Inside frame trucks were historically unacceptable on freight cars, because of bearing maintenance problems which the modern roller bearing eliminated. This paper is a design study showing the potential advantages of a modern inside frame truck particularly in improvements in reducing weight and maintenance requirements, and was inspired by a short wheelbase inside bearing four wheel truck that the auhor designed to replace the original single axle trucks on an updated version of the Iron Highway articulated integral train. The new truck had to be interchangeable with the original without frame or car structure: a four wheel truck in a two wheel space! The design was completed, operation simulated, and a truck built, but the development stopped, for economic reasons, prior to equipping a demonstration train. This effort, though, suggested that an AAR compatible version of that truck might be advantageous, and this paper outlines how and why such a truck might be built. The paper is divided into six sections: 1) Background in the Iron Highway; 2) Requirement dictating conversion to a 4 wheel truck; 3) Design of a 286,000lb. GRL North American freight truck; 4) Maintenance considerations; 5) Economic Considerations; and 6) an Annex describing testing by the Pennsylvania Railroad of Timken inside frame roller bearing trucks 80 years ago.

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