Full Steam Ahead suggested he would like to see Bachmann produce a New York Central 4-6-4 (and he took an unfortunate amount of ribbing due to his typing); the engine, as he pointed out, is a classic, but as some of the others suggested, has been or is in production by others, going back as far as an American Flyer AC version in the prewar era, in the same time period as Varney's Dockside and MDC-Roundhouse 0-6-0. For that reason, even I would question that choice; in some ways, it would be like another Pennsy K-4.
At the same time, to produce a new 4-6-4 has a number of marketing challenges. Not many other roads have the following of the NYC and its 275 4-6-4s, and of the others that had the type, the rosters were much smaller. The second-largest owner of Hudsons was Canadian Pacific, with 65 engines; other owners had a dozen or less, and two, the Toronto Hamilton & Buffalo and the Maine Central, had only two each. This is not a small consideration, especially when you consider that a new engine is supposedly a $250,000 investment in tooling and other incidentals.
One thing that could help is the fact that most 4-6-4s had 79 or 80 inch drivers. This is important because most modern steam locomotives--essentially anything with a trailing truck--had a driver axle spacing about 3 or 4 inches greater than the diameter of the drivers. I suspect this is the minimum clearance that would accommodate flange clearance and brake rigging. Some engines would have greater spacing, but this was usually due to weight distribution (USRA 0-8-0s), or to allow for other components (such as a firebox that would drop between axles in a 4-6-0 or 2-8-0). Basically, this means a common mechanism can often be used for engines of the same driving diameter; Bachmann already does this with its 80-inch drivered 4-8-4s, based on AT&SF, NYC (Niagara), and Southern Pacific (Daylight) prototypes.
On this basis, here are what would be my suggestions for new 4-6-4s:
My first example requires I declare a certain amount of prejudice, as I am a C&O modeler. Still, C&O's 4-6-4s used a tender Bachmann makes that goes with the C&O 2-8-4; certain other parts, such as a trailing truck, were interchangeable, too. Both the Baker-geared 1942 L2s and the poppet-valved postwar L2as were built by Baldwin; 78" drivers:
http://www.cohs.org/repository/Archives/cohs/web/cohs-11.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1050.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1106.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1158.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1162.jpg
Another one, Chicago, Burlington & Quincy, Baker gear, 78" drivers:
http://www.flickr.com/photos/photos_by_laurence/3801376761/
http://www.flickr.com/photos/thomas-merton/3918657600/
http://www.flickr.com/photos/thomas-merton/3917872735/in/photostream/
http://www.llarson.com/steam/schenzinger/images/NA42.jpg
http://abpr.railfan.net/abprphoto.cgi?//july98/07-07-98/cbxq3003.jpg
The Milwaukee's conventional 4-6-4s had 80" drivers:
http://www.yesteryeardepot.com/MIL137.JPG
http://www.oldmilwaukeeroad.com/content/progress/photopages/photo09a.htm
DL&W:
http://www.northeast.railfan.net/images/tr_dlw1151.jpg
Wabash, 80" drivers (home rebuild from 2-8-2):
http://abpr.railfan.net/abprphoto.cgi?//january99/01-01-99/ns1394.jpg
http://abpr.railfan.net/abprphoto.cgi?//january99/01-01-99/ns1395.jpg
New Haven (made elsewhere, so not necessarily a candidate here), 80":
http://abpr.railfan.net/abprphoto.cgi?//july99/07-26-99/nh1408.jpg
http://www.steamlocomotive.com/hudson/nynhh1409.jpg
There are other 4-6-4s, but they are not included here, as the change in driver size is too great, resulting in different overall proportions.
There is another bit of a hole, and that's in medium-drivered 4-8-4s with wheels in the 74-to-76 inch range. Again, the idea is that a common mechanism can help amortize the cost of tooling.
