An axle assembly includes a spindle (12) that extends through a mounting collar (28) into the open end of the axle. A cam key (70) moves through a key hole (22) in the axle and registers with the cam slot (54) of the spindle. The cam surface (76) of the cam key (70) is reversible with the cam surface (76) engaging either the bearing surface (58) or the bearing surface (60) of the spindle, to urge the spindle into or out of the axle.