What is the difference between regular brakes and air brakes?

Question

I need to know this for my CDL test and I cant seem to get a simple answer!

Answer 1

One break is regular and one break use air

Answer 2

air breaks use air

Answer 3

Regular brakes work by sending pressurized hydraulic fluid to the wheel cylinders to expand the brake shoes and stop the vehicle. The problem is that brakes generate heat and hydraulic fluid can boil if too hot. When hydraulic fluid boils you no longer have pressure to the brake cylinders. Heavy vehicles generate too much heat in the brakes to safely use hydraulics. Additionally if a hydraulic line breaks you lose your brakes. Therefore they use air to actuate the brake cylinders for heavy vehicles. Additionally the parking or Emergency brake is spring activated and the air pressure deactivates it. So with air brakes, loss of air will activate the emergency brake for safety purposes.