Improvements in Apparatus for Working Railway Brakes by Fluid Pressure.
Year: 1890

page_text: Date of Application, 3rd June, 1890
Complete Specification Left, 3rd Mar., 1891-Accepted, 11th Apr., 1891
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Working Railway Brakes by Fluid
Pressure.
I, ADOLPHE WENGER, of No. 23, Boulevard de Strasbourg, Paris, France,
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to improvements in the construction of that description of
fluid pressure railway brake apparatus for which I have previously obtained Letters
Patent; one part of the invention relates to an improved construction of the
pressure regulator whereby a greater accuracy of the adjustment of the fluid pressure
to the brake power required, is obtained than in the apparatus heretofore employed.
For this purpose the regulating apparatus consists of a casing containing three
separate chambers, one of which communicates by a branch opening with the fluid
pressure pipe this chamber communicates by an opening closed by a spring valve
with the second chamber, so that when the valve is forced open, as will be presently
described, the fluid pressure passes into the second chamber the pressure in which is
regulated by the degree of opening of the valve and from which the fluid pressure
passes to the cylinder of the brake apparatus.
The opening of the regulating valve is effected by the action of a piston which
separates the second from the third chamber; in the construction previously
employed, this third chamber was always open to the atmosphere, and consequently
the spring contained therein which acted on the piston in the contrary direction to
the fluid pressure contained in the second chamber, required to be of sufficient force
not only to balance that pressure, but also to overcome the considerable friction of
the cup
leather of the piston against the walls of the cylinder. The spring conse-
quently required to be so strong that it did not possess sufficient sensitiveness to act
for moderate variations of pressure, and as a consequence a uniform pressure in the
second chamber could not be maintained. According to my present invention I
obviate this defect firstly by closing the communication between the third chamber
and the atmosphere by means of a valve kept closed by a spring of regulated
pressure, so that the third chamber only communicates with the atmosphere when
the fluid pressure therein exceeds that of the spring upon the valve. Secondly, I
establish a communication, by a very small passage through the piston, between the
second and the third chamber. By this arrangement the pressures on each side of
the piston are in equilibrio, and consequently as the spring in the third chamber has
only to overcome the friction of the cup leather of the piston and the pressure of
the spring of the regulating valve in the first chamber, it can be comparatively
weak and therefore will possess the required sensitiveness for maintaining a constant
pressure in the second chamber.
The valve in the third chamber might be replaced by a very small orifice opening
into the atmosphere but this would have the disadvantage firstly, of allowing a
continual small leakage of fluid pressure, and secondly that the small hole would be
liable to get choked with dirt.
In order to reduce the friction of the piston as much as possible, I provide in the
casing a gun metal cylindrical hood-shaped lining, in which the piston works,
instead of against the casing itself, and which is closed at the end presented to the
second chamber with the exception of one or more small openings which allow the
fluid pressure to penetrate into the hood so as to act upon the piston.
By this means the piston and the surfaces on which it slides are protected against
the desiccating effect of the rush of fluid pressure that takes place through the
second chamber, and the surfaces can consequently be kept well lubricated.

