All Nation AAR Type B Truck KIT UNASSEMBLED 40″ Wheels (Single) (minus brake cylinders) PN#445ANK


This item is a KIT (Brake Cylinder not included).  Assembled photo is for example only and not included in this sale.

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For Sale:  All Nation AAR Type B Truck KIT UNASSEMBLED 40″ Wheels (Single) (minus brake cylinders) PN#445ANK

This item is a KIT that does not include the Brake Cylinders.  Assembled photos are for example only and not included in this sale.

The well known AAR Type A truck used on railroad locomotives was patented by Martin P. Blomberg of Hinsdale, Illinois assigned to General Motors Corporation. Working with General Steel Corporation other patents followed. The design was for a railway locomotive truck and of course found on many model railroad layouts under switcher engines. The Type B variant was for road engines and a little research indicates the prototype had GE or Westinghouse traction motors. Oddly enough, EMD opted not to use this truck design, instead went with their own Blomberg model.

This project was on my bucket list for a long time so after developing the Type A truck for my model engines, I had the desire to put the Type B under several engines such as a GE U-Boat, GP30 and RS11. Currently, we are testing this on our non-powered engines and later with our power truck transmission drives.

We believe the kit will be fun to build because it will not be a static model, rather a fully sprung operational and functioning component under your engines. Assembling the kit does not require a high degree of skill or modeling experience, only following a fairly straight forward procedure.

The plastic parts in this kit are not resin printed. Developed in the CAD program, all parts are engineered for FDM printing using high grade polymer blends. Hours of prints and reprints to test the plastics, the recent introduction of a Poly Carbonate ABS blend solved a number of problems. The ABS gave us the right combination for details and the Poly Carbonate the strength and reduced friction of moving parts. The parts drill and tap nicely compared to other available filaments. The leaf springs and the sway bars are printed using TPU 98A. The reason for the TPU, the properties have a slightly more rubbery flexibility with strength such that it allows the frame to flex in multiple directions whereas a solid sway bar or leaf spring makes for an entirely rigid frame. Thus, as one may have noticed a resin printing of parts or even brass castings would not give us the realistic suspension action we wanted to achieve as with the prototype adhesion to the rail head was designed into the truck. This truck was a swing bolster version that was equalized by keeping the weight even on each wheel, even when operating on uneven track. While the coil springs were the primary dampeners, the leaf springs came as secondary cushions.

Assembly Instructions do not come with this AAR Type B kit. But we have a video to advise and suggest the best way to go about building the kit right the first time.

Parts List:

AAR Truck Type B Parts List

2 Side Frames

4 Journals

8 Coil Springs

4 Coil Spring bottom pads

2 Leaf Spring Assemblies TPU 98A

1 Bolster

4 4-40 x 3/8” Fillister Head Bolster Screws to mount leaf spring assembly to side frames

4 2-56″ x 3/16″ Flat Head Bolster Screws

8 0-90 x 1/4″ Hex machine screws for brake adjuster mounting

4 0-90 x 5/16″ Hex machine screws for

4 Clasp Air Brake

4 Brake Adjusters

4 Axle Ball Bearings

4 Roller Bearing Journal Covers

2 Sway Bar End Frames TPU 98A

Tools Required:

0-90 Hex Wrench

Screw Driver

CA Glue

Medium File

0-90 Tap and #60 Drill Bit

2-56 Tap and #50 plus #42 Drill Bits,tap & clearance, respectively

4-40 Tap and #43

We suggest before doing any assembly to layout all the parts and become familiar with them. Inspect all the 3D printed parts  and remove any excess plastic from parts such as support material, threads etc. and file them smooth. Check that the journals slide freely in the side frames and if necessary smooth or polish surfaces with a light touch of the file.

While this truck kit is intended for non-powered engines, it can be converted later by removing the wheel sets and installing our transmissions.



Made in the USA