CDL Air Brakes Test (2024) - FREE Missouri CDL Practice Test

1. Some vehicles have a separate air tank which can be used to:

turn on the 4-way emergency flashers.
release the spring brakes.
hold the vehicle or combination of vehicles stationary.

2. If you must drive slowly, how should you alert following drivers?

Flash your brake lights
Turn on your taillights
Use your emergency flashers if it is legal

3. 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.
should move more than one inch where the push rods attach to them.

4. Brake drums or discs must not have cracks longer than ____ the width of the friction area.

5. The safety valve is usually set to open at:

6. Which of the following is NOT TRUE? When you drive a tractor-trailer combination with ABS, you should:

drive slower to keep your vehicle in a straight line.
monitor your tractor and trailer as you slow down, and if it is safe to do so, back off the brakes to stay in control.
brake the same way, regardless of whether you have ABS on the tractor, the trailer, or both.

7. If the air tanks are not drained:

your speed must be reduced to 5 MPH below your “safe” speed.
the air pressure in the tanks is reduced.
the water can freeze in cold weather and cause brake failure.

8. Some air brake systems have an alcohol evaporator to:

reduce the stopping power of the vehicle.
reduce the danger of slipping.
prevent ice from forming in the brake system.

9. Truck tractors with air brakes built after March 1, 1997, are required to be equipped with:

10. Before driving a truck or bus with a dual air brake system, the minimum pressure in both the primary and secondary systems should be at least:

MISSOURI CDL AIR BRAKES PRACTICE TEST