If official records are to be believed, the locomotive shown here was never meant to be built. During the design work on the boiler for the new class 655A, the design staff decided to push to its limits the computer gasflow modelling program they were using to see how long a boiler could be calculated. The result is shown above, mounted on the eleven-axle chassis it would have needed to carry it. The weight calculation gave an axle load of 23.8 tonnes. In other words, the design was plausible (actually IS plausible - there is no reason to suppose that the drawings have not been kept). Curve negotiation would be a challenge but certainly feasible. Performance would be similiar to that of the 655A, although in theory some 16% higher, thanks to the extra driving axle.

Text and graphics © Norman Clubb 2012