Steam locomotive exhaust system

The exhaust from the cylinders on the first steam locomotive – built by Richard Trevithick – was directed up the chimney, and he noted its effect on increasing the draft through the fire at the time.

At Wylam, Timothy Hackworth also employed a blastpipe on his earliest locomotives, but it is not clear whether this was an independent discovery or a copy of Trevithick's design.

Shortly after Hackworth, George Stephenson also employed the same method but again it is not clear whether it was an independent discovery or a copy of a design from one of the other engineers.

The combination of multi-tube boiler and steam blast are often cited as the principal reasons for the high performance of Rocket of 1829 at the Rainhill Trials.

The aim of exhaust system development is to obtain maximum smokebox vacuum with minimum back pressure on the pistons.

These principles were adopted on the Great Western Railway by Churchward, and later developed by Samuel Ell in the 1950s using the GWR (then nationalised under BR) stationary testing plant.