A motor vehicle is slowed down or stopped with the help of the 'Brake' device, which is a combination of interacting parts of the vehicle creating friction mechanism. At the time of normal driving conditions, a foot-operated brake is used for hindering, stopping and controlling the automotive vehicle. Air brakes in Presidio are used on heavy vehicles such as buses and trains, since those work by means of compressed air. However, emergency brakes are operated by the driver with his or her hand and the same is used in emergencies only. There are two types of wheel-brake mechanisms ; such as drum brakes and disk brakes. Drum brakes are used in older vehicles, and at the rear wheels of many vehicles, the front disk brakes are used.