Improvements in Brake Apparatus for Railway Trains.
Year: 1887

page_text: COMPLETE SPECIFICATION.
Improvements in Brake Apparatus for Railway Trains.
I, JOHN THEODORE HEWITT, of Osborne Road Southampton, in the County of
Hants, Student, do hereby declare the nature of the said 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 certain improvements in or applicable to air or other fluid
pressure brake apparatus for railway rolling stock, being especially applicable to
arrangements of such apparatus wherein an auxiliary reservoir is adapted to each
carriage, and wherein a distributing valve in communication with the train pipe and
with the said reservoir is used for admitting the air or fluid pressure from the train
pipe or from the said reservoir to the brake cylinder; and consists essentially in the
application to the auxiliary reservoir of each carriage of adjustable means which will
permit of air being stored therein at any required pressure upwards from atmospheric
pressure (and will prevent air at any higher pressure from entering the reservoir,)
and by means of which the apparatus will be rendered automatic in setting on the
brakes on the train parting at any point, the brakes being normally applied direct
from the train pipe with a comparatively small expenditure of air only slightly in
excess of pressure of that in the reservoir; and in an improved and simplified
construction of the distributing valve.
On the accompanying drawings; Fig. 1, represents in sectional elevation an
auxiliary reservoir adapted to operate in accordance with the said improvements; and
Figs. 2 and 3 respectively represent, in sectional elevation through the line a, b Fig. 3,
and in end view, the improved construction of distributing valve.

page_text: 4, represents the auxiliary reservoir, the inlet end, 5, of which is, in accordance
with the said improvements, adapted with a cylindrical extension, 6, in which is fitted
a piston, 7, formed with rod extensions, 8. 9: the former of which rods is fitted with
a conical or other suitably formed valve, 10, adapted to close the inlet aperture, 11,
when a certain predetermined pressure is reached in the reservoir, 4, or when air
above such pressure is admitted to the connected train pipe, 23, and the latter of
which rods projects through the cylinder cover, 12, and is fitted with a lug, 13, and is
encircled by a spring, 14, by which the said pressure is determined, and which is dis-
posed between such lug and an adjustable bearing plate, 15, which is guided by, and
adjusted as desired by means of nuts, 16, on, rods. 17, projecting from the cover, 12,
the normal tendency of the spring being to keep the valve, 10, open. The valve, 10,
may, however, be caused to keep the inlet into the reservoir, 4, closed, by means of a
nut, 18, on the rod, 9, so that the apparatus can be made to work with a simple
pressure brake.
Thus when the reservoir is in connection with the train pipe, and air is driven into
the latter from the engine either by pumping or from a reservoir, such apparatus is
effective in preventing the pressure in the reservoir exceeding that to which the spring
is set, as when the air entering the reservoir, 4, exceeds such pressure, the piston, 7,
is actuated against the resistance of the spring, 14, in such a manner as to close the
valve, 10, against the reservoir inlet.
The improved distributing valve consists essentially of a segmental casing, 19, and
of a segmental swinging valve piece, 20, centred in the casing at, 22, and having a
movement about such centre against the inner segmental face of the casing, the
movements of the valve being limited by the opposite inner sides of the casing.
The casing is formed with an air inlet, 24, leading air from the outlet, 25, of the
reservoir, 4; to within the casing on one side of the valve piece, 20, and with an
air inlet, 26, leading air directly from the train pipe, 23, to within the casing
on the opposite side of the valve piece. So long as the pressure on both sides
of the valve, 20, remains equal, the valve remains in its central position, in
which the brake cylinder is in communication with the atmosphere through the
opening, 27, in the casing, the opening, 29, in the valve, and the outlet 21, the
breaks being off.
The brakes are normally applied by admitting compressed air only slightly in
excess of the pressure of that in the auxiliary reservoir, from the engine or main
reservoir into the brake cylinder directly through the train pipe and valve casing, 19,
through the inlet, 26, and opening, 27, the valve, 20, yielding to the excess of
pressure on this side and rotating on its axis and permitting of such connection, after
closing the said connection of the brake cylinder with the atmosphere.
When the driver wishes to take the brakes off, he reduces the pressure in the train
pipe equal to that in the reservoir, 4, when the valve, 20, again swings into the central
position, whereon the brake cylinder is again put in connection with the atmosphere
as aforesaid. Either the valve, 20, or the inner sides of the casing, 19, should be
faced with any suitable soft or yielding substances, as at, 28, to prevent sudden shock
of the metallic parts in case of rapid diminution of pressure in the train pipe such as
would be caused by the train parting at any point, whereupon the brakes are
automatically applied by the excess of pressure in the auxiliary reservoir.
As above stated the said pressure regulating apparatus may be set so that the
brakes may be applied only by simple pressure, in which case the compressed air when
admitted into the train pipe is prevented from obtaining access into the reservoir, 4,
but obtains access into the brake cylinder through the valve casing thus applying the
brakes which then require to be released by taking off the pressure.
Among other advantages attendant upon the application of the present improve-
ments, the said regulating apparatus permits of the usual running pressure being such
as only to stop the wheels evenly, without always skidding them as occurs in existing
arrangements, and the brake may be adjusted so as to work either with a simple
pressure or with an automatic pressure fitted train.

page_text: Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The application and use in combination with the auxiliary reservoir of pressure
regulating apparatus constructed and operating substantially in the manner herein-
before described.
2. The herein before described improved construction of distributing valve for
admitting air under pressure into the brake cylinder either from the said auxiliary
reservoir or direct from the train pipe.
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C.,
Agents for the Applicant.