Abstract
To maintain legal speed on downslope, to maintain the trajectory on downhill curves, to avoid exaggerate use of brakes, or their blocking or burning, and thus avoiding heavy traffic accidentsespecially with heavy trucks, it is usual and necessary to practice engine braking, which occurs by means of changing gears down.
The necessary energy to brake is taken over by the engine. Because of its growth in time, it is recommended to do that as soon as possible.