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The air brakes endorsement applies to applicants who wish to drive a vehicle with air brakes in Class A, B, or C CDL. To drive a vehicle with air brakes, you must pass the air brake component of the Texas CDL knowledge test. The TX CDL air brakes test consists of 25 questions, and you'll need at least 20 correct answers to pass (80%). The test covers the information found in the air brakes section of the Texas CDL Manual. Take this TX CDL practice test now to prepare for the actual air brakes test!
1. Most hydraulic brake failures occur for one of two reasons, one of which is:
excessive downshifting.
relying too much on the engine braking effect.
loss of hydraulic pressure.
driving in cold weather.
2. At 55 mph, the total stopping distance for vehicles with air brake systems traveling in ideal conditions is:
less than 250 feet.
over 450 feet.
over 250 feet.
less than 150 feet.
3. If your ABS malfunctions:
you still have normal brake functions.
the parking brakes will not work.
you should immediately come to a complete stop.
the service brake will not work.
4. The supply pressure gauges tell you how much air pressure:
you are applying to the brakes.
is in the air tanks.
is in the air brakes.
is going to the brake chambers.
5. Front brake limiting valves were used to:
prevent overheating of the front tires.
reduce the chance of the front wheels skidding on slippery surfaces.
reduce your speed so further braking or shifting is not required.
reduce exhaust emissions.
6. The air brake lag distance at 55 mph on dry pavement adds about:
32 feet.
60 feet.
75 feet.
16 feet.
7. To operate a vehicle equipped with air brakes, you must pass the air brakes knowledge test. Why?
If you don't, you will only receive a CDL permit.
If you don't pass the air brakes test, you can't get a CDL.
All trucks have air brakes.
If you don't pass the air brakes test, you will be restricted to driving vehicles without air brakes.
8. When you use your mirrors while driving on the road, you should:
avoid checking them regularly.
only use the driver's side mirror.
check them quickly.
stare for a long time at the mirror.
9. Slack adjusters:
regulate the distance between the rear wheels.
regulate the distance that the air brake has to travel to apply friction to the wheel.
are available in four types: manual, automatic, robotic and analog.
should move more than one inch where the push rods attach to them.
10. Before transporting sealed loads, you should check that:
the load is properly secured.
the load can be inspected.
the seal numbers match the placard numbers.
All of the above.
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TX Air Brakes CDL Test

Number of questions: 25
Correct answers to pass:20
Passing score:80%
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