IMPROVEMENTS IN AIR COMPRESSORS AND COUPLINGS FOR RAILWAY BRAKE APPARATUS, AND ALSO APPLICABLE TO PUMPS, MOTORS, AND METERS
Year: 1880

page_text: PROVISIONAL SPECIFICATION left by Edmund Hunt at the Office of the
Commissioners of Patents on the 21st April 1880.
EDMUND HUNT, of Glasgow, in the County of Lanark, North Britain, Patent
Agent. "IMPROVEMENTS IN AIR COMPRESSORS AND COUPLINGS FOR RAILWAY
BRAKE APPARATUS, AND ALSO APPLICABLE TO PUMPS, MOTORS, AND METERS."
This Invention has principally for its object to improve the construction and
action of certain parts of apparatus employed for actuating railway brakes by
means of compressed air; but the improvements or some of them are also applicable
otherwise, namely, to apparatus for pumping air, water, or other fluid to motors
and to meters.
The improvements in air compressors relate more particularly to the motor
cylinder by which the compressor pump is worked, the former being directly
connected to the latter without the intervention of a rotating shaft.
In carrying out this part of the Invention a valve chamber or space, by preference
of a general cylindrical form, is made parallel to and at the side of the cylinder with
which it communicates at the extreme ends by short direct openings or passages.
The inlet pipe for the steam or motive fluid communicates with the middle of the
valve chamber, and the outlet or exhaust pipe communicates with a passage parallel to
the valve chamber and opening into two annular passages, one near each end of
the chamber. These annular exhaust passages are by preference formed by
inserting in the ends of the chamber cylindrical pieces with grooves constituting
the passages formed on the outside of them, and holes are bored through to the
inside of the cylindrical pieces at the grooved parts, these holes being the exhaust
ports. Other rings of holes forming the steam inlet ports are bored through parts
of the cylindrical pieces nearer the middle of the chamber, the pieces being reduced
externally to admit the steam thereto. The valves are cylindrical cups rigidly
connected together by a tube or otherwise, and each is made with one ring of holes
at its inner part so placed that when the valves are at one end of their stroke the
holes communicate with the inlet holes or ports at that end, the inlet holes at the
other end being covered, and the exhaust holes uncovered. The steam pressure
exerted at one end tends to move the valves towards the other end but is prevented
from doing so by a catch, which is released on the piston reaching the other end of
its stroke. A rod or pair of rods connected to the catch details passes through the
valves and is at each. end connected to a lever which extends through the end

page_text: passage into the cylinder so as to be acted on by the piston. The catch is
double, being in the form of a lever with a catch at each end, and as it releases
one holding part it engages with another so as to prevent the premature return of
the valves.
A spring is by preference added to ensure the proper action of the
parts, and when the effective pressure is very little, as in a meter, this spring is
made strong enough to move the valves, the action of the end levers straining or
compressing it until the precise point for the release of the catch is reached. With
the improved arrangement of valves their motion is arrested by the cushioning
action of the steam itself which presses in the opposite direction to their motion
the instant it gains admission to either end.
The improved coupling is for connecting flexible or other pipes through which
air or other fluid under pressure is to be transinitted, and is designed so that the
pipes do not become open to the atmosphere when being coupled or uncoupled.
In carrying out this part of the Invention a short intermediate coupling pipe is
employed, and is formed with openings round each end. A mouth piece is fitted
to cach pipe length having inside it a cylindrical piece of rubber or leather, or
other suitable material, acting like a cup leather. Through this pieco the end of
the coupling pipe is forced when coupling, and the internal pressure acting on it
makes the joint tight. When the coupling pipe is withdrawn a plug held within
the mouth piece and having a spring applied to it follows the coupling pipe so far
within the cup leather or equivalent as close the opening, this plug being
pushed inwards when the coupling pipe is entered. The coupling pipo has on it
two claw picces which are fitted so that they can move along it but not turn on it,
and each has a tubular part which is screwed externally, one with a right hand and
the other with a left hand thread. An outer tube which is screwed internally engages
with the claw pieces and is fitted with a weighted lever or wheel for turning
it by.
When applying the coupling the claws of one end are engaged on
horns formed for the purpose on the mouth piece of one pipe length, and the claws
of the other end are engaged on the horns of the other pipe length. The outer
tube is then turned and by the screwing action makes the mouth pieces of the
pipe lengths approach each other, and at the same time forces the ends of
the coupling pipes into them. The screwing action is reversed for uncoupling.
The improved coupling is rendered suitable for connecting pipes in which the
pressure is less than that of the atmosphere by reversing the cup leather or
equivalent.