FRA Air Brake Systems & Testing 2 — Questions and Answers
Question 1: What is the purpose of the retaining valve on a freight car?
- To increase brake cylinder pressure during descent
- To retain air pressure in the brake cylinder after a brake application is released (Correct answer)
- To prevent brake pipe pressure from dropping below 60 psi
- To hold emergency reservoir pressure constant
Correct answer: To retain air pressure in the brake cylinder after a brake application is released
Retaining valves hold a portion of brake cylinder pressure after a release, used primarily on steep descending grades to prevent overheating of brake shoes.
Question 2: Under FRA regulations, what is the minimum brake pipe pressure required before a train departs?
- 75 psi
- 80 psi
- 85 psi
- 90 psi (Correct answer)
Correct answer: 90 psi
FRA regulations require a minimum brake pipe pressure of 90 psi before a train may depart.
Question 3: What does it mean when a triple valve 'kicks' during an initial terminal test?
- The triple valve is functioning correctly (Correct answer)
- The triple valve failed to respond to the brake pipe reduction
- The auxiliary reservoir is overcharged
- The brake cylinder piston travel is excessive
Correct answer: The triple valve is functioning correctly
A 'kick' or exhaust of air from the triple valve during charging indicates the valve is cycling correctly and releasing trapped pressure.
Question 4: In an emergency brake application, air from which reservoir supplements brake cylinder pressure?
- Auxiliary reservoir only
- Emergency reservoir only
- Both auxiliary and emergency reservoirs (Correct answer)
- Main reservoir only
Correct answer: Both auxiliary and emergency reservoirs
During an emergency application, both the auxiliary reservoir and the emergency reservoir supply air to maximize brake cylinder pressure.
Question 5: What is the primary function of the brake pipe in an automatic air brake system?
- To supply air directly to the brake cylinders
- To carry the control signal and supply reservoir charging air throughout the train (Correct answer)
- To equalize pressure between front and rear cars
- To provide air for the retaining valves
Correct answer: To carry the control signal and supply reservoir charging air throughout the train
The brake pipe serves as both the control signal conduit (via pressure reductions) and the charging medium for auxiliary and emergency reservoirs throughout the train.
Question 6: What is the maximum allowable brake cylinder piston travel for a standard freight car with 10-inch brake cylinders?
- 5 inches
- 7 inches
- 9 inches (Correct answer)
- 11 inches
Correct answer: 9 inches
FRA regulations specify that brake cylinder piston travel on a 10-inch cylinder must not exceed 9 inches for a car to pass inspection.
Question 7: During a Class I brake test, what must be verified after the brake pipe pressure reduction is made?
- Only that brake shoes are contacting wheels on the locomotive
- That brakes apply on every car in the train (Correct answer)
- That retaining valves are in the 'exhaust' position
- That emergency reservoirs are fully charged
Correct answer: That brakes apply on every car in the train
A Class I brake test requires visual inspection to confirm brakes have applied on every car in the train.
FRA Air Brake Systems & Testing 2
What is the purpose of the retaining valve on a freight car?