GB2245627A - Manhole cover and frame assembly - Google Patents

Abstract

A manhole cover has a projection (22) which engages a floor when the cover is removed from its frame and placed on the floor, a sealing face (21) of the cover thereby being maintained clear of the floor.

Description

Description of Invention The present invention relates to a manhole cover and frame assembly comprising a frame which defines an access opening and a cover which cooperates with the frame to close the opening, the frame and the cover having respective sealing faces which extend completely around the opening and engage each other to provide a seal between the cover and the frame. An assembly of this kind is hereinafter referred to as an assembly of the kind specified.

According to a first aspect of the invention, there is provided in or for an assembly of the kind specified a manhole cover having at its underside at least one projection for bearing on a flat floor to support the cover thereon with the sealing face spaced from the floor.

There are known manhole covers wherein the sealing face is the lowest face of the cover. If the cover is removed from the frame and is placed on a floor, the sealing face of the cover is likely to be contaminated, for example by adhesion of particles present on the floor. If the cover is replaced in the frame without being cleaned, the contaminating particles will be trapped between the sealing faces of the frame and cover. This will impair the ability of the cover and frame to provide a proper seal. At least one of the sealing faces is usually presented by a relative soft element and in this case contaminating particles are likely to become embedded in the soft element so that this element is permanently damaged.

According to a second aspect of the invention, there is provided an assembly of the kind specified wherein the cover is a cover according to the first aspect of the invention and wherein the frame incorporates a relatively soft element on which the sealing face of the frame is formed.

The frame preferably has a well to receive the projection of the cover and to retain a flowable composition and the projection preferably extends completely around the cover between the periphery of the cover and the sealing face of the cover. If the well is charged with a flowable composition and the projection is submerged or partly submerged in that composition, the flowable composition provides a further seal between the cover and the frame.

According to a third aspect of the invention, there is provided a cover in or for an assembly of the kind specified, wherein the cover comprises a subframe and a plurality of blocks, each block having a lifting formation for cooperation with detachable lifting means for lifting the cover, wherein each said block and the sub-frame have respective interfitting formations which cooperate to transfer a gravitational load on the sub-frame to the blocks during lifting of the cover by means of the lifting formations of the blocks.

Examples of assemblies of the kind specified which embody the first, second and third aspects of the present invention will now be described, with reference to the accompanying drawings, wherein: FIGURE 1 shows a partial cross section through the frame of a first assembly, FIGURE 2 shows a partial cross section through the cover and frame of the first assembly, FIGURE 3 shows a partial cross section through the frame of a second assembly and FIGURE 4 shows a partial cross section through the cover of the second assembly.

The frame of the assembly illustrated in Figures 1 and 2 of the accompanying drawings is a polygonal frame defining a polygonal access opening.

Typically, the access opening is rectangular. Figure 1 shows a cross section through one side member only of the frame, this cross section being in a plane perpendicular to the length of that side member, and Figure 2 shows a cross section in the same plane through a part of the cover.

The frame illustrated in Figure 1 is a rectangular frame defining a rectangular access opening. For use, the frame would typically be embedded in a floor, for example a concrete floor. The access opening provides access to a chamber or other cavity beneath the floor. The frame is fabricated from four rectilinear members which form respective sides of the frame. A transverse cross section through one of these members is shown at 10 in Figure 1 of the drawing.

The member 10 has a uniform transverse cross section along its entire length and the transverse cross section of the other members of the frame is the same as that of the member 10.

The frame member 10 comprises three components, namely a bar 11 which extends along the entire length of the frame member, a cap 12 which forms the uppermost part of the frame member and also extends along the entire length of that member and an elastomeric seal 13 mounted in a recess defined by the bar 11. The other frame members comprise corresponding components and the bars of the frame members are united with each other by fusion.

