Improvements in Vacuum Brake Apparatus suitable for Railway Vehicles.
Year: 1894

page_text: Date of Application, 24th Jan., 1894
Complete Specification Left, 23rd Oct., 1894-Accepted, 24th Nov., 1394
PROVISIONAL SPECIFICATION.
Improvements in Vacuum Brake Apparatus suitable for Railway
Vehicles.
I, ALFRED GEORGE SPENCER, of 77 Cannon Street, in the City of London,
Engineer, do hereby declare the nature of this invention to be as follows:-
Vacuum brake apparatus, such as is used for railway vehicles, is constructed
with vacuum chambers containing elastic diaphragms with plates connected by rods
to the brake-block carrying appliances. Such vacuum chambers are commonly
made in halves with flanges adapted to be fastened together, the edges of the
elastic diaphragm being held between these flanges and there being plates secured
to the diaphragm, the position of which in the vacuum chamber depends upon
whether there is a vacuum (or partial vacuum) at one side of the diaphragm
or not.-
The constant working and strain upon the diaphragm near the plates and walls
of the vacuum chamber is liable to rapidly injure the diaphragm at those parts,
and my invention is designed to obviate this evil so as to increase the durability of
the diaphragm.
For this purpose the vacuum chamber and diaphragm are so constructed and
arranged that the plates of the diaphragm can assume an extreme position against
the wall of the chamber at either side without the necessity of turning the
diaphragm inside out or bending it first in one direction and then in the opposite
direction, thereby obviating injurious stress upon the elastic material of the
diaphragm which is made relatively larger and more loose than is now commonly
the practice. The details of construction may be variously modified.
According to one arrangement the edges of the diaphragm are held between the
flanged end of the vacuum chamber and a plate or cover attached thereto, and the
diaphragm is made of such form and size as to allow the plate thereof to bear
against the opposite side of the chamber without stretching the material of the
diaphragm. Thus the width of the annular portion of the diaphragm that is
between the flanged end of the vacuum chamber and the diaphragm plates may
be such that when the said diaphragm plates are adjacent to the plate or cover of
the vacuum pan, the said annular portion of the diaphragm will assume
approximately vee-shaped form in cross section with a curved vertex.
30
In another arrangement the edge of the diaphragm is clamped between the
flanges of two pans and the portion of the diaphragm between the flanges and the
diaphragm plate is curved for a short distance in one direction and then in
the opposite direction and thence extends to the diaphragm plates between which
its central portion is clamped. The arrangement is such that by movement of the
diaphragm, the curved portion of the diaphragm is caused to travel to and from
the clamped edge but neither this curved portion or that adjacent to the diaphragm
plates ever becomes bent alternately in opposite directions."
Dated this 24th day of January 1894.

page_text: CUMI LEID DI BUIFICATION.
Improvements in Vacuum Brake Apparatus suitable for Railway
Vehicles.
I, ALFRED GEORGE SPENCER, of 77 Cannon Street, in the City of London,
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 :-
Vacuum brake apparatus such as is used for railway vehicles, is constructed
with vacuum chambers containing elastic diaphragms with plates connected by
rods to the brake-block carrying appliances. Such vacuum chambers are commonly
made in halves with flanges adapted to be fastened together, the edges of the
elastic diaphragm being held between these flanges and there being plates secured
to the diaphragm, the position of which in the vacuum chamber depends upon
whether there is a vacuum (or partial vacuum) at one side of the diaphragm
or not.
The constant working and strain upon the diaphragm near the plates and walls
of the vacuum chamber is liable to rapidly injure the diaphragm at those parts,
and my invention is designed to obviate this evil so as to increase the durability of
the diaphragm.
For this purpose the vacuum chamber and diaphragm are so constructed and
arranged that the plates of the diaphragm can assume an extreme position against
the wall of the chamber at either side without the necessity of turning the
diaphragm inside out or bending it first in one direction and then in the opposite
direction, thereby obviating injurious stress upon the elastic material of the
diaphragm which is made relatively larger and more loose than is now commonly
the practice. The details of construction may be variously modified.
In the accompanying drawings,
Fig. 1 shows in central vertical section, one construction of vacuum chamber and
diaphragm according to this invention.
In this arrangement, the outer edge a of the diaphragm is held between the
flanged end of the vacuum chamber b and a plate or cover c attached thereto,
and the diaphragm is made of such form and size as to allow the plates d secured
to opposite sides of its central portion al to bear against the opposite side 6² of the
chamber without stretching the material of the diaphragm. For this purpose the
width of the annular portion a² of the diaphragm that is between the flanged end b
of the vacuum chamber and the diaphragm plates d, is made such that when the
said diaphragm plates are adjacent to the plate or cover e, the said annular portion
of the diaphragm will assume an approximately vee-shaped form in cross section
with a curved vertex a³ as shown.
The diaphragm, which may be composed of combined india rubber and canvas as
usual, is of circular form in plan, the annular portion a² being composed of two
truncated conical parts arranged one inside the other and connected together by
the curved portion a³, the inner conical portion being inverted. Such a diaphragm
may conveniently be made of the form shown by moulding.
By the construction described it will be seen that when the diaphragm with its
plates d is moved from the position shown in full lines to that shown in dotted
fines and vice versa, the curved connecting portion a³ will be caused to travel to and
from the clamped edge a so that it will vary its position, relatively to the ends of
the vacuum chamber, but not its form, consequently neither this portion, nor the
portion of the diaphragm adjacent to the plates d, will ever be bent alternately
in opposite directions, and so subjected to excessive wear.
Fig. 2 is a similar view to Fig. 1 showing another arrangement in which the
outer edge a of the diaphragm is clamped between the flanges 6' of two pans, b, and

page_text: the annular portion a' of the diaphragm between the said flanges and the diaphragm
plates d is curved for a short distance in one direction and then in the opposite
direction as shown at a³ and thence extends to the diaphragm plates between which
its central portion is clamped. As will be seen, this arrangement is equivalent to
that shown in Fig. 1, as by movement of the diaphragm, the curved portion a³ of
the diaphragm will be caused to travel to and from the clamped edge a but neither
this curved portion, or that a* adjacent to the diaphragm plates will ever become
bent alternately in opposite directions.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is ;-
1. Vacuum brake apparatus of the kind herein referred to wherein the vacuum
chamber and diaphragm are so constructed and arranged that the plates of the
diaphragm can be moved from one extreme position to the other without turning
the diaphragm inside out or bending it first in one direction and then in the opposite
direction, substantially as herein described for the purpose specified.
2. In vacuum brake apparatus, vacuum chambers with diaphragms constructed
and arranged substantially as hereinbefore described with reference respectively to
and shown in Fig. 1; and in Fig. 2 of the drawings annexed.
Dated this 23rd day of October 1894.
ALFRED G SPENCER.
W. Lloyd Wise,
46, Lincoln's Inn Fields, London, W.C., Applicant's Agent.