High-pressure steam locomotive

However, both implementations are dead ends: the first one is limited by the loading gauge while the second one tends to be self-defeating because of frictional losses in the greatly increased volumes of exhaust steam to be handled.

It was not simply a matter of building a normal fire-tube boiler with suitably increased strength and stoking harder.

Structural strength requirements in the boiler shell make this impractical; it becomes impossibly thick and heavy.

This was a major drawback with the early water-tube boilers, such as the Du Temple design, tested on the French Nord network in 1907 and 1910.

This was demonstrated by the Fury tragedy, though the reason for the tube failure in that case was concluded to be overheating due to lack of steam flow rather than scaling.

One way to avoid corrosion and scale problems at high pressure is to use distilled water, as is done in power stations.

[citation needed] Dissolved gases such as oxygen and carbon dioxide also cause corrosion at high temperatures and pressures, and must be kept out.

The New York Central HS-1a and the Canadian 8000 also used the Schmidt system but were a size larger altogether- the 8000 weighed more than twice the Fury.

Only a quarter of this was fed to the HP cylinders; the rest was returned to the steam generator where its heat evaporated more water to continue the cycle.

Nevertheless, high maintenance costs and poor reliability negated the fuel economies promised by high-pressure and compounding, and the design was not repeated.

The vertical fire-tube boiler was wound with piano wire, and the connecting rods and cranks were fully enclosed and geared to one axle.

[5][6] In Great Britain, the LNER Class W1 was built with marine-type water-tube boiler working at 450 psi (3.10 MPa) in 1929.