Method and means for adjusting the elevation of manhole covers

Abstract

The level of a manhole cover is raised to correspond with the level of a new road surface without changing the position of a manhole frame. A ring on which a manhole cover can rest, is a position elevated with respect to its original position, is installed within a recess of the manhole frame, the ring having a rim which surrounds the manhole cover to the height of the new road surface, the ring and the rim being split and expansible within the frame to sit snugly within it.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to raising the elevation of a manhole cover when the surface of a roadway is raised.

2. Description of the Prior Art

A manhole cover is normally supported in a recess of a manhole frame in a roadway. The frame is embedded in the roadway, the road surface being laid around it approximately level with the top surface of the manhole cover. When it becomes necessary to add a new road surface to the existing one, the usual practice is to break up the road bed and the concrete in which the manhole frame is embedded, to allow the manhole frame to be raised by an amount approximately equal to the desired thickness of the new road surface layer.

SUMMARY OF THE INVENTION

According to the present invention, it is possible to raise the level of a manhole cover in accordance with the level of a new road surface without changing the position of the manhole frame. An elevating band comprising a ring, on which a manhole cover can rest, in a position elevated with respect to its original position, is installed within the recess of the manhole frame, the ring having a rim which surrounds the manhole cover to the height of the new road surface, the band being split at a single point on its periphery so that it is expansible within the frame to fit snugly within it. The thickness of the ring is chosen to substantially equal the thickness of the new road surface, thus raising the manhole cover by the desired amount.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will be described with reference to the accompanying drawings in which:

FIG. 1 is a fragmentary sectional view of a manhole cover installed on a manhole frame in a roadway;

FIG. 2 is a fragmentary sectional view with the manhole cover removed and showing the installation of a manhole elevating band, which rests within the manhole frame;

FIG. 3 is a sectional view of the manhole cover installed on the band, with a new road surface laid; and

FIG. 4 is a top view of the band installed in the manhole frame with the manhole cover removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings in greater detail, in FIG. 1, a conventional manhole frame 1 is embedded in concrete 2 covered by an asphalt road surface 3. An annular surface 4a of an internal annular lip 4 of the manhole frame 1 supports a manhole cover 5 such that the top surface of the manhole cover 5 is level with the top of the road surface 3, the cover 5 resting within an inverted frusto conical recess defined by the surface 4a and by the inner surface 9a of an upwardly extending flange 9 of the manhole frame. The upper end of the flange 9 is also level with the top of the road surface 3. This arrangement is conventional.

In FIG. 2, the manhole cover 5 has been removed and an elevating band comprising a base ring 6 has been laid on the annular surface 4a of the manhole frame 1. A rim 7, welded around the ring 6, extends upwardly beyond the top surface of the ring 6 to a level higher than the road surface 3. Bendable lugs 8, one of which is shown in FIG. 2, are welded to and extend downwardly from the ring 6 below the lip 4.

As shown in FIGS. 3 and 4, the ring 6 and the rim 7 are split at a point 11 in their curvature. Adjacent each side of the split 11, the ring 6 has inwardly projecting abutments 12, 13. A bolt 14 is threaded through the abutment 13, and is thereby supported by the ring 6, and can be advanced against the abutment 12 to widen the split 11 and expand the ring 6 and rim 7 so that the outer surface of the rim 7 is pressed against the flange 9 as shown in FIG. 3. The rim 7 is inverted frusto-conical in shape, increasing in diameter from bottom to top to conform to the shape of the flange surface 9a. The lugs 8 extending downwardly from the ring 6 are bent under the lip 4 to secure the band 6, 7 firmly to the manhole frame 1. Because the band is expansible it will accommodate the tolerances common to most municipal manhole frame castings.

In most manhole frames, the annular surface 4a is rough machined for flatness, while the flange surface 9a is not machined. The downward projection of the ring 6 relative to the rim 7 creates a gap 10 between the ring 6 and the flange 9, so that any unevenness adjacent the juncture of surfaces 4a and 9a does not affect the fit of the elevating band 6, 7 within the recess of the manhole frame.

After the ring 6 and the rim 7 are locked in position, a new road surface 14 is laid substantially level with the top of the rim 7, the height of the rim 7 above the ring 6 being equal to the thickness of the manhole cover so that the top of the latter will be flush with the surface 14 when the cover rests on the ring 6 and within the rim 7.

