Union Pacific Air Brake Qualification Test
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. What is the primary purpose of a locomotive and train air brake
system?
A. To increase locomotive horsepower
B. To provide compressed air for locomotive cooling
C. To control and safely stop or slow the train
D. To operate the locomotive headlights
Rationale: The air brake system provides the means to control train
speed and bring the train to a stop. Because railroad trains can be
extremely heavy and require substantial stopping distance,
dependable braking equipment and proper operating procedures are
essential for safe train handling.
2. Which component stores compressed air on a locomotive for use
by the air brake system?
,A. Equalizing reservoir
B. Brake cylinder
C. Main reservoir
D. Main reservoir
Rationale: The main reservoir stores compressed air produced by the
locomotive's air compressor. This stored air supplies the various
pneumatic systems on the locomotive and provides the source of air
used for brake-system operation.
3. What does the brake cylinder do when a brake application is
made?
A. Removes air from the brake pipe
B. Charges the main reservoir
C. Converts air pressure into mechanical force for applying the brakes
D. Releases the locomotive independent brake
Rationale: Compressed air entering the brake cylinder moves a piston.
The piston force is transmitted through the brake rigging to apply the
brake shoes or other friction equipment against the wheels or braking
surfaces.
4. What is the primary function of the brake pipe?
,A. To supply fuel to locomotives
B. To cool brake shoes
C. To communicate brake commands and provide a continuous air
passage through the train
D. To supply electrical power to the caboose
Rationale: The brake pipe is a continuous pneumatic line running
through the train. Changes in brake-pipe pressure are used to initiate
brake applications and releases, while the pipe also provides air for
charging individual car reservoirs.
5. A reduction in brake-pipe pressure normally causes the train
brakes to:
A. Release
B. Remain unchanged
C. Apply
D. Increase locomotive speed
Rationale: Conventional automatic air brakes are designed so that a
reduction in brake-pipe pressure produces a brake application. This
fail-safe principle allows a loss or significant reduction of brake-pipe
pressure to result in braking rather than an unintended release.
6. What is the purpose of a car's auxiliary reservoir?
, A. To store locomotive fuel
B. To store brake-cylinder exhaust air
C. To store compressed air used for a brake application
D. To regulate locomotive throttle position
Rationale: Each equipped car generally has an auxiliary reservoir that
stores compressed air after the brake system is charged. When a
brake-pipe reduction is sensed, the control valve allows air from the
reservoir to enter the brake cylinder.
7. What is the function of a control valve on a freight car?
A. To control locomotive engine speed
B. To regulate fuel pressure
C. To respond to brake-pipe pressure changes and control air flow to
and from the brake cylinder and reservoir
D. To operate the train's electrical system
Rationale: The control valve is a critical part of the automatic brake
equipment. It detects changes in brake-pipe pressure and directs air
appropriately for applying, maintaining, or releasing the car's brakes.
8. During a normal automatic brake application, brake-pipe pressure
is:
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a locomotive and train air brake
system?
A. To increase locomotive horsepower
B. To provide compressed air for locomotive cooling
C. To control and safely stop or slow the train
D. To operate the locomotive headlights
Rationale: The air brake system provides the means to control train
speed and bring the train to a stop. Because railroad trains can be
extremely heavy and require substantial stopping distance,
dependable braking equipment and proper operating procedures are
essential for safe train handling.
2. Which component stores compressed air on a locomotive for use
by the air brake system?
,A. Equalizing reservoir
B. Brake cylinder
C. Main reservoir
D. Main reservoir
Rationale: The main reservoir stores compressed air produced by the
locomotive's air compressor. This stored air supplies the various
pneumatic systems on the locomotive and provides the source of air
used for brake-system operation.
3. What does the brake cylinder do when a brake application is
made?
A. Removes air from the brake pipe
B. Charges the main reservoir
C. Converts air pressure into mechanical force for applying the brakes
D. Releases the locomotive independent brake
Rationale: Compressed air entering the brake cylinder moves a piston.
The piston force is transmitted through the brake rigging to apply the
brake shoes or other friction equipment against the wheels or braking
surfaces.
4. What is the primary function of the brake pipe?
,A. To supply fuel to locomotives
B. To cool brake shoes
C. To communicate brake commands and provide a continuous air
passage through the train
D. To supply electrical power to the caboose
Rationale: The brake pipe is a continuous pneumatic line running
through the train. Changes in brake-pipe pressure are used to initiate
brake applications and releases, while the pipe also provides air for
charging individual car reservoirs.
5. A reduction in brake-pipe pressure normally causes the train
brakes to:
A. Release
B. Remain unchanged
C. Apply
D. Increase locomotive speed
Rationale: Conventional automatic air brakes are designed so that a
reduction in brake-pipe pressure produces a brake application. This
fail-safe principle allows a loss or significant reduction of brake-pipe
pressure to result in braking rather than an unintended release.
6. What is the purpose of a car's auxiliary reservoir?
, A. To store locomotive fuel
B. To store brake-cylinder exhaust air
C. To store compressed air used for a brake application
D. To regulate locomotive throttle position
Rationale: Each equipped car generally has an auxiliary reservoir that
stores compressed air after the brake system is charged. When a
brake-pipe reduction is sensed, the control valve allows air from the
reservoir to enter the brake cylinder.
7. What is the function of a control valve on a freight car?
A. To control locomotive engine speed
B. To regulate fuel pressure
C. To respond to brake-pipe pressure changes and control air flow to
and from the brake cylinder and reservoir
D. To operate the train's electrical system
Rationale: The control valve is a critical part of the automatic brake
equipment. It detects changes in brake-pipe pressure and directs air
appropriately for applying, maintaining, or releasing the car's brakes.
8. During a normal automatic brake application, brake-pipe pressure
is:
