Blowback

A blowback (also blow back or blow-back) is a failure of a steam locomotive, which can be catastrophic. One type of blowback is caused when atmospheric air blows down the locomotive's chimney, causing the flow of hot gases through the boiler tubes to be reversed, with the fire itself being blown through the firehole onto the footplate, with potentially serious consequences for the crew. The risk of backdraught is higher when the locomotive enters a tunnel because of the pressure shock. Such blowbacks can be prevented by opening the blower before closing the regulator. Similar blowback can be caused by debris or other obstructions in the smokebox. In the days when steam-hauled trains were common in the United Kingdom, blowbacks occurred fairly frequently. In a 1955 report on an accident near Dunstable, the Inspector wrote: He also recommended that the British Transport Commission carry out an investigation into the causes of blowbacks.