Mixed Deck — All LEC Topics Flashcards

On an AC traction locomotive, what advantage does it have over DC traction on steep grades?

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.

Which condition would cause a 'sticking brake' on a freight car?

Answer: A broken release spring in the brake cylinder

A broken release spring in the brake cylinder prevents the piston from returning, leaving brakes applied even after the brake pipe is recharged.

A locomotive's air compressor fails to build pressure. Which system is most immediately affected?

Answer: Automatic and independent brakes

The automatic and independent brake systems rely on compressed air; without adequate pressure, brakes cannot be applied or released properly.

A locomotive engineer reports that the exhaust stack is emitting white smoke during cold startup. What is the most likely cause?

Answer: Water vapor and unburned fuel condensing in cold exhaust

White smoke during cold startup is typically water vapor condensing and unburned fuel misting as the engine and exhaust system reach operating temperature.

A locomotive engineer must report which of the following conditions to the proper authority before operating the locomotive?

Answer: Any physical or mental condition that may impair safe operation

FRA regulations require engineers to self-disclose any physical or mental impairment that could affect safe locomotive operation.

A locomotive's truck is said to have 'rock and roll' motion. What does this describe?

Answer: Combined lateral rocking and vertical rolling of the car body

Rock and roll refers to simultaneous lateral (rocking) and rotational (rolling) oscillation of the locomotive body on its suspension.

What is the role of the 'excitation' control in a diesel-electric locomotive's drivetrain power flow?

Answer: It regulates main generator field current to control power output at each throttle notch

Excitation control varies the current in the main generator's field windings, which determines the generator's voltage and power output at any given engine speed.

Which gauge or indicator directly tells the engineer whether the automatic brake is releasing or applying in terms of brake pipe pressure?

Answer: Brake pipe pressure gauge

The brake pipe pressure gauge shows whether brake pipe pressure is increasing (release) or decreasing (application), directly indicating brake system status.

When bleeding air from a diesel fuel system after filter replacement, where should the engineer begin?

Answer: At the primary filter, then the secondary filter, then the injection pump

Air bleeding proceeds from the low-pressure side (primary filter) toward the high-pressure side (injection pump) to systematically purge all trapped air.

What is 'brake shoe squeeze-out,' and what does it indicate?

Answer: Uneven brake shoe contact causing the shoe to slide partially off the wheel tread

Brake shoe squeeze-out occurs when misaligned or worn brake rigging causes the shoe to partially leave the wheel tread, indicating a rigging defect requiring inspection.

How does risk management apply to daily practice in Drivetrain & Transmission for Locomotive Engineer professionals?

Answer: Through proactive identification of potential hazards and implementation of preventive measures

Effective risk management in Drivetrain & Transmission requires proactive hazard identification and preventive measures, not just reactive responses. This approach reduces incidents, improves outcomes, and protects both professionals and clients.

What is the correct action when a locomotive's wheel slides during dynamic braking?

Answer: Reduce dynamic brake effort to allow wheels to recover traction

Reducing dynamic brake effort decreases the retarding force, allowing slipping wheels to recover traction before increasing braking again.

In a locomotive consist (multiple units), how is traction power typically coordinated between units?

Answer: Multiple-unit (MU) control cables transmit throttle and brake commands from the lead unit to all trailing units

MU cables carry control signals (throttle position, brake commands, direction) from the controlling locomotive to all units in the consist, so one engineer operates all units.

What is the primary purpose of track geometry measurement cars operated by railroads and the FRA?

Answer: To measure track parameters such as gauge, alignment, and surface to detect defects before failure

Track geometry cars use sensors and measurement systems to continuously record rail gauge, cross-level, alignment, surface, and curvature, allowing railroads to identify and prioritize track defects before they cause derailments.

When a conflict arises between standard procedures and a unique situation in Fuel Systems & Injection, what should a LEC professional prioritize?

Answer: Safety and ethical obligations while seeking expert consultation

Safety and ethics always take priority in Fuel Systems & Injection. When standard procedures don't adequately address a unique situation, consulting with experienced colleagues or supervisors ensures both safety and professional standards are maintained.

What is the primary purpose of 'field shunting' (field weakening) in DC traction motor operation?

Answer: To reduce motor field strength, allowing higher motor speed above base speed for higher train speeds

Field weakening reduces the back-EMF generated by the motor, allowing it to spin faster at the same voltage, extending the locomotive's speed range beyond the base transition point.

A locomotive engineer reports a 'stiff ride' with harsh impacts over track joints. Which suspension component is most likely at fault?

Answer: Failed or hardened suspension springs or dampers

Failed or hardened springs and dampers lose their ability to absorb track irregularities, transmitting impacts directly to the locomotive body as a harsh ride.

A locomotive equipped with an Alertness/Vigilance device (dead-man pedal) requires the engineer to respond within how many seconds before an automatic penalty brake application occurs?

Answer: 30 seconds

Most FRA-compliant vigilance systems require the engineer to respond to the alerter within approximately 30 seconds to prevent a penalty brake application.

A yaw damper is fitted between the truck and the carbody on some high-speed locomotives. What motion does it resist?

Answer: Rotational (yawing) oscillation of the truck relative to the carbody

Yaw dampers resist the rotational hunting and yawing of the truck about the vertical axis, improving high-speed stability.

A diesel locomotive engine experiences a sudden drop in oil pressure while operating at Notch 8. The engineer should FIRST:

Answer: Immediately place throttle to idle and prepare to shut down

A sudden oil pressure drop is a critical emergency requiring immediate throttle reduction to idle and engine shutdown preparation to prevent severe engine damage.