A blowback (also blow back or blow-back) is a failure of a

steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, oil or, rarely, wood) to heat water in the locomot ...

, 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 A smokebox is one of the major basic parts of a steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is e ...

. 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 Dunstable ( ) is a market town and civil parishes in England, civil parish in Bedfordshire, England, east of the Chiltern Hills, north of London. There are several steep chalk escarpments, most noticeable when approaching Dunstable from the ...

, the Inspector wrote: He also recommended that the

British Transport Commission The British Transport Commission (BTC) was created by Clement Attlee's post-war Labour government as a part of its nationalisation programme, to oversee railways, canals and road freight transport in Great Britain (Northern Ireland had the se ...

carry out an investigation into the causes of blowbacks. Blowbacks can also occur when a steam tube (or pipe) bursts in the boiler, allowing high-pressure steam to enter the firebox and thus egress onto the footplate. Other potential causes are unused mining explosives in the coal used to fuel the engine, and unburnt gases collecting in the firebox and then igniting.

Examples

The 1965 Winsford railway accident was caused by a blowback. Driver

Wallace Oakes Wallace Arnold Oakes GC (23 April 1932 – 12 June 1965), known as Wally Oakes, was an engine driver with British Railways who was born in Barbridge, Cheshire and lived at Wheelock Heath, Sandbach, Cheshire. 1965 train accident On 5 June 196 ...

died as a result, and his fireman Gwilym Roberts was severely injured.

References

{{Steam engine configurations Locomotive boilers Steam locomotive fireboxes Steam locomotive exhaust systems Explosions