The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1894-12-30

portant valve, which controls the air
pressure and by which the air brakes
are set and released. the air passes
through another pipe to the train pipe.
This pipe runs under each car and is
connected between cars by rubber hose
so that when the connections are made
the pipe is continuous from one end TO
the other. Through the train pipe the
air is admitted to the auxiliary air res
ervoirs under the cars, one pipe TO the
car reservoir through the triple valve.
and it is this triple valve which makes
the system automatic.
The air is pumped into the main res
ervoir on the locomotive until a pressure
of about ninety pounds to the square
inch is secured. When the engine backs
up the train and is coupled on the
brakeman connects the train pipe of
the tender to the pipe of the baggage
car. or whatever the front car is. and
by this connection the entire train Is
connected with the main reservoir. Then
the engineer charges the train pipe and
through it the reservoirs under the cars,
which, through the triple valves are
connected with the brake cylinders. The
engineers valve is a composite valve
Oh srated by one handle. 1t has five po-
sitions, but three of these only are COM
monty used BY this valve the air is let
from the reservoir tank on the engine
into the train pipe, and thus the reser-
same valve also let's the air out of the
train pipe, slowly or rapidly at will.
thus decreasing the pressure in the pipe
and setting the brakes. When the ham
die is moved TO set the brakes the port
through which the air enters the train
pipe from the main reservoir is closed,
so that no air is released from this tank
while the brakes are being set. A gov
ernor on the pump shuts off the steam
and thus stops the pump when the max
imum air pressure has been accumu-
lated in the train pipe and reservoirs.
About seventy pounds Of air are kept
in the auxiliary reservoirs, for ex-
perience has shown that higher pres
sure sets the brakes so hard that the
wheels slide. The air in the main res
ervoir is kept at about ninety pounds
pressure. so that the engineer always
has an excess Of pressure at his COM
mand.
ADDITIONAL DETAILS.
The triple valve is the controlling me-
chanism of the system after the air gets
past the engineer. 1t is called the triple
valve because through it the auxiliary
reservoir is charged from the train pipe;
the brake cylinder is charged from the
auxiliary reservoir and. in an emergen-
cy stop, from the train pipe, and the
air Is released from the brake cylinder
after the brakes are set and the train
is ready to move on. These triple func-
tons are secured by an arrangement Of
valves within the casing of the triple
valve When the engineer opens the
port in his valve, which permits the air
from the main reservoir to escape into
the train pipe, he holds IL open until the
pressure gauge before him tells him that
the train pipe has seventy pounds of
air. The air passes from the train pipe
into the triple valve and through a
small opening on the rim of the seat
of q large valve into the auxiliary res
eryoir Until. the auxiliary reservoir is
fully charged the pressure on this large
seated valve is greater on the side
next to the train pipe, but when the
reservoir is fully charged the pressure
is the same and the valve is balanced.
In this condition there is TO pressure in
the brake cylinder. and. in fact, by
means Of port or opening in the triple
valve, the brake cylinder is open to the
outside air. When the engineer APP
proaches a station he moves the handle
OF his valve to certain position and
allows some of the air In the train to
pipo to escape. The instant this Is