Manhole cover, trapdoor and grill for street use or otherwise, vertically adjustable by 70 millimetres or more, pivoting through 360 degrees with angle of inclination of +/- 4 percent or more

摘要

The subject of the invention is a manhole cover with substantial innovative aspects, including progressive adjustment (upward, downward, sloping), lightweight, explosion-proof, dielectric, with easily replaceable wearing surface. IMAGE