change wheel

plural change wheels

1. engineeringOne of a set of wheels of different sizes and number of teeth, that may be changed or substituted for one another in machinery, to produce a different but definite rate of angular velocity in an axis, as in cutting screws, gear, etc.

   The spindle is the first factor, being the driver, and the lead screw is driven therefrom through the change wheels—the variables—which determine the number of revolutions of the latter whether the same, or slower, or faster than the spindle.

   1911, “Screw”, in Encyclopædia Britannica, 11th edition, New York, N.Y.: Encyclopædia Britannica, Inc.