Question 1: How does grade resistance affect the horsepower required to maintain a constant speed?

• Grade resistance only matters when train weight exceeds locomotive rated capacity
• Grade resistance reduces required horsepower on descending grades and increases it on ascending grades (Correct answer)
• Grade resistance increases horsepower requirements on both ascending and descending grades
• Grade resistance has no effect on horsepower requirements at constant speed

Correct answer: Grade resistance reduces required horsepower on descending grades and increases it on ascending grades

On an ascending grade, gravity adds to rolling resistance requiring more power; on a descending grade, gravity assists movement, requiring less power or braking.

Question 2: Which standard of practice is MOST important for ensuring quality in Suspension & Steering?

• Strictly adhering to the same procedure in every situation
• Using the most advanced technology available regardless of need
• Minimizing documentation to focus on practical work
• Following evidence-based protocols while adapting to specific circumstances (Correct answer)

Correct answer: Following evidence-based protocols while adapting to specific circumstances

Evidence-based protocols provide a foundation of proven practices, but effective Locomotive Engineer professionals must also adapt their approach based on specific circumstances and individual case needs within Suspension & Steering.

Question 3: What is the purpose of the throttle control on a locomotive?

• To control the direction of the train.
• To control the brakes.
• To regulate the speed of the train by adjusting engine power.
• To monitor engine temperature.

The throttle control on a locomotive is the primary interface for the engineer to manage the train's speed and power output. By adjusting the throttle, the engineer controls the amount of fuel delivered to the engine, thereby increasing or decreasing the engine's RPMs and the power generated. This directly impacts the tractive effort applied to the wheels, allowing for precise control over the train's acceleration and speed.

Question 4: In Brake Systems & Safety, what is the FIRST step a LEC professional should take when encountering a new case or situation?

• Implement an immediate solution based on past experience
• Conduct a comprehensive assessment and gather all relevant information (Correct answer)
• Document the situation and wait for further instructions
• Consult with a supervisor before taking any action

Correct answer: Conduct a comprehensive assessment and gather all relevant information

In Brake Systems & Safety, a thorough initial assessment ensures all relevant factors are identified before deciding on an appropriate course of action. This systematic approach is fundamental to Locomotive Engineer practice.

Question 5: When a conflict arises between standard procedures and a unique situation in Brake Systems & Safety, what should a LEC professional prioritize?

• The most cost-effective solution available
• Safety and ethical obligations while seeking expert consultation (Correct answer)
• The preference of the client or stakeholder
• Strict adherence to written procedures without exception

Correct answer: Safety and ethical obligations while seeking expert consultation

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

Question 6: How should a locomotive engineer handle a steep downgrade?

• Switch to a backup locomotive.
• Increase throttle to maintain speed.
• Turn off all braking systems.
• Apply brakes to prevent the train from accelerating too much.

On a steep downgrade, gravity will naturally cause the train to accelerate. To maintain control and prevent excessive speed, the engineer must judiciously apply brakes, often using dynamic braking in conjunction with air brakes, to regulate the train's speed and ensure a safe descent. This prevents runaway situations and maintains safe operating parameters.

Question 7: What happens to air conditioning system performance at very high altitudes during locomotive operations?

• Performance improves due to lower ambient temperatures
• Performance increases because compressor load decreases
• Performance is unaffected because refrigerant pressure is self-regulating
• Performance decreases because lower air density reduces heat exchanger efficiency (Correct answer)

Correct answer: Performance decreases because lower air density reduces heat exchanger efficiency

At high altitudes, lower air density reduces the efficiency of condenser heat rejection, decreasing overall AC system performance.

Question 8: What is the PRIMARY purpose of continuing education requirements in Fuel Systems & Injection for LEC professionals?

• Fulfilling mandatory regulatory requirements only
• Earning additional credentials for career advancement
• Maintaining current knowledge and competency as the field evolves (Correct answer)
• Networking with other professionals in the field

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Fuel Systems & Injection ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the Locomotive Engineer field.

Question 9: Which system on a locomotive continuously monitors axle bearing temperatures and alerts the crew to overheating?

