U.S. Patent Number 8,246,096 – Differential action railroad car axle assembly
Every Tuesday, the United States Patent and Trademark Office publishes newly granted patents. This blog post is part of a weekly series in which I pick an interesting new patent that has Idaho connections and briefly describe it.
Inventors: Thomas W. Blasingame (Boise, ID), Robert E. Hord (Richmond, VA)
According to this week’s featured patent, railroad axles are usually one piece and therefore the wheels are fixed to each other in rotation. This arrangement causes problems when the railcar goes around a corner, because the outside wheel wants to turn faster. The traditional fix for this problem is a tapered wheel that is commonly seen on railcars. However, this solution is not effective “enough to fully accommodate the adverse action of the rigid mounting,” and so the track gets worn down.
Another seemingly-obvious solution, separately-rotating wheels (such as by the use of mechanical differentials), is problematic because electrical continuity must be maintained between the two rails for signaling systems. Even metallic bearings in a mechanical differential degrade electrical signals.
The device in the featured patent allows electrical continuity between the two wheels across an axle while providing independent rotation of the wheels with respect to each other. Another advantage of this device is that it has low maintenance needs (no more than conventional railroad wheels).