IMPROVEMENTS IN AUTOMATIC BRAKES WORKED BY FLUID PRESSURE
Year: 1879

page_text: LETTERS PATENT to Edward Dunning Barker, of 45, Bedford Row, in the
County of Middlesex, for the Invention of "IMPROVEMENTS IN AUTOMATIC
BRAKES WORKED BY FLUID PRESSURE."
Sealed the 20th January 1880, and dated the 23rd July 1879.
PROVISIONAL SPECIFICATION left by the said Edward Dunning Barker
at the Office of the Commissioners of Patents on the 23rd July 1879.
EDWARD DUNNING BARKER, of 45, Bedford Row, in the County of Middlesex.
"IMPROVEMENTS IN AUTOMATIC BRAKES WORKED BY FLUID PRESSURE."
The object of this Invention is to enable brakes that are automatic in their
action (or which are self applied if the train becomes disconnected) to be used
effectually in the ordinary working of trains. For this purpose it is requisite that
the brakes should be capable of being applied with greater or less force, and that
provision should be made for increasing or diminishing this force at the pleasure of
the engine driver or operator.
In the automatic brakes at present in use air or other fluid is stored under
pressure in reservoirs upon the carriages, and when the brakes have to be applied
the fluid is allowed to pass from the reservoirs into the brake cylinders; valves
being then permitted to open by the reduction of the pressure in a main pipe laid
along the train. There is a small piston in connection with each valve, and when
the piston is thus relieved from pressure on one side it yields to a counter pressure
on the other side, thereby moving the valve and permitting the fluid to flow from
the reservoir to the brake cylinder. When the pressure in the main pipe is
restored the piston operates to close the communication between the reservoir and
the brake cylinder, and to open a passage for the escape of the air or fluid from the
brake cylinder.
Now in such automatic brakes, in order that the amount of pressure upon the
brakes may be completely under control, I employ a regulating cylinder in com-
munication with the brake cylinder, and containing another piston also connected
with the admission and exhaust valve of the brake cylinder. When there is
pressure within the brake cylinder this pressure operating on the piston in the
regulating cylinder acts in conjunction with the pressure in the main pipe to hold
the valve closed to the passage of fluid from the reservoir to the brake cylinder, and

page_text: open for the escape of fluid froin the brake cylinder. With this arrangement a
reduction of pressure in the main pipe first causes the valve to open as usual for
-the-passage of air or fluid-from-the-reservoir-into-the-brake-cylinder, but-this-only-
continues until the pressure in the brake cylinder is such that acting in the
regulating cylinder in aid of the pressure on the valve piston, the two together
suffice to close the valve again against the passage of fluid from the reservoir to
the brake cylinder.
Thus the pressure in the brake cylinder is at all times dependent on the pressure
in the main pipe, and whatever may be the pressure in the brake cylinder at any
time a slight increase in the pressure in the main pipe (which is under the direct
control of the engine driver or operator) causes a corresponding diminution of the
pressure in the break cylinder; and a decrease in the pressure in the main pipe
causes a corresponding increase of pressure in the regulating cylinder and in the
brake cylinder.
Regulating cylinders may be applied in the manner I have described to the
existing valves of automatic brakes, but I prefer the following arrangement :-
I employ two pistons of different sizes formed in one piece or fixed on the same
rod; these pistons are received into a cylinder bored to two diameters to fit the
pistons. The main pipe communicates with the end of the cylinder in which the
smaller piston works: There is also an aperture in this part of the cylinder by
which the air or fluid can pass from the cylinder past a check valve (which
prevents return) into a valve box on the side of the cylinder, and from this valve
box by a pipe to the reservoir. The valve box contains a slide valve working over
two ports, one being an opening into the centre part of the cylinder or to the space
between the two pistons, which space is always in communication with the brake
cylinder and the other being an outlet passage by which the fluid is allowed to
escape from the brake cylinder when it is necessary to reduce the pressure upon
the brake blocks. The valve moves with the pistons with which it is connected by
a stud or projection passing through the first mentioned port or passage. A coiled
spring abuts upon the larger piston tending to force the pistons to the end of the
cylinder, at which the air or fluid under pressure enters it from the main pipe.
