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The independent brake shall be fully applied and left in that position to prevent the locomotive
from moving while refueling or anytime the locomotive is left standing. The independent brake
shall be applied except during maintenance of the brakes. In cases where independent brakes
cannot be applied, the locomotive shall be chained to the track.
e. Speed Control. The train should be operated within the speed limits set for the track
being traversed. However, additional speed issues should be closely monitored.
On cars with truck spacing about equal to the rail length (approximately 39 feet), there is a critical
speed at which the car will encounter low joints in harmony with its natural frequency. When the
train is traveling at this critical speed, harmonic rock and roll motion can build up to the point
where wheel lift occurs and a derailment can result. The critical speed is in the 13 to 20 mph
range. This critical speed should be avoided when possible to reduce the risk of harmonic rock
and roll derailments. Refer to Figure 3-11. When necessary to pass through this critical speed,
the engineer shall plan ahead and avoid this speed by going slower or faster. This critical speed
can be determined by observing the train. Crew members shall be on the lookout for excessive
rocking which can indicate that harmonic rock and roll is imminent. The engineer shall take
appropriate action if there is a problem.
f. Use of Sand. One of the principal factors affecting the tractive effort of a locomotive
is adhesion. Adhesion allows for starting, acceleration, maintaining speed, slowing, or stopping.
The condition of the rail can have a large effect on adhesion. To overcome the adverse effect of
contamination of rail by oil, dirt, water, snow, ice, insects and other substances, most locomotives
are equipped with sanders to deliver sand to the rail. The sand will help to increase the adhesion
of the locomotive when the above conditions are present. The following cautions apply when
using sand:
Sand use should be restricted to the minimum amount necessary. Excessive use of
sand defeats the intended purpose.
Use of sand in curves should be avoided due to derailment risk resulting from
increased curve resistance and the resulting high lateral forces.
Sanding should be used to prevent wheel slip rather than correct it.
g. Extreme Emergencies. An extreme emergency is when emergency braking needs to
be applied because the brake system has failed. When this occurs, use the following emergency
procedures:
Place throttle in idle.
Place reverser in opposite direction.
Place throttle in No. 1 notch only.
NOTE A LOCOMOTIVE SHALL NOT BE REVERSED WHILE MOVING EXCEPT TO STOP THE
LOCOMOTIVE UNDER EXTREME EMERGENCY SITUATIONS.
THIS PROCEDURE WILL RESULT IN DAMAGE TO THE TRACTION MOTORS AND WHEELS AND
SHOULD ONLY BE USED AS A LAST RESORT TO AVOID AN ACCIDENT.
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