The present invention will be seen to provide a method of maintaining a manhole cover at an elevation substantially flush with a road surface despite a change in elevation of the road surface when a new road surface layer is added, while permitting the manhole frame to be permanently installed in the roadway and without the necessity of dislodging the manhole frame when the cover is to be elevated. The height of the flange 9 is substantially equal to the thickness of the manhole cover 5, so that, as seen in FIG. 1, the tops of both the flange 9 and the cover 5 are substantially flush with the road surface 3, as initially constructed. To elevate the cover 5 so as to be flush with the new road layer 14, the procedure is to remove the manhole cover 5 from the recess and select an elevating band having a base ring 6 of thickness approximately equal to the desired thickness of the new road surface layer 14. The rim 7 projects above the base ring 6 by a distance equal to the height of the flange 9 and the thickness of the cover 5, irrespective of the thickness of layer 14 and thus of ring 6. The band 6, 7 is laid on the surface 4a, and is expanded by means of the bolt 14 so that the rim 7 engages the surface 9a of the recess in which the band is located, and the clips 8 are bent under the lip 4. Then, the new road surface layer 14 is laid up to the rim 7, the manhole cover resting on the ring 6 within the rim 7.

The rim 7 prevents the breakdown of the asphalt surrounding it, and prevents the manhole cover 5 from being forced against the surrounding asphalt as vehicles pass over the cover 5.

In the event that it is desired to add a further road surface to surface layer 14, the manhole cover 5 can again be raised by placing a second elevating band, similar to the first band 6, 7, on the top surface of the ring 6, and expanding the second band against the rim 7 of the first band. Then a further road surface can be added, the height of the ring of the new elevating band being approximately equal to the thickness of the further road surface.

Claims

What I claim as my invention is:

1. An elevating band for supporting a manhole cover in an elevated relationship to an inverted frusto conical recess defined in a manhole frame by an internal annular lip defining a manhole opening and a flange extending upwardly from the lip, the band being split at a single point on its periphery and comprising an expansible base ring seatable on said lip, an expansible inverted frusto conical rim welded to the out periphery of the base ring and engageable on expansion with said upwardly extending flange, abutments on the base ring adjacent the split in the periphery of the band, screw means acting between said abutments to expand the band, and lugs depending from said band and bendable beneath said lip.

2. An assembly comprising a circular manhole cover and a manhole frame, the frame having an internal annular lip defining a circular manhole opening and an upwardly extending flange defining an inverted frusto conical recess above the lip to receive the manhole cover, an elevating band, split at a single point on its periphery, received in the frusto conical recess and resting on the lip, the elevating band comprising a base ring, an inverted frusto conical rim welded to the outer periphery of the base ring and extending above the flange of the manhole frame by a distance substantially equal to the thickness of the base ring, abutments on the base ring adjacent the split in the periphery of the elevating band, screw means acting between said abutment and holding said ring and said rim in expanded condition with said rim in engagement with the flange defining the frusto conical recess, the base ring having an external diameter less than the minimum diameter of the frusto conical recess, and lugs depending from the inner periphery of the base ring and bent beneath said annular lip, the manhole cover being received within said rim and resting on said base ring.

3. A method of raising the elevating of a circular manhole cover relative to a manhole frame when a new road surface layer is to be laid around it, the frame defining an inverted frusto conical recess within which the cover is received and having an annular manhole defining lip on which the cover rests, comprising the steps of removing the manhole cover, placing an annular elevating band in the inverted frusto conical recess, the elevating band being divided at a single point in its periphery and having a base ring, an inverted frusto conical rim portion welded to the base ring so that the latter extends beneath the rim, abutments on the base ring adjacent the point of division of the elevating band and lugs depending from the inner periphery of the base ring so as to pass low the manhole defining lip, the elevating device being selected so that the axial extent of the base ring and the projection of the rim portion above the manhole lip are both substantially equal to the thickness of the road surface layer to be laid, actuating a screw extending between said abutments so as to expand the inverted frusto conical rim portion into engagement with the wall of the inverted frusto conical recess, bending the depending lugs beneath the manhole defining lip, and placing the manhole cover within the rim portion of the elevating device so that it rests on the base ring.

4. An elevating band for a manhole cover, comprising an expansible base ring split at one point on its periphery and having a thickness substantially equal to the distance by which a manhole cover is to be elevated, an inverted frusto conical expansible rim split at one point on its periphery, the rim being welded around the outer periphery of the base ring so that it projects upwardly beyond the base ring for a distance substantially equal to the thickness of a manhole cover to be elevated, the base ring projecting downwardly beyond the rim, abutments projecting inwardly from the base ring adjacent the split in its periphery, means acting between said abutments to expand the split base ring and rim, and a plurality of bendable lugs depending from the inner periphery of the base ring.

5. An elevating band as claimed in claim 4, where the means for expanding the split base ring comprises a bolt extending through a threaded bore in one abutment into contact with the other abutment.