When the fluid in the main pipe is at the full working pressure the spring is over-
come and the pistons are pressed back; the valve is thus placed in such a position
that the centre space between the pistons is in communication with the exhaust
passage, so that no pressure is retained either here or in the brake cylinder.
Hence at this time the brakes are off, and the reservoir is charged under pressure.
When a reduction is made in the pressure in the main pipe the pistons nove
under the influence of the spring carrying the valve with them, thereby closing the
exhaust passage and opening the port by which fluid enters between the pistons;
the passage of fluid from the reservoir to the brake cylinder is thus permitted. As
the pressure accumulates between the pistons however it acts on the piston of the
larger area in such manner as to aid in compressing the spring, and when a
-sufficient compensation-is thus obtained-for-the-reduction-of-pressure which has
been made in the main pipe the pistons return carrying back the valve, so that no
further rise of pressure in the brake cylinder can take place until a further
reduction of pressure is made in the main pipe. On the other hand when the
pressure in the main pipe is increased the pistons and valve move in the contrary
direction;
and fluid is permitted to escape from the brake cylinders, reducing the
pressure therein or relieving it entirely so as to take off the brakes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Dunning Barker in the Great Seal Patent Office on the
23rd January 1880.
EDWARD DUNNING BARKER, of 45, Bedford Row, in the County of Middlesex.
"IMPROVEMENTS IN AUTOMATIC BRAKES WORKED BY FLUID PRESSURE."
The object of this Invention is to enable brakes that are automatic in their
action (or which are self applied if the train becomes disconnected) to be used
effectually in the ordinary working of trains.
For this purpose it is requisite that the brakes should be capable of being applied
with greater or less force, and that provision should be made for increasing or
diminishing this force at the pleasure of the engine driver or operator.
In the automatic brakes at present in use air or other fluid is stored under
pressure in reservoirs upon the carriages, and when the brakes have to he applied
the fluid is allowed to pass from the reservoirs into the brake cylinders, valves
being then permitted to open by the reduction of the pressure in a main pipe laid
along the train. There is a small piston in connection with each valve, and when
the piston is thus relieved from pressure on one side it yields to a counter pressure
on the other side, thereby moving the valve and permitting the fluid to flow from
the reservoir to the brake cylinder. When the pressure in the main pipe is
restored the piston operates to close the communication between the reservoir and
the brake cylinder, and to open a passage for the escape of the air or fluid from the
brake cylinder.
Now in such automatic brakes in order that the amount of pressure upon the
brakes may be completely under control, 1 employ a regulating cylinder in
communication with the brake cylinder, and containing another piston also
connected with the admission and exhaust valve of the brake cylinder. When
there is pressure within the brake cylinder, this pressure operating on the piston in
the regulating cylinder acts in conjunction with the pressure in the main pipe to
hold the valve closed to the passage of fluid from the reservoir to the brake
cylinder, and open for the escape of fluid from the brake cylinder. With this
arrangement a reduction of pressure in the main pipe first causes the valve to open
as usual for the passage of air or fluid from the reservoir into the brake cylinder,
but this only continues until the pressure in the brake cylinder is such that acting
in the regulating cylinder in aid of the pressure on the valve piston, the two
together suffice to close the valve again against the passage of fluid from the
reservoir to the brake cylinder. Thus the pressure in the brake cylinder is at all
times dependent on the pressure in any main pipe, and whatever may be the
pressure in the brake cylinder at the time, a slight increase in the pressure in the
inain pipe (which is under the direct control of the engine driver or operator)
causes a corresponding diminution of the pressure in the brake cylinder; and a
decrease in the pressure in the main pipe causes a corresponding increase of
pressure in the regulating cylinder and in the brake cylinder.
In the Drawings hereunto annexed I have shewn four ways of arranging the
valve apparatus of automatic brakes to act in the manner above described: this
valve apparatus is fitted upon each of the carriages of a train that is furnished
with automatic brake apparatus.
