Soffiante e tirafumo

La quantità di ossigeno presente nell'aria determina l'intensità con cui il combustibile brucia e, di conseguenza, la temperatura all'interno del forno della locomotiva a vapore.

The primary way to feed air to the firebox is by opening the regulator and propelling the vehicle. As the steam is expelled from the boiler through steam chest and cylinders out into the atmosphere, fresh air is drawn to the firebox. This happens with every gear cycle, and the higher the cutoff setting the more the airflow.

Inoltre sono presenti due meccanismi di controllo progettati per regolare il tiraggio, ovvero il soffiante e il tirafumo.

Blower is usually operated by a valve. When open, it releases steam from the boiler around the chimney area. This creates vacuum, pulling in air into the firebox. This is used when a vehicle is stationary. Having the blower open while accelerating is wasteful however, because the acceleration airflow is vastly superior to blower.

Damper is usually operated by a lever. When closed (pushed down) it chokes the airflow, drastically reducing fire temperature. This is used to intentionally cut steam production when it is no longer needed.