LEC Locomotive Operation and Control 3 — Questions and Answers
Question 1: When descending a long grade with a fully loaded train, the engineer notices brake pipe pressure is slowly declining despite no brake application. The most appropriate action is to:
- Increase throttle to compensate for the speed increase
- Stop the train and perform a brake test to locate the air leak (Correct answer)
- Apply full service brakes immediately and notify the dispatcher
- Switch to dynamic braking only and ignore the pressure drop
Correct answer: Stop the train and perform a brake test to locate the air leak
A slow unexplained drop in brake pipe pressure indicates a leak in the system that must be identified and corrected before proceeding on a grade.
Question 2: The '26-L' brake system's equalizing reservoir is used primarily to:
- Store emergency air supply for quick brake application
- Control automatic brake valve movements and reduce engineer workload (Correct answer)
- Pre-charge the train line before departure
- Provide air to the independent brake cylinder directly
Correct answer: Control automatic brake valve movements and reduce engineer workload
The equalizing reservoir in the 26-L system acts as a pilot that controls brake pipe pressure, making brake applications smoother and less physically demanding for the engineer.
Question 3: A train is traveling at 40 mph when the engineer observes a stop signal 1 mile ahead. Using the '1 mph per car length' rule of thumb, a 100-car train requires approximately how much distance to stop?
- About 0.5 miles
- About 1 mile (Correct answer)
- About 2 miles
- About 3 miles
Correct answer: About 1 mile
A common rule of thumb places stopping distance for freight trains at roughly 1 mile from 40 mph when accounting for train length and brake system lag.
Question 4: What is the purpose of the 'bail-off' feature on the independent brake handle?
- To apply maximum independent brake force quickly
- To release locomotive brakes while keeping the automatic train brake applied (Correct answer)
- To test the communication between lead and trailing locomotives
- To activate the dynamic brake blending automatically
Correct answer: To release locomotive brakes while keeping the automatic train brake applied
Bail-off allows the engineer to release locomotive brakes independently of the automatic brake to prevent wheel sliding when the train brake is fully applied.
Question 5: Which operating condition requires the use of the 'suppression' or 'service override' position on the automatic brake valve?
- When setting out cars at an intermediate yard
- When recovering from an unintended automatic brake application without increasing brake pipe pressure past full release (Correct answer)
- When testing the emergency brake system at a terminal
- When applying continuous service brakes on a flat grade
Correct answer: When recovering from an unintended automatic brake application without increasing brake pipe pressure past full release
Suppression allows the engineer to hold the current brake pipe pressure steady after an unintended application rather than inflating it back to the run position, which would further release brakes on triple valves.
Question 6: On an AC traction locomotive, what advantage does it have over DC traction on steep grades?
- AC motors produce more noise to warn pedestrians
- AC traction systems can apply more continuous pulling force without overheating at low speeds (Correct answer)
- AC locomotives require less coolant fluid at high altitudes
- AC motors automatically engage dynamic brakes above 30 mph
Correct answer: AC traction systems can apply more continuous pulling force without overheating at low speeds
AC traction motors can sustain higher continuous tractive effort at very low speeds without overheating, making them superior to DC motors on steep ruling grades.
Question 7: What is the correct procedure when a locomotive's alerter (deadman device) sounds an alarm?
- Immediately reduce throttle to idle and wait for the alarm to reset automatically
- Acknowledge it by pressing the reset button, foot pedal, or moving a control within the allowed time (Correct answer)
- Apply emergency brakes and exit the cab
- Notify the conductor and transfer control to the rear unit
Correct answer: Acknowledge it by pressing the reset button, foot pedal, or moving a control within the allowed time
The alerter requires periodic acknowledgment from the engineer via reset button, foot pedal, or control movement; failure to acknowledge within the time limit triggers an automatic brake application.
LEC Locomotive Operation and Control 3
When descending a long grade with a fully loaded train, the engineer notices brake pipe pressure is slowly declining despite no brake application.
The most appropriate action is to: