First of all, you have to understand the difference between hydraulic brakes and air brakes. Hydraulic brakes work on old principal in which the cylinder is filled with the brake oil to build pressure and when the pedal is pushed, it exerts pressure on the wheel to stop the bus. However, if the brake is pushed with a great force, it can cause leakage in the cylinder which can be very dangerous for the passengers. Nonetheless, with the advancement in the automobile industry, the engineers have managed to develop a braking system which doesn’t work on the principal of hydraulic cylinder filled with oil. In air braking system, compressed air is used to stop the vehicle. Furthermore, it makes it really easy to stop the vehicle within much lesser time as compared to the hydraulic brakes.
You should know that the air brakes include three different braking systems namely service brakes, parking brakes and emergency brakes. Service brakes are used for stopping the vehicle when it is going on a particular speed on the road. You can simply stop or slow the vehicle by pushing the brake pedal. The parking brakes are used to park the car at a specific place so that it may not move to any other place. Additionally, the emergency brakes are only used in case of an emergency when the service brakes have failed to work.
It is extremely important for you to learn all the three systems of air brakes well in order to apply them in the hour of need.