Method and apparatus for locking a manhole cover

Abstract

A manhole cover lock includes a lock body which is mounted to the cover and a lock arm mounted for rotation relative to the lock body. The lock arm is mounted to a pin which is positioned in a passage through the lock body. The pin has a specially shaped head for engagement by a special tool. A nut is threaded onto a bottom end of the lock body at a bottom side of the cover. The lock arm can be rotated with the pin from an unlocked position to a locked position, the arm in the locked position rotated under or into engagement with a support or other structure which underlies the manhole cover. The lock arm is retained in its locked position by being biased upwardly to a position where tabs on the lock arm fit into a slot in the lock body.

Description

FIELD OF THE INVENTION [0001] The present invention relates to methods and devices for locking manhole covers to prevent their removal. BACKGROUND OF THE INVENTION [0002] Manhole covers are utilized for a variety of purposes. Often, access points to sewers and underground utilities are provided via passages leading to the surface of the earth. It is desirable to close those passages when they are not in use in order to prevent people, animals and the like from falling into the passages. [0003] Manhole covers are frequently used for this purpose. Manhole covers are typically iron or steel plates which are located over the access hole or passage. FIG. 1 illustrates one example of a manhole cover. The particular manhole cover which is illustrated is generally circular in shape and has opposing top and bottom sides. The top side may display ornamentation, such as one or more designs, to make it aesthetically pleasing. In addition, one or more small holes or depressions may be located in...

AI Technical Summary

Benefits of technology

[0013] In one embodiment, the lock body is secured to the manhole cover to prevent its removal therefrom and its rotation relative thereto. In one embodiment, a nut is threaded onto the bottom end of the lock body at the bottom side of the manhole cover, thus preventing removal of the lock body from the top of the manhole cover. A pin is preferably placed into the cap of the lock body and into engagement with the manhole cover at the top side thereof in order to prevent rotation of the lock body relative to the manhole cover.

Problems solved by technology

Unfortunately, because the manhole cover is maintained in position by gravity only, manhole covers are often undesirably removed.

For example, a vehicle passing over a manhole cover may cause the cover to spring upward off of its frame, thus partially or entirely uncovering the opening O. In the case of sewers, excessive fluid flow, such as in the event of a thunderstorm with significant precipitation, may cause the manhole cover to be lifted out of position.

In addition, manhole covers are often stolen for their value in metal.

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