A sudden reversal of the airflow through a steam locomotive boiler, pushing flames, hot gases, and smoke out of the firebox door into the cab. This typically happens when the throttle is closed abruptly while the engine is working hard, killing the exhaust draft before the crew can turn on the blower. It poses a severe burn hazard to the engine crew.
The hogger chopped the throttle without warning and we got a nasty blowback that scorched my overalls.
Firemen learn early to always crack the blower valve right before the engineer shuts off steam to maintain a positive draft up the stack.
Related terms
Blastpipe
An exhaust nozzle inside a steam locomotive smokebox that directs spent steam up the stack to draw air through the fire.
Firebox
The combustion chamber of a steam locomotive where fuel is burned to heat water.
Regulator
A throttle valve that controls the flow of steam to the cylinders of a locomotive.