IMPROVEMENTS IN THE CONSTRUCTION OF AIR AND VACUUM BRAKE APPARATUS
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Percival Everitt at the Office of the
Commissioners of Patents on the 27th April 1880.
PERCIVAL EVERITT, of Queen Victoria Street, in the City of London, Engineer.
"IMPROVEMENTS IN THE CONSTRUCTION OF AIR AND VACUUM BRAKE APPARATUS."
This Invention relates, firstly, to a novel construction of pipe coupling, which is
applicable both to vacuum and air brakes, the objects being to open communi-
cation between the coupled up pipes in the act of connecting them together, to
close the pipes in the act of disconnecting them by hand, and to provide for the
pipes remaining open when they are torn apart by an accident to the train. The
flexible ends of the pipes I fit with a metal termination suitably shaped to form a
butt joint. These metal terminations I provide with a transverso plug similar to
that of an ordinary stop cock, and to the stem of each plug I attach an elastic
coupling arm, which may be used as a handle to the plug. The clastic arms of
the several plugs are so shaped as to form wedge shaped catches, which when
moved over lugs or flanges of adjacent pipes will draw the same together and
make an air tight joint. These coupling arms are so arranged with respect to the
bore of their respective plugs that in the act of coupling up they will open their
respective plugs, and when moved backwards to uncouple they will, by turning
their plugs in the opposite direction, close their respective pipes. Should however
the coupling be torn asunder the plugs will remain open, and the vacuum or the
air pressure in the pipes (as the case may be), will be destroyed; the brakes will
thus be automatically applied.
As an improvement in automatic vacuum brakes I propose to employ the
following arrangement to prevent the "creeping on" of the brakes when the
vacuum from any cause drops below a maximum:-
The so called vacuum cylinder is fitted with a sock as usual, and at opposite
sides of this sock, to which the brake rod is attached, I connect the cylinder with
the continuous train pipe. The sock may be fitted as usual with a valve opening
outwards, and in the branch pipe which leads to the interior of the sock I fit a
valve which has a tendency to remain partially open. This arrangement allows
of the vacuum cylinder being exhausted from its opposite ends. When therefore
the vacuum falls below its maximum the effect will be the same on both sides of
the sock, and therefore no movement of the brake rod will take place. So soon
however as air is admitted to the cylinder for the purpose of applying the brakes

page_text: the valve in the branch pipe will close, and the vacuum within the sock being
sealed the brake apparatus will come into instant action. To permit of carriages
fitted with this apparatus being coupled up with carriages fitted with brake
apparatus, in which the vacuum is established only at the moment of applying the
brakes, I fit the branch pipe which connects the bottom of the vacuum cylinder to
the train pipe with a cock, which cuts off that connection and opens the cylinder
to the atmosphere. I also connect the interior of the sock by a second branchi
pipe with the train pipe, fitting the same with a stop cock for closing this com-
munication when the apparatus is to work automatically; thus the sock will be
exhausted from one or other of the branch pipes when the brakes are to be applied,
and when the brakes are to be taken off the air will pass through this additional
branch pipe to the sock.
As a modification of the automatic arrangement instead of the branch pipe with
its open valve a tendency may be given to the valve in the sock bottom to remain
open, and thereby equalize the vacuum at both sides of the sock.
It will be necessary to provide that a sudden rush of air shall seat the valve and
thereby give efficiency to the vacuum in the sock.
In order to simplify the construction and improve the efficiency of air pressure
brake apparatus, thus rendering the complex arrangement of valves unnecessary,
and preventing the "creeping on" of the brakes, I connect the lower end of the
brake cylinder direct with the auxiliary air reservoir, and both ends also by means
of a breeches pipe or otherwise with the train pipe.
In the branch leading to the lower end of the cylinder is a valve, which opens
toward the cylinder, and has a tendency to remain open for the purpose of main-
taining an equal pressure on both sides of the piston. Through this valve air
under pressure passes to the cylinder and thence to the auxiliary reservoir. Tho
brakes are held out of action by their own weight or by springs, but so soon as
the air pressure is taken off the top of the piston either by accident or design the
piston will rise under the pressure of air in the reservoir and apply the brakes, the
valve in the breeches pipe being seated, and thereby stopping the escape of the air
from below the piston.