| 摘要 |
<p>An improvement for increasing the resistance of manhole cover supports to deformation is provided. The improvement consists of a succession of gussets (28, 24) pressed onto the base (18) of the keeper (14) or combination thereof. Hollow walls (230, 231) are also employed for strengthening the apparatus. Alternate embodiments include rectangular shaped covers adapted to fit rectangularly shaped manholes. Stiffeners (76) are employed to improve stiffness of a split ring manhole cover.</p> |