• Locomotive Event Recorder (LER)
• Wheel profile sensor
• Hot bearing detector (HBD) wayside system
• Onboard bearing temperature monitoring system (Correct answer)

Correct answer: Onboard bearing temperature monitoring system

The onboard bearing temperature monitoring system uses sensors on each axle to detect abnormal heat and alert the engineer before a hotbox failure occurs.

Question 10: What is the primary advantage of distributing power throughout a long train (distributed power units)?

• Distributed power reduces fuel consumption by 30% compared to head-end power only
• It allows the train to operate without a brake pipe connection between units
• Distributed power units can be operated at higher notch settings than head-end units
• It reduces in-train forces by applying traction and braking closer to where it is needed (Correct answer)

Correct answer: It reduces in-train forces by applying traction and braking closer to where it is needed

Distributed power units apply traction and braking forces along the train's length, dramatically reducing peak buff and draft forces on couplers.

Question 11: A locomotive engineer notices smoke coming from a journal box on a freight car. The FIRST action should be to:

• Increase speed to reduce friction
• Notify the conductor and wait for instructions
• Continue to the next siding and report
• Stop the train and inspect the defect (Correct answer)

Correct answer: Stop the train and inspect the defect

A smoking journal box indicates a potential overheated bearing that could cause a derailment, requiring an immediate stop and inspection.

Question 12: What is the PRIMARY purpose of continuing education requirements in Electrical & Electronic Systems for LEC professionals?

• Networking with other professionals in the field
• Maintaining current knowledge and competency as the field evolves (Correct answer)
• Earning additional credentials for career advancement
• Fulfilling mandatory regulatory requirements only

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Electrical & Electronic Systems ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the Locomotive Engineer field.

Question 13: What is the PRIMARY purpose of continuing education requirements in Brake Systems & Safety for LEC professionals?

• Fulfilling mandatory regulatory requirements only
• Earning additional credentials for career advancement
• Networking with other professionals in the field
• Maintaining current knowledge and competency as the field evolves (Correct answer)

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Brake Systems & Safety ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the Locomotive Engineer field.

Question 14: How does the load weight of a train affect its performance?

• It reduces the time needed to accelerate.
• It makes the train more stable.
• It increases fuel efficiency.
• It requires more power to move and increases stopping distances.

A heavier train requires significantly more power from the locomotive's engines to overcome inertia and friction, thus increasing the effort needed to accelerate and maintain speed. Additionally, greater mass means more momentum, which in turn requires a longer distance and more braking effort to bring the train to a complete stop safely.

Question 15: What is the purpose of the high-pressure cutout switch in a locomotive AC system?

• It disconnects power to the evaporator blower if cab temperature drops too low
• It limits the maximum cab temperature by cutting out the heating system
• It shuts down the AC compressor if refrigerant pressure exceeds a safe limit to prevent component damage (Correct answer)
• It controls the speed of the condenser fan based on discharge pressure

Correct answer: It shuts down the AC compressor if refrigerant pressure exceeds a safe limit to prevent component damage

The high-pressure cutout switch protects the compressor and system components from damage by shutting down the AC if discharge pressure becomes dangerously high.

Question 16: What sensor is used to measure the rotational speed of traction motor armatures (or rotor speed on AC motors) for wheel slip detection?

• Pressure transducer
• Current transformer
• Speed pickup (tachometer-generator or speed sensor) (Correct answer)
• Thermocouple

Correct answer: Speed pickup (tachometer-generator or speed sensor)

Speed pickups (tachometer-generators or digital speed sensors) mounted on axles or motors measure rotational speed so the control system can detect axle speed differentials indicating wheel slip.

Question 17: When operating a long train through an 'S-curve' (reverse curves), what is the main train handling concern?

• Wheel flanges wear faster due to alternating rail contact
• Coupler angles change direction, increasing lateral forces that can derail cars (Correct answer)
• Track superelevation conflicts create excessive speed restrictions
• Signal visibility is limited through compound curves

Correct answer: Coupler angles change direction, increasing lateral forces that can derail cars

In S-curves, couplers change from one angle to the opposite, and combined with any slack action this can create high lateral forces and potential derailments.

