Air Brakes #2
Air Brakes Endorsement Test | District Of Columbia 2026 #2 Page 3 of 4
Train for FREE online with our District Of Columbia CDL air brake test. The official exam test consists of several obligatory parts, with all of them checking your knowledge of different blocks of road rules. If you need to obtain a DC Class A/Class B driver license in 2026, practice as much as possible. Free sample tests published on our website will help you check and improve your knowledge and boost your grades. Please bear in mind that the requirements for CDL may vary from state to state.
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13 . What does the air compressor governor do?
Controls the temperature of the air leaving the air storage tanks.
In an air brake system, the air compressor governor controls when the air compressor pumps air into the air storage tanks.
14 . When inspecting your brakes, a slack adjuster should move ____ from where it is attached to the push rod.
No more than one inch
Check each slack adjuster after setting wheel chocks and disengaging the parking brake. Pull the slack adjusters to make sure they do not move more than about one inch from where the push rod is attached. If they move more than one inch, they may be out of adjustment and will need to be fixed.
15 . A modulating control valve can control the:
Anti-lock braking system (ABS).
A modulating control valve allows a driver to gradually apply spring brakes. In equipped vehicles, the valve is controlled by a lever located on the dashboard.
16 . When traveling down a steep downgrade, the best way to use your brakes is to:
Apply consistent pressure to the brake pedal all the way down the hill.
On a long or steep downgrade, brakes should only be used to supplement the braking effect of the engine. Apply the brakes just enough to feel a definite slowing down, then release them once you are about 5 mph below your target "safe" speed. Once your vehicle reaches its safe speed again, repeat this process.
17 . What can happen if parking brakes are used in very wet weather with temperatures below freezing?
The brakes may become too smooth to be used.
Parking brakes should not be used in very wet weather when temperatures are below freezing. The brakes could become frozen in place, making it impossible to move the vehicle.
18 . Most heavy-duty vehicles use:
Quadruple air brake systems.
Most heavy-duty vehicles use dual air brake systems, in which there are two separate braking systems operated by a single set of controls. Each system operates the brakes on different axles.
2026 District Of Columbia | Frequently Asked Questions
To acquire a CDL Passenger endorsement in the District of Columbia, you must first hold a valid CDL. You then need to pass a written passenger endorsement test and a skills test in a vehicle similar to the one you'll be driving. The test covers topics like vehicle inspection, loading/unloading passengers, and emergency procedures.
To obtain a CDL Passenger license in the District of Columbia, an applicant must possess a valid CDL, pass the Passenger Transport written test, complete a Federal Motor Carrier Safety Administration medical examination, and successfully pass a skills test in the type of vehicle similar to the one they will be driving. The applicant must also be at least 21 years old.
Yes, specific training is necessary to earn a CDL Passenger endorsement in the District of Columbia. You must pass a written passenger endorsement test and a skills test in a vehicle similar to the one you'll be driving. While not mandatory, practical experience driving similar vehicles can be beneficial for passing the skills test.
Yes, to secure a CDL Passenger endorsement in the District of Columbia, you are required to pass a written passenger endorsement test. This test covers topics such as vehicle inspection, loading/unloading passengers, and emergency procedures. It is designed to ensure you have the necessary knowledge to safely operate a passenger vehicle.
During the CDL Passenger endorsement skills test, you'll need to demonstrate your ability to safely operate a passenger vehicle. This includes pre-trip vehicle inspection, proper use of mirrors and signals, safe lane changes and turns, proper loading/unloading procedures, and emergency protocol. Your ability to control and maneuver the vehicle in various traffic situations will also be assessed.
No, it is illegal to transport passengers without holding a valid CDL Passenger endorsement in the District of Columbia. A CDL Passenger endorsement is required to operate a commercial vehicle that is designed to transport 16 or more passengers, including the driver. Failure to have the proper endorsement can result in fines and penalties.
Yes, you can add the CDL Passenger endorsement to your existing commercial driver's license. You don't need a new application. However, you must pass the Passenger endorsement written test and a skills test in a passenger vehicle. Remember to bring your current CDL to the DMV when you go for your tests.
Yes, there are specific restrictions for drivers with a CDL Passenger endorsement. For instance, you cannot transport more passengers than your vehicle is designed to carry. Additionally, you are subject to stricter blood alcohol content (BAC) limits and may be disqualified for serious traffic violations or multiple minor violations.
Yes, there are age-related prerequisites and limitations for acquiring the CDL Passenger endorsement in the District of Columbia. To obtain the endorsement, you must be at least 18 years old. However, if you plan to transport passengers across state lines or operate a vehicle with hazardous materials, you must be at least 21 years old. Additionally, certain medical and physical requirements must be met to qualify for the endorsement.
With a CDL Passenger endorsement, you'll be eligible to operate vehicles such as buses, shuttles, or any other vehicle designed to transport 16 or more passengers, including the driver. This includes school buses if you also have a School Bus endorsement. It's important to note that the specific vehicle must match the class of your CDL.