Air Brakes #2
Air Brakes Endorsement Test | Missouri 2025 #2 Page 4 of 4
Train for FREE online with our Missouri 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 MO Class A/Class B driver license in 2025, 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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19 . Friction in an S-cam brake is caused when the brake shoes and linings:
Friction inside a brake drum is caused when the brake shoes and linings push against the inside of the drum. The friction in the drums will slow and stop the vehicle.
20 . Manual air tank drains should be:
Compressed air in an air brake system usually contains a certain amount of water and compressor oil. The water and oil can damage the brakes if left to accumulate in the system. Manually operated air tank drains must be opened daily to remove this build-up.
21 . A wig wag is:
Vehicles with air brakes are required to be equipped with a low pressure warning device. A wig wag is a type of low air pressure warning device. This device drops a mechanical arm into the driver's view if the pressure in the tanks drops to a level between 55 and 75 psi.
22 . Some water and compressor oil is usually found in the compressed air within an air brake system. The water and compressor oil:
If water and compressor oil are left to build up in an air brake system, the system can be damaged. Air storage tanks are equipped with drains to allow this accumulation to be removed. Manually controlled drains should be operated at the end of each day of driving.
23 . What is brake lag?
Because air takes time to flow through the air lines to the brakes, air brakes cannot begin working instantly. There is often a brake lag of at least one-half of a second between the moment the brake pedal is pressed and the moment the brakes begin to work.
24 . What does an air compressor do in an air brake system?
In an air brake system, the air compressor pumps air into the air storage tanks. The air compressor is controlled by the air compressor governor.
25 . Air storage tanks:
In an air brake system, the air storage tanks hold compressed air to be used by the brakes. The number and size of air tanks varies among vehicles.
2025 Missouri | Frequently Asked Questions
A CDL Class A license in Missouri is defined as a commercial driver's license that allows the holder to operate any combination of vehicles with a Gross Combination Weight Rating (GCWR) of 26,001 pounds or more, given that the Gross Vehicle Weight Rating (GVWR) of the vehicle(s) being towed is over 10,000 pounds.
A Class A Commercial Driver's License (CDL) in Missouri allows operation of any combination of vehicles with a Gross Combination Weight Rating (GCWR) of 26,001 pounds or more, provided the Gross Vehicle Weight Rating (GVWR) of the vehicle(s) being towed exceeds 10,000 pounds. Examples include tractor-trailers, truck and trailer combinations, tank vehicles, livestock carriers, and flatbeds.
To obtain a Class A CDL in Missouri, you must be at least 18 years old (21 for interstate travel), possess a valid non-commercial driver's license, and pass a vision test. You also need to pass the written knowledge test and skills tests, which include a pre-trip vehicle inspection, a basic vehicle control test, and an on-road driving exam.
In Missouri, to qualify for a Class A Commercial Driver's License (CDL), you must be at least 18 years old. However, if you plan on driving across state lines or want to qualify to drive a vehicle carrying hazardous materials, you must be at least 21 years old.
While specific endorsements are not required to obtain a Class A CDL in Missouri, they can provide additional driving privileges. Endorsements include T for double/triple trailers, P for passenger vehicles, N for tank vehicles, H for hazardous materials, S for school bus, and X for a combination of tank vehicle and hazardous materials. Each endorsement requires passing additional tests.
The Class A CDL skills test in Missouri encompasses three parts: the Vehicle Inspection Test, the Basic Controls Test, and the Road Test. The Vehicle Inspection Test checks your ability to assess the safety of your vehicle. The Basic Controls Test evaluates your control over the vehicle. The Road Test examines your on-road driving skills.
Yes, there are limitations on Class A CDL license holders in Missouri. These could include restrictions related to corrective lenses, automatic transmission, no passengers, intrastate driving only, or no air brakes. Restrictions are based on the driver's abilities, the type of vehicle used during the driving test, and any medical conditions.
In Missouri, the written Class A CDL test is primarily administered in English. However, some locations may offer the test in Spanish. It's important to check with your local testing center for language options. Please note, even if the test is taken in another language, federal regulations require all CDL holders to read and speak English.
Yes, you can request accommodations for the Class A CDL written test in Missouri if you have a disability. The Missouri Department of Revenue is committed to making testing accessible. You should contact the department or your local testing center ahead of time to discuss your needs and arrange for appropriate accommodations.
Yes, you can retake the Class A CDL written test in Missouri if you don't pass on your first attempt. You must wait at least one day before retaking the test. However, if you fail the test four times, you have to wait a minimum of 30 days before your next attempt. Additional fees may also apply for each retest.