IMPROVEMENTS IN APPARATUS FOR WORKING RAILWAY BRAKES BY FLUID PRESSURE
Year: 1881

page_text: LETTERS PATENT to John Imray, of No. 28, Southampton Buildings, in the
County of Middlesex, for an Invention of "IMPROVEMENTS IN APPARATUS
FOR WORKING RAILWAY BRAKES BY FLUID PRESSURE." A communication
from abroad by Adolphe Wenger, of Paris, France, Engineer.
PROVISIONAL SPECIFICATION left by the said John Imray at the Office of
the Commissioners of Patents on the 5th January 1881.
"
JOHN IMRAY, of No. 28, Southampton Buildings, in the County of Middlesex.
IMPROVEMENTS IN APPARATUS FOR WORKING RAILWAY BRAKES BY FLUID
PRESSURE." [A communication from abroad by Adolphe Wenger, of Paris, France,
Engineer.]
This Invention relates to the construction and arrangement of apparatus for
working brakes on railway trains by fluid pressure, the chief objects aimed at
being to render the action of the brakes rapid and certain, to maintain them in
action as long as may be necessary, to regulate the braking force as desired, and to
bring the brakes into action automatically in case of accident to the train or to the
apparatus. The pressure employed may be either that of compressed air or the
excess of the atmospheric pressure above that of rarefied air. The following
description applies in the former case, it being understood however that by suitable
inversion of valves and other parts, the apparatus could be arranged for vacuum
action. For working by compressed air, the apparatus is arranged as follows:--An
engine pump on the locomotive compresses air in a reservoir. From this reservoir,
in which for the sake of compactness the pressure may be very high, a pipe leads
the air at reduced but still considerable pressure throughout the train, the reduction
of pressure being effected by a reducing valve worked by a differential piston, on the
smaller area of which the reservoir pressure acts, tending to open the valve whilst
the pressure in the train pipe acts on the larger area tending to close the valve.

page_text: From the first train pipe thus supplied a branch communicates through another
reducing or regulating valve with a second train pipe, this regulating valve having
a piston connected to a spring, the tension of which is adjustable by a hand screw,
so that any desired reduction of pressure may be effected and maintained in the
air supplying the second train pipe. The two train pipes are connected from
carriage to carriage by couplings, each made in two equal and similar halves.
These halves are brought together face to face, and by a partial turn on their
common axis a projecting quadrant rib of the one is made to engage in a corre-
sponding notch of the other. The apertures by which the half couplings com-
municate with one another are provided with caoutchouc lips which act as packings,
preventing leakage when the two halves are connected. It is of advantage to make
these lips in the form of cup leathers laid on their sides, so that the air pressure
acting in their internal cavities bulges them, causing them to press firmly against
each other, and so prevent leakage. The two train pipes as they pass under each
carriage of the train cross each other, so that at each end of the carriage one of the
pipes always presents itself to the same hand, and thus no mistake can occur in
coupling each length to the next. The first or higher pressure pipe is continued
throughout the train without stop-cocks or other interruptions, its end at the last
carriage being closed by a blank half coupling. The second or lower pressure pipe
has a stop cock at each end of every carriage, which stop cock is opened when the
train is made up, but can be closed when the carriages are separated. On each
brake carriage are fixed two vertical brake cylinders, one for each pair of wheels.
