Handling: hand and hoist-line implements – Hand bars and hand barrows – Cant hook type
Reexamination Certificate
2001-03-19
2002-08-27
Lillis, Eileen D. (Department: 3652)
Handling: hand and hoist-line implements
Hand bars and hand barrows
Cant hook type
C294S034000, C254S131000
Reexamination Certificate
active
06439628
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a tool for removing the cover from a manhole and, more particularly, to a tool which locks onto the periphery of a manhole cover and includes a lifting arm for safety removing the cover.
BACKGROUND OF THE INVENTION
Manhole covers, although particularly well-known with regard to sewer systems, are also used in association with a variety of different types of in-ground installations, for example, water, electric, cable, telephone, water main supply valves, transformers, and the like. To gain access to the equipment/installation underneath the ground, one must first lift and then remove the manhole cover. The covers most generally are fabricated from cast iron or reinforced concrete and as a result are heavy and difficult to maneuver, most weighing over 150 pounds. Conventional manhole covers generally have at least two holes near to the outer circumferential edge of the cover for use in removing the cover from the entrance hole. In position, the cover is seated in a cover support ring situated such that the cover and the ring are substantially in the plane of the surrounding surface, such as that of the road or sidewalk surface.
The technique generally used in the prior art for lifting a manhole cover is to use a crow bar, trap hook, or similar rod-like tool that is inserted in one of the circumferential edge holes. The crow bar is then used to pry a portion of the cover away from the opening, where an individual then grabs the cover, lifts and rolls the cover out of the way. In most cases, very little control over the movement of the cover can be maintained and, furthermore, there is always the chance that the cover may drop off the tool and injure the operator, for example, by falling on his legs or feet.
The prior art is replete with various tools to aid in removing manhole covers. See, for example, U.S. Pat. No. 4,076,217, “Apparatus for Lifting a Manhole Cover”; U.S. Pat. No. 4,991,893, “Manhole Cover Lifting Device”; U.S. Pat. No. 5,775,674, “Lift Apparatus Having a Pivoting Pole for Lifting and Moving a Manhole Cover”; and U.S. Pat. No. 5,788,406, “Double Pivot Semi-Automatic Manhole Cover Lifting Device”. However, in most instances, only one side of the lid is “grabbed” and can always result in the lid separating from the tool. Thus, a need remains in the prior art for an efficient, simple manhole cover removal tool that grabs more of the cover surface and reduces the chances for injury during removal.
SUMMARY OF THE INVENTION
The need remaining in the prior art is addressed by the present invention, which relates to a tool for removing the cover from a manhole and, more particularly, to a tool which locks onto the periphery of a manhole cover and includes a lifting arm for safely removing the cover.
In accordance with the present invention, a manhole cover removal tool comprises a pair of hook arms, where the hook portion of each arm engages with one of the removal openings formed on the manhole top surface. One of the arms includes a locking collar, or similar arrangement, for joining together the two arms once they are inserted in the removal openings. A lifting arm connector is formed on one of the arms and is used to provide the attachment of a separate lifting arm to the joined hook arms. A threaded connection may be used to attach the lifting arm to the joined hook arms. With the lifting arm attached, the craftperson can then lift the entire manhole cover away from the opening in one movement, using leg muscles to lift and move (instead of back muscles, which are involved in moving manhole covers when using prior art “lever arm” removal tools).
In a preferred embodiment of the present invention, the pair of hook arms is disposed in opposing hook holes (if there are more than two holes formed on the manhole cover surface) so that the perimeter of the entire manhole cover will be held secure. In one embodiment, the locking collar may be a threaded device, which is tightened until a secure attachment between the hook arms is achieved. Advantageously, the use of a threaded device accommodates for slight differences in diameter of various manholes.
Other and further advantages and arrangements of the present invention will become apparent during the course of the following discussion and by reference to the accompanying drawings.
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Eslambolchi Hossein
Huffman John Sinclair
Chin Paul T.
Koba Wendy W.
Lillis Eileen D.
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