Automatic assembling method and apparatus for differential gear

An automatic assembling method for a differential gear, comprising steps of:

• positioning a pair of side gears opposing to each other, within a differential case along a predetermined one of three orthogonal axial directions with respect to a central portion of the differential case;
• inserting a pair of pinion gears and a pair of spherical washers into the differential case from a pair of openings formed in the differential case in another axial direction orthogonal to the predetermined one of the axial directions;
• aligning the pair of pinion gears and the pair of spherical washers at respective central axes thereof in a remaining one of said three orthogonal axial directions;
• and thereafter,
• inserting a shaft directly to shaft insertion bores formed at central axial portions of the pinion gears and the spherical washers from a shaft hole of said differential case,
• inserting an internal chuck directly into each shaft insertion bore from an inner side of the pinion gear after aligning the spherical washer outside of said pinion gear, so as to hold the pinion gear and the spherical washer as a unit;
• meshing gear teeth of the pinion gear and the side gear with each other in a vicinity of the opening of said differential case;
• and then,
• allowing the side gear to rotate and moving the internal chuck into a predetermined direction, thereby positioning the central axes of the pinion gear and the spherical washer into a predetermined axial direction.