Differential gear mechanism and improved axle retention arrangement therefor

A differential gear mechanism ( 11 ) and improved axle shaft ( 53 ) retention arrangement for the axle shaft. The mechanism includes a side gear ( 27 ) defining first internal splines, a coupling ( 35 ) defining second internal splines ( 35 S), and a rotor ( 49 ) of a gerotor pump defining third internal splines ( 49 S). The axle shaft includes external splines ( 55 ), an annular groove ( 57 ), and a collapsible and expandable retention ring ( 59 ) within the groove. The assembly operator aligns the external splines with the third internal splines ( 49 S), then with the second internal splines ( 35 S), and finally, with the first internal splines ( 27 S), before exerting force ("F" in FIG. 3 ) on the axle shaft to collapse the retention ring by passing it through the third internal splines ( 49 S) until the ring can expand (FIG. 4 ). The axle shaft is retained as the retention ring engages an inboard end ( 69 ) of the third internal splines.