FRA Air Brake Systems & Testing 3 — Questions and Answers
Question 1: What is the purpose of the AB control valve's 'service' position?
- To charge the emergency reservoir
- To direct air from reservoirs to the brake cylinder proportional to a brake pipe reduction (Correct answer)
- To dump all brake cylinder pressure immediately
- To isolate the car from the train brake pipe
Correct answer: To direct air from reservoirs to the brake cylinder proportional to a brake pipe reduction
In the service position, the AB control valve meters air from the auxiliary reservoir into the brake cylinder in proportion to the brake pipe pressure reduction.
Question 2: What is the significance of a '26-pound' brake pipe reduction?
- It is the minimum reduction required to move the control valve to emergency
- It is the standard full service reduction in most North American freight operations (Correct answer)
- It is the minimum reduction that will produce any brake application
- It is the maximum reduction before emergency is triggered
Correct answer: It is the standard full service reduction in most North American freight operations
A 26-pound reduction from 90 psi to 64 psi is the standard full service brake application in North American freight railroad operations.
Question 3: How is the rate of brake release controlled in a graduated release brake system?
- By adjusting the main reservoir pressure
- By increasing brake pipe pressure incrementally above the last reduced level (Correct answer)
- By opening the retaining valve
- By manually bleeding brake cylinders
Correct answer: By increasing brake pipe pressure incrementally above the last reduced level
Graduated release valves allow partial release of brakes by restoring brake pipe pressure in small increments, proportionally reducing brake cylinder pressure.
Question 4: Which FRA regulation part specifically governs freight car air brake systems?
- 49 CFR Part 218
- 49 CFR Part 229
- 49 CFR Part 232 (Correct answer)
- 49 CFR Part 236
Correct answer: 49 CFR Part 232
49 CFR Part 232 covers railroad power brakes and drawbars, establishing requirements for freight and passenger car air brake systems.
Question 5: What condition requires a car to be 'set out' (removed from service) regarding its air brakes?
- Brake cylinder piston travel of 8 inches on a 10-inch cylinder
- A cut-out cock in the open position
- Inoperative or ineffective brakes that cannot be repaired en route (Correct answer)
- Retaining valves set to the 'high pressure' position
Correct answer: Inoperative or ineffective brakes that cannot be repaired en route
FRA regulations require a car with inoperative or defective brakes that cannot be corrected en route to be set out at the nearest repair point.
Question 6: What is the function of the 'dirt collector' in an air brake system?
- To filter moisture from brake pipe air before it enters control valves (Correct answer)
- To capture brake shoe debris
- To collect dust from auxiliary reservoirs
- To filter exhaust air from brake cylinders
Correct answer: To filter moisture from brake pipe air before it enters control valves
The dirt collector (strainer) filters contaminants and moisture from the brake pipe air before it enters the control valve, preventing valve damage.
Question 7: What happens to train braking performance when a significant number of cars have their angle cocks closed (brakes cut out)?
- Braking force increases due to reduced train length
- Braking force is unaffected if the locomotive brakes are working
- Overall train braking force is reduced, increasing stopping distance (Correct answer)
- Retaining valves compensate automatically
Correct answer: Overall train braking force is reduced, increasing stopping distance
Cutting out brakes on cars reduces the total braking force available to the train, directly increasing stopping distance and creating a safety hazard.
FRA Air Brake Systems & Testing 3
What is the purpose of the AB control valve's 'service' position?