Why are early GE locomotives known by weight, like “70 tonner”? Why are contemporary ones known as, say a “zillion tonner”?
may have to do with the 90,000 lb rule that didn’t require a fireman on the engine? Just a thought. a new SD70ACE is 204 tons
The locomotives were designed for light rail, industrial and short line switching. Weight designation allowed decsion based on track, bridge, and structure weight limits.
Back in the days when GE made most of these switchers, they weren’t making road locomotives. And weight would be the biggest factor differentiating between models, which basically all have the same operating characteristics. That 90000-pound rule did factor in (explaining why the 44-ton locomotive was so popular).
Nowadays, of course, you have AC or DC traction, four or six axles, various gear ratios. Specifying these differences by the weight of the unit (which may or may not be able to be used for this purpose) would hardly seem to be the easiest way to go.
And if you flip it the other way, most of the early locos were 4 axle DC traction diesels…the only differences between them in many cases being weight and horsepower - the latter of which not mattering much when dealing with that light rail and three car trains.