There is another current post about someone wanting to make a Yellowstone out of a Big Boy plastic model. That’s a good thread, but has kind of become “watered down” with a discussion of general interest in a 2-8-8-4. I thought it might be helpful & useful to separate the interest from the kitbashing project.
I grew up in the Ohio Valley and I’m led to believe that the Ohio Valley was the last bastion of the B&O’s EM-1s. I never saw those engines but have seen pictures of them in places that were familiar to me. There was even an article a long time ago in one of the prototype train magazines about a local guy who got to fire an EM-1 from Benwood west on the B&O line that went through Bellaire & Bridgeport, then west towards Columbus. So, yes, I’d be interested in one of those.
My brother was a steelworker and had quite a collection of the smaller AHM ore cars. A nice long string of those would look good behind a DM&IR Yellowstone, so I could go either way. I gather from the other thread that there is some similar heritage in the two engines… perhaps a manufacturer coul get a “two-fer” by using the same basic mechanism and just changing details to get close to both of them.
My thought is not to use a Big Boy for that kit bash since it is so much different in so many ways. The AC12 Cab Forward is very closely related to the Yellowstones since it was built by the same Baldwin and shares some of the same parts. It is in effect a Yellowstone in reverse.
The details are different, but Baldwin locomotive built the EM1 and the M3 and M4’s about the same time frame using the 63" drivers and many standard Baldwin items. The last SP Cab Forwards were built during the war also and Bal
With the basic mechanism, it wouldn’t be too hard to turn a Missabe M-3/4 into a B&O EM. Actually, back when Akane was producing both models in brass HO, they used the same driver chassis for both models. Both prototypes were built by Baldwin around the same time and shared some common construction methods (wheel-base, driver diameter, etc.). There were differences in boiler diameter, and especially tractive effort–the Missabe’s were one of the most powerful steam locos ever built with 140-145,000 lbs TE to the EM’s lighter 124,000 lbs TE, but the EM was built to B&O specific requirements, and was a highly successful articulated. The Missabe’s were built specifically for heavy ore trains on uneven grades in Minnesota.
Of course, the Missabe Yellowstones spent their winters during WWII off the home property, being borrowed by the Rio Grande, Great Northern, Northern Pacific and Western Pacific to alleviate these railroad’s own power shortages during WWII and did an amazing job in varied terrain.
Both the B&O and Missabe Yellowstones were constructed to haul at speeds up to 70 mph should the occasion arise (though I don’t think it ever did), but I know that they were capable at hauling maximum tonnage at comfortable speeds of over 50mph (I’ve got a video of a Missabe being paced with a long load of empties, clicking away at well over 50mph).
But if a manufacturer were to construct the basic chassis, then yes, it would be possible to turn that chassis into either a M-3/4 or an EM with a different boiler, tender and other basic details. In fact, it might be possible to use the same chassis for a Lima-built Southern Pacific AC-9 (Espee’s only cab-back 2-8-8-4). And by substituting spoked drivers for the Boxpox, you might even come up with a respectable Northern Pacific Z-series