Diesel 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. Andy Harman provided the following information on them. 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 truck cross section showing leaf springs and bolster stop.
Cast aluminum Blomberg truck frames for a 3/4 inch F3. Photo by John Hudak.
1 inch scale Blomberg truck castings, photo by Bernie Grow.

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 modeled 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 accommodate speed indicators or other axle equipment.

Drawings

EMD Blomberg B Trucks

Blomberg B Truck Sub-Assembly EMD 8140660 (Note: This is a large file, and may not display properly in your browser. Save the file and view with the Windows Photo Viewer or other tool.)

Blomberg M

This is the "Dash 2" version of the truck, used on GP38-2, GP40-2, GP50, and 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. These trucks were used on GP60's and GP60M's.

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.

Six Wheel

U.S. Patent 2,189,125 provides detailed drawings and description of the Blomberg six-wheel truck.

AAR

Type A

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.

Patent 2,137,074 provides detailed drawings and description of the AAR Type A Blomberg trucks.

AAR Type A Truck
AAR Type A on flatcar Salt Lake City, UT, October 1991. Photo by Don Strack.
AAR Type A end on flatcar Salt Lake City, UT, October 1991. Photo by Don Strack.
AAR Type A Trucks for 3/4 inch scale SW1500
AAR Type A truck in 1-1/2 inch scale by MDM Locomotive Works
AAR Type A trucks in 1-1/2 inch scale by Boston Locomotive Works.

Drawings

Type B

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.

An AAR type B truck from an ALCO locomotive of A&M. Photo by Mike Condren.
AAR Type B power trucks in 1-inch scale, 4-3/4 inch gauge, by Despatch Railroad Products LLC.
Alco AAR Type B truck frames in 1-1/2 inch scale cast in ductile iron.
Alco AAR Type B truck frame cast in zinc.
AAR Type B frames cast in sections.

Drawings

EMD Radial Steer

Overview of EMD's patented Radial Steer truck.

GM HTC

Loco112 writes:

This is the same blueprint that Lee Wright used to build the incredible SD locomotive HTC trucks for his world class 7.5" gauge Electromotive diesel locomotives. Lee sold me this drawing and said; "If you ever want to build a GM SD locomotive, you will have to use this blueprint".

It has incredible details of the three-axle HTC trucks as used on the iconic locomotives of the GM SD locomotive line of the 1970's, 80's and early 90's. I believe these were first sold on the new in 1972 on the SD-40-2 and they were the trucks to have all through the SD-60's until the HTC-II arrived on the SD-70's with its steerable features, and great complexity.

GM HTC Truck

Mark C. Gregor wrote on LiveDiesel@YahooGroups.com:

Sometime in the late 1990’s, I purchased a full set of rough castings from Cannonball for the SD-HTC locomotive trucks. Included with my purchase was a very large original set of blue prints from EMD that was in excess of twelve feet in length.

Lee Wright kept my blue prints as he was going to construct a second SD-60 and needed them for reference.

Documents:

"Design Features and Performance Characteristics of the High-Traction, Three Axle Truck", ASME

Suppliers:

EMD 3 Axle HTC Truck, TuneTrains.com

References

Diesel Trucks

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