Blower & Damper

On a steam engine , the firebox temperature, as it burns fuel , mostly depends on the available airflow, since oxygen in the air fuels the fire.

The primary way to feed air to the firebox is by opening the regulator and cutoff fully, and propelling the vehicle. As the steam is expelled from cylinders out into the atmosphere through the chimney, with every gear cycle, it creates a vacuum in the firebox, drawing in fresh air.

However, full acceleration isn't always desirable, which is why there are additional controls to adjust airflow: blower and damper.

The blower is usually operated by a valve. When open, it releases some steam from the boiler to the chimney. This creates vacuum in the firebox, drawing in fresh air. However, since this airflow is vastly inferior to the acceleration airflow, the blower is only efficient when used on a stationary engine.

The damper is usually operated by a lever. When closed (pushed down) it chokes the airflow, drastically reducing fire temperature, even if the vehicle is accelerating. This is used to intentionally cut steam production when it is no longer needed, although doing so with a well-timed water injection is an even more efficient alternative.