5at Train

The 5AT Group - Steaming Ahead with Advanced Technology

Enhancing Performance -- Improving Reliability -- Reducing Costs -- Controlling Emissions

Aren't the performance claims for the 5AT a bit exaggerated?:

The following answer is taken from Wardale's response to Leonard Staghurst whose letter was published in Steam Railway #277 (copied below):

"Unfortunately Mr. Staghurst's comments betray his lack of knowledge, not only of what is possible with steam traction but also of what has already been achieved. Consider the following.

Item SAR 26 Class 4-8-4 5AT 4-6-0
Type of locomotive Rebuild of 1950's design New design
Quality of thermodynamic design Restricted by structural limitations of existing design State of the art
Number of cylinders 2 2
Simple or compound Simple Simple
Valves/valve gear Piston/Walschaerts Piston/Walschaerts
Boiler pressure, lb. per sq. in. 225 305
Fuel Coal Gas oil or diesel fuel
Ash content of fuel 15% 0
Fuel calorific value Btu/lb. 12,000 18,400
Engine weight (excluding tender), metric tons 123 80
Maximum indicated h.p. 5060 (peak of measured i.h.p. curve) 3460 (calculated)
i.h.p. per ton of engine weight 41.1 43.3

The above figures, which are amply supported by other data, show eloquently enough that the calculated power capacity of the 5AT is perfectly realistic, and I regard achieving it as a formality (and surpassing it a probability) - even on this planet! Likewise all factors concerning thermal efficiency, except the target combustion efficiency at maximum evaporation, which I have acknowledged will be a difficult problem. But that does not mean impossible, simply that very good engineering will be required to achieve it."