Vermont CDL — Air Brakes practice
Vermont CDL — Air Brakes: Safe Driving Practices practice test
Following distance, scanning, blind spots, using your lights, and the habits that prevent crashes and keep you in control.
Content reviewed against official driver handbooks · August 12, 2026
20 questions · pass with 16 correct. You get instant feedback and an explanation after every answer.
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12 sample Safe Driving Practices 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. Which pairing of governor setting and approximate tank pressure matches the manual?
Correct answer: Cut-out around 125 psi, cut-in around 100 psi
The compressor stops pumping at the cut-out level, around 125 psi, and is allowed to pump again when tank pressure drops to the cut-in level, around 100 psi.
Source: Vermont Commercial Driver's Manual — Section 5.1.2, Air Compressor Governor
2. You move from one air-braked truck to another and notice a different number of air tanks. What does the manual say about that?
Correct answer: Tank count and tank size differ from one vehicle to the next
Air storage tanks hold the compressed air, and the manual notes that how many there are and how big they are is not the same on every vehicle.
Source: Vermont Commercial Driver's Manual — Section 5.1.3, Air Storage Tanks
3. Section 11 limits hand-pulled pushrod travel on manual slack adjustors to one inch. In what condition must the brakes be when you make that check?
Correct answer: Released
The one-inch limit applies with the brakes released. Section 11 also has you look over the slack adjustors and pushrods for parts that are broken, loose or missing.
Source: Vermont Commercial Driver's Manual — Section 11.2.3, Brakes
4. Which sequence matches the manual's normal stop in an air-braked truck with a manual transmission?
Correct answer: Press the pedal with controlled pressure, push the clutch in only when engine rpm is close to idle, then pick a starting gear once stopped
For a normal stop you press the pedal and manage the pressure so the stop is smooth and safe. With a manual transmission the clutch stays out until rpm has dropped nearly to idle, and a starting gear is selected after the vehicle stops.
Source: Vermont Commercial Driver's Manual — Section 5.4.1, Normal Stops
5. Which statement about the air compressor does NOT match the manual?
Correct answer: It is driven by its own electric motor, separate from the engine
The manual describes a compressor driven off the engine by gears or a v-belt, cooled by air or by the engine cooling system, and feeding the storage tanks. It says nothing of a separate electric motor.
Source: Vermont Commercial Driver's Manual — Section 5.1.1, Air Compressor
6. Which of these is NOT something Section 11 tells you to confirm about a brake chamber?
Correct answer: That it has been drained of moisture that day
Section 11 has you see that each brake chamber is free of leaks, cracks and dents and is securely mounted with every clamp tight and present. Draining moisture applies to the air tanks, not the chambers.
Source: Vermont Commercial Driver's Manual — Section 11.2.3, Brakes
7. Besides drums, linings and hoses, the walk-around brake check covers the brakes' mechanical parts. What does the manual require of them?
Correct answer: They must be in place, with nothing broken or missing
The Step 5 check says the mechanical parts of the brakes have to be present and intact. A broken or missing part is a defect to fix before driving.
Source: Vermont Commercial Driver's Manual — Section 5.3.2, During Step 5 Walk-around Inspection
8. You run the applied-brake leakage test on a tractor-trailer: engine off, parking brake and tractor protection valve released, foot brake held down. In one minute the gauge falls 5 psi. What does the manual say?
Correct answer: The loss is too great; with the foot brake applied, a combination may drop no more than 4 psi in a minute
With the foot brake fully applied, the limit is a 3 psi drop in a minute for a single vehicle and 4 psi for a combination. A 5 psi loss exceeds it, so the leaks have to be found and repaired before the vehicle is driven.
Source: Vermont Commercial Driver's Manual — Section 5.3.3, Step 7 Final Air Brake Check
9. A new driver thinks the air compressor governor sets how hard the brakes apply. What does the manual say the governor actually controls?
Correct answer: When the compressor pumps air into the storage tanks
The governor decides when the compressor pumps. It stops the pumping at the cut-out level and lets it resume once tank pressure has fallen to the cut-in level.
Source: Vermont Commercial Driver's Manual — Section 5.1.2, Air Compressor Governor
10. At the end of the day you crack open each manual drain valve for a second and close it again. How does that square with the manual?
Correct answer: It falls short, because the tanks are supposed to be drained completely
Water and compressor oil settle at the bottom of each tank and are bad for the system. The manual tells you to make sure the tanks are drained completely, not just vented briefly.
Source: Vermont Commercial Driver's Manual — Section 5.1.4, Air Tank Drains
11. Which statement about wedge brakes does NOT match the manual?
Correct answer: They are the most common type of foundation brake
The s-cam drum brake is the most common type; wedge brakes are less common. The other three statements follow the manual's description of how wedge brakes work and how they are kept adjusted.
Source: Vermont Commercial Driver's Manual — Section 5.1.8, Foundation Brakes
12. On the external inspection in Section 11 you look for cracked, worn or leaking brake hoses and lines. Which other item does the manual put in that same check?
Correct answer: Couplings
Section 11 lists hoses, lines and couplings together under the brake inspection. A crack, wear or a leak in any of them is a defect.
Source: Vermont Commercial Driver's Manual — Section 11.2.3, Brakes
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