The brake piston is in each case of differential area, its lower side having a trunk
by which it is linked to the brake levers. This trunk has a shoulder which, when
the piston is at the lower extreme of its stroke, seats on packing as a valve
preventing leakage. The lower end of the cylinder (which extends some distance
below the piston at its lowest) communicates by a branch pipe and check valve
with the higher pressure train pipe, and the upper end of the cylinder communicates
by a branch pipe and valve box with the lower pressure train pipe, the latter valve
box having a valve governing an outlet passage. This valve is worked by a piston
subject to the, pressure in the branch pipe, and the piston is made with a small hole
or groove, or it may be a small spring valve, allowing passage of air enough to
maintain equal pressure on both sides of the piston under ordinary circumstances,
but not enough when the pressure in the second train pipe is suddenly reduced
either voluntarily or in consequence of accident, for the purpose of putting on the
brakes, in which case the piston is moved so as to open the outlet valve, permitting
the air to escape directly from the upper end of each brake cylinder, the air in the
lower end of the cylinder being in each case retained by the check valve. The lever
worked by each brake piston projects from a rocking shaft, which has short arms
carrying the brake blocks for the one side of each pair of wheels, and other arms
linked to a similar rocking shaft carrying the brake blocks for the other side, so
that when the brake piston ascends, both sets of blocks are pressed against the
wheels, clamping them between them, and when the piston descends the blocks are
released. As the blocks are poised on the arms which carry them, springs are
provided in these arms to keep the upper ends of the blocks from touching the
wheels when the brakes are off. The action of the apparatus is as follows:-As
long as the pressures in the two train pipes are such that the lower pressure acting
on the full area on the upper side of each brake piston balances or nearly so the
higher pressure acting on the smaller annular area on its lower side, the brakes
are held off by the weight of the brake pistons. But when the pressure in the
second train pipe is reduced so that the brake pistons are subjected to greater
pressure below, these ascend, putting on the brakes with a force depending on the
difference of pressure in the two pipes, which difference can be varied at will by
means of the regulating valve on the locomotive, the braking force being thus
under complete control. In the event of fracture or separation of the second train
pipe, the pressure in it being thus reduced, the brakes become automatically applied,

page_text: and should the first train pipe be opened by the same accident, the escape of air
from it does not interfere with the action of the brakes, as the check valves prevent
escape from the lower ends of the brake cylinders. The outlet valves in the
branches leading to the upper ends of the brake cylinders ensure rapidity of action
in putting on the brakes, as they permit direct escape of air from each cylinder
when the pressure in the second train pipe is lowered, and thus no time is lost, such
as would be occupied if the issuing air had to traverse a considerable length of pipe
before escaping. It is of advantage to provide stop cocks in the branches from the
train pipes to the brake cylinders and their valves, so that in case of any of these
being deranged, they can be excluded from the system.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Imray in the Great Seal Patent Office on the 5th July
ss
1881.
JOHN IMRAY, of No. 28, Southampton Buildings, in the County of Middlesex.
'IMPROVEMENTS IN APPARATUS FOR WORKING RAILWAY BRAKES BY FLUID
PRESSURE." A communication from abroad by Adolphe Wenger, of Paris, France,
Engineer.
This Invention relates to the construction and arrangement of apparatus for
working brakes on railway trains by fluid pressure, the chief objects aimed at
being to render the action of the brakes rapid and certain, to maintain them in
action as long as may be necessary, to regulate the braking force as desired, and
to bring the brakes into action automatically in case of accident to the train or to
the apparatus. The pressure employed may be either that of compressed air or the
excess of the atmospheric pressure above that of rarefied air. The following
description applies in the former case, it being understood however that by
suitable inversion of valves and other parts the apparatus could be arranged for
vacuum action.
For working by compressed air the apparatus is arranged as
follows:-
An engine pump on the locomotive compresses air in a reservoir. From this
reservoir, in which for the sake of compactness the pressure may be very high, a
pipe leads the air at reduced but still considerable pressure throughout the train,
the reduction of pressure being effected by a reducing valve worked by a differential
piston, on the smaller area of which the reservoir pressure acts, tending to open the
valve, whilst the pressure in the train pipe acts on the larger area, tending to close
the valve. From the first train pipe thus supplied a branch communicates through
