In the average length in the figure, the typical form of traction engines is outlined, on which we can discuss the pieces. The tank, located under the locomotive system, takes up the space a four-sided fire, which is in the rust b, and under this the ash pan c. The latter must be properly closed to prevent a fall out of the burning carbon parts, only the front door can be opened in an adjustable length, in order to be necessary for combustion air into the furnace. On the front side of the fire-box is the elliptical aperture d, which receives the fire door. In the rear panel of the combustion bushing lead the ebullition tube e, a number of cylindrical wrought-iron tubes, which direct the combustion gases from the combustion space in the smoke bush f give, while its heat to the cylindrical in the boiler i water present, and get finally g in the chimney.