Hush-Hush: Gresley’s High Pressure Experiment

In the drive to create more efficient steam locomotives, many different ideas were tested in the first half of the 20th century. As we saw on the previous pages, a great deal of effort was directed at high-pressure boilers, which were predicted to deliver higher power and greater fuel efficiency than conventional steam traction.

At the end of 1924, the USA’s American Locomotive Co. (Alco) produced the world’s first main line locomotive with a marine type high-pressure water-tube boiler. This 2-8-0 goods locomotive, No. 1400 , was built for the Delaware & Hudson Railroad. It used two-cylinder compound expansion and had a 350psi boiler, built by Alco with assistance from Clyde shipbuilder