Tom Moungovan Wrote:
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> Even over time, some things tend to stick in your
> mind. Many years ago, the late Harry Wright of
> Hillcrest Lbr. Co. on Vancouver Island showed me a
> document that he'd been given. It was for their
> Climax 10, which has been active at Mt. Rainier
> Scenic Ry. in WA for many recent years. The
> boiler horsepower was given as....71. I expressed
> doubt, but was told that was correct.
Boiler horsepower is an awfully limited metric for discussing locomotives, and the figure given may be correct and wrong at the same time. I suspect it isn't reflective of maximum performance, as I suspect a Climax working to its utmost can evaporate more than ~294 gallons of water per hour. Quite possibly the boiler horsepower was figured off the locomotive heating surface, and depending on the method of calculation (there are several) the locomotive boiler may in practice exceed the given value, sometimes by a large amount.
One rough formula for calculating maximum locomotive boiler horsepower is 1/6 the grate area times the boiler pressure, but that was obviously not the method used in the case of this Climax. Other calculations are simply a division of the heating surface by some figure; I've seen 10, 8, and some other numbers given in various sources. What are the specifications of this Climax?
I consider boiler horsepower nearly useless as a measure of locomotive performance; it serves better when consistent performance can be expected of a boiler, such as in home heating installations. Short of measuring actual water use when working as hard as possible, there's no sure fire way to know a locomotive's boiler horsepower, and even then it's a crummy metric for locomotives because the motive work done by the water used will depend on things like boiler pressure and cylinder cutoff and how much of it went to the cylinders versus out the safety valves or lost to other causes.
