Michigan Airbrake CDL Test |Complete Questions
with A+ Graded Answers
The air brake system on a commercial motor vehicle is comprised of three separate systems. Can you
name them?
Service, Parking, Emergency brake system
How often should the air tank be drained in the air brake system?
If it is a manual drain valve, it should be drained of water and contaminants at the end of every day's
driving.
At what PSI does the air compressor "cut out"?
The air compressor will shut down or "cut out" when the pressure in the air tank reaches about 125
PSI. It will start building pressure again if the pressure drops to about 100 PSI.
What is a foundation brake?
The foundation brake is the component found at each wheel, most commonly comprising a drum
brake, brake shoes, and S-cam.
What is an s-cam?
It is literally an "S" shaped device that, when turned or pivoted, forces the brake shoes apart where
they then come in contact with the brake drum, to create friction that will slow the vehicle.
What are spring brakes?
Spring brakes are a part of the emergency and parking brake systems. They are engaged
automatically, via spring power, if the air pressure drops below 20-45 PSI.
Which knob in the cab of the truck controls the parking brakes?
The diamond-shaped, yellow knob controls the parking brakes.
How can you check to see if the spring brakes are operating properly?
Chock the wheels, release the parking brakes (press in the yellow knob), and shut the engine off.Step
on and off the brake pedal to release the air pressure built up in the system.
The parking brake or spring brakes should automatically come on when the air pressure falls to
between 20-45 PSI.The knob on the dash will pop out if they are working properly.
What is a "dual air brake" system?
This is the type of air brake system that relies on two separate sets of air tanks, lines, and hoses
managed by a single set of brake controls.
How quickly should a vehicle build air pressure?
The pressure should build from 85 to 100 PSI in about 45 seconds
What danger could be caused by a vehicle that is slow to build air pressure?
If a vehicle cannot build pressure quickly enough during use, the spring brakes may be activated,
causing an emergency or uncontrolled stop.
with A+ Graded Answers
The air brake system on a commercial motor vehicle is comprised of three separate systems. Can you
name them?
Service, Parking, Emergency brake system
How often should the air tank be drained in the air brake system?
If it is a manual drain valve, it should be drained of water and contaminants at the end of every day's
driving.
At what PSI does the air compressor "cut out"?
The air compressor will shut down or "cut out" when the pressure in the air tank reaches about 125
PSI. It will start building pressure again if the pressure drops to about 100 PSI.
What is a foundation brake?
The foundation brake is the component found at each wheel, most commonly comprising a drum
brake, brake shoes, and S-cam.
What is an s-cam?
It is literally an "S" shaped device that, when turned or pivoted, forces the brake shoes apart where
they then come in contact with the brake drum, to create friction that will slow the vehicle.
What are spring brakes?
Spring brakes are a part of the emergency and parking brake systems. They are engaged
automatically, via spring power, if the air pressure drops below 20-45 PSI.
Which knob in the cab of the truck controls the parking brakes?
The diamond-shaped, yellow knob controls the parking brakes.
How can you check to see if the spring brakes are operating properly?
Chock the wheels, release the parking brakes (press in the yellow knob), and shut the engine off.Step
on and off the brake pedal to release the air pressure built up in the system.
The parking brake or spring brakes should automatically come on when the air pressure falls to
between 20-45 PSI.The knob on the dash will pop out if they are working properly.
What is a "dual air brake" system?
This is the type of air brake system that relies on two separate sets of air tanks, lines, and hoses
managed by a single set of brake controls.
How quickly should a vehicle build air pressure?
The pressure should build from 85 to 100 PSI in about 45 seconds
What danger could be caused by a vehicle that is slow to build air pressure?
If a vehicle cannot build pressure quickly enough during use, the spring brakes may be activated,
causing an emergency or uncontrolled stop.
