| 摘要 |
To support the stair treads (15) two rings (11) are joined to form a double ring (12), one ring acting as double ring bearing and the second ring to take the tread. The rings are joined by web (13) or screw bolt and the ring of one pair (12) supporting the ring of the adjoining double ring has an abutment (17) below for the standing bolt (16) of the tread and is designed (17) as a cover (17) complete with hole for the bolt. |
