Dual rate bias spring for antibacklashing gears

Abstract

An improved mechanism is provided for biasing a driven gear in a gear train of the variable center distance type in which the driven gear is meshed with a drive gear and rotates about an axis which is not fixed, at least radially, relative to the axis of the drive gear. The biasing mechanism includes spring means engaged with the driven gear for biasing the same substantially radially toward the driven gear into mesh therewith at a force which provides appropriate relatively low-level engagement forces between the meshed gear teeth. A stop is provided for limiting deflection of the spring means in a direction corresponding to unmeshing of the drive and driven gears. The stop is positioned to limit such deflection of the spring means to an amount less than the deflection required for unmeshing of the gears. The mechanism has first and second spring rates defined, for separate first and second operating regions thereof, so that the maximum bias force developed by the spring means in the first operating region of the mechanism is substantially at the threshold of the second region and corresponds substantially to the desired meshing force of the driven gear with the drive gear. The threshold of the second region corresponds to engagement of the spring means with the stop. The minimum force developed by the mechanism on the driven gear when the mechanism is operating in its second region is at least ten times greater than the maximum force developed thereby when operating in its first region.

Dependencies are inferred from the claim text.