| 摘要 |
A roller shell (23) has a first circular cylinder section (231) and a second circular cylinder section (232). The outer diameter of the first circular cylinder section (231) is greater than that of the second circular cylinder section (232), and the inner diameter of the first circular cylinder section (231) is smaller than that of the second circular cylinder section (232). The first circular cylinder section (231) is fitted to a bush small-diameter section (22C), and the second circular cylinder section (232) is fitted to a bush large-diameter section (22D). The second circular cylinder section (232) has a slit (23E) extending through the outer peripheral surface and inner peripheral surface of the second circular cylinder section (232) and opening at an end surface (23F). The roller shell (23) is engaged with a stepped section (22E). An engagement member (33) is fitted in a groove (22F) and is engaged with the slit (23E). A retainer (24) is formed in an annular shape, is removably attached to a bush (22), and holds down an end surface of the roller shell (23). |