In the arrangement shewn at Figure 1, A is the inlet from the main pipe which
passes from end to end of a train, and contains air or other fluid under pressure ;
B is the outlet to which is attached a pipe leading to the cylinders of the brake
apparatus of the carriage upon which the valve apparatus is fitted; C is the
passage communicating with a reservoir in which air or other fluid is stored up
under pressure; and D is the outlet or exhaust passage by which the air or fluid is
allowed to escape froin the pipe B. which leads to the brake cylinders.

page_text: The air or other fluid under pressure passing in through the inlet A enters the
lower part of a cylinder E, in which is a piston F; the upper part of this cylinder
is-bored to a larger diameter, and in it is a piston G which forms the regulating
piston the pistons-are-as-shewn-fixed-or-formed on one rod, and above_the_larger
piston is a coiled-spring-H-which-tends-always-to-force-the-pistons downwards..
The spring is contained within a cap which closes the top of the cylinder E as
shewn. From the bottom of the cylinder E is formed a small passage I, by which
air or fluid can pass from the cylinder E-to-a-valve-chamber-J; the passage-I is.
fitted with a stop valve as shewn, to prevent any air or fluid which has entered the
_valve.chamber from passing back to the bottom of the cylinder E. In the valve
chamber J is also a slide valve K, which in the position shewn in the Drawing
closes a passage from the valve chamber to the central part of the cylinder E inter-
mediate of the two pistons which it contains, and in the arrangement shewn in this
Figure the slide valve is also formed to at the same time open a communication
between this part of the cylinder and the small exhaust passage D, so allowing air
or fluid under pressure to escape from this part of the cylinder and from the pipe
which passes from this part of the cylinder to the cylinders of the brake apparatus.
The stein of the pistons F, G, is connected by a pin L with the slide valve K, so
that when the pistons are forced downwards by the coiled spring H the slide valve
is moved downwards also, and then closes the communication between the central
portion of the cylinder and the exhaust passage, and opens a communication
between this part of the cylinder and the reservoir containing air or fluid under
pressure, so that this air may pass to the pipe leading to the brake cylinders, and
so cause the brakes to be applied. The slide valve is held up to the valve seat
against which it works by a small plate M. pressed against the back of the valve by
a coiled spring. At the bottom of the valve chamber is a receptacle N in which
if air under pressure is the fluid being used for applying the brakes any water
which may be deposited from the air may collect. This receptacle may from time
to time be unscrewed and emptied.
The action of the apparatus is as follows:-
When air under pressure enters the inlet A it acts against the underside of the
piston F, and also passes through the passage I and to the air reservoir and brake
cylinders; when the pressure on the two pistons F and G is sufficiently high to
overcome the pressure of the spring H, the pistons lift into the position shewn in
the Drawing. Air then continues to pass through the passage I and so to the
reservoir, and as the pressure rises below the piston F the piston again lifes and
opens the exhaust until the downward pressure of the spring again exceeds the
sum of the pressures on the two pistons, and this goes on until the pressure on the
bottom of the piston F is sufficient of itself to overcome the spring; there is then
à free exit for air from the brake cylinders, whilst the pressure of air in the
reservoir is maintained at the same pressure as the air in the main pipe. When
however the pressure-in-the-main-pipe-is-reduced by letting air escape from it, the
spring H forces the pistons downwards and shifts the slide valve so that air may
pass from the reservoir to the cylinders of the brake apparatus, and so soon as the
pressure of the air passing to the brake cylinders and also acting on the under side
of the piston G is sufficient when added to the diminished pressure acting on the
under side of the piston F to overcome the spring H the pistons again rise and
shift the slide valve, so as to cut off any further supply of air under pressure to the
brake cylinders. Thus if the effective area of the piston G is the same as the area
of the bottom piston and the pressure of air in the main pipe is reduced, say, from
60 lbs. to 30 lbs. to the inch, the pistons would be forced down by the spring H and
air under pressure would pass to the brake cylinders until the pressure of air in
these cylinders had risen to 30 lbs. to the inch, the sum of the pressures on the
pistons F and G would then overcome the spring H, and all further supply of air.
under pressure would be cut off from the brake cylinders, and the acting pressure
in these cylinders would cease to increase. Thus the pressure of air in the pipe
passing to the cylinders used for applying the brakes to the wheels will be

page_text: controlled by the pressure of air in the main supply pipe, and when the pressure in
the inain supply pipe acting on the under side of the piston is sufficient by itself to
overcome the spring H, the pressure of air in the pipe leading to the brakes
becomes the same as the pressure of the external air.
