A journal following the history, design, construction and operation of Bernard Kempinski's O Scale model railroad depicting the U. S. Military Railroad (USMRR) Aquia-Falmouth line in 1863, and other model railroad projects.
©Bernard Kempinski All text and images, except as noted, on this blog are copyrighted by the author and may not be used without permission.

December 8, 2009

New Wooden Truck Design

I spent the weekend working on a new design for wooden rigid beam trucks for my freight cars.

The first wooden truck I developed just didn't look right to me. They were a tad chunky using 1/8th inch wood and the design actually caused the freight cars to ride too high. The photo at the left shows the new design on the left and the old design on the right.

The new design is based on a NY&H RR truck. The wheelbase is the same, but the parts are made using 3/32nd basswood. By omitting the delrin bearings, I was able to make the truck narrower.

It is difficult to model these cars to prototype dimensions because a standard gauge O scale wheel set has gauge that is .062 inches too wide, and has wheel tread and flange height that are bigger than scale. Once you modify one dimesion to accommodate the over scale wheels, the dimensions of the rest of the truck design must be adjusted to maintain clearance. It took seven iterations of design, laser cut, build and test before I settled on the final design.

I also modified the journals. The new design does not use a delrin bearing. The metal axle point rides in an appropriate hole in the journal. With a touch of Wahl Clipper oil, the wheels roll very freely. So just like real railroad trucks, these journals need to be oiled. I made the journals on one side of the truck as separate pieces, so the truck is easier to assemble. Now you first assemble the frame, then install the axles without having to force the axle into the frame.

I did not add working brakes to this car. I am thinking about etching parts for the brakes. Each truck has 32 NBWs!

This new flat car is also sporting the new photo etched link and pin couplers. They are a fold-up design using etched stainless steel. They are quite sturdy and will show shiny metal when the facing surfaces wear.

I also tried making white lettering decals on my laser. They actually worked out. They look great as there is no clear film associated with each letter.


  1. HOW did you do white decals on a laser printer???

  2. Lemme guess, Laser + White = Pulsar Decal pro FX?

  3. Not that complicated. I'll post more later, once I try it on different designs.

  4. Source of drawings for these trucks? I need to build something in 3/4" scale.


    1. I believe they were a NY and Harlem design. I found them in a late 19th century book on google docs. I will see if I can find the scans.