NEB&W Guide to AHM Steam Locomotive Models

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AHM started producing highly-detailed ready-to-run plastic steam in the 1960's, but insisted on large knife-flanged wheels that wouldn't work on scale track. In order to get around tight 18 inch radius curves, they added a lot of sideways sloop to the mechanism, which did work as intended. (Other manufacturers chose to make the center drivers "blind" which is noticeable.)

AHM locos were unusual for their time in being styrene ready-to-run, when most other models were cast-metal kits.

AHM (American Hobby Manufacturers) was the importer of a number of European manufacturers, including Rivarossi, who made most and the best of the steam locos. AHM went defunct but sort of resurfaced as IHC, who continued to import Rivarossi engines and sold them under the IHC name. Rivarossi also sold the same products under their own name, so also see IHC and Rivarossi, below.






Mikados 2-8-2's

  • 5089-C MKT USRA Heavy Mikado
  • 5089-D NYC USRA Heavy Mikado
  • 5089-E CB&Q USRA Heavy Mikado
  • 5089-F GN USRA Heavy Mikado
    The original USRA heavies were distributed as follows:
  • CB&Q, 15 locos, class O-4, nos. 5500-5514.
  • CNJ, 10 locos.
  • CNW (their subsidiary, the Omaha, four locos.
  • Milwaukee, 100 locos.
  • EJ&E, five locos.
  • EP&SW, five locos.
  • FW&DC (Burlington subsidiary), five locos.
  • GN, four locos.
  • L&N, 20 locos (and 18 of the light version).
  • NKP (W&LE), 20 locos.
  • NYC (P&LE), 15 locos.
  • NYC (PMcK&Y), 15 locos. There were a total of 233 of the heavy Mikados (and 625 light, or nearly three times as many).
    The AHM model is their heavy Pacific superstructure on a 2-8-2 mechanism, introduced around 1978. First of all, the USRA light Mikado used the boiler of the heavy Pacific and therefore the heavy Mikado would have a somewhat fatter boiler than a model made from the Pacific. AHM did not really copy the characteristic USRA cab, although what they came up with is not too far off. They also used a cast Commonwealth trailing truck instead of the built-up one used on all USRA orginals. (Easy to switch out a trailing truck.)

On the AHM Pacific, they used their NKP Berkshire tender. On this Mikado model, I think they used their USRA 0-6-0 switcher tender.
The MKT did not have any USRA Mikados. As far as I know, the NYC's subsidiaries had some. However the Central itself only had light Mikados.

  • 5189-08 C&O 2-8-2 - In 1978, AHM took their heavy Mikado model and modified it to represent the C&O's K-2 class. The C&O had been getting Mikados as far back as 1911 through 1914. These only had 56 inch drivers. They didn't get any USRA Mikados. In 1924, they got 50 class K-2 Mikados from Alco, nos. 1160-1209. The same year, they got another 50 K-3 Mikados from the same builder, Alco, and another 50 K-3a engines, again from Alco, in 1925-'26. I understand the three classes were fairly similar except for the tender. All had 63 inch drivers like the USRA engine. I've seen a photo of a K-3, which looked like the AHM K-2 model, except for the Vanderbilt tender and the characteristic C&O notched cab. The AHM model used the NKP tender. I assume the cab would have been similarly notched as on the K-3. Don't know if it would be easier to modify the existing cab or substituting one taken from the IHC 4-8-4.

  • 5089-09 GN Mikado - Numbered 3380 and painted in the "Glacier Park" green color scheme with silver firebox and smokebox, oxide red roof, and colorful mountain goat herald. The GN had standardized on the Belpaire firebox, but they did get 9 USRA standard heavy Mikados, nos. 3200-3208, class O3. Apparently four came from the SP&S and the other five came from the El Paso & Southwestern, but I'm not sure when. (I think early, like in 1919.) In 1979, AHM modified their heavy Mikado to make two versions of the GN O3's. The first version was basically just the use of the correct paint scheme.

Berkshires 2-8-4's

  • 2-8-4 Berkshire - Again, a model based on a prototype (NKP 759) that became famous in post-steam days simply because it survived (and in this case, restored to service and ran all over the country in excursions). (I don't mean to slight NKP modelers, but what survived and what didn't was more a matter of chance than not.) The original 2-8-4 loco was basically a super powerful version of a 2-8-2, a freight engine. The pony truck did not track as wheel as the four-wheel version so it couldn't run as well at speed. I understand by the time of the NKP version, they had improved the two-wheel lead truck to where such a loco could be used on passenger and other high speed service. The first 15 were built in 1934.

No. 779 was the last steam locomotive built by Lima, in 1948, one of 10 engines, S-3, nos. 770-779, and one of 65 Berkshires total for the NKP. Nearly identical locos were built for the Pere Marquette and very similar to a few other roads.
The Mars headlight, mounted just above the main headlight which is centered on the smokebox, is one clue of the late construction of this loco. (Or it might have been retrofitted on some or all of these in the late '40's.)
The C&O started getting their Berkshires in '43 from Alco, nos. 2700-2739. In '46, they got 10 more from Lima, nos. 2740-2749, another 10 from Lima the next year ('47), nos. 2750-2759, class K-4, and 20 from Alco the same year of 1947, nos. 2760-2789.

The Pere Marquette got 39 Berkshires from Lima. Nos. 1210-1215, class N, were built in '37. Nos. 1216-1227, class N-1, were built in '41, and nos. 1228-1239, class N-2, built in '44. When the PM was merged into the C&O in a few years, the class N locos were renumbered as C&O 2685-2699. The other two classes remained lettered and numbered for the PM.
The Virginian's five Berkshires were built by Lima in '46, class BA, nos. 505-509. Due to remaining war restrictions, the VGN locos were built identical to the C&O's K-4 class.

The Wheeling & Lake Erie's 32 Berkshires, all built by Alco between 1937 and '42, class K-1, were basically copies of the NKP locos. C. '49, they were relettered NKP with the same numbers and then around 1952, the first two digits, "64", replaced by "8". (In other words, 6401 became 801, 6402 became 802, and so on.) They lasted until 1961-'64, fairly late for steam.

  • 5061-06 RF&P Berkshire - The Richmond, Fredericksburg & Potomac got 10 Berkshires from Lima in 1943, nos. 571-580 and were all retired 9 years later, in '52. The sand box was not as massive as the NKP one, which is a hallmark of the NKP design. In 1979, AHM modified their NKP Berkshire to represent one of these locos. I think the only modification they did was to eliminate the Mars light.


  • 5093-02 B&O 2-8-8-0 Mallet - Said to be based on the Baltimore & Ohio's EL-3 class of locos built by Baldwin in 1917. AHM simply took their N&W Y-6b 2-8-8-2 model (see below), left off the trailing truck, modified the front end and substituted their B&O 2-10-2 Vanderbilt tender. This model was produced around 1978.
Apparently there was the similar EL-5 class on the B&O, built by Baldwin in 1919-'20, nos. 7145-7170.

  • 5092 N&W 2-8-8-2 Mallet - Based on a specific N&W class of locos, which in turn were copies of the USRA standard design of the same wheel arrangement. The N&W Y-class of locos date back to the original USRA locos and over time they got a total of 191 of these. The model is of the last class, the Y6b, built from 1948 until '52, nos. 2170-2200. The model scales out to be 116 feet long.
According to Steve Orth (Dec. 2005 Railmodel Journal), the N&W, Virginian, and Clinchfield got the original engines. After WWI, clones were acquired by the D&RGW and NP.
AHM also offered this model decorated for the PRR (model no. 5090) and ATSF (model no. 5091). The Pennsy and Santa Fe got original USRA Mallets from the N&W.
Perhaps the biggest difference between a USRA Mallet and the Y6b/this model is the cab. The USRA loco had a pretty standard looking style cab, while this version had a shorter slanted-front cab. If you were desperate, you could backdate this model by substituting a cab from the USRA Pacific or Mikado. The tender, too, is more modern looking and using a USRA tender, the so-called long version, would help.

Santa Fes 2-10-2

  • 2-10-2 B&O - According to the review in the Dec. '67, the B&O got their original "Santa Fe's" from Baldwin in 1914, class S-1. Subclass S-1a were built by Lima (unknown date), series 6175-6199 and series 6200-6224 were built by Baldwin in 1926. (I assume the Lima engines were also built in '26.) I would think the AHM model is based on the later S-1a which were essentially the same as the original engines, but with a larger tender. The last engines lasted until 1959.
The engine has a Vanderbilt tender. The engine also has a characteristic B&O-style cab. (It would be interesting to switch out the cab for a different look.) There were two sand domes and they were unusual in each being split in two (because the loco boiler was so close to vertical clearance, there wasn't much room left for the dome at the top?).
This is one of the few Rivarossi models that has not be resurrected since it was first introduced.

Models With Four-Wheel Lead Trucks