Method and apparatus for checking a gear

Apparatus for checking a sample gear having a central axis, said apparatus comprising means for holding said gear in a stationary position in a checking station, a support, a head mounted on said support to rotate about an axis alined axially with the axis of said gear, a carriage mounted on said head to rotate therewith and to move back and forth on said head along a path extending perpendicular to the rotational axis thereof, a master gear mounted on said carriage to rotate about an axis extending parallel to and offset radially from the axis of said sample gear, means for turning said head about its rotational axis to cause said master gear to orbit around said sample gear, means for shifting said carriage on said head in a direction to bring said master gear into engagement with said sample gear, means for indicating the radial distance between the axes of said gears during rotation of said head and as said master gear orbits and rolls around said sample gear, and means for shifting said carriage on said head in a direction to retract said master gear out of engagement with said sample gear.

A method of checking a sample gear having a central axis, said method comprising the steps of, holding said gear in a rotationally stationary position, orbiting a carriage means mounting a rotatable master gear around the axis of said sample gear, moving said master gear radially into engagement with said sample gear, holding said master gear in rolling engagement with said sample gear but allowing said master gear to shift radially relative to said sample gear while said master gear orbits around said sample gear, and detecting the radial displacement of said master gear as the latter orbits and rolls around said stationary gear.