IMPROVEMENTS IN STEAM BRAKE VALVES
Year: 1880

page_text: LETTERS PATENT to John Dewrance, of 176, Great Dover Street, Borough, in
the County of Surrey, and Bowman Malcolm, of Belfast, in the County of
Antrim, for an Invention of "IMPROVEMENTS IN STEAM BRAKE VALVES."
PROVISIONAL SPECIFICATION left by the said John Dewrance at the
Office of the Commissioners of Patents on the 24th September 1880.
JOHN DEWRANCE, of 176, Great Dover Street, Borough, in the County of Surrey,
and BOWMAN MALCOLM, of Belfast, in tho County of Antrim. "IMPROVEMENTS
IN STEAM BRAKE VALVES."
This Invention has for its object improvements in steam brake valves.
In working steam brakes it is required that steam should be admitted from the
boiler to the brake cylinder at pressures varying according to the greater or less
force with which it is desired that the brakes should be applied.
This has been done by employing a valve sufficiently loaded to keep it on its
seat until it is required that steam should pass from the boiler to the brake cylinder.
When the brakes are to be put on, a handle is moved by the engine driver a greater
or less distance, according to the degree of pressure with which he desires the
brakes to be applied. The movement of the handle influences the valve through a
spring (either that by which the valve is loaded, or another), and the valve-being
thus relieved or aided to rise, steam from the boiler passes it and enters the brake
cylinder. Pressure thus accumulates in the brake cylinder and at the back of the
valve, and this pressure deprives the valve of the relief or aid which caused the
valve to rise from its seat, and consequently it closes and prevents any increase of
pressure in the brake cylinder. When the handle is moved back an exhaust valve
is opened, which permits the steam to escape from the brake cylinder.
In an arrangement of this sort employed by one of us under a Patent, No. 4553,
in the year 1879, a double or equilibrium valve is employed, which is raised from
its seat by the piston when this is moved upwards, by the handle acting through an
external spring. We now apply the spring within the piston, which is made hollow
to receive it, and the spring is in compression, not in tension as before. A bracket
from the side of the cylinder carries the axis of the band lever. A short arm of the
D11

page_text: lever enters through slots in the sides of the cylinder and piston, and by means of
a jointed finger supports a button upon which the base of the spring rests. The
arrangement is such that in case the spring should break or become inoperative, the
piston will still be moved by the operation of the short arun of the lever, but
the automatic control over the pressure which the spring affords will be tem-
porarily lost.
The short arm of the lever also comes against a part of the piston and causes the
piston to return if it has any tendency to stick. The return of the piston permits
the steam to escape from the brake cylinder, and the brakes are then taken off.
If it be desired to apply a stop valve in case the equilibrium valve should leak,
we do so by providing another arm upon the hand lover, and this arm operates the
stop valve, forcing it away from its face when the handle is first moved, and so
admitting the steam to the equilibrium valve. In this way the advantages to be
derived from the use of a stop valve are attained, without its being possible that
the stop valve should be closed when the brake power is required.
In some cases in the same arrangement we substitute for the equilibrium valve
a simple cone valve, loaded with a spring which is competant to hold it to its seat
against the pressure of the boiler steam. The projection upon the upper side of
the piston then operates upon a flange formed upon the valvo above its scat.
Sometimes we employ a cone valve loaded with a spring, which when fully
compressed holds it on its seat against the pressure-of-the-steam in-the-boiler. -
The pressure is put on this spring by a bonnet screwed into the valve case, and
which bonnet.has.a.square_projection on it fitting into a corresponding cavity on
the underside of a circular disc valve, which is actuated by a hand lever.
The circular disc valve serves as a cut off for the steam supply on one side, and-
as an exhaust valve on the other side. The disc is kept on its seat by the pressure
of a nut acting upon a ring of asbestos packing, which rests on a shoulder on the
spindle of the disc valve and also forins the stuffing box.
In place of the disc valvo wo sometimes employ a slide valve which serves as a
cut off for the steam supply, and also forms the exhaust valve. An inclined
plane on the underside regulates the position of the bonnet which compresses the
spring.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Dowrance in the Great Seal Patent Office on the 24th March
1881.
JOHN DEWRANCE, of 176, Great Dover Street, Borough, in the County of Surrey,
and BOWMAN MALCOLM, of Belfast, in the County of Antrim. "IMPROVEMENTS
IN STEAM BRAKE VALVES."
