MANHOLE COVER LOCKING DEVICE Russian patent published in 1997 - IPC

FIELD: manholes in municipal services and other branches of industry. SUBSTANCE: locking device is made in the form of disk-type lower cover with bottom and edge bent outside for a rubber gasket to be pulled over. Located on bottom are two diametrically opposite eye-lugs. One eye-lug is in the form of a catch sliding in its lodgement under bottom due to opening provided in bottom. Other eye-lug is stationary. Lower cover and upper cover are installed on one internal circular protrusion in manhole case. First, lower cover is installed and locked, then upper cover is installed upon it in following succession of operations: lower cover is taken by hand grips and inclined with its stationary eye-lug facing downwards, cover is moved upon internal circular protrusion, its lifted end is lowered down and cover is seated upon circular protrusion. Movable eye-lug is pushed below circular protrusion and locked. Finally upper cover is installed upon. EFFECT: high efficiency. 3 cl, 3 dwg