Q, What parts are found on the car ?

A. The discharge valve (Fig. 26), the signal cord
running the length of the car, and the signal-pipe con-
nections as shown in Fig. 25.
' Q' Where is the discharge valve {Fig, 26) usual-
ly located ?

A. As shown in Fig. 25, although it is sometimes
found inside the car over the door.
Q, Why is it better placed outside ?
A. When it is so placed the noise of the discharge
will not affect nervous people.
Q. How does the car discharge valve work ?

A. The signal cord is attached to the valve in the
hole of 5 (Fig. 26) ; when the cord is pulled, valve 3 is
forced from its seat, allowing whistle-line pressure to
escape to the atmosphere.
Q, What is the trouble when there is a constant
leak from the discharge valve?
A. There is dirt on the seat of valve 3 (Fig. 26).
Q, Where is the signal valve {Fig, 2f) located ?

A. Under the foot-boards of the cab. Convenience
determines whether it will be on the fireman's or
engineer's side.
Q, Where are the reducing valves {Figs. 28 and
j6) usually placed?

A. It was formerly customary to locate them outside,
next to the main reservoir, as in Fig. 24, but now good
practice locates them inside the cab where they cannot
freeze in winter.
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146



Air-Brake Catechism.
Q. Which valve is now being sent out with all
new equipment?

A. The valve represented by Fig. 28, as this is the
latest, although there are still many like Fig. 30 in use.
Q. What is the duty of these valves ?

A. To maintain a constant pressure on the whistle
line.
