Wheel structure and wheel mounting method

A wheel structure comprising:

• a hub including both a cup-like hub body and a side wall member for closing an opening formed in said hub body;
• a first bearing disposed on a hub body side of said wheel and a second bearing disposed on a side wall member side of said wheel for rotatably mounting said hub to an axle;
• a cylindrical inner collar fitted on said axle for maintaining said first and said second bearings spaced from each other;
• a cylindrical outer collar for surrounding said inner collar, said cylindrical outer collar is connected to both said hub body and said side wall member.

A method for mounting a wheel to an axle, said wheel having a hub which comprises a generally cup-like hub body and a side wall member for closing an opening formed in said hub body, said method comprising the following steps:

• connecting said side wall member to said hub body;
• inserting a cylindrical outer collar into said hub body through a hub body hole formed in a bottom of the hub body and abutting a tip of said outer collar against said side wall member;
• fitting a first bearing into said hub body hole;
• inserting a cylindrical inner collar into said outer collar through a side wall hole formed centrally of said side wall member and abutting a tip of said inner collar against said first bearing;
• fitting a second bearing into said side wall hole and abutting said second bearing against said inner collar;
• and
• disposing the axle so as to be fitted within said second bearing, said inner collar and said first bearing.

A method for mounting a wheel to an axle, said wheel having a hub which comprises a generally cup-like hub body and a side wall member for closing an opening formed in said hub body, said method comprising the following steps:

• connecting said hub body and said side wall member with each other while holding a cylindrical outer collar between the hub body and the side wall member;
• fitting a first bearing into a hub body hole formed in a bottom of said hub body;
• inserting a cylindrical inner collar into said outer collar through a side wall hole formed centrally of said side wall member and abutting a tip of said inner collar against a first bearing;
• fitting a second bearing into said side wall hole and abutting said second bearing against said inner collar;
• and
• disposing the axle so as to be fitted within said second bearing, said inner collar and said first bearing.