Brake is designed to transfer an automobile's kinetic energy into thermal energy (which activates brake action) by using thefrictional force generated from the the driver's operating forceor auxiliary power. As for automobiles, friction type, particularly hydraulic type, is generally used. The hydraulic type brake is designed to transform theforce generated when the driver activates the pedal into braking force through hydraulic media. Unlike sedans, big-sized automobiles like buses or trucks generally have air brakes.