Abstract: The apparatus for measuring the parameters of an axle gear includes an attachment mechanism for providing a surface parallel to the gear axis and positioned at a distance equal to the base circle radius from the gear axis. A displacement measuring device is positioned with the flat lower surface in contact with the attachment mechanism surface. Extending from the side of displacement measuring device is a probe, the probe positioned to be in the same plane as the flat lower surface and extending parallel to the axis of the gear. The probe of the displacement measuring device is placed in contact with a surface of a gear tooth and the displacement device is rotated without slipping on the attachment mechanism surface. When the displacement measuring device is rotated, the probe will be displaced only within preselected limits when in contact with a gear tooth surface between the top of the tooth and the root of the tooth for an acceptable gear.

Abstract: Apparatus for measuring departures from specified parameters for involute type gears and pinions is described. Wheels having a radius of the gear base circle are coupled to the axis of the gears. The base circle radius wheels travel along parallel tracks as the gear/wheel assembly is rotated. To measure the departure of a gear tooth contour from an ideal profile, a probe is forced against the tooth surface on a line tangent to the base circle radius. By definition of an involute gear or pinion, travel of the gear on the base circle results in the tooth profile passing through a point fixed in space on the line tangent to the base circle. By placing the probe in contact with the gear tooth surface on the base circle tangent line, the tooth contour will pass through the point. The probe therefore can determine departures from an ideal tooth profile by displacement of the probe during the travel of the gear/wheel assembly.