IMPROVEMENTS IN RAILWAY BRAKES
Year: 1879

page_text: LETTERS PATENT to David Maitland Yeomans, of Queen Victoria Street, in
the City of London, for the Invention of "IMPROVEMENTS IN RAILWAY
BRAKES."
Sealed the 7th May 1880, and dated the 9th December 1879.
PROVISIONAL SPECIFICATION left by the said David Maitland Yeomans
at the Office of the Commissioners of Patents on the 9th December 1879.
DAVID MAITLAND YEOMANS, of Queen Victoria Street, in the City of London.
"IMPROVEMENTS IN RAILWAY BRAKES."
My Invention relates to improvements in what is known as Smith's vacuum
brake, and has reference both to the class of brakes which are automatic, and
to those which are non-automatic in their action.
In carrying out my Invention as applied to the construction of an automatic
brake, the sack is enclosed in an air tight casing through which the rod or spindle
leading to the brake levers passes, as little space as possible to admit of free
working of the sack being left between the casing and the sack in communication
with the air exhaust pipe extending throughout the train. The space within the
sack communicates with this vacuum space by means of a valve opening outwards,
which will admit of the air being exhausted from the interior of the sack, but will
close by means of a weight when the vacuum at opposite sides of the valve is in
equilibrio. During the normal condition of the parts the vacuum is maintained
both in the small space and within the sack, the brakes being off the wheels. On
the admission however of air to the continuous pipe, either by hand or by accident,
and thence to the space around the outside of sack, the sack is forced inwards (the
vacuum within being retained by the valve), and the brakes are immediately
applied to the wheels, the reverse action being produced by again exhausting the
air from the space outside the sack and restoring the equilibrium.
In applying my Invention to non-automatic brakes, I partially enclose the sack
in a casing or chamber from which the air is exhausted in order to apply the
brakes, and I arrange the sack in such a manner that it is distended or elongated
when forced in in the act of applying the brakes, and compressed when the brakes
are off, in lieu of the converse conditions which characterize the action of the
ordinary brake. By means of this arrangement I am enabled to obtain the same
stroke with less space for forming vacuum, thereby securing much more rapid
action, whilst at the same time protecting the sack from exposure, and consequent
liability to injury.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said David Maitland Yeomans in the Great Seal Patent Office on the
9th June 1880.
DAVID MAITLAND YEOMANS, of Queen Victoria Street, in the City of London.
"IMPROVEMENTS IN RAILWAY BRAKES."
My said Invention relates to improvements in what is known as Smith's vacuum
brake, and has reference to the class of brakes which are automatic in their action.
In carrying out my said Invention the sack is enclosed in an air tight casing
through which the rod or spindle leading to the brake levers passes, a space (as
small as possible to admit of the free working of the sack) being left between the
casing and the sack in communication with the air exhaust pipe extending
throughout the train. The space within the sack communicates with this vacuum
space by means of a valve opening outwards, which will admit of the air being
exhausted from the interior of the sack, but will close by means of a weight or its
equivalent when the vacuum at opposite sides of the valve is in equilibrio.
During the normal condition of the parts the vacuum is maintained both in the
small space and within the sack, the brakes being off the wheels. On the ad-
mission however of air to the continuous pipe, either by hand or by accident, and
thence to a vacuum space around the exterior of the sack, the sack is forced
inwards, "the vacuum within being retained by the valve," and the brakes are
immediately applied to the wheels, the reverse action being produced by again
exhausting the air from the vacuum space outside the sack and restoring the
equilibrium.
The accompanying Drawing represents a sectional elevation of a vacuum
cylinder and its immediate connections constructed and arranged according to my
said Invention.
the
C is the sack which is rigidly secured at one end a, and carries at its opposite
end a rigid head b, to which the rod or spindle c leading to the brake lever dis
attached. This sack is inclosed in an air tight casing E, through a gland in which
the rod or spindle c passes, and the said casing is in communication by means of a
branch pipe H with the air exhaust pipe D extending throughout the train;
space A between the exterior of the sack and the interior of the casing being
made as small as possible consistent with the free working of the sack. During
the normal condition of the apparatus a vacuum is maintained in the pipe D, and
consequently in the space A at the exterior of the sack C, and as the space within
the sack C communicates with this vacuum space A by means of a valve B opening
outwards, a vacuum is also normally maintained within the sack, the valve B
admitting of the air being exhausted from the interior of the sack, but closing by
means of a weight e when the vacuum at opposite sides of the valve is in
equilibrio.
During the maintenance of the vacuum in the space A and within the sack C,
(which as before mentioned is the normal condition of the apparatus, and that
indicated in the Drawing), the sack is distended and the brakes are off the wheels.
On the admission however of air to the pipe D (either by hand by the intentional
opening of a valve or cock, or accidentally by the rupture of the pipe), air passes to
the space A at the exterior of the sack C, and the vacuum within the sack being
retained by the valve B the sack is immediately forced inwards, and the brakes
are thus applied to the wheels, the reverse action being produced by again ex-
hausting the air from the space A and restoring the equilibrium, when the sack
will descend by gravitation to the normal position indicated in the Drawings.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original,

page_text: and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
The employment in automatic vacuum brakes of enclosed sacks, substantially as
and for the purpose hereinbefore described.
In witness whereof, I, the said David Maitland Yeomans, have to this my
Specification set my hand and seal, the Seventh day of June, One thousand
eight hundred and eighty.
DAVID MAITLAND YEOMANS. (L.S.)