Self-locking self-adjustment manhole cover

Pressure-bearing:210KN-600KN (It is professional to press Europe ) EN124 standard and 97S5012 standard) Material:Nodular cast iron Characteristic:It is not straight that the special design of well frame makes well frame fall down to seat on well, but conduct is a road surface Part may bear the most of pressures on well cover by roadbed therefore. Under the role of external pressure, well frame can follow road surface , ascend and descend makes it and road surface keep all along on same level. Design pressure spring lock may prevent that well cover pulsates; Shockproof washer may prevent that well cover shakes and avoids noise Applicable place (for certain activities) :Expressway and city trunk road , national highway: Wait for circular well