Question 18: What is the primary function of the main reservoir in a locomotive's pneumatic/electrical control system?

• Regulate voltage to cab electronics
• Filter electrical surges from the power grid
• Store compressed air for brakes and controls (Correct answer)
• Cool the traction motors

Correct answer: Store compressed air for brakes and controls

The main reservoir stores compressed air used to operate brakes, whistles, and various pneumatic controls on the locomotive.

Question 19: What documentation practice is considered essential in Heating, Ventilation & AC within the Locomotive Engineer field?

• Using shorthand notes that can be expanded later if needed
• Only documenting unusual events or complications
• Completing all documentation at the end of the workday
• Recording actions, observations, and outcomes in real-time or as close to the event as possible (Correct answer)

Correct answer: Recording actions, observations, and outcomes in real-time or as close to the event as possible

Real-time or near-real-time documentation in Heating, Ventilation & AC ensures accuracy, provides a contemporaneous record, and is considered the gold standard for professional accountability and legal defensibility.

Question 20: Under FRA regulations, if a locomotive's heating system fails during cold weather operations (below 32°F), what is generally required?

• The engineer may operate at reduced speed to minimize exposure time
• The locomotive must be removed from service or the heating system repaired before continued operation (Correct answer)
• The locomotive may continue in service with additional crew clothing
• A waiver from the railroad superintendent allows continued operation for up to 8 hours

Correct answer: The locomotive must be removed from service or the heating system repaired before continued operation

FRA regulations generally require that locomotives with inoperative heating systems be removed from service in cold conditions to protect crew safety.

Question 21: How does risk management apply to daily practice in Heating, Ventilation & AC for Locomotive Engineer professionals?

• By avoiding high-risk situations entirely
• Only through responding to incidents after they occur
• Through annual safety audits exclusively
• Through proactive identification of potential hazards and implementation of preventive measures (Correct answer)

Correct answer: Through proactive identification of potential hazards and implementation of preventive measures

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

Question 22: Why is it important for the locomotive engineer to monitor train handling during operations?

• To ensure safe operation and prevent accidents.
• To improve the passenger experience.
• To optimize fuel efficiency.
• To decrease the wear on train tracks.

Monitoring train handling is crucial for a locomotive engineer because it directly impacts safety. Proper handling prevents derailments, collisions, and other incidents that could endanger the crew, passengers, cargo, and the public. It allows the engineer to react to changing conditions and maintain control, ensuring the train operates within safe parameters.

Question 23: Which regulation governs the required temperature range that must be maintained in a locomotive cab during cold weather operations in the U.S.?

• EPA 40 CFR Part 82
• OSHA 29 CFR 1910.94
• AAR Manual of Standards Section 5
• FRA 49 CFR Part 229 (Correct answer)

Correct answer: FRA 49 CFR Part 229

FRA 49 CFR Part 229 covers locomotive safety standards, including cab environment requirements such as heating during cold weather.

Question 24: When a conflict arises between standard procedures and a unique situation in Heating, Ventilation & AC, what should a LEC professional prioritize?

• Strict adherence to written procedures without exception
• The most cost-effective solution available
• The preference of the client or stakeholder
• Safety and ethical obligations while seeking expert consultation (Correct answer)

Correct answer: Safety and ethical obligations while seeking expert consultation

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

Question 25: When a locomotive experiences a 'wheel slip' indication, which system is primarily responding?

• Brake pipe pressure control
• Dynamic brake blending unit
• Fuel injection controller
• Wheel slip detection and correction system (Correct answer)

Correct answer: Wheel slip detection and correction system

The wheel slip detection and correction system monitors axle speed differentials and reduces tractive effort to restore adhesion when slipping is detected.

Question 26: What effect does a dirty or clogged cabin air filter have on locomotive HVAC performance?

• It restricts airflow, reducing system efficiency and increasing blower motor strain (Correct answer)
• It has no measurable effect on performance until the filter is completely blocked
• It causes the refrigerant to overheat and triggers the high-pressure cutout
• It increases airflow velocity through the evaporator, improving cooling

Correct answer: It restricts airflow, reducing system efficiency and increasing blower motor strain

A clogged cabin filter restricts airflow through the system, degrading both heating and cooling performance and stressing the blower motor.