A precisely similar arrangement of apparatus to that above described is shewn
at Figure 2, except that in the arrangement shewn at Figure 2 diaphragmns are
used in place of pistons.
The arrangement shewn at Figure 3 differs from that shewn at Figure 1 in
that the slide valve K is used only to control the passage of air from the air
reservoir to the pipe leading to the brake cylinders, whilst the escape of air from
the pipe leading to the brake cylinders is controlled by a separate valve O pressed
down towards its seat by a coiled spring P, and held up from its seat by the
pressure of air in the pipe leading to the brake cylinders, and also by the pressure
of air in the main supply pipe acting upon the bottom of a piston Q contained
within a cylindrical cavity in the piston F. When the sum of the pressures upon
the under side of the piston Q and the valve O are sufficient to overcome the
spring P the valve O opens, but when the sum of the upward pressures is less than
the downward pressure of the spring the valve closes. Thus the action of the
apparatus will be precisely the same as the action of the one first described. The
only difference is that in the arrangement first described one regulating piston G
is used to control, not only the supply of air to the pipe leading to the brake
cylinders, but also the exit of air from this pipe; whereas in the arrangement
shewn in Figure 3 it only controls the supply of air to the pipe, and the exit of
air from the pipe is controlled by a separate valve and regulating piston. The
strength of the springs H and P should be so proportioned that the valve O shall
remain closed until the sum of the pressures on the two pistons is somewhat more
than sufficient to close the inlet slide valve.
The arrangement shewn at Figure 4 shews how the valve apparatus of what is
known as the Westinghouse brake may have a regulating cylinder combined with
it to enable the apparatus to be used as above described, so that in the ordinary
working the pressure of air used for applying the brakes can be controlled and
varied with the greatest ease. The same letters of reference are used as in the
former Figures.
acts on the bottom of the
Air can then leak past the
Afterwards if the pressure
This
When the pressure of air in the main supply pipe
piston Fit holds up this piston in the position shewn
piston by the small passage I and fill the air reservoir.
in the main supply pipe is rapidly lowered the pressure of air acting on the top of
the piston is greater than on the bottom, and the piston is forced down.
shifts the slide valve and permits air to pass from the air reservoir to the pipe
leading to the brake cylinders, and also, as the Drawing shews, to a cylinder in
which the regulating piston G works, and when the combined pressures upon the
under sides of the pistons F and G are greater than the pressure of air upon the
top of the piston F the pistons will again rise and shift the slide valve, so con-
trolling the pressure at which the air is allowed to act in the cylinders by which
the brakes are applied, as in the arrangements of apparatus previously described.
Having thus described the nature of my Invention and the manner of performing
the same, I would have it understood that I do not confine myself to the precise
arrangements of mechanism shewn, in the Drawings hereunto annexed, but
I claim,
First. The construction of automatic brake apparatus with a regulating piston or
diaphragın acting substantially in the manner herein before described to control
the passage of air or other fluid from each of the several air or fluid reservoirs on
the several carriages to the pipes leading to the cylinders of the mechanism by
which the brakes are applied.
Second. The construction of automatic brake apparatus acting substantially in
the manner herein before described.

page_text: Third. The construction of automatic brake apparatus, substantially in the ways.
herein before described and shewn in the Drawings annexed.
In witness whereof, I, the said Edward Dunning Barker, have hereunto set
my hand and seal, this Twenty second-day-of-January-in-the-year-of-ourt
Lord One thousand eight hundred and eighty.