Texas CDL — Air Brakes practice
Texas CDL — Air Brakes: Handling Emergencies practice test
What to do when things go wrong — brake failure, tire blowouts, skids, and stalling on railroad tracks.
Content reviewed against official driver handbooks · August 12, 2026
12 questions · pass with 10 correct. You get instant feedback and an explanation after every answer.
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Study questions with answers
12 sample Handling Emergencies questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
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1. If a leak drains all the air out of the brake system while you drive, what physically applies the spring brakes?
Correct answer: The force of powerful springs no longer held back by air pressure
Powerful springs, normally held back by air pressure, apply the brakes when air pressure is lost. That is why they are called spring brakes — the spring does the work, not the air.
2. At roughly what air pressure range will tractor and straight truck spring brakes come fully on by themselves?
Correct answer: 20 to 45 psi
Spring brakes usually apply automatically when air pressure falls into the 20 to 45 psi range. You should already have stopped safely long before pressure drops that far.
3. Why should you avoid pressing the brake pedal down while the spring brakes are applied?
Correct answer: The combined spring and air forces could damage the brakes
The combined force of the springs and the air pressure could exceed what the brake parts were designed for and damage them. Many systems prevent this, but you should not rely on that protection.
4. Using the proper snub braking technique on a long downgrade, the safe speed is 40 mph. When and how should you brake?
Correct answer: At 40 mph, brake firmly down to about 35 mph, release, and repeat
Once the vehicle reaches the safe speed, apply the brakes hard enough to feel a definite slowdown and reduce speed about 5 mph below it (to about 35 mph), then release. Repeat each time the vehicle drifts back up to the safe speed.
5. Some buses have dual parking control valves and a separate air tank that can release the spring brakes after main air pressure is lost. Why must you plan carefully before using it to move?
Correct answer: The separate tank holds only enough air to release the brakes a few times
The extra tank is there so you can move the vehicle out of a dangerous spot in an emergency. Each push of the spring-loaded control uses some of that small supply, and the spring brakes reapply when you let go, so you could end up stuck somewhere unsafe once it runs out.
6. One half of your dual air brake system suddenly loses pressure on the highway. What should you do?
Correct answer: Stop right away and have the air brake system fixed
Either the low pressure warning or braking that feels different tells you one system has failed. The other system can still stop the vehicle, but you should stop right away and have the brakes repaired.
7. The low air pressure warning comes on while you are driving. What is the correct response?
Correct answer: Stop and safely park as soon as possible
Stop and safely park as soon as possible. If the leak continues, the spring brakes could lock the wheels while you are still moving, or you could lose braking entirely, making the vehicle very dangerous to control.
8. What is the main cause of brake fade on a long, steep downhill run?
Correct answer: Overheating from relying on the brakes instead of engine braking
Excessive heat from using the brakes too much instead of relying on the braking effect of the engine causes fade. Overheated linings lose friction, and the brakes may eventually fail entirely.
9. The yellow ABS malfunction lamp stayed lit after the start-up bulb check and is still on as you cruise down the highway. What does that tell you?
Correct answer: You may have lost antilock control at one or more wheels
A lamp that stays on after the bulb check, or comes on once you are moving, signals that ABS may not be working at one or more wheels. ABS is an addition to your regular brakes, so those still function; drive normally and have the system serviced soon.
10. The braking power of the spring brakes depends on what?
Correct answer: The service brakes being properly adjusted
The manual ties spring brake braking power to proper brake adjustment. When the brakes are out of adjustment, neither the regular service brakes nor the parking/emergency brakes will work properly.
11. What is the main reason some vehicles have a modulating control valve that applies the spring brakes gradually?
Correct answer: To let you brake with the springs if the service brakes fail
A modulating valve is a spring-loaded dash handle: the farther you move it, the harder the spring brakes apply, and you can feel the braking action. That gradual control means a driver whose service brakes have failed can still bring the vehicle down with the springs.
12. Your air pressure is dropping and you keep driving until the spring brakes come on by themselves. Why is this especially risky in a heavily loaded vehicle?
Correct answer: Spring brakes don't work on every axle, so the stop takes a long distance
Spring brakes are not on every axle, so a heavy load can take a long way to stop on them alone. A lightly loaded vehicle, or one on a slippery road, may instead skid when they apply. It is far safer to stop while enough air remains to use the foot brake.
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Texas Practice Test Pack — 2026 Printable Edition
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Our own printable edition — nobody paid us to show it to you, and everything in it is free to read here too.