page_text: For forcing outward the cup leather or packing rings of the piston, I employ
segmental pressing plates that are pressed upon by a helical spring on the piston
rod, which abuts on a collar on the latter.
I have found it advisable to establish the communication between the distributing
apparatus of each carriage and the main fluid pressure supply pipe of the train, by
a very small hole (about one milimetre diameter) in order to prevent the unequal
charging of the reservoir cylinders of the several carriages after the brakes are
taken off that otherwise occurs, the front reservoir cylinders becoming charged
much quicker than the rear ones, so that if directly after taking off the brakes
these are put on again, the front brakes would be applied with much greater
force than those at the rear. For the above purpose I construct the shut off
cocks in the branch pipes leading from the main supply pipe to the distributing
apparatus of the carriage in the following manner.
The plug of the cock, instead of having a perfectly open through-passage as
usual, has a central diaphragm in the middle of such passage in which diaphragm is
the before mentioned small hole, through which the fluid pressure consequently
On turning the plug of the cock into the shut-off position, the passage with
the diaphragm is brought opposite two opposite holes in the cock casing, so that a
pin can be introduced through these for clearing the small hole should this get
choked.
.passes.
The pressure supply pipe is made to communicate by a small passage formed
through the top of the plug with a space in the chamber above the plug's upper
surface, so as, by the downward pressure exerted on the plug, to keep this airtight.
The plug also has a recess at right angles to its passage, which communicates by
a small hole with that part of the passage which is on the distribution side of the
diaphragm, so that when the cock plug is turned into the last named position the
air pressure will escape from the lower part of the distributor through the said
opening and through the opening in the cock casing, and thus the brakes of the
particular carriage will be applied and the reservoir thereof be emptied of fluid
pressure without having to operate the main supply pipe for this purpose.
Dated this 3rd day of June 1890.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Working Railway Brakes by Fluid
Pressure.
I, ADOLPHE WENGER, of No. 23, Boulevard de Strasbourg, Paris, France,
Civil Engineer, do hereby declare the nature of this invention, and in what manner
the same
is to be performed, to be particularly described and ascertained in
and by the following statement :-
This invention relates to improvements in the construction of that description of
fluid pressure railway brake apparatus for which I have previously obtained Letters
Patent one part of the invention relates to an improved construction of the pressure
regulator whereby a greater accuracy of the adjustment of the fluid pressure to the
brake power required, is obtained than in the apparatus heretofore employed.
I will describe my said improvements with reference to the accompanying
drawings in which Fig. 1 shews a longitudinal section of the apparatus.
The regulating apparatus consists of a casing containing three separate
chambers ABC, one of which A communicates. by a branch opening a_with_the
fluid pressure pipe; this chamber communicates by an opening closed by a spring
valves with the second chamber B, so that when the valve is forced open, as will
be presently described, the fluid pressure passes into the second chamber, the

page_text: pressure in which is regulated by the degree of opening of the valve and from
which the fluid pressure passes to the cylinder of the brake apparatus.
The opening of the regulating valve is effected by the action of a piston e with
cup leather which separates the second from the third chamber C.
In the con-
struction previously employed, this third chamber was always open to the atmo-
sphere, and consequently the spring contained therein which acted on the piston e
in the contrary direction to the fluid pressure contained in the second chamber,
required to be of sufficient force not only to balance that pressure, but also to
overcome the considerable friction of the cup leather of the piston against the walls
of the cylinder, which will generally be sufficient to cause a variation equal to
24 per cent. of the regulated pressure. The spring consequently required to be so
strong that it did not possess sufficient sensitiveness to act for moderate variations
of pressure, unless it were made of inconvenient length, and as a consequence a
uniform pressure
in the second chamber could not be maintained. According to my
present invention I obviate this defect firstly by closing the free communication
between the third chamber C and the atmosphere by means of a valve m kept closed
by a spring n of regulated pressure, so that the third chamber only communicates
with the atmosphere when the fluid pressure therein exceeds that of the spring upon
the valve. Secondly, establish a communication, by a very small passage p
through the piston e between the second and the third chamber through which C is
continuously fed with air pressure.
The fluid pressure in C is limited by the valve m, and the spring K of the piston e
need only be of slight strength, sufficient to overcome the weight of the piston e,
the upper valves, the pressure of the spring bearing on this valve, and the
fluid pressure acting upon the same. The spring K consequently need only be
equal to a pressure of about kilo. per square centimetre of the piston e, and
thus the variation of pressure, whatever may be the regulated final pressure will not
exceed 0-24 x=0.12 kilos. per square centimetre.
which bears upon
By increasing or decreasing the tension of the spring
valve m, the pressure in the chamber C will be increased or decreased, and
consequently also the pressure in chamber B, which is equal to that in the
chamber C, plus that due to the pressure of the spring K distributed over the
piston e.
7"
As the friction of the piston leather is considerable, as above stated, it is made
to work in a bronze lining which communicates with the chamber B by a small
hole which, while it allows of the pressure in B being transmitted to above the
piston e, does not allow the desiccating action of the strong air current passing
through valves to injuriously affect the lubricant used for the piston leather.
A small bronze cap d placed over the end of the piston rod also protects the
passage of the rod through the top of the lining.
The valve m might be replaced by a simple hole of definite size. Thus if σ be
the section of the orifice p and that of the orifice replacing the valve S, and
assuming for the flow of the fluid the law of Toricelli, and terming H the pressure
on the piston e, that is, the regulated pressure, while is the pressure in the
chamber C, then we have o√H-h=√√h 2.
H
-
being constant and equal to the action of the spring K on the piston e ;
being constant, will be constant and consequently also H, as
also, and
H=+K.
But this arrangement, though simple, would have an inconvenience, because, in
order not to lose much air pressure, the orifices must be very small, and as con-
sequently the least particle of dust would alter their relative areas, the action
would probably not be very reliable.
At Fig. 2 is shewn a section of a special construction of piston with segmental
packing which might be employed in the above apparatus. It consists simply in
constructing the piston with a loose plate on the side where the pressure is effected
instead of constructing it of one piece with a groove for receiving the segmental

page_text: packing, such loose plate being pressed upon the packing by a spring. By this
means any wedging of the segmental packing in its groove is prevented and the
packing can be placed in position without deformation, as it does not require
to be sprung open, as is the case with split spring packing rings that are sprung
into piston grooves, and consequently they fit the piston much more accurately and
wear better.
I have found it advisable to establish the communication between the distributing
apparatus of each carriage and the main fluid pressure supply pipe of the train,
by a very small hole. (about one millimetre diameter) in order to prevent the
unequal charging of the reservoir cylinders of the several carriages after the brakes
are taken off that otherwise occurs, the front reservoir cylinders becoming charged
much quicker than the rear ones, so that if directly after taking off the brakes
these are put on again, the front brakes would be applied with much greater force
han those at the rear.
A simple solution of this difficulty would be to interpose a simple perforated
diaphragm between the shut off cock of each vehicle and the distributor."
But this small hole would risk becoming choked, and in order to clear it, it
would be necessary to disconnect the joint.
To avoid this I make use of the cock itself to form the perforated partition, for
which purpose I construct it as shewn in vertical section at Fig. 3 and in horizontal
section on line 1-2 Fig. 3, at Fig. 4 while Fig. 5 shews the same section with
the cock in the closed position.
The pipe D indicated in dotted lines corresponds to the drain pipe; the pipe E
communicates with the distributor.
When the cock is open as at Figs. 3 and 4, the air pressure coming from the
train pipe D passes into the groove F of the plug, and thence firstly through the
small channel to the space above the plug, so as to effect a tight fit, and secondly
through the small opening o of the partition in the plug into the second groove G
thereof, whence it passes to the distributor through E. The casing of the cock
has, at a height corresponding to that of the hole o, two opposite holes q which
are closed when the cock is in the open position. When the hole o becomes
choked with dirt, the plug is turned into the closed position shewn at Fig. 5, at
right angles to the open one, whereupon the hole o can be readily cleared by a
needle through one of the holes 4.
At the same time, a recess u in the plug is brought opposite the passage leading
to E so that the compressed air can escape from below the distributor E into u and
The corre-
thence through a small opening into G and thence out through 7.
sponding brake is consequently put in action, and the reservoir of this brake
apparatus can be emptied without operating the train pipe.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, 1 declare that what I
claim is
1. The herein described improved pressure regulating apparatus wherein the
lower chamber, instead of cominunicating with the atmosphere, is made as a closed
chamber only communicating with the atmosphere through an adjustably loaded
valve, the piston being formed with a small passage by means of which the said
lower chamber is fed with pressure, so that the piston spring can be made very
slight.
2. The herein described improved construction of shut-off cock for the separate
vehicles, wherein the rotatable plug has a partition with a small hole for the
passage of the fluid pressure, while the casing has openings opposite which the said
hole is brought when the plug is in the closed position so as to be accessible for
clearing, while at the same time a passage in the plug establishes a communication
between the pipe leading to the distributor and the atmosphere so that the brakes
are applied, and the reservoir of the carriage can be emptied.

page_text: 3. The herein described improved construction of piston wherein a spring
packing ring is held between a fixed disc and a loose disc of the piston, the loose
disc being pressed against the packing by a spring.
Dated this 3rd day of March 1890.
ABEL & IMRAY,
Agents for the Applicant