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Discussion in 'HO Scale Model Trains' started by aslan, May 31, 2006.
I've heard this term a number of times. What exactly does it mean?
the USRA had standard design's light meant a lighter engine the heavy refered to a engine that was bigger and heaver with the same wheel arrangement.
I had a hunch that was what it meant. Thanks for helping out a newby.
If you are referring to Steam Engines, the term heavy usually applied to a type of USRA engine. USRA ( United States Railroad Administration) was formed during WWI to run the railroads, with the idea that a single entity could more efficiently run the railroads during a time of very heavy freight demands.
During this period, the USRA also designed (pretty well, by most accounts) some standardized passenger and freight locomotives, with some of those having heavy and light variations. The most common example in modeldom right now are the heavy and light mikados (2-8-2). In this case, they both used identical running gear, but the heavy had a larger boiler, larger cylinders (and therefore, higher tractive effort) and was, well, heavier. Both were used for similar purposes, with the lights generally used for lines with lighter traffic or where axle loadings had to be kept down.
Heavy and light variations were also produced in 4-8-2, 4-6-2 and 2-10-2 wheel arrangements (possibly more).
If you are not talking about steam engines, never mind...