To allow it to go around tighter curves, it's fairly commonplace on steam locomotives with a large number of rigidly mounted driving wheels in a single locomotive frame to have one or more pairs of driving wheels without flanges. A flangeless wheel is described as being blind. Without a flange, the wheels in question are of course no longer restricted in their sideways motion with respect to the rail.

Blind drivers are very common in ten-coupled locomotives - 0-10-0s, 2-10-0 Decapods, 2-10-2 Santa Fes, and 2-10-4 Texases. Generally, the center pair of drivers will be blind; less commonly, two or even three pairs of central drivers will be blind.

Obviously, the more pairs of drivers that are blind, the greater the forces imposed on the flanges of the others when going around a tight curve.

If one looks carefully, blind pairs of drivers can be identified in photographs, but they're normally not obvious unless you're looking for them.

The later invention of lateral motion devices, allowing some wheels/axles to move sideways in a limited manner, reduced the need for blind drivers, to the extent that while the Union Pacific's enormous 4-12-2 9000 class locomotives were built with one pair of blind drivers, they proved not to need them at all thanks to the lateral motion devices fitted, and later some were fitted with all flanged wheelsets.

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