US Patent 7341398 Lift-assisted manhole cover

A lift-assisted manhole cover assembly with a flush surface and external pivot shaft. The cover includes a mounting tab that extends beyond the general periphery of the cover. The mounting tab may be connected to a shaft that is threadedly engaged with the frame. A spring may be mounted between the frame and the mounting tab, for example, in a sleeve, to provide a mechanical assist in lifting the cover. The sleeve may be disposed outside the manhole opening where it does not block access to the manhole opening.