Manhole cover with sound deadening ring - has U=shaped ring with unequal limbs between cover and encircling frame

摘要

The cover for a street manhole has a noise damping ring (10) positioned between the cover (1) and the encircling frame (11). The ring has holes through which pass projections (15) on the cover. The projections extend radially from the cover. The ring has a U-shaped cross-section with the U lying on its side having a short top limb (14) and a long lower limb (13). the cover has a cast section (1) whose centre (2) is filled with concrete and which has ventilation holes (3). The lower limb (13) of the resilient ring lies between the support surface (5) of the cover and the support surface (13) of the frame. The shorter upper limb (14) rests on the shoulder (7) of the cover.