Question 27: What is the primary purpose of a Track Warrant (Form B) in railroad operations?

• To grant a train authority to occupy a defined section of track in non-signaled territory (Correct answer)
• To record the engineer's hours of service for FRA compliance
• To authorize maintenance crews to perform track inspections
• To authorize a locomotive to exceed the posted track speed limit

Correct answer: To grant a train authority to occupy a defined section of track in non-signaled territory

A Track Warrant (Form B) grants written authority for a train to operate over a specific segment of track, particularly in dark or non-signaled territory where no automatic block signals exist.

Question 28: What is the PRIMARY purpose of continuing education requirements in Emissions Control Systems for LEC professionals?

• Fulfilling mandatory regulatory requirements only
• Maintaining current knowledge and competency as the field evolves (Correct answer)
• Earning additional credentials for career advancement
• Networking with other professionals in the field

Correct answer: Maintaining current knowledge and competency as the field evolves

Continuing education in Emissions Control Systems ensures professionals maintain current knowledge and skills as standards, technologies, and best practices evolve in the Locomotive Engineer field.

Question 29: What documentation practice is considered essential in Brake Systems & Safety within the Locomotive Engineer field?

• Only documenting unusual events or complications
• Completing all documentation at the end of the workday
• Using shorthand notes that can be expanded later if needed
• Recording actions, observations, and outcomes in real-time or as close to the event as possible (Correct answer)

Correct answer: Recording actions, observations, and outcomes in real-time or as close to the event as possible

Real-time or near-real-time documentation in Brake Systems & Safety ensures accuracy, provides a contemporaneous record, and is considered the gold standard for professional accountability and legal defensibility.

Question 30: What does it mean to 'cut off' a train?

• To stop the train for a scheduled break.
• To disconnect the train's brakes.
• To increase the train's speed.
• To disconnect the locomotive from the cars for maintenance or switching.

In railroad terminology, "cutting off" a train refers to the act of uncoupling or disconnecting the locomotive (or a section of cars) from the rest of the train. This procedure is commonly performed for various operational reasons, such as moving the locomotive to a different track, attaching it to a new set of cars, or performing maintenance. It is a fundamental part of switching and yard operations.

Question 31: What documentation practice is considered essential in Electrical & Electronic Systems within the Locomotive Engineer field?

• Using shorthand notes that can be expanded later if needed
• Completing all documentation at the end of the workday
• Only documenting unusual events or complications
• Recording actions, observations, and outcomes in real-time or as close to the event as possible (Correct answer)

Correct answer: Recording actions, observations, and outcomes in real-time or as close to the event as possible

Real-time or near-real-time documentation in Electrical & Electronic Systems ensures accuracy, provides a contemporaneous record, and is considered the gold standard for professional accountability and legal defensibility.

Question 32: Under the Locomotive Safety Standards (49 CFR Part 229), which condition requires a locomotive to be removed from service?

• A speedometer reading 2 mph off at high speed
• A non-functioning auxiliary cab light
• Any safety-critical defect listed in the FRA's locomotive defect list (Correct answer)
• A minor cab door that doesn't seal tightly

Correct answer: Any safety-critical defect listed in the FRA's locomotive defect list

Any defect classified as a safety-critical item under 49 CFR Part 229 requires the locomotive to be removed from service until repaired.

Question 33: What is the primary safety responsibility of a locomotive engineer?

• To monitor train performance.
• To repair faulty equipment on the train.
• To ensure the safety of the train crew, passengers, and cargo.
• To handle maintenance tasks on the locomotive.

The primary safety responsibility of a locomotive engineer is paramount and encompasses the well-being of everyone and everything on the train, as well as the public. This involves adhering to strict operating rules, monitoring conditions, and making critical decisions to prevent accidents and ensure a safe journey. While other tasks are important, safety is the overarching priority.

Question 34: When calculating a train's stopping distance, which variable does NOT directly factor into the calculation?

