upper seat of the check valve 13. This passage Fi
is controlled by a valve 33 automatically opening and closing communication
between said passage F and the passage 34. This positive release valve 33 is
carried by a piston 30 fitting a cylindrical perforation 31, which, above the
piston 30, communicates by a port C with the brake cylinder passage 3. The
valve 33 is thus a differential one, its larger area formed by the piston 30 being
exposed to whatever pressure is in the brake cylinder, and its smaller area to the
train pipe pressure. Its operation is such that upon a reduction in train pipe
pressure and an accumulation of pressure in the brake cylinder said valve 33 will
move from its normal position opening the passage F' as in Fig. 9 into its closing
position shown in Fig. 12, and thus prevent any of the train pipe pressure passing
through said passage, this change in position being effected quickly on account of
difference in areas of the two exposed sides of the valve. This communication is
closed by the valve 33 so long as there is sufficient pressure in the brake cylinder
acting on its larger area to overcome the pressure on the small area, and thus the
pressure is retained in the train pipe until the triple valve is brought to its exhaust
position to relieve the pressure in the brake cylinder. As soon as the brake
cylinder pressure has exhausted to the atmosphere or nearly so, the train pipe
pressure will move the valve 33 back to its normal position, Fig. 9, opening the
bye-passage F'.
In the modification shown in Figs. 15 and 16 the double seated check valve 13
is formed of two separable parts so that during ordinary operation a sufficient
opening is left to allow the pressure to pass the check valve into the valve
chamber 2, and at another time provide a larger opening to allow the pressure to
pass the check valve more freely and quickly. This check valve is provided with
a disk 13ª which in diameter nearly approaches the valve space 5" so that a very
small annular passage for the pressure is formed when the valve is between its
two seats 13ª, 13. The disk 13ª has larger openings 13 and is mounted on the
upper stem of the valve and held yielding against the top of the valve by a
spring 13. In the usual operations of the check valve 13 both of its parts move
together as a single piece and the larger openings 13 through the disk are not
exposed, as in Fig. 15, but when the free flow of air from the train pipe is needed
as in emergency position, the end of the valve stem 18* strikes the stop or stop
finger 18, as in Fig. 16, arresting the upward movement of the valve 13 but
allowing the air pressure upon the disk 13d to move such disk upward against the
pressure of the spring 13 and against the upper seat 13, thus having separated
from the valve 13 and opened the larger openings 13 for the free passage of the
train pipe pressure through the valve. This separable two part check valve
renders it possible to confine as much of a slowly accumulating train pipe pressure
as possible to the back of the operating piston 15 so that its proper and timely

page_text: movement is ensured. When the train pipe pressure is raised slightly it is
permitted to pass the check valve 13 through a minimum sized opening and thence
into the auxiliary reservoir without affecting the position of the triple valve as
when the parts are in Fig. 11 position to recharge said reservoir while the brakes
are held on; but should such pressure be increased the check valve will seat
against its upper seat; and when at emergency position the maximum sized
opening is formed by the separation of the two parts of the valve. By making the
check valve in two parts in this manner, the upward blow of the end 18* against the
stop 18 is lessened and all danger of the stem 18 being bent avoided.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
:-
1. A triple valve having two positions at an equilibrium of pressure, one
normally holding the brake cylinder open to exhaust and the other holding
pressure in the brake cylinder while the auxiliary reservoir is being recharged.
2. A triple valve having an imperforate operating piston with the train pipe
passage to the auxiliary reservoir on one side of said piston and a passage from
the train pipe leading only to the opposite side of the piston with a check valve in
the train pipe passage.
3. A triple valve having a yielding stop ceasing its action upon the triple valve
as soon as the valve has closed communication between the auxiliary reservoir and
the brake cylinder.
4. The slide valves, substantially as shown in Figs. 1 to 8 inclusive.
5. A triple valve in which the service stop port and the exhaust controlling port
are moved at one time one in advance of the other so that the brake cylinder is
held open to exhaust for a longer period.
6. The slide valves substantially as shown in Figs. 9 to 14 inclusive.
7. The positive release valve retaining the pressure in the train pipe and confining
it so as to act only on one side of the operating piston to effect the movement of
the triple valve quickly and absolutely to exhaust position at the desired time.
8. The positive release valve of differential areas controlled by pressure in the
brake cylinder.
9. A stop or stop-finger for preventing the seating of the check valve in the
train pipe passage.
10. An automatically operated piston carrying the stop-finger to prevent the
seating of the check valve upon an emergency stop.
11. The automatically operative piston opening a passage from the auxiliary
reservoir to the brake cylinder independent of the triple valve.
12. The two part check valve, the two parts of which are separable to provide
a larger opening past the check valve.
Dated this 23rd day of October 1893.
CRUIKSHANK & FAIRWEATHER,
62, Saint Vincent Street, Glasgow, Agents.