Air Brake system

Air brakes aren't located in any one spot they are several components located in many places. What are you looking for?the brakes are on the wheels just like any other brake. There are air tanks under the coach air compressor bolted to the engine and air dryer located somewhere in the rear wheel or engine area. Air valves at the brake pedal and "parking brake " push pull.
I google air brakes and get a ton of hits ... your air brakes are no different than a semi trucks in design .. read up on their use. To understand better how they work . What's it not doing ? Perhaps someone can help with more info