| 摘要 |
The cast iron frame has a support surface for the cover, with lower pockets for dirt buckets and segments with recesses. The walls (6) of the recesses (7) facing the pockets (4) have apertures (10). The recesses contain four projecting knobs (9), and bores (14) in damper strips (12) in the recesses engage over the knobs. All surfaces in contact with the damper strips are untreated. Bores and knobs are circular, and the bore diameter is slightly smaller than that of the knobs. |
