While charging a train, the main reservoir pressure drops below 100-psi. To what position may the throttle be increased in order to bring the main reservoir pressure back up?

While charging a train, the main reservoir pressure drops below 100-psi. To what position may the throttle be increased in order to bring the main reservoir pressure back up?

• A. Throttle notch 0
• B. Throttle notch 1
• C. Throttle notch 2
• D. Throttle notch 3

Answer: (C)

The key idea is that recharging the main reservoir is done by the air compressor, which is driven by the throttle setting. When the main reservoir pressure falls below the needed level, you raise the throttle just enough to start the compressor and push air into the reservoir. This is the lowest setting that provides a true charging flow—any lower and the compressor won’t run, any higher and you risk moving the locomotive or wasting air. So you choose the throttle position that activates the compressor sufficiently to rebuild pressure without moving the train.

The key idea is that recharging the main reservoir is done by the air compressor, which is driven by the throttle setting. When the main reservoir pressure falls below the needed level, you raise the throttle just enough to start the compressor and push air into the reservoir. This is the lowest setting that provides a true charging flow—any lower and the compressor won’t run, any higher and you risk moving the locomotive or wasting air. So you choose the throttle position that activates the compressor sufficiently to rebuild pressure without moving the train.