Hub unit bearing apparatus with improved pre-loading arrangement

A hub unit bearing apparatus comprising:

• a shaft (1) of a constant velocity joint having a first enlarged diameter portion (2), a first reduced diameter portion (3) and a first stepped portion (4) connecting said first enlarged and reduced diameter portions to each other;
• a first male threaded portion (27) formed on an outer peripheral surface of an outer end of said first reduced diameter portion;
• a cylindrical hub (7) having an outer peripheral surface on which a first flange (10) for supporting a vehicle wheel is formed;
• a first inner race track (13) directly formed on an outer peripheral surface of a second enlarged diameter portion (12) of said hub at an intermediate portion thereof;
• an inner race (15) fitted on an outer peripheral surface of a second reduced diameter portion (14) of said hub at an inner end thereof;
• a second inner race track (16) formed on an outer peripheral surface of said inner race;
• a second male threaded portion (28) formed on the outer peripheral surface of said hub at the inner end thereof;
• a first nut (29) threaded on said second male threaded portion to sandwich said inner race between said first nut and a second stepped portion (17) formed between said second enlarged and reduced diameter portions, and having an inner, end face protruding inwardly more than an said inner end face of said hub;
• an outer race (26) having an inner peripheral surface on which a pair of outer race tracks (20) are formed in confronting relation to said first and second inner race tracks and an outer peripheral surface on which a second flange (22) for supporting said outer race by a suspension system is formed;
• and
• a second nut (30) threaded on said first male threaded portion to sandwich and secure said first nut, inner race and said hub between said second nut and said first stepped portion.