Again, we start with the C&O J3 and J3a, the latter class including an engine numbered 614:
http://leesome1226.tripod.com/Pictures/co614erietable.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-39.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-142.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-21056.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1418.jpg
Burlington's burly O-5 and O-5a:
http://www.rrpicturearchives.net/showPicture.aspx?id=1602802
http://www.rrpicturearchives.net/showPicture.aspx?id=1312191
http://www.rrpicturearchives.net/showPicture.aspx?id=293065
http://www.rrpicturearchives.net/showPicture.aspx?id=1082789
http://www.rrpicturearchives.net/showPicture.aspx?id=1082793
Full-sized "brass" Burlington 5632:
http://www.railpictures.net/viewphoto.php?id=265628
Lackawanna had several types of 4-8-4s; the Q-4 had 74" drivers:
http://www.bachmanntrains.com/home-usa/board/index.php?action=post2;start=0;board=2
Southern Pacific's first daylights were GS-2s, 76" drivers:
http://www.yesteryeardepot.com/SP4412.JPG
Speaking of the GS-2s also brings up the GS-3s, which had 80" drivers like the currently produced GS-4. Hmm, a change to single headlight insert, an open cab, modified tender with gangway account of open cab--could the GS-4 tooling provide a different engine?
http://www.bachmanntrains.com/home-usa/board/index.php?action=post2;start=0;board=2
A recent excursion favorite, 74" drivers:
http://www.railpictures.net/viewphoto.php?id=298516&nseq=5
http://www.railpictures.net/viewphoto.php?id=298239&nseq=6
http://www.railpictures.net/viewphoto.php?id=293804&nseq=7
http://www.railpictures.net/viewphoto.php?id=284738&nseq=10
2008--or 1948?
http://www.railpictures.net/viewphoto.php?id=280515&nseq=16
There may be others; what else could you suggest?
Finally, Bachmann might even want to consider a New York Central 4-8-2, specifically an L1 or L2 of some sort, which was a freight engine with 70" drivers and Baker valve gear on the L2, like the USRA 4-8-2 currently in the line. Note the variations in subclasses; I personally like the earlier engines with heavy, overhanging Elesco feedwater heaters that looked like H-10 2-8-2s on steroids rather than the later ones, which looked like Hudsons:
http://www.railarchive.net/nyccollection/nyc2967_rcl.htm
http://www.yesteryeardepot.com/NYC2618.JPG
http://www.yesteryeardepot.com/NYC2872.JPG
http://transportmuseumassociation.org/images/exhibits/newyorkcentral2933.jpg
Have fun.
At the same time, to produce a new 4-6-4 has a number of marketing challenges. Not many other roads have the following of the NYC and its 275 4-6-4s, and of the others that had the type, the rosters were much smaller. The second-largest owner of Hudsons was Canadian Pacific, with 65 engines; other owners had a dozen or less, and two, the Toronto Hamilton & Buffalo and the Maine Central, had only two each. This is not a small consideration, especially when you consider that a new engine is supposedly a $250,000 investment in tooling and other incidentals.
One thing that could help is the fact that most 4-6-4s had 79 or 80 inch drivers. This is important because most modern steam locomotives--essentially anything with a trailing truck--had a driver axle spacing about 3 or 4 inches greater than the diameter of the drivers. I suspect this is the minimum clearance that would accommodate flange clearance and brake rigging. Some engines would have greater spacing, but this was usually due to weight distribution (USRA 0-8-0s), or to allow for other components (such as a firebox that would drop between axles in a 4-6-0 or 2-8-0). Basically, this means a common mechanism can often be used for engines of the same driving diameter; Bachmann already does this with its 80-inch drivered 4-8-4s, based on AT&SF, NYC (Niagara), and Southern Pacific (Daylight) prototypes.
On this basis, here are what would be my suggestions for new 4-6-4s:
My first example requires I declare a certain amount of prejudice, as I am a C&O modeler. Still, C&O's 4-6-4s used a tender Bachmann makes that goes with the C&O 2-8-4; certain other parts, such as a trailing truck, were interchangeable, too. Both the Baker-geared 1942 L2s and the poppet-valved postwar L2as were built by Baldwin; 78" drivers:
http://www.cohs.org/repository/Archives/cohs/web/cohs-11.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1050.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1106.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1158.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1162.jpg
Another one, Chicago, Burlington & Quincy, Baker gear, 78" drivers:
http://www.flickr.com/photos/photos_by_laurence/3801376761/
http://www.flickr.com/photos/thomas-merton/3918657600/
http://www.flickr.com/photos/thomas-merton/3917872735/in/photostream/
http://www.llarson.com/steam/schenzinger/images/NA42.jpg
http://abpr.railfan.net/abprphoto.cgi?//july98/07-07-98/cbxq3003.jpg
The Milwaukee's conventional 4-6-4s had 80" drivers:
http://www.yesteryeardepot.com/MIL137.JPG
http://www.oldmilwaukeeroad.com/content/progress/photopages/photo09a.htm
DL&W:
http://www.northeast.railfan.net/images/tr_dlw1151.jpg
Wabash, 80" drivers (home rebuild from 2-8-2):
http://abpr.railfan.net/abprphoto.cgi?//january99/01-01-99/ns1394.jpg
http://abpr.railfan.net/abprphoto.cgi?//january99/01-01-99/ns1395.jpg
New Haven (made elsewhere, so not necessarily a candidate here), 80":
http://abpr.railfan.net/abprphoto.cgi?//july99/07-26-99/nh1408.jpg
http://www.steamlocomotive.com/hudson/nynhh1409.jpg
There are other 4-6-4s, but they are not included here, as the change in driver size is too great, resulting in different overall proportions.
There is another bit of a hole, and that's in medium-drivered 4-8-4s with wheels in the 74-to-76 inch range. Again, the idea is that a common mechanism can help amortize the cost of tooling.
Again, we start with the C&O J3 and J3a, the latter class including an engine numbered 614:
http://leesome1226.tripod.com/Pictures/co614erietable.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-39.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-142.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-21056.jpg
http://www.cohs.org/repository/Archives/cohs/web/cohs-1418.jpg
Burlington's burly O-5 and O-5a:
http://www.rrpicturearchives.net/showPicture.aspx?id=1602802
http://www.rrpicturearchives.net/showPicture.aspx?id=1312191
http://www.rrpicturearchives.net/showPicture.aspx?id=293065
http://www.rrpicturearchives.net/showPicture.aspx?id=1082789
http://www.rrpicturearchives.net/showPicture.aspx?id=1082793
Full-sized "brass" Burlington 5632:
http://www.railpictures.net/viewphoto.php?id=265628
Lackawanna had several types of 4-8-4s; the Q-4 had 74" drivers:
http://www.bachmanntrains.com/home-usa/board/index.php?action=post2;start=0;board=2
Southern Pacific's first daylights were GS-2s, 76" drivers:
http://www.yesteryeardepot.com/SP4412.JPG
Speaking of the GS-2s also brings up the GS-3s, which had 80" drivers like the currently produced GS-4. Hmm, a change to single headlight insert, an open cab, modified tender with gangway account of open cab--could the GS-4 tooling provide a different engine?
http://www.bachmanntrains.com/home-usa/board/index.php?action=post2;start=0;board=2
A recent excursion favorite, 74" drivers:
http://www.railpictures.net/viewphoto.php?id=298516&nseq=5
http://www.railpictures.net/viewphoto.php?id=298239&nseq=6
http://www.railpictures.net/viewphoto.php?id=293804&nseq=7
http://www.railpictures.net/viewphoto.php?id=284738&nseq=10
2008--or 1948?
http://www.railpictures.net/viewphoto.php?id=280515&nseq=16
There may be others; what else could you suggest?
Finally, Bachmann might even want to consider a New York Central 4-8-2, specifically an L1 or L2 of some sort, which was a freight engine with 70" drivers and Baker valve gear on the L2, like the USRA 4-8-2 currently in the line. Note the variations in subclasses; I personally like the earlier engines with heavy, overhanging Elesco feedwater heaters that looked like H-10 2-8-2s on steroids rather than the later ones, which looked like Hudsons:
http://www.railarchive.net/nyccollection/nyc2967_rcl.htm
http://www.yesteryeardepot.com/NYC2618.JPG
http://www.yesteryeardepot.com/NYC2872.JPG
http://transportmuseumassociation.org/images/exhibits/newyorkcentral2933.jpg
Have fun.