N&W 611 (and other big 4-8-4)

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Re: N&W 611 (and other big 4-8-4)

Postby rlsteam » Wed Aug 26, 2015 8:35 pm

Also, regarding the the S-1a's 75-inch drivers, as opposed to 79-inch, I was given to understand that it was designed with the smaller drivers so it could pass wartime restrictions as freight power, but the frame was built to permit later retrofitting with the larger drivers (which was eventually done). There was an article by William D.Middleton in a postwar issue of RAILROAD MAGAZINE (unfortunately, my clipping lacks a date) that includes a photo (presumably of the 6000, only the running gear is shown) with caption that mentions the design's intent to accommodate larger drivers.
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Re: N&W 611 (and other big 4-8-4)

Postby Pneudyne » Thu Aug 27, 2015 4:28 am

Thanks for that. It suggests that the NYC was in fact thinking of a passenger 4-8-4 fairly early on, and not just a more powerful L-4. It had probably noted that D&H had obtained WPB approval for a 75-inch 4-8-4, so perhaps had reasoned that it too could expect to do the same. I suppose that if one started with the D&H K-62, stretched it a bit to accommodate 79-inch drivers, and then enlarged the boiler and firebox to match, one could end up with the Niagara more-or-less. Alco at least would also have had in mind the UP FEF key dimensions as a reference point for a “big” passenger 4-8-4.

Re the Wabash 4-8-2 and 4-8-4 pair, I have never seen an explanation as to why both types were ordered. Worth checking maybe is whether, for example, the 4-8-2 could run over more parts of the system than the 4-8-4. Axle loadings were about the same, but there might have been some underline bridges that could not handle the 4-8-4. I vaguely recall that bridge loading limitation was why B&M opted for a big 4-8-2 and not a 4-8-4.

Or perhaps Wabash ordered its big 4-8-2 before the 4-8-4 was considered to be a suitable freight locomotive. In the pre-4-8-4 era, the 4-8-2 was primarily a passenger locomotive. NYC had also established its [the 4-8-2's] credentials as a freight locomotive, but that idea was not generally taken up. A 4-8-4 freighter would have been really avant garde, perhaps a bold step that the Wabash was not ready to take. So if not exactly stepping out, the Wabash was already taking the path less trodden when choosing the 4-8-2. But then Alco and the Rock Island did step out and introduced a freight 4-8-4, something of a gamechanger perhaps. Maybe the Wabash looked at it, and said “nice idea; we want some of those too”. Its new and up-to-date 4-8-2 would have been the logical starting point for its own 4-8-4.

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