| 摘要 |
An aperture (15) is formed through the cylindrical rim (13A) of a cup-shaped bridge portion of a castor fork. The inner end of the aperture (15) opens into an annular groove which is formed in the cylindrical inner wall of the cylindrical rim (13A) opposite another annular groove (14C) which is formed in the radially outer cylindrical surface of a hollow cylindrical stem portion (14A) of a mounting component of the castor which is located within the cavity of the cup-shaped bridge portion. A row of bearing balls (16), which were inserted through the aperture (15) during assembly of the castor, are engaged with the opposed annular grooves so that the stem portion (14A) and the cylindrical rim (13A) together comprise inner and outer races of a rolling bearing assembly by which the fork is mounted for swivelling movement relative to the mounting component about the vertical axis of the bridge portion. The aperture (15) is located in an area where the bearing balls (16) are not subjected to a load as the castor is in service. |
