Use of Sand

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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