IMPROVEMENTS IN RAILWAY LOCOMotive Exhaust Apparatus
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Joseph Armstrong at the Office of the
Commissioners of Patents on the 2nd August 1883.
JOSEPH ARMSTRONG of 30 Wellington Street, New Swindon in the county of
Wilts, Engineer, "IMPROVEMENTS IN RAILWAY LOCOMotive Exhaust Apparatus"
On ordinary locomotives the steam is usually admitted directly from the cylinders
to the blast pipe, and from thence into the atmosphere.-The vacuum obtained in
the Smoke box is therefore variable, owing to the steam at the beginning of the
exhaust being at a higher pressure than at the finish of the exhaust. The high
vacuum has a detrimental action on the fire, as sparks and unburnt particles of fuel
are drawn through the tubes.
I place in any convenient position on a locomotive, by preference near the
cylinders and forming a partial jacket, a reservoir connected with the exhaust
ports, so that when an exhaust port is open to the cylinders, the steam flows into
the reservoir and there expands until the steam pressure in the blast pipe falls
low enough to allow its escape to the atmosphere.-I sometimes place a check valve
or valves between the ports and reservoir or reservoirs so constructed that the
steam can enter the reservoirs from the exhaust ports, but cannot flow back ;—
this steam I conduct directly to the mouth of the blast pipe which is so constructed
as to allow the reservoir steam to flow, when steam may not be flowing from tho
main blast pipes.
This arrangements is sometimes desirable so as to obtain a more continuous blast
Sometimes, in the aforementioned check valves, I cut a hole to a convenient size, so
that the steam can enter the reservoirs from the exhaust port or blast pipe through
the full opening but can only return through the small hole or passage which can
be regulated at will-I construct the blast pipe so as to obtain a large amount of
contact surface between the steam issuing from the blast pipe and the gases in the
smoke box-in order that a sufficient vacuum can be obtained in the smoke box-
when the steam is flowing from the blast pipe at a slow speed-Occasionally I
form the blast pipe in a long rectangular shape but I prefer to construct it with an
annular opening so that the gases come in contact not only with the outside but
also with the inside of the hollow cylinder of escaping steam-I sometimes prefer
to connect the inside space of the annular blast pipe with tubes or pipes which I
lead towards the lower part of the smoke box, in order that the vacuum obtained
at the bottom of the smoke box may be as great, if not greater than the vacuum
at the top, for it is sometimes the case that the bottom rows of tubes require &
higher vacuum owing to their being baffled, in the firebox by the customary brick

page_text: arch or pocket-I occasionally arrange at the end of these blast pipes an auxilliary
top that is smaller in area than the main top in order that when necessary a higher
vacuum may be obtained in the smoke box through the steam being let out at a
greater pressure; this top I fix with a lever or slide-I sometimes arrango an
automatic valve on the top, or inside the blast pipe so that the escape area may bo
better proportioned to that of the pressure in the blast pipe-I sometimes work
this valve with a piston, diaphragm, or its equivalent or by the friction of the
steam on a cone, disc, or any movable surface which I place in contact with the
escaping steam The piston, diaphragm or its equivalent and the frictional moving
surfaces I load with a weight or spring or by a portion of the steam acting in the
opposite direction-Sometimes I regulate the valve or valves by a piston
diaphragm or its equivalent weighted to the degree of vacuum necessary, worked
by the low vacuum in the smoke box-Sometimes I connect the regulating valve
to the reversing lever, screw or bridle rod so that the area is increased or decreased
as the engineman moves them forward or backward.
It is sometimes necessary that the pet cocks on the cylinders or steam chests
make no noise I occasionally arrange the reservoir underneath the cylinders with
the pet cocks placed inside it or between it and the cylinders-The reservoir or
reservoirs I connect direct to the bottom part of the exhaust ports so that when
any water or steam is delivered by the pet cocks into the reservoir the steam
escapes through the exhaust port and chimney to the atmosphere and the water is
collected in the reservoir.
I sometimes place on the reservoir or reservoirs automatic valves, so arranged,
that, when steam is shut off from the steam chest or cylinders, the automatic valve
or valves open and the water flows away to any desired spot. I occasionally
arrange an automatic valve so constructed that when a certain quantity of water
has accumulated in the reservoir from the draining of the cylinders, condensation,
or other causes, a valve opens automatically and allows the water to flow away.
Sometimes I lend a small pipe from the reservoir into the top of the tender or tank,
the diameter of which can be adjusted by a valve so that the pressure of steam in
the reservoir forces the collected water into the tender or tank or to any desired
position. It is sometimes desirable that the noise caused by the steam escaping by
the use of brake ejectors should be reduced as much as possible-I generally lenil
the steam issuing from the mouth of the ejector, or ejectors into the aforementioned
reservoir or reservoirs in order that it may be expanded considerably before
reaching the atinosphere through the chimney.
Inside the reservoir I place a tube into which a large number of small holes are
drilled, the total area of these holes to be equal or greater than the area of the
mouth of the ejector or ejectors-Between the ejector and the reservoir I place a
check valve or valves so arranged as to prevent the steam entering the ejector or
ejectors from the reservoir-1 sometimes arrange the steam escaping from the safety
valves to be led to the reservoir and expanded in a similar way in order to reduce
the noise. I sometimes arrange for the waste water or steam from the injectors to
be led into the reservoir or reservoirs and forced back into the tank or tender
or to any convenient position by the pressure of steam through a convenient pipe.
A check valve, I sometimes place between the injectors and the reservoir to prevent
the steam reaching the injector
On locomotives that condense the steam into tanks and do not eject it from their
blast pipes, 1 place the reservoir or reservoirs in any convenient position and
connect it in the usual way with the condensing pipe; a considerable saving in 5
back pressure is thus obtained.