specially designed transformer, resistors, and a rectifier.
The resistors are usually in series and one is manually
adjustable to compensate for wheel wear. Refer to
f. The indicating instrument is of the D'Arsonval
permanent-magnet moving coil type of design. Handle
the indicator with care to avoid damaging jewel
bearings. Do not hammer on the panel on which the
indicator is mounted. Check that the pointer is on the
for adjustment instructions.
27. Air System
cylinder, two stage, air cooled, pressure
It is suitable for
continuous service against 115 pounds air
pressure at speeds up to 610 rpm.
Figure 4. Bell ringer operating valve.
Inasmuch as the locomotive engines
operate at idling speeds when the motive
by position of cam edge of rotor lapping control port.
power is not needed, and the compressor
b. When valve
is closed, exhaust port opens and
runs continuously, a load and unload type
control is provided to maintain the main
c. An occasional drop of light oil is all this valve
reservoir pressure between the desire
will require to provide years of trouble-free service.
113 for adjustment and maintenance
the compressor governor.
(2) The belts should be maintained tight
26. Speed-Indicating Equipment
enough to prevent excessive slippage, but
a. The speed-indicating equipment is designed to
not tight enough to place undue strain on
give a continuous indication of train speed.
b. The complete speed-indicating equipment
will result in excessive heating of these
consists of three units.
bearings and increase tile power required.
When belt replacement is necessary,
replace all belts with a matched set.
(2) Transformer-resistor box.
Refer to TM 55-2034 for maintenance
(3) D indicating instrument.
c. The indicator scale is calibrated in miles per
b. Airbrakes. Refer
to TM 55-2029 for operation
hour, thus making it possible to read the train speed at
and maintenance of the airbrake equipment.
the instrument panel.
. The generator
by the axle