Diesel "B" truck sideframes

The models and variants

B trucks

EMD Blomberg trucks

There are at least 4 versions of the Blomberg 2 axle truck, not counting a few sub-versions that are out there. The following information Andy Harman provided the following information on them, which I have reformatted only slightly to suit this forum. Some Pennsy F3's may have come with the brass journal equipped Blomberg B trucks, while the later F7's, FP7's, and GP units were all equipped with roller bearing Blomberg B trucks. The Blombergs have a 9 foot wheelbase. They were cast mostly by LFM in the U.S. and Dofasco in Canada, but GSC also made some.
Blomberg B
Sometimes called "Regular Blombergs", these were the standard EMD B truck from the FT up until the "Dash 2" line, and some roads continued to specify them even on their "Dash 2"'s. The earliest version, as modelled for the Stewart FTs, had plain bearings with an unusual lid on the journals. Another early version had sloped and/or square journals with brass bushings, an apparent carry-over from the earlier plain bearing style. The square journals were to accomodate speed indicators or other axle equipment. Detail Associates makes both journal styles.

The traditional roller bearing Blomberg B is the one Athearn did such an incredible job on, and it comes with all of their F-units, GP9's, and GP35's. Proto 1000 and 2000 units thus far have a rather lame rendition of the regular Blomberg that looks pretty weak next to Athearn's. Use the Athearn as a cheap, drop-on replacement (you may need to trim the large pin that fits into the truck itself) and you'll get a 100% improvement in overall appearance. The Kato version, as found on the Atlas GP7 and Stewart F units, and the Kato GP35, isn't quite as nice as the Athearn, but it's still good. The Bachmann Spectrum GP30 and Bachmann Plus GP35 come with a very weak Blomberg; Unfortunately there's no easy way to replace it. The Atlas/E-R FP7, made by Roco, also has a cruder Blomberg than the Athearn or Kato, but it's not nearly as bad as the Bachmanns.
Everyone and their mother, it seems, has done it. Here are a few. Atlas/Kato GP7 Atlas/Roco FP7 Proto 1000 F3A Proto 2000 GP30 Stewart/Kato F3B

Blomberg M
This is the "Dash 2" version of the truck. Athearn has also done this truck nicely on their GP38-2, GP40-2, GP50, and the various GP60's. Instead of the leaf spring in the center, it has a rubber thing of some kind; There are no outboard brake shoes and only one brake cylinder on the left. There is a strut or "shock absorber" on the right journal. It is used for dampening, to keep the truck from "hunting" at high speeds. Very common truck also.
Blomberg M phase II
This version has two differences from a Blomberg M; the center spring is once again a leaf spring, and one side of the truck has a weird strut that goes from the top of the sideframe up to the loco frame. Detail Associates/Train Station Products makes a so-so rendition of this truck; Overland's is better. These trucks were used on GP60's and GP60M's, so Athearn's use of the standard "M" is incorrect for their GP60.
Blomberg MR
Another version, used on the F40PH. It was a Blomberg M, but the spring system was reversed to clear the ladder on the conductors' side of the F40 carbody.

AAR Type A switcher trucks

The AAR Type A switcher truck has an 8 foot wheelbase. It is double equalized with drop equalizers. They are equipped with journals. GSC made the majority of these, though they cast some with the Alco logo on them. Adirondack did make some later versions of it.

The AAR Type A switcher truck was used by EMD, Baldwin, Alco, Lima, and Fairbanks-Morse on various models. Pennsy engines equipped with AAR Type A trucks included Alco S-3, S-4 and T-6, Baldwin VO660, VO1000, DS-4-4-600, DS-4-4-750, DS-4-4-1000, S-8 and S-12, EMD SW, SW1, NW2, SW7, SW900, SW1200 and Fairbanks-Morse H-10-44 and H-12-44. HO scale renditions are available from Atlas, Roco (on the Walthers SW-1 and H-10-44/H-12-44), Kato (also used on some versions of the Con-Cor SW-7), Athearn, and Proto 2000. Tiger Valley Models also has Type A sideframes, sans journals, and they make the appropriate journals for you to attach.
Here's the one found on a Atlas/Roco S4.

