Oarb00,
These are based on axle loading:
C Under 50,000 lbs
B Under 55,000 lbs
A Under 61,500 lbs
AA Under 64,500 lbs
AAA Over 64,500 lbs
For example, an Alco S-4 switcher is a 'A'. A GP7 is an 'AA', and an SD45 is a 'AAA' class engine.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
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I recently finished custom painting an N scale Atlas GP38-2 for CNW. I am wondering what the significance of the three A's under the cab means. I thought maybe it would denote axle arrangement or maybe type of servace but I see a single A on GP15-1's and 2 A's on my GP35, and 3 A's on SDxx's. Any Ideas?
Modeling the BN and CNW in N scale in the late 1970's midwest.