another reducing or regulating valve with a second train pipe, this regulating valve
having a piston connected to a spring, the tension of which is adjustable by a
hand screw, so that any desired reduction of pressure may be effected and
maintained in the air supplying the second train pipe. The two train pipes are
connected from carriage to carriage by couplings, each made in two equal and
similar halves. These halves are brought together face to face, and by a partial
turn on their common axis a projecting quadrant rib of the one is made to engage
in a corresponding notch of the other. The apertures by which the half couplings
communicate with one another are provided with caoutchouc lips, which act as
packings, preventing leakage when the two halves are connected. It is of advantage
to make these lips in the form of cup leathers laid on their sides, so that the air
pressure acting in their internal cavities bulges them, causing them to press firmly
against each other, and so prevent leakage. The two train pipes as they pass under
each carriage of the train cross each other, so that at each end of the carriage one
of the pipes always presents itself to the same hand, and thus no mistake can occur
in coupling each length to the next. The first or higher pressure pipe is continued
throughout the train without stop-cocks or other interruptions, its end at the last
carriage being closed by a blank half coupling. The second or lower pressure pipe
has a stop cock at each end of every carriage, which stop cock is opened when the
train is made up, but can be closed when the carriages are separated. On each
brake carriage are fixed two brake cylinders, one for each pair of wheels or one
double cylinder. The brake piston is in each case of differential area, its one side
having a trunk by which it is linked to the brake levers. This trunk has a
shoulder which, when the piston is at the extreme of its outstroke, seats on packing
as a valve preventing leakage. The outer end of the cylinder (which extends
some distance beyond the piston at its extreme) communicates by a branch pipe

page_text: and check valve with the higher pressure train pipe, and the inner end of a
cylinder communicates by a branch pipe and valve box with the lower pressure
train pipe, the latter valve box having a valve governing an outlet passage. This
valve is worked by a piston subject to the pressure in the branch pipe, and the
piston is made with a small hole or groove, or it may be a small spring valve,
allowing passage of air enough to maintain equal pressure on both sides of the
piston under ordinary circumstances, but not enough when the pressure in the
second train pipe is suddenly reduced, either voluntarily or in consequence of
accident, for the purpose of putting on the brakes, in which case the piston is
moved so as to open the outlet valve, permitting the air to escape directly from
the inner end of each brake cylinder, the air in the outer end of the cylinder being
in each case retained by the check valve. The lever worked by each brake piston
projects from a rocking shaft, which has short arms carrying the brake blocks for
the one side of each pair of wheels, and other arms linked to a similar rocking
shaft carrying the brake blocks for the other side, so that when the brake piston
moves inwards both sets of blocks are pressed against the wheels, clamping them
between them, and when the piston moves outwards the blocks are released. As
the blocks are poised on the arms which carry them, springs are provided in these
arms to keep the upper ends of the blocks from touching the wheels when the
brakes are off. The action of the apparatus is as follows:-As long as the pressures
in the two train pipes are such that the lower pressure acting on the full area on
the inner side of each brake piston balances or nearly so the higher pressure acting
on the smaller annular area on its outer side, the brakes are held off by weights or
springs; but when the pressure in the second train pipe is reduced so that the
brake pistons are subjected to greater outside pressure, these move in, putting on
the brakes with a force depending on the difference of pressure in the two pipes,
which difference can be varied at will by means of the regulating valve on the
locomotive, the braking force being thus under complete control. In the event of
fracture or separation of the second train pipe, the pressure in it being thus
reduced, the brakes become automatically applied, and should the first train pipe
be opened by the same accident the escape of air from it does not interfere with
the action of the brakes, as the check valves prevent escape from the outer ends of
the brake cylinders. The outlet valves in the branches leading to the inner ends
of the brake cylinders ensure rapidity of action in putting on the brakes, as they
permit direct escape of air from each cylinder when the pressure in the second
train pipe is lowered, and thus no time is lost such as would be occupied if the
issuing air had to traverse a considerable length of pipe before escaping. It is of
advantage to provide stop cocks in the branches from the train pipes to the brake
cylinders and their valves, so that in case of any of these being deranged they can
be excluded from the system,
DESCRIPTION OF THE DRAWINGS.
