The primary supply of air to the fire is from below, via the ashpan. Dampers are the flaps, operated from the cab, which regulate the flow of air through the ashpan. They also provided access to rake out clinker and ash from the ashpan.
Controls that vary airflow through an air outlet, inlet, or duct. A damper position may be immovable, manually adjustable or part of an automated control system.
the amount of heat that is produced by a fire is governed by the amount of air admitted to it. This can be adjusted by opening or closing damper doors in the locomotive's ashpan assembly. These are worked by levers situated in the locomotive cab.