• Grade of the track in the stopping zone
• Total train weight (gross rail load)
• Locomotive cab color and visibility markings (Correct answer)
• Train speed at the point of brake application

Correct answer: Locomotive cab color and visibility markings

Stopping distance is determined by physics—speed, weight, brake force, and grade—not by the visual markings on the locomotive.

Question 35: What is the purpose of 'wheel creep control' in modern AC traction locomotive systems?

• Automatically apply sand when wheel slip exceeds 10 mph
• Reduce speed to 5 mph when entering yards
• Maintain a small, controlled amount of wheel slip to maximize tractive effort at the adhesion limit (Correct answer)
• Prevent wheels from turning during braking

Correct answer: Maintain a small, controlled amount of wheel slip to maximize tractive effort at the adhesion limit

Wheel creep control intentionally maintains a slight, optimized slip ratio between wheel and rail, which maximizes tractive effort by operating at the peak of the adhesion curve.

Question 36: Which condition would cause a locomotive's ground fault indicator to illuminate?

• Wheel slip exceeding 5 mph
• Loss of cab signal reception
• Battery voltage dropping below 60V
• Unintended electrical continuity between a traction circuit conductor and the locomotive frame (Correct answer)

Correct answer: Unintended electrical continuity between a traction circuit conductor and the locomotive frame

A ground fault occurs when a normally isolated high-voltage traction circuit conductor makes unintended contact with the grounded locomotive frame.

Question 37: What is the function of the 'alerter' (deadman) system on a locomotive?

• Automatically apply brakes when fuel is low
• Control horn activation at grade crossings
• Ensure the engineer is awake and alert by requiring periodic acknowledgment (Correct answer)
• Detect mechanical failures in couplers

Correct answer: Ensure the engineer is awake and alert by requiring periodic acknowledgment

The alerter system monitors for engineer inactivity and applies brakes if the engineer does not acknowledge a periodic alarm within a set time interval.

Question 38: When a conflict arises between standard procedures and a unique situation in Engine Performance & Diagnostics, what should a LEC professional prioritize?

• Strict adherence to written procedures without exception
• The most cost-effective solution available
• The preference of the client or stakeholder
• Safety and ethical obligations while seeking expert consultation (Correct answer)

Correct answer: Safety and ethical obligations while seeking expert consultation

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

Question 39: How does risk management apply to daily practice in Brake Systems & Safety for Locomotive Engineer professionals?

• By avoiding high-risk situations entirely
• Through proactive identification of potential hazards and implementation of preventive measures (Correct answer)
• Only through responding to incidents after they occur
• Through annual safety audits exclusively

Correct answer: Through proactive identification of potential hazards and implementation of preventive measures

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

Question 40: Why is it important to follow safety protocols when approaching railway crossings?

• To reduce the train's fuel consumption.
• To avoid accidents and collisions at crossings.
• To ensure the train remains on schedule.
• To optimize train speed.

Railway crossings are high-risk areas where trains and vehicles or pedestrians intersect. Following safety protocols, such as sounding the horn, reducing speed, and being prepared to stop, is crucial to prevent devastating accidents and collisions, ensuring the safety of everyone involved. These measures minimize the potential for fatalities, injuries, and property damage.

Question 41: An engineer notices the 'low oil pressure' light illuminating while running at full throttle. What is the correct initial response?

• Increase throttle to build more pressure
• Switch to dynamic braking to reduce engine load
• Reduce throttle and notify dispatch while monitoring the situation (Correct answer)
• Apply emergency brakes immediately

Correct answer: Reduce throttle and notify dispatch while monitoring the situation

Reducing throttle decreases engine load while monitoring oil pressure; the engineer should notify dispatch and follow railroad procedures to protect the prime mover.

Question 42: Under FRA regulations, which of the following is a mandatory brake test before a train departs on a trip?

• Locomotive cab signal test
• Initial terminal air brake test (Correct answer)
• Retainer valve setting test
• Dynamic brake test

Correct answer: Initial terminal air brake test

A full initial terminal air brake test is required before a train departs a terminal to verify that the brake system is properly functioning.

