Mississippi CDL Air Brakes Practice Test (MS) 2

5 out of 5 (42 votes)
80% Passing score
20 Questions
4 Mistakes allowed
Gearing up for your commercial driver's license in Mississippi? Our Mississippi CDL air brakes practice test is just what you need to confidently tackle the air brakes endorsement section. This all-inclusive practice permit test features 20 multiple-choice questions that cover key topics such as air brake components, their operation, safety inspections, and stopping distance calculations. For instance, you'll delve into crucial details like the use of dual air brake systems, which enhance safety by providing a backup in case one system fails. To pass, you'll need to correctly answer at least 16 questions, making sure you're well-prepared for the real deal. In Mississippi, driving isn't just about getting from point A to point B. It's about navigating diverse terrains, from the flatlands of the Delta to the rolling hills of the north. Understanding how to handle your vehicle's air brakes in these varied conditions is crucial, and our Mississippi DMV practice test ensures you're ready for anything the Magnolia State roads throw at you. While this MS CDL air brakes practice test doesn't replace a state-certified drivers ed or Entry-Level Driver Training (ELDT) course, it's an excellent complementary tool. You can use it alongside your coursework to reinforce your understanding of the material. Plus, it's incredibly convenient - available online 24/7, you can take the Mississippi DMV practice test whenever it fits your schedule, not just when your driving school can fit you in. Our CDL air brake practice test is designed with a variety of questions pulled from a large pool of permit test questions and answers. This extensive range helps ensure you're thoroughly prepared for the Mississippi CDL air brake test. Each session offers a comprehensive review, so you can cover all necessary topics in one go. Remember, understanding air brakes isn't just about passing the test - it's about ensuring your safety and the safety of others on Mississippi's highways and byways. With our Mississippi CDL air brakes practice test, you'll be on the road to success, equipped with the knowledge you need to navigate confidently and safely.
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Sample Mississippi Air Brakes Test Questions

Question 1

A combination vehicle fails the applied air-leakage test whenever pressure drops by more than 1 psi in one minute.

  1. A True
  2. B False

Correct answer: B – False

Under the Mississippi CDL manual’s applied leakage test, the engine is off and the foot brake is held fully down for one minute. A combination vehicle’s pressure must not drop by more than 4 psi during that minute. A loss greater than 4 psi is excessive and must be repaired before driving.

Source: Mississippi Commercial Driver’s License Manual (March 2025) — § 5.3.3, “Step 7 Final Air Brake Check”

Question 2

During the applied air-leakage test, what is the maximum acceptable pressure drop for a single vehicle?

  1. A 3 psi in one minute
  2. B 2 psi in 45 seconds
  3. C 1 psi in one minute
  4. D 1 psi in 30 seconds

Correct answer: A – 3 psi in one minute

Build the pressure to governor cutoff, turn off the engine, release the parking brake, and fully apply the foot brake. For a single vehicle, a pressure loss of more than 3 psi in one minute is excessive. Air leaks must be located and repaired before the vehicle is driven.

Source: Mississippi Commercial Driver’s License Manual (March 2025) — § 5.3.3, “Step 7 Final Air Brake Check”

Question 3

Which factor adds extra distance to an air-brake vehicle’s total stopping distance?

  1. A Perception distance
  2. B Driver reaction distance
  3. C Brake-lag distance
  4. D Braking distance

Correct answer: C – Brake-lag distance

The Mississippi CDL manual calls the added delay “brake lag.” Air takes a short time—one-half second or more—to travel through the lines and activate the brakes. Total stopping distance for an air-brake vehicle includes perception distance, reaction distance, brake-lag distance, and braking distance.

Source: Mississippi Commercial Driver’s License Manual (March 2025) — § 5.4.4, “Stopping Distance”

Question 4

A lightly loaded vehicle is less likely to skid if spring brakes apply automatically because of low air pressure.

  1. A True
  2. B False

Correct answer: B – False

Lightly loaded vehicles and vehicles traveling on slippery roads may skid out of control when spring brakes apply. Spring brakes may not act on every axle and are not a substitute for a controlled stop. When the low-air warning activates, stop safely while enough pressure remains to operate the service brakes.

Source: Mississippi Commercial Driver’s License Manual (March 2025) — § 5.4.7, “Low Air Pressure”

Question 5

Which force can hold a parking brake applied without depending on retained air or fluid pressure?

  1. A Spring pressure
  2. B Air pressure
  3. C Hydraulic-fluid pressure
  4. D Any of these

Correct answer: A – Spring pressure

Spring action supplies mechanical force that does not depend on stored air pressure. The CDL manual explains that spring brakes are commonly used because air can eventually leak away. For vehicles covered by 49 CFR 393.41(c), federal rules require the applied parking brake to be held by energy other than fluid pressure, air pressure, or electric energy.

Source: Mississippi Commercial Driver’s License Manual (March 2025) — § 5.1.14, “Spring Brakes”, 49 CFR § 393.41(c)(2)–(3) – Parking Brake System

Question 6

Under normal conditions, when should an air-brake vehicle’s parking brakes be used?

  1. A Only during vehicle inspections
  2. B Whenever the vehicle is parked
  3. C Only when parking on a grade
  4. D While slowing the vehicle

Correct answer: B – Whenever the vehicle is parked

The Mississippi CDL manual directs drivers to use the parking brakes whenever they park. Exceptions apply when the brakes are extremely hot or are very wet in freezing temperatures, because application could cause damage or freezing. In those situations, secure the vehicle with wheel chocks on a level surface and follow the manual’s cooling or drying procedure.

Source: Mississippi Commercial Driver’s License Manual (March 2025) — § 5.4.8, “Parking Brakes”

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