Michigan CDL Air Brakes Exam Complete
Questions with Graded A+ Correct Answers
3 different braking systems that make up Air Brakes
Service Brake, Parking Brake, Emergency Brake
Air Compressor
Pumps air into storage tanks and connected to the engine via gears or a v-belt.
Air Compressor Governor
Controls when the air compressor will pump air into the air storage tanks. When tank pressure rises
to the cut-out level, the governor stops the compressor from pumping. When the tank pressure falls
to the cut-in level, the governor allow the compressor to pump again.
Cut-Out Level
125 PSI (Governor stops the compressor from pumping air)
Cut-In Level
100 PSI (Governor allows compressor to start pumping again)
Air Storage Tanks
Holds the compressed air.
Air Tank Drains
Valve to drain oil and water from the tanks.
Alcohol Evaporator
Puts alcohol into the air system to reduce risk of ice in the valves.
Safety Valve
In the first take air is pumped in to...protects the tank and system from too much pressure. Set to
open at 150 PSI.
Foundation Brakes
Used at each wheel...most common type is the S-Cam drum brake.
Drums, Shoes and Linings
Drums located on each end of the axles. Wheels are bolted to the drums. To stop, the brake shoes
and linings are pushed against the inside of the drum.
S-Cam Brakes
Pressure pushes the rod out, moving the slack adjuster, thus twisting the brake camshaft. Forces the
brake shoes away from one another and presses them against the inside of the brake drum.
Supply Pressure Gauges
Questions with Graded A+ Correct Answers
3 different braking systems that make up Air Brakes
Service Brake, Parking Brake, Emergency Brake
Air Compressor
Pumps air into storage tanks and connected to the engine via gears or a v-belt.
Air Compressor Governor
Controls when the air compressor will pump air into the air storage tanks. When tank pressure rises
to the cut-out level, the governor stops the compressor from pumping. When the tank pressure falls
to the cut-in level, the governor allow the compressor to pump again.
Cut-Out Level
125 PSI (Governor stops the compressor from pumping air)
Cut-In Level
100 PSI (Governor allows compressor to start pumping again)
Air Storage Tanks
Holds the compressed air.
Air Tank Drains
Valve to drain oil and water from the tanks.
Alcohol Evaporator
Puts alcohol into the air system to reduce risk of ice in the valves.
Safety Valve
In the first take air is pumped in to...protects the tank and system from too much pressure. Set to
open at 150 PSI.
Foundation Brakes
Used at each wheel...most common type is the S-Cam drum brake.
Drums, Shoes and Linings
Drums located on each end of the axles. Wheels are bolted to the drums. To stop, the brake shoes
and linings are pushed against the inside of the drum.
S-Cam Brakes
Pressure pushes the rod out, moving the slack adjuster, thus twisting the brake camshaft. Forces the
brake shoes away from one another and presses them against the inside of the brake drum.
Supply Pressure Gauges