Question 43: How does the locomotive's generator contribute to its operation?

• By cooling the train’s electrical components.
• By controlling engine temperature.
• By providing electrical energy for essential systems.
• By providing mechanical power to the wheels.

In a diesel-electric locomotive, the main generator (or alternator) converts the mechanical power from the diesel engine into electrical energy. This electrical energy is then supplied to the traction motors to propel the train and also powers various auxiliary systems, making it fundamental for the locomotive's overall operation.

Question 44: Which standard of practice is MOST important for ensuring quality in Brake Systems & Safety?

• Following evidence-based protocols while adapting to specific circumstances (Correct answer)
• Using the most advanced technology available regardless of need
• Strictly adhering to the same procedure in every situation
• Minimizing documentation to focus on practical work

Correct answer: Following evidence-based protocols while adapting to specific circumstances

Evidence-based protocols provide a foundation of proven practices, but effective Locomotive Engineer professionals must also adapt their approach based on specific circumstances and individual case needs within Brake Systems & Safety.

Question 45: What is the primary factor affecting train acceleration?

• Engine power and track conditions.
• Track conditions and train length.
• Weight of the train and brake performance.
• Engine power and weather conditions.

Train acceleration is primarily determined by the locomotive's engine power, which provides the tractive effort to overcome inertia and resistance. Track conditions, such as grade (uphill/downhill) and curvature, also significantly influence acceleration by affecting the resistance the train experiences. While other factors play a role, engine power and track conditions are the most direct determinants of how quickly a train can gain speed.

Question 46: What does 'MU (multiple unit) operation' require regarding electrical connections between locomotives?

• Direct wiring of traction motors across units
• A 27-point electrical MU cable connecting control circuits between units (Correct answer)
• Only mechanical couplings are needed
• A separate radio link for each locomotive cab

Correct answer: A 27-point electrical MU cable connecting control circuits between units

MU operation uses a 27-point electrical cable (jumper) to connect the control circuits of multiple locomotives so one engineer can control all units simultaneously.

Question 47: What is 'train line pressure equalization' and why does it matter before a brake test?

• Allowing brake pipe pressure to stabilize after charging so test reductions reflect true brake response (Correct answer)
• Balancing the locomotive's main reservoir with the brake pipe pressure
• The process of ensuring all brake cylinder pressures are equal before movement
• Resetting all triple valves to the release position simultaneously

Correct answer: Allowing brake pipe pressure to stabilize after charging so test reductions reflect true brake response

Equalization allows the brake pipe pressure to stabilize at full charge so that a subsequent reduction produces accurate, consistent brake response throughout the train.

Question 48: What is the purpose of the train horn?

• To alert others of the train's presence and prevent accidents.
• To synchronize the train's movement with other trains.
• To signal for an increase in speed.
• To signal the train to stop.

The train horn is a crucial safety device used by locomotive engineers to audibly warn people and animals of an approaching train. It is particularly important at grade crossings, curves, and in areas with limited visibility. By sounding the horn, the engineer aims to prevent accidents and ensure the safety of anyone near the tracks, fulfilling a vital role in public safety.

Question 49: What does the term 'absolute block' mean in railroad operations?

• A block where trains may follow each other at reduced speed
• A block that only one train may occupy at a time under any circumstances (Correct answer)
• A block that requires cab signal operation only
• A section of track reserved for maintenance equipment

Correct answer: A block that only one train may occupy at a time under any circumstances

An absolute block permits only one train to occupy the block at any time, providing the highest level of separation between trains.

Question 50: When an engineer observes that dynamic brake effort is not responding to handle position changes, what is the correct initial response?

• Cycle dynamic brake handle to zero and re-apply to reset the system
• Shut down the affected locomotive unit and isolate it
• Apply automatic brakes immediately to compensate for lost braking capacity (Correct answer)
• Notify the conductor and continue at reduced speed using air brakes only

Correct answer: Apply automatic brakes immediately to compensate for lost braking capacity

Loss of dynamic brake response requires immediate application of automatic brakes to maintain train control, as dynamic braking is no longer a reliable retarding force.