>>1742660The underlying tradeoffs that go into designing a steam locomotive ensure that big-boys were not "multi capable". In practice, 4000s were rarely, if ever, used for anything than lugging tonnage at 30 mph up the Wasatch and were never ( or, exceedingly rarely ) used in passenger service. For all it's worth, UP would be much better off with a clone of Y6. Which actually were the most efficient, peak performance, american freight steam locomotive. H8 was failure on all fronts.
>>1742629Big boys were a product of "superpower steam" era in the 30s and 40s. They were actually were not that well suited to the kind of work they were performing, but that was the zeitgeist of the time.
>>1742600Big-Boys raised to prominence, in my opinion, not because they were exceptional, but because UP didn't, like most RRs, embrace the MU capability of the diesel, but kept at making superpowered 'single' locomotives for an extended time. 9000 class led to Challengers, which led to Big-Boys, which led to Verandas and Big-Blows and all that culminated with DDA35 and later DDA40X. All that led to the raise of the mythos of the Big-Boy.
On the flip side - N&W just silently scrapped Y6x, in spite of using them longer than most railroads, and just bought a bunch of off the shelf diesels in their place.
