There was a post some time ago explaining these. How and what steers? Does each axle of the set of three have the ability to pivot just a bit? Thanks
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The ideal truck is one that has the axles parallel on straight track and radial on curved track. A radial axle is an axle whose center line is pointed at the center point of the curve. To do this the axles have to come out of parallel on a curve. The ideal radial truck uses linkage to the car body to force the axles into their radial position. This arrangement is complicated, heavy and expensive. Wheels with the proper geometry will naturally try to assume a radial position. There are trucks designed to passively allow the axles to assume a redial position. This is done with links on the truck frame and rubber chevron suspension elements to allow the axles to move independent of each other. A locomotive with radial trucks will produce less wheel and rail wear and use less fuel.
I assume a truck that allows individual wheel sets to "follow" the rails with less contact resistance; instead of fighting the shape of a given section rail - i.e. curves.
I imagine 3 axle trucks(trucks with 3 axles and 6 wheels) that are long and rigid... they would create significant surface friction/tension, when the rails/track, the trucks were following, started to curve... when the track wasn't dead straight, anymore.
Rick
Go to this link, many illustrations that show how it works. This is the patent for it.
