LEC Locomotive Operation and Control 2 — Questions and Answers
Question 1: When applying dynamic braking on a steep descending grade, the engineer should primarily monitor which parameter to avoid overheating traction motors?
- Brake cylinder pressure
- Motor current amperage (Correct answer)
- Throttle notch position
- Train line voltage
Correct answer: Motor current amperage
Dynamic brake effectiveness and heat dissipation are monitored via motor current amperage to prevent traction motor overheating on long descending grades.
Question 2: A locomotive's independent brake is released but the automatic brake remains applied. What is the most likely cause?
- Equalizing reservoir leak
- Triple valve malfunction on the locomotive only
- Brake pipe pressure below 90 psi (Correct answer)
- MU hose disconnected
Correct answer: Brake pipe pressure below 90 psi
When brake pipe pressure falls below approximately 90 psi, automatic brakes apply throughout the train and will not fully release until proper pressure is restored.
Question 3: Which throttle technique is recommended when starting a heavy freight train on a level track to minimize slack run-out?
- Immediately apply full throttle for quick acceleration
- Gradually increase throttle in small increments from Notch 1 (Correct answer)
- Apply emergency sand and jump to Notch 4
- Hold at Notch 8 until train fully stretches
Correct answer: Gradually increase throttle in small increments from Notch 1
Gradually increasing throttle in small increments allows coupler slack to take up progressively, reducing the risk of run-out and coupler damage.
Question 4: During cold weather operations, what is the primary reason for pre-charging the train brake system before departure?
- To warm the locomotive engine faster
- To ensure all brake cylinders are fully charged and frozen moisture is expelled (Correct answer)
- To test the emergency brake valve
- To synchronize MU locomotive throttles
Correct answer: To ensure all brake cylinders are fully charged and frozen moisture is expelled
Pre-charging ensures all brake cylinders reach full pressure and helps expel any moisture that could freeze and impair brake function in cold conditions.
Question 5: When operating in multiple unit (MU) configuration, if the lead locomotive loses its control stand, the engineer should:
- Immediately apply emergency brakes and abandon the cab
- Transfer control to the rear unit using the MU changeover switch (Correct answer)
- Continue operating using manual throttle from the engine room
- Reduce to Notch 1 and wait for dispatcher instructions
Correct answer: Transfer control to the rear unit using the MU changeover switch
The MU changeover switch allows the engineer to transfer locomotive control to a functioning unit when the lead cab's control stand fails.
Question 6: What does a 'wheel slip' light indicate on the locomotive control panel, and what is the correct initial response?
- A hot wheel bearing; stop and inspect immediately
- Loss of traction adhesion on one or more axles; reduce throttle and apply sand (Correct answer)
- Brake cylinder overpressure; release independent brake
- Low fuel level; switch to reserve tank
Correct answer: Loss of traction adhesion on one or more axles; reduce throttle and apply sand
Wheel slip means one or more driving axles have lost adhesion and are spinning freely; reducing throttle and applying sand restores traction.
Question 7: Under FRA regulations, a locomotive engineer must inspect the cab and controls before each trip. Which item is NOT typically included in a pre-departure cab inspection?
- Functioning headlight and ditch lights
- Proper operation of alerter/deadman device
- Fuel tank capacity verification (Correct answer)
- Audible warning device (horn/bell) operation
Correct answer: Fuel tank capacity verification
Fuel tank capacity is a maintenance and servicing concern, not a cab inspection item; cab inspections focus on safety-critical operating controls and signals.
LEC Locomotive Operation and Control 2
When applying dynamic braking on a steep descending grade, the engineer should primarily monitor which parameter to avoid overheating traction motors?