AAR Type B road trucks

The AAR Type B road truck was available in 2 versions. One, equipped with GE traction motors, has a wheelbase of 9 feet 4 inches, while the comparable Westinghouse traction motor equipped AAR Type B has a 9 foot 10 inch wheelbase. They are equipped with roller bearings. GSC cast most of the GE traction-motored versions of this truck. Generally, the Westinghouse-motored version had 4 sets of the leaf springs, the GE, 3. However, the GE-equipped trucks under some RS-1s also had 4 sets of springs.

Both GSC and Adirondack made GE trucks; There are no known examples of Westinghouse trucks which actually bear an Adirondack logo. Older GE trucks made by GSC have the GSC logo above the inner coil spring on the left side of the frame casting, but newer GSCs seem to omit this. Some GSC trucks made for Alco have a rectangular Alco logo centered above the leaf spring set. Adirondack GE trucks have a small hole above the outer coil springs, one on each side. Older Adirondack GE trucks have the AD logo just to the left of the leaf springs, but newer ones have the logo centered above the leaf springs. Westinghouse trucks have a GSC logo above the leaf spring set, sometimes offset to the right or left.

Some Canadian Alcos used a lightweight version of this truck, with a wheelbase of only 8 feet 10 inches; It lacked the leaf springs found in the other versions.

Most renditions are of the GE version, I know of none of the Westinghouse version. Among PRR models equipped with AAR B trucks were the Baldwin DR-4-4-1500 and RF-16 sharks, RS-12 and DRS-4-4-1000 (with the Westinghouse version), the Fairbanks-Morse H-20-44 (also Westinghouse), the GE U25B, and the Alco DL-640(RS-27), RS-1, RS-3, RS-11, FA-1, FB-1, FA-2 and FB-2, all with the GE traction motor version. The version under the Roco FA-2 and Shark is not correct for either, but does have 4 leaf springs as is correct for a Westinghouse variant. GE versions are available from Proto 2000 (also found under the MDC RS-3), Atlas, Stewart, Walthers, and Athearn; The Athearn version, also found under some Stewart units, is too short. It's actually an EMD 9 foot wheelbase truck.
Here are renditions from: Atlas/Kato RS1("friction" bearings) Atlas/Kato RS11 MDC/Proto 2000 RS3 Model Power/Roco Sharknose B

Fairbanks-Morse C-Liner trucks

Starting with the F-M C-Liner, Fairbanks-Morse designed their own single-equalized B truck, which they also used under some of their H-16-44s, including those of the Pennsy. The Pennsy C-Liners, not surprisingly, also had them. They were designed to house a Westinghouse traction motor, though later they had F-M-designed traction motors. They had a 9 foot, 4 inch wheelbase. Bachmann's H-16-44 is equipped with these trucks, and Train Station Products makes sideframes to fit Athearn trucks.

GE Electric unit B truck

GE used a different B truck design under the Virginian EL-2Bs of 1948. (placeholder)

Alco Blunt trucks

Before switching to the standard AAR Type A truck, early Alco switchers, the S-1 and S-2, came equipped with a switcher truck designed by a man named Blunt. It had an 8 foot wheelbase. When they switched to the standard truck, the model designator also changed. The truck was phased out in 1950; John Kirkland reported it was due to pressure from the AAR. Atlas makes a model of this truck, and Train Station Products makes a sideframe set to fit the Athearn switcher truck.

Alco Black Maria

Another Blunt design, found under the Black Maria testbed units.

Alco Hi-Adhesion truck


Baldwin Batz truck

This truck had a wheelbase of 8 feet, 4 inches, and used 40 inch wheels. It was a Santa Fe design used under license by Baldwin, and could be found under some of their early switchers.

EMD HT-B truck

Used on GP40X. (placeholder)

Rockwell/LFM FB-2 truck


Adirondack FB-2 truck


EMD Flexicoil B truck



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