Air brakes test

  1. Why must air tanks be drained?

Compressed air usually has some water and some compressor

oil in it which is bad for the air brake system. For

example, the water can freeze in cold weather and cause

brake failure. The water and oil tend to collect in the bottom

of the air tank

  1. What is a supply pressure gauge used for?
  1. These gauges tell you how much pressure is in the airtanks.

3. All vehicles with air brakes must have a low air pressurewarning signal.

True or False?

true

  1. What are spring brakes?

powerful springs are held back by airpressure. If the air pressure is removed, the springs put onthe brakes.

  1. Front wheel brakes are good under all conditions.
  2. True or

False?

true

These questions may be on your test. If you can’t answer

them all, re-read Section 5.1.

  1. What is a dual air brake system?

. A dual air brake system has two separate airbrake systems which use a single set of brake controls.

Each system has its own air tanks, hoses, lines, etc. One

system typically operates the regular brakes on the rear axle

or axles. The other system operates the regular brakes on

the front axle (and possibly one rear axle). Both systems supply air to the trailer if there is one.

The first system iscalled the “primary” system. The other is called the “secondary”system.

  1. What are the slack adjusters?

A lever, connecting the brake chamber push rod with the foundation brake camshaft

  1. How can you check slack adjusters?

By pulling hard on each slack adjuster.

  1. How can you test the low pressure warning signal?

Test Low Pressure Warning Signal. Shut the engine off

when you have enough air pressure so that the low pressure

warning signal is not on.

Turn the electrical power on andstep on and off the brake pedal to reduce air tank pressure.

The low air pressure warning signal must come on beforethe pressure drops to less than 60 psi in the air tank.

with the lowest air pressure, in dual air systems).

  1. What can you check that the spring brakes come on automatically?

Chock the wheels, release the parking brakes when youhave enough air pressure to do it, and shut the engine off.

Step on and off the brake pedal to reduce the air tank pressureThe “parking brake” knob should pop out when the air

pressure falls to the manufacturer’s specification (usually in

a range between 20-40 psi). This causes the spring brakes

to come on.

  1. What are the maximum leakage rates for an air brake system?

The loss rate should be less than two psi in one minute for single vehicles andless than three psi in one minute for combination vehicles.

These questions may be on your test. If you can’t answer

them all, re-read Sections 5.2 and 5.3.

1. Why should you be in the proper gear before startingdown a hill?

brakes can fade or fail from excessive heat caused by usingthem too much and not relying on the engine braking effect.

2. What factors can cause brakes to fade or fail?

brakes can fade or fail from excessive heat caused by usingthem too much and not relying on the engine braking effect.

Excessive use of the service brakes results in overheating

and leads to brake fade

Brakes that are out of adjustment

3. The use of brakes on a long steep downgrade is only asupplement to the braking effect of the engine.

True or

False?

true

4. If you are away from your vehicle only a short time, youdon’t need to use the parking brake. True or False?

false

  1. How often should you drain air tanks?
  1. Drainyour air tanks at the end of each working day

These questions may be on your test. If you can’t answer

them all, re-read Section 5.4.

Air

Air Brake Test

Below is a link to the Free CDL Air Brake Practice Test. This is one of the most important CDL Tests to practice and study. Unlike high school trigonometry you will need to know this CDL air brake information. You have to understand how air brakes work to be a truck driver. There are so many things that can go wrong with air brakes you will not be able to trouble shoot problems if you don’t understand these systems work.

The end result is you sitting on the side of the road for hours waiting on breakdown or worse yet, driving off the edge of a cliff! Study the air brake section of any CDL DMV manual and take this air brake practice test as many times as you like!

Air Brake Test

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