IMPROVEMENTS IN OR APPLICABLE TO VACUUM BRAKE APPARATUS
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by James Gresham at the Office of the
Commissioners of Patents on the 4th August 1882.
JAMES GRESHAM of the firm of Gresham and Craven, of Craven Iron Works,
Salford, in the County of Lancaster, Engineers and Machinists, "IMPROVEMENTS IN
OR APPLICABLE TO VACUUM BRAKE APPARATUS."
Firstly, My invention relates to improved arrangements for packing or
preventing leakage past the rods connected with the pistons or diaphragms of
vacuum brake apparatus.
In what is known as the Clayton type of automatic vacuum brakes there is only
a packing ring to prevent leakage past the piston rod, when the piston is at its
closest position to the cover as shown in fig 11 of the specification of Letters
Patent granted to me and Numbered 5109, A D 1881, and in the diaphragm or
Hardy Sack type, a flexible sleeve is used to prevent leakage past the rod as shown
in fig 10 of my aforesaid specification.
This part of my invention consists in combining and arranging a gland with the
types of automatic vacuum brake cylinders above referred to, formed to receive an
india rubber or other elastic ring which will be rolled by the movement of the
piston or diaphragm rod upon the rod and against the interior of the gland which is
provided at each end with relieving grooves in which the elastic ring can expand
and adjust itself at the end of the stroke, and so that when by the movement of the
rod the ring is rolled from one of these grooves it is compressed between the
interior of the gland and the surface of the rod sufficiently to prevent the passage
of fluid.
When my improved mode of packing is used with the Hardy type of cylinders
I prefer to mount each cylinder on trunnions so that its diaphragm rod can be
jointed directly to the lever to be actuated.
Secondly, My invention relates to improvements upon the valve arrangements
shown in connection with figs 10 and 11 of my aforesaid specification.
By the present improvements the valve seating is formed on the end of a
horizontal short pipe or projection from the casing and one end of a tube is fitted
to slide upon the exterior of the short pipe or projection and inside this tube the
ball valve is placed, which tube has side passages for the air to pass through from
the passage in the casing at the exterior of the tube.

page_text: A plug is screwed into the interior of this tube for the ball valve, which plug
secures the central part of a diaphragm between the end of the tube and the
shoulder on the screw plug, while the outer margin of the diaphragm is secured
between a gland or guide for the end of the screw plug and the casing in which
the gland screws.
By this arrangement the hall valve can be pulled away from its seating when
required with certainty, and should there be any leakage past the diaphragm at any
time it will pass into the train pipe and not into the vacuum chamber as in my
former arrangements.
This arrangement also allows the ball valve to be readily removed and replaced
when required without breaking joints.
Combined with my improved arrangement of ball valve a passage is made in the
casing leading from that going to the ball valve, and a seating is formed in this
passage for another ball valve to open outwards.
As the latter ball valve is arranged at the lowest part of the passage connected
with the brake cylinder all moisture in it will drain to this outlet and can escape
through this valve (which I term the drip valve) which remains open when the
vacuum is not operating.
This part of my invention also consists in applying a drip valve to the Hardy
type of automatic vacuum brake cylinders worked by diaphragms, which drip
valve is combined with, and is formed by preference in the gland for the rod from
the diaphragm or the gland for the rolling packing referred to under the first head
of my invention.
Thirdly, My invention relates to the arrangements described in the specification
of Letters Patent granted to me and Numbered 4642 and dated 24th day of October
1881, and illustrated by fig 7 of the drawings.
The arrangements therein shown are described in connection with simple vacuum
brakes for signalling, but the same arrangements may also be used for putting on
the brakes in the case of automatic vacuum brakes by admitting air into the
train pipe, and my improvements relate to the arrangement of the glass and its
case with means for breaking the glass to admit the atmosphere into the train pipe
without injury to the passenger from the broken glass, and consists in combining
with the glass and case a ball retained in front of the glass by a metallic guard so
that when the ball is struck the glass is broken and falls into the case along with
the ball and thus shows from which compartment or carriage the signal was made
or the stoppage originated.