Delaware CDL Air Brakes Practice Test (DE) 2

4.8 out of 5 (46 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Get ready to ace your commercial driver's license with our Delaware CDL air brakes practice test. This comprehensive test is specifically designed to prepare you for the air brakes endorsement section of the CDL test. Featuring 20 multiple-choice questions, this Delaware DMV practice test covers a wide range of essential topics such as components, operation, safety inspections, and stopping distance calculations. With questions crafted to closely mirror the real DMV test experience, you'll gain a clear understanding of the core concepts needed to succeed. One key feature of our Delaware DMV air brake test is its focus on the use of dual air brake systems. This system enhances safety by providing a backup in case one system fails, a crucial aspect for any commercial driver. To pass this CDL air brake test, you need to correctly answer 16 out of the 20 questions. This thorough coverage ensures you are fully prepared for the official CDL test. The practice permit test is available online 24/7, offering the flexibility to fit your busy schedule. Whether you're a night owl or an early bird, you can study at the time that suits you best. The format of our Delaware DMV test practice is identical to the actual written permit test, helping you get comfortable with the process of eliminating incorrect answers to find the right one. Driving in Delaware comes with its unique set of challenges. From navigating the bustling traffic of Wilmington to driving through the scenic but sometimes narrow roads of Sussex County, being well-prepared is essential. The Delaware CDL air brakes practice test is crafted with these local driving conditions in mind, ensuring that you are not only ready for the test but also for real-world driving in the First State. This driving test practice session is perfect for those looking to cover all necessary topics in one comprehensive session. The Delaware drivers license test practice ensures that you grasp the essential facts and are ready to hit the road with confidence.
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Sample Delaware Air Brakes Test Questions

Question 1

During cold weather, what daily check should you make if the air-brake system has an alcohol evaporator?

  1. A Drain all alcohol from the container
  2. B Lubricate the evaporator with engine oil
  3. C Replace the alcohol container each day
  4. D Check the alcohol container and refill it as needed

Correct answer: D – Check the alcohol container and refill it as needed

The Delaware CDL manual directs drivers to check the alcohol container every day during cold weather and add alcohol when necessary. The evaporator puts alcohol into the air system to reduce the risk of ice in valves and other components. This check does not replace required air-tank drainage unless the system has automatic drain valves.

Source: Delaware Commercial Driver’s Manual — § 5.1.5, “Alcohol Evaporator”

Question 2

Why does an air-brake vehicle have additional brake lag compared with a hydraulic-brake vehicle?

  1. A Its brake drums must cool before each application
  2. B Compressed air needs time to travel through the lines to the brakes
  3. C Its return springs must be compressed first
  4. D Its parking brakes must engage before the service brakes

Correct answer: B – Compressed air needs time to travel through the lines to the brakes

After the driver presses the pedal, compressed air must move through the lines before the brakes apply. The manual describes this delay as brake lag and notes that it may take one-half second or more. Brake-lag distance is added to perception distance, reaction distance, and braking distance when calculating total stopping distance.

Source: Delaware Commercial Driver’s Manual — § 5.4.4, “Stopping Distance”

Question 3

With the engine off, parking brake released, and foot brake fully applied, what is the maximum one-minute air loss for a single vehicle?

  1. A 3 psi
  2. B 2 psi
  3. C 1 psi
  4. D 4 psi

Correct answer: A – 3 psi

During the applied-leakage test, hold the foot brake for one minute and watch the pressure gauge. A single vehicle must not lose more than 3 psi during that minute; the corresponding limit for a combination vehicle is 4 psi. A greater pressure drop indicates excessive leakage that must be repaired before the vehicle is driven.

Source: Delaware Commercial Driver’s Manual — § 5.3.3, “Step 7 Final Air Brake Check”

Question 4

When checking the low-air warning device, which pressure is the standard activation benchmark unless the manufacturer specifies another level?

  1. A 45 psi
  2. B 50 psi
  3. C 55 psi
  4. D 80 psi

Correct answer: C – 55 psi

The Delaware manual’s standard check requires the low-air warning to activate before pressure falls below 55 psi, unless the manufacturer specifies another level. Federal equipment rules also establish a continuous audible or visible warning at 55 psi and below, or one-half the compressor governor cutout pressure, whichever is less, for power units not originally subject to the applicable federal vehicle standard.

Source: Delaware Commercial Driver’s Manual — §§ 5.1.11 and 5.3.3, “Low Air Pressure Warning” and “Step 7 Final Air Brake Check”, 49 CFR § 393.51(c) — Warning Signals, Air Pressure and Vacuum Gauges

Question 5

What force normally applies spring brakes when their holding air pressure is removed?

  1. A Compressed-air force
  2. B Electrical current
  3. C Hydraulic pressure
  4. D Mechanical spring force

Correct answer: D – Mechanical spring force

Spring brakes use mechanical spring force to apply the brakes. During normal operation, air pressure compresses or holds back the springs. If that air pressure is removed, the springs apply the brakes, allowing the system to serve parking and emergency functions without depending on air pressure to remain applied.

Source: Delaware Commercial Driver’s Manual — § 5.1.14, “Spring Brakes”

Question 6

Why should you avoid repeatedly pressing and releasing the air-brake pedal when it is unnecessary?

  1. A It prevents the compressor from operating
  2. B It causes the air tanks to overfill
  3. C It can release air faster than the compressor replaces it
  4. D It automatically applies the parking brakes

Correct answer: C – It can release air faster than the compressor replaces it

The Delaware CDL manual explains that releasing the brake pedal allows compressed air to escape, reducing tank pressure. Repeated unnecessary applications and releases can use air faster than the compressor can replace it. If pressure becomes too low, the service brakes may no longer operate properly and the spring brakes may eventually apply.

Source: Delaware Commercial Driver’s Manual — § 5.1.7, “The Brake Pedal”

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