This Invention has for its object improvements in steam brake valvos.
In working steam brakes it is required that steam should be admitted from the
boiler to the brake cylinder at pressures varying according to the greater or less
force with which it is desired that the brakes should be applied.
This has been done by employing a valve sufficiently loaded to keep it on its
seat until it is required that steam should pass from the boiler to the brake cylinder.
When the brakes are to be put on, a handle is moved by the engino driver a greater
or less distance, according to the degree of pressure with which ho desires the
brakes to be applied. The movement of the handle influences the valve through a
spring (either that by which the valve is loaded, or another), and the valve being
thus relieved or aided to rise, steam from the boiler passes it and enters the brake
cylinder. Pressure thus accumulates in the brake cylinder and at the back of the
valve, and this pressure deprives the valve of the relief or aid which caused the
valve to rise from its sent, and consequently it closes and prevents any increase of
pressure in the brake cylinder. When the handle is moved back, an exhaust valve
is opened, which permits the steam to escape from the brake cylinder.
In an arrangement of this sort, employed by one of us under a Patent, No. 4553,
in the year 1879, a double or equilibrium valve is employed, which is raised from
its seat by the piston, when this is moved upwards by the handle acting through
an external spring. We now apply the spring within the piston, which is made
hollow to receive it, and the spring is in compression, not in tension as before. A
bracket from the side of the cylinder carries the axis of the band lever. A short
arm of the lever enters through slots in the sides of the cylinder and piston and
(by means of a jointed finger) supports a button upon which the base of the spring
rests. The arrangement is such that in case the spring should break or become
inoperative the piston will still be moved by the operation of the short arm of the
lever, but the automatic control over the pressure which the spring affords will be
temporarily lost. The short arm of the lever also comes against a part of the piston
and causes the piston to return if it has any tendency to stick. The return of the
piston permits the steam to escape from the brake cylinder, and the brakes are
then taken off.
If it be desired to apply a stop valve in case the equilibrium valve should leak,
we do so by providing another arm upon the hand lever, and this arm operates the
stop valve, forcing it away from its face when the handle is first moved, and so
admitting the steam to the equilibrium valve. In this way the advantages to be
derived from the use of a stop valve are attained without its being possible that
the stop valve should be closed when the brake power is required.
In some cases in the same arrangement we substitute for the equilibrium valve a
simple cone valve loaded with a spring, which is competent to hold it to its
seat against the pressure of the boiler steam. The projection upon the upper
side of the piston then operates upon a flange formed upon the valve above its
seat.
Sometimes we employ a cone valve loaded with a spring, which, when fully
compressed, holds it on its seat against the pressure of the steam in the boiler.

page_text: The pressure is put on this spring by a bonnet screwed into the valve case, and
which bonnet has a square projection on it fitting into a corresponding cavity on
the underside of a circular disc valve which is actuated by a hand lever.
The circular disc valve serves as a cut off for the steam supply on one side and
as an exhaust valve on the other side. The disc is kept on its seat by the pressure
of a nut acting upon a ring of asbestos packing, which rests on a shoulder on the
spindle of the disc valve, and also forms the stuffing box.
In place of the disc valve we sometimes employ a slide valve which serves as a
cut off for the steam supply, and also forms the exhaust valve. An inclined
plane on the underside regulates the position of the bonnet which compresses the
spring.
In order that our Invention may be most fully understood and readily carried
Figure 1 is an elevation, and Figure 2 is a vertical section of a steam brake 1
valve constructed according to our Invention; Figure 3 is a vertical section of the
shell of the apparatus with the moving parts removed; Figure 4 is an horizontal
section on the line 1, 1, in Figure 3; a and a¹ are the scats formed in the shell for
the double or equilibrium valve b. The passage cc, by which steam is..admitted.
from the boiler terminates between the seats a and a; d is a cap closing the
-upper-part.of the shell; it contains within it a spring e, which is able (but not
much more than able) to keep the double valve to its seats, notwithstanding the
difference in area of the passages at a-and-a: The-upper-passage-is made-larger_
than the lower in order that the valve may be able to enter. The cap d is made
to receive a pressure gauge which will indicate the pressure applied to the brakes ;
ff, is the portion of the shell which forms the cylinder, and g is a hollow piston
working within it. The piston is supported by the spring h which is within or
beneath it, and the base of the spring rests upon the button i. The bracket f¹,
projecting from the cylinder f, carries the pin k, forming the axis for a hand lever l.
These parts are seen in Figure 5, which is an horizontal section on the line 2, 2, in
Figure 1; Figure 6 is an elevation of the lower part of the cylinder f, and Figure 7
is a longitudinal section of the piston g.
The hand lever works along a ratchet sector on the shell which serves to retain
it in any position in which it may be placed. It has an arm l, and to this the
finger m is jointed; its free end enters a recess in the head of the button i, and
the movement of the hand lever is so transmitted to the button.
The button when moved upwards operates through the spring h upon the
piston g. raising it into contact with the double valve b, and then lifting this valve
from its seat so that the steam is able to issue into the chamber n, which by the
passage o is in direct communication with the cylinder or apparatus by which the
brake is applied. The head of the piston g is exposed to any pressure there may
be in the chamber n, and the spring has to sustain this pressure before any
further action can take place upon the valvo b, or more steam be drawn from the
boiler.
The button i, it will be observed, has a stem which when the spring / is fully
compressed comes into direct contact with the piston g, so that when the hand
lever is fully drawn back and so remains, the brakes are applied with the full
force of the boiler pressure, and in this way the hand lever can operate direct upon
the valve, in case the spring should happen to break.
The Drawings represent the piston g in its lowest position, and then there can
be no pressure in the chamber n or operating upon the brakes, for in this position
the piston leaves the port p uncovered, and this port opens into a free outlet
passage marked with the same letter. The hand lever can also operate directly to

page_text: draw back the piston, for when it is placed in the position in which it is indicated
in Figures 1 and 2, the end of its arm l' comes into contact with the plug forming
the lower end of the piston, and moves it downwards even if the spring should be
set fast and inoperative. It is a considerable advantage in this apparatus that it
is not rendered useless by the breaking of the spring.
If it be desired to have a stop valve in addition to the valve b, which may some-
times leak, such a valve may be provided and operated by another arm upon the
hand lever l.
Figure 8 is a vertical section of a steam brake valve constructed according to
our Invention, and in which a stop valve is employed.
Here is also a very important development of our Invention, viz., simplifaction of
our apparatus, by adapting the piston itself to serve as the valve in place of
employing separate parts. In Figure 8 the parts are shown in the position of rest
and with no pressure applied to the brakes.
Figure 9 shows a vertical section of the apparatus, but the position here is that
in which the parts stand when the brakes are applied with a force corresponding
to the position in which the lever handle stands. Figure 10 is a section on the
line 1, 1, in Figure 9. The piston, spring, button, and hand lever are lettered as in
the Figures already described. It will be observed that in this case the hand lever
operates directly upon the button, and the jointed finger is dispensed with. q is the
stop valve in the passage by which the steam comes from the boiler. It is furnished
with a spring to ensure its closing, and when the hand lever is used to apply the
brakes, the stop valve is lifted by a stem r which rests upon a cam like arm
or projection of the hand lever 7. The steam from the boiler after passing the
stop valve arrives at the port 8, and when this port is uncovered it passes into the
chamber n, which is in direct communication by the passage o with the cylinder or
apparatus by which the brake is applied. When the parts are in the position in
which they are represented in Figure 9, the pressure applied to the brakes and
the pressure in the chamber n is such that, operating upon the piston g, it is
competent to compress the spring h to the extent indicated, and to the point of
just closing the steam port 8. When the piston is raised a little higher than the
position in which it is here shown, the recess g² in it comes opposite to the steam
port s, and the steam has vent into the chamber n, the piston being grooved at
the back to give it free passage. In the position in which the parts stand in
Figure 8 the outlet port p is open.
In some cases steam brakes on the engine are arranged to cooperate with vacuum
brakes on the train. Our steam brake valve with a slight modification is well
suited for use in this manner. A vacuum chamber such as is used on the carriages,
but smaller, is applied also upon the engine, not to act directly on the brakes, but
upon the handle of the steam break valve. We adapt our steam brake valve
Figures 8, 9, and 10, to be used in this way by omitting the spring h (the vacuum
apparatus itself being an atmospheric spring), and causing the lever corresponding
to the hand lever to act directly upon the piston g. When the vacuum in the
connecting pipes is destroyed or lessened in order that the brakes may be applied,
the pressure of the air on the piston in the vacuum chamber moves the lever of the
steam brake valve, and causes the brakes to be applied with more or less
force according to the amount of the unbalanced pressure on the piston in the
vacuum chamber; Figure 11 is a vertical section showing an arrangement similar
to that first described, except that the double or equilibrium valve b is replaced
by a simple cone valve loaded with a spring competent to resist the full boiler
pressure.
Figure 12 is a plan; Figure 13 a front elevation, and Figure 14 is also a front
elevation, but with the cover removed; Figure 15 is a section on the line A, B, in
Figure 14; Figure 16 is a section on the line C, D, in Figure 14, and Figure 17 is
a section on the line E, F, in Figure 16, of another arrangement in which a simple
cone valve is used; it is employed in combination with a circular disc valve,

page_text: serving both as a stop valve and for controlling the exhaust. The cone valve and
the disc valvo are also coupled together, so that by turning the latter the load or
spring pressure upon the former can be lessened or increased.
a is the shell or case containing the cone valve b, and faced for the disc valve o
to work upon it. The surface of the valve c which is against the face is shown at
Figure 18 d is the cover by which the disc valve is kept in place; there is a
stuffing box upon it through which the stem of the valve passes. The stuffing box
serves to make a steam tight joint, and also to keep the disc to the face with the
requisite pressure; e is a bonnet which scrows into a recess in the shell a, and
contains the spring f. The bonnet has a square stem which enters a corresponding
recess in the face of the disc valve, so that the disc valve and bonnet turn together,
and they are both moved by means of the hand lever g, which is fixed upon the
stem of the disc valve. The spring f presses the valve b towards its seat, and it is
so adjusted that when the hand lever g is at one end of its course, the spring is
compressed by the bonnet e to such an extent that the valve will remain closed
under the full boiler pressure. In the other extreme position of the hand lever the
spring exerts little or no pressure upon the valve; these adjustments however admit
of some variation; h is a passage by which steam is taken from the boiler, and i is
a passage by which this steam passes beneath the valve b. This however it is not
free to do until the hand lever has been moved so that the cavity c' of the valvo
covers the ends of both passages and i. The same movement of the band lever
so far relieves the pressure upon the valve b that the steam is able to pass it. The
steam then goes to the. brake cylinder by the passage ; but after a time, as with
the valve apparatus.previously-described,-its-pressure-accumulates-at-the-back-of-
the valve sufficiently to cause the valve to close.
k
To take off the brakes the hand lever is moved back, which closes the steam
passage h, and also puts the passage & leading to the brakes into communication
with the outlet passage, the mouths of these two passages being then both
covered by the cavity in the valve c.
We can substitute a slide valve for the disc, and arrange an incline on the
slide to operate upon the bonnet; but the arrangement shown is that which we
prefer.
Having thus described the nature of our said Invention, and the manner of
performing the same, we would have it understood that we claim,—
First. Our improved steam brake valves, substantially as described and
illustrated by the Drawings.
Second. The combination in a steam brake valve of a piston, a spring, and a
hand lever; the hand lever operating on the piston through the spring, and in the
case of the breakage of the spring being capable also of operating the piston
directly, substantially as described.
Third. The combination in a steam brake valve of a piston, a spring, a band
lever, and a stop valve; the hand lever operating on the piston through the spring,
and also opening and closing the stop valve, substantially as described.
Fourth. The use in a steain brake valve of a piston influenced in opposition to a
spring by the steam pressure operative upon the brakes, such piston also forming a
slide valve governing the passage of steam to the brake apparatus, substantially
as described,
Fifth. The combination in a steam brake valve of a disc or rotating or slide
valve, and a spring loaded valve; this disc or rotating or slide serving as a stop
valve, and the spring loaded valve serving to admit steam to apply force to the
brakes; the combination being such also that the movement of the stop valve in
the direction of opening progressively lessens the pressure of the spring upon the
spring loaded valve, substantially as described.
Sixth. The combination in a steam brake valve of a disc or rotating valve and a
spring loaded valve; the disc or rotating valve serving as a stop valve, and the
spring loaded valve serving to admit steam to apply force to the brakes; the

page_text: combination being such also that the disc or rotating valve when moved turns a
screwed bonnet, and so varies the pressure of the spring upon the loaded valve,
substantially as described.
In witness whereof, I, the said John Dewrance, have herounto set my hand
and seal, this Twenty third day of March, in the year of our Lord One
thousand eight hundred and eighty one.
JOHN DEWRANCE. (L.S.)