LEC Cheat Sheet 2026

The 30 highest-yield LEC facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. A locomotive engineer reports that the exhaust stack is emitting white smoke during cold startup. What is the most likely cause? → Water vapor and unburned fuel condensing in cold exhaust
2. What is the role of the center plate (center bowl) in a locomotive truck assembly? → It is the pivot point that allows the truck to rotate under the locomotive body
3. What does water in the fuel system primarily cause in a diesel locomotive? → Injector seizure, corrosion, and microbial growth
4. Which type of brake shoe provides a higher friction coefficient at low speeds but tends to overheat on long downgrades? → Cast iron shoes
5. Which electrical protection relay specifically prevents damage from excessive current flow through the traction motors? → Overload (overcurrent) relay
6. What is the primary purpose of the independent brake valve on a locomotive? → Controls only the locomotive brakes without affecting train brakes
7. What is the maximum authorized speed for freight trains on FRA Class 5 track? → 80 mph
8. Which component in the fuel system prevents air from entering the injection lines? → The check valve
9. A locomotive is found to have a negative wheel load (wheel lifting) on one corner during curve negotiation. What is the most dangerous consequence? → Potential derailment due to unloaded wheel climbing the rail
10. A yaw damper is fitted between the truck and the carbody on some high-speed locomotives. What motion does it resist? → Rotational (yawing) oscillation of the truck relative to the carbody
11. What does the term 'notch' refer to in relation to locomotive throttle operation? → A discrete throttle position that controls engine power output
12. Which condition is described as a 'rough ride with a periodic shock approximately once per wheel revolution'? → Flat spot (wheel flat) impacting the rail once per revolution
13. What is the consequence of operating a locomotive with a malfunctioning DEF doser in an SCR-equipped engine? → NOx emissions will exceed EPA limits
14. Which gauge or indicator directly tells the engineer whether the automatic brake is releasing or applying in terms of brake pipe pressure? → Brake pipe pressure gauge
15. Which signal aspect requires an engineer to stop and stay at that point? → Stop
16. Which type of emission is primarily responsible for the blue-gray smoke sometimes seen from locomotive exhaust? → Oil being burned in the combustion chamber
17. An engine overspeed trip activates during a downhill grade with dynamic brakes applied. What is the most likely cause? → The dynamic brake grids have failed open, removing the load from the engine
18. Which component in a locomotive HVAC system is responsible for removing humidity from cab air? → The evaporator coil
19. Which standard of practice is MOST important for ensuring quality in Suspension & Steering? → Following evidence-based protocols while adapting to specific circumstances
20. When must a locomotive engineer conduct a 'set and release' brake test after switching operations? → Before departing if cars have been added, removed, or brake hoses reconnected
21. Which train handling technique best prevents run-in when transitioning from upgrade to level track? → Reducing throttle gradually as lead units approach the crest
22. What does the term 'absolute block' mean in railroad operations? → A block that only one train may occupy at a time under any circumstances
23. Under FRA regulations, what action must be taken if a locomotive is found with a broken main suspension spring in a revenue service inspection? → Remove the locomotive from service until the spring is repaired or replaced
24. During a train handling situation with a long train on undulating terrain, 'power braking' refers to: → Applying brakes while in throttle to control speed and manage slack
25. A locomotive engineer notices smoke coming from a journal box on a freight car. The FIRST action should be to: → Stop the train and inspect the defect
26. Which locomotive inspection standard requires checking suspension components for cracks, worn wedges, and spring condition? → FRA 49 CFR Part 229 (Railroad Locomotive Safety Standards)
27. What does 'track authority' mean for a locomotive engineer in non-signaled territory? → The legal permission to occupy and operate over a defined segment of track
28. Under the EPA's smoke opacity standards, what is the maximum allowable exhaust opacity during a full-load acceleration for a Tier 0 locomotive? → 40%
29. How does biodiesel blending (B20) affect cold-weather operability of locomotive fuel systems? → It raises the cloud point, increasing risk of fuel gelling at low temperatures
30. In a diesel-hydraulic locomotive drivetrain, what component replaces the traction motors used in diesel-electric designs? → A hydraulic torque converter and mechanical gearbox