Fig. 1, Sheet I., is a side view, and Fig. 2 a plan shewing the arrangement on a
locomotive of the engine pump P, the high pressure reservoir R charged with air
compressed by the pump P, and communicating by the pipe A with the reducing
valve D, and thence by a branch furnished with a stop cock with the high pressure
pipe A extending along the train. A branch from A after passing the reducing
valve D leads through the second reducing or regulating valve C to the second
train pipe B, which is also provided with a stop cock r, and with another ² used
when the locomotive is separated from the train. Fig. 1, Sheet II., is a side view ;
Fig. 2 an end view, and Fig. 3 a plan shewing the arrangement of the pipes and
brake gear on each brake carriage. The pipes A and B are crossed so that each
presents itself to the same hand at each end of the vehicle. The pipe B has at
each end a stopcock which is kept open when the train is made up, but can be
closed when the vehicles are separated. The brake cylinder F shewn to an enlarged
scale in one form by the longitudinal section, Fig. 4, Sheet II., and in a modified

page_text: form at Fig 5, Sheet II., has two pistons K, K, and side ports a², a², for admitting
air under pressure to put on the brakes, and a port 62 for pressure to take them
off. When the pistons are at the extreme of their out stroke packings e¹ in the
one case and j' in the other case, prevent leakage around their rods or trunks. The
cup leather of Fig. 5, Sheet II., is shewn to an enlarged scale at Fig. 6, Sheet II.,
embraced by a caoutchouc ring to press it tightly against the trunk of the
piston. In the construction shewn in Fig. 4, Sheet II., small pistons P' are
employed instead of trunks working through stuffing boxes. Fig. 7, Sheet II.,
shews a similar single acting cylinder with one piston. When the rod L connecting
the piston with the brake levers extends into the piston and is jointed thereto to
give freedom of lateral movement, it may be connected, as shewn at Fig. 8, Sheet II.,
the rod L¹ being jointed to the piston by a pin at o', and the hole for the pin
being closed by a screw vl with a packing washer 13. Each brake cylinder F may
be disconnected from the train pipes A and B by closing stop cocks 5, 7, in the
communicating branches a¹, 61. Fig. 3, Sheet I., is a vertical section of the
reducing valve D. It is fitted with two pistons p and p¹ of different areas having
their common rod M connected to a valve S. The branch c communicates with the
high pressure reservoir R, and the branch c¹ with the train pipe A and regulator
valve C. The pressure in the latter is reduced in proportion as the area of the
piston p¹ exceeds that of p. Figs. 4 and 5, Sheet I., are sections of the regulator
valve C shewn in two different positions. The cylindrical body of the valve box
is divided by partitions into four compartments d, d, d², d³, and through packings
in these partitions works a plunger I connected by a rod e passing through a
boss g¹ to a head i¹ within a helical spring g, which can be extended or compressed
by a hand screw i working in a nut à attached to the spring. The compartment &
communicates with the train pipe A, the two compartments d' and d³ communicate
with the train pipe B, and d² communicates with an escape aperture Z. The left
end of the plunger I is thus always subject to the pressure in A, and the right end
to the pressure in B. If no force be exerted by the screw the piston I will be
pressed towards the right, admitting air from A to B till the pressures, including
that of the spring g, come to equilibrium. If by means of the screw i the plunger
be drawn towards the left, as shewn in Fig. 5, Sheet I., air will escape from B
through d² and Z until the pressure in B is so far reduced that the superior pressure
in A overcomes the tension of the spring g. Thus there is always maintained in
the train pipe B a pressure less than that in A by the amount that is due to the
tension of the spring g, as determined by the driver working the handscrew i, the
braking force throughout the train being thus adjusted as required by the driver.
Should the pipe B give way the brakes are put on by the superior pressure in the
parts of the brake cylinders communicating with A. Should the pipe A give way
then the piston I of the regulator valve will move to the left, as shewn in Fig. 5,
Sheet I., and the pipe B will become discharged through the aperture Z, having the
same effect of putting on the brakes by the reduction of pressure between the
pistons of the brake cylinders. Fig. 6, Šheet I., shews a modified construction of
the regulator valve, in which a slide 7 is used to govern ports leading respectively
to B and Z, the slide case being in communication with A, so that the pressure in
A acts on the underside of a piston I attached to the slide, while the pressure in B
communicated through a passage l acts on the upper side of I, which is subject to
the force of the spring g adjusted by the screw i and handle m. The brake
cylinder F is connected to the pipes A and B through two interposed valve boxes G
and G¹, as shewn in the transverse section, Fig. 12, Sheet II. The check valve
box G is shewn by two sections at right angles to each other at Figs. 9 and 10
of Sheet II. It is divided by a partition having through it a hole o covered by a
Under the valve the box communicates by the branch a with the train
pipe A, and above the valve it communicates by a branch a with the
ports a², a², of the brake cylinder F; thus compressed air can pass from A to F,
but the valve n closes against its return. p is a stop cock for blowing
out moisture. The escape valve box G¹ (Fig. 12, Sheet II.), is shewn in
valve n.

page_text: vertical section at Fig. 11, Sheet II. It contains a piston t having its rod p
attached to the escape valve q, and having small holes r at its lower end. While
the valve q is seated air can pass from the train pipe B through the holes r to
the port 6 of the brake cylinder F. When by reduction of pressure in the train
pipe B the pressure communicated from the brake cylinder forces the piston t
upwards, the holes r are closed, but the valve q is opened, allowing immediate
escape from the middle of the brake cylinder, so that the brakes are put on. Figs.
7 and 8, Sheet I., shew respectively a plan and section of the half couplings for the
train pipes. It is made with a groove u receiving a dovetail caoutchouc ring v.
Round one quarter of the circumference there is an undercut projection O, and
round the opposite quarter there is a hollow P, the hollow of each half coupling
receiving the projection of the other when the halves are pressed together face to
face and partly turned round their common axis. The flexible tube is attached to
the branch N inclined at about 30° to the plane of the face. Figs. 9 and 10,
Sheet I., shew a modified construction, the projection O being within the packing
ring, and stops Q being provided to limit the extent of turning the halves. Figs.
11 and 12, Sheet I., shew another modification, also Figs. 13 and 14, in which
latter construction the packing ring v is made hollow, so that the internal pressure
bulging it renders the joint tight. For working by vacuum the hollow of the ring v
is made outside so as to be bulged inwards by the superior atmospheric pressure.
The arrangement of the brakes themselves is shewn in Figs. 1 and 2, Sheet II.
Each brake block S has two side cheeks a¹ enclosing the suspending rod 62, which
is jointed at c¹ to the underframe of the vehicle, and at o' to the brake block. If
the brake blocks could turn freely on the pins o¹ they might when the brakes are
off touch the wheels. To prevent this the joints at o' are stiffened, as shewn by
the section to an enlarged scale at Fig. 15, Sheet I., stiff springs d¹ being inserted
in holes of the hangers 62 to bear hard against the cheeks a¹ of the brake blocks.
It is of advantage to provide, as shewn in Fig. 12, Sheet II., a pipe t¹ connecting
the train pipes A and B with a stop cock, by opening which and closing the
one pipe B may be used alone.
When the train is made up all the stopcocks in the several lengths of the pipe B
are open. In separating a train so as to introduce other carriages before uncoupling
the lengths of B, the stop cocks next to the point of separation should be closed in
order to maintain the pressure in the pipe, and not opened until the pipes are
coupled. As if some of the stop cocks should negligently be left closed, the brakes
behind them will be inoperative, the proper condition of the cocks when the train is
made up should be thus tested.
Having thus described the nature of this Invention and in what manner the
same is to be performed, as communicated to me by my foreign correspondent, I
claim in respect of apparatus for working railway brakes by fluid pressure,
First. The combination of two pipes extending along the train with reducing,
regulating, and check and escape valves and brake cylinders baving differential
pistons, all so arranged that a variable but determinable difference of pressure of air
in the two pipes acts on the differential areas of the brake pistons to cause the
brakes to be put on and taken off, substantially as herein described.
Second. The use in combination with the air reservoir R of the reducing valve D,
so arranged that while a comparatively small volume of air is contained in the
reservoir under high pressure, the train pipe A is supplied therefrom with air at
lower pressure, as herein described with reference to Figs. 1, 2, and 3, Sheet I.
Third. The use, in combination with the two train pipes A and B, of the
regulating valve C, whereby the difference of pressure in the two pipes can be varied
at will, as herein described with reference to Figs. 1, 2, 4, and 5, Sheet I.
Fourth. The construction of the check valve G for the high pressure pipe, as
described with reference to Figs. 9 and 10, Sheet II.
Fifth. The construction of the escape valve G₁ for the low pressure pipe, as
described with reference to Fig. 11, Sheet II.

page_text: Sixth. The construction of the brake cylinder described with reference to Figs. 4
and 7, Sheet II.
Seventh. The modified construction of the brake cylinder and its packings,
described with reference to Figs. 5, 6, and 8, Sheet II.
Eighth. The construction of coupling described with reference to Figs. 7, 8, 9, 10,
11, and 12, Sheet I.
Ninth. The modified construction of coupling with hollow packing ring, described
with reference to Figs. 13 and 14, Sheet I.
Tenth. The means described with reference to Fig. 15, Sheet I., for stiffening the
jointing of the brake blocks to their suspending rods.
In witness whereof, I, the said John Imray, have hereunto set my hand
and seal, this Fourth day of July, in the year of our Lord One thousand
eight hundred and eighty one.
JUHN IMKAY.
(L.S.)