Can anyone simply explain to an idiot how air brakes work?
Sure. Instead of a hydraulic cylinder like on a car you have an air cylinder at each wheel which actuates the brake (pushes the shoes against the drum or the pads against the rotor depending on drum or disk setup) when air is supplied to them by pressing on the brake pedal. Not that much different than hydraulic brakes on a car except that the air isn’t affected by heat the way hydraulic fluid is. When hydraulic fluid exceeds a set temperature it will boil. When it boils it becomes a gas and cannot be compressed. That’s bad as the brakes will no longer work. With a car you don’t have too much to worry about but with a heavy truck heat can build a lot faster in the brakes and hydraulic brakes become useless. Even with air operation you can still get truck brakes hot enough to fail but it takes a lot longer.