The cover illustrated in Figure 2 is intended to close the access opening defined by the frame of Figure 1 and has a size and shape corresponding to those of the frame so that the cover can be received in the frame to rest on the seal 13. The cover comprises a sub-frame 14 fabricated from four rectilinear members, one of which is shown in transverse cross section at 15. On an upper portion of each of these members, there is mounted a cap 16 corresponding to the cap 12 and at least one lifting block 17 is mounted on each of two of the sub-frame members, the lifting block having an upper surface which is substantially coplanar with the upper surface of the cap 16. The cover further comprises a base plate 18 which rests on the sub-frame and a filling 19 of concrete or other setable material which also has an upper surface at the same height as the upper surface of the cap 16.The filling may incorporate reinforcement and the reinforcement may rest on or be attached by fusion to an upstand 20 provided on the sub-frame.

At the underside of the sub-frame 14 there is a downwardly facing sealing face 21 which, when the cover is assembled with the frame, rests on the seal 13 at an upwardly facing surface thereof which is called herein the seal face of the seal. The seal face 21 is flat and extends completely around the cover so that a seal is provided between the cover and the frame at the sealing face 21.

As shown, the sealing face 21 is preferably formed on a downwardly projecting rib to ensure that there is a vertical clearance between parts of the bar 11 adjacent to the seal 13, on the one hand, and corresponding parts of the sub frame, on the other hand. The sub-frame also includes a projection 22 which extends downwards beyond the sealing face 21, preferably by a distance of at least 3 mm and more preferably by a distance of at least 5 mm. Since the projection 22 is incorporated in each of the four main rectilinear members of the cover, the projection surrounds the sealing face 21 entirely. Alternatively, there could be substituted for the continuous projection 22 a plurality of legs spaced from each other around the cover.

When the cover is removed from the frame and is placed on a flat floor, it rests on the floor by the projection 22 and the sealing face 21 is supported at a position well above the floor surface. Since the sealing face is surrounded by the projection 22, there is no substantial risk of particles present on the floor surface becoming adhered to the sealing face 21.

There is provided in the frame a well 23 for receiving the projection 22 with clearance when the cover is assembled with the frame. The well may be charged with a flowable sealant in which the projection 22 is partly submerged, to provide a further seal between the frame and the cover.

The lifting block 17 is provided with a known formation for cooperation with known detachable lifting means for lifting the cover. This lifting formation is at the top of the block and is therefore accessible when the cover is assembled with the frame. At respective positions spaced downwardly from the top of the lifting block, the lifting block and the sub-frame 14 are provided with respective interfitting formations arranged for cooperation to transmit to the block a gravitational load on the sub-frame during lifting of the cover by means of the lifting block. In the example illustrated, the formation 25 is an inwardly projecting rib and the formation 24 is a shoulder for engaging beneath this rib.

As shown in the drawing, a further rib may be provided on the sub-frame above the rib 25 and a rib may be provided on the lifting block for engagement beneath this further rib of the sub-frame.

The formations 24 and 25 are at the outer face of the lifting block 17 at the inwardly facing surface of the lifting block, there are provided on the lifting block and sub-frame 14 further formations for cooperation to transfer gravitational load from the sub-frame to the lifting block. These further formations comprise an outwardly projecting rib 26 on the upstand 20 and shoulders defining a channel 27 in the lifting block for receiving the rib 26. It will be noted that the lifting block fits close to the upstand 20 and close to an outer wall of the sub-frame. The lifting block is inserted into the member of the sub-frame prior to assembly of that member with other members of the subframe. The lifting block is preferably fixed in position on the sub-frame by welding or by deformation of the sub-frame and/or of the lifting block.

Known anchoring means (not shown) for anchoring the cover to the frame is provided in the region between the peripheral wall of the sub-frame, on the one hand, and the upstand 20 and projection 22, on the other hand. It will be noted that the anchoring means is spaced outwardly from the sealing faces of the cover and frame so that the anchoring means does not interfere with attainment of a proper seal between the cover and the frame. The bar 11 and the main members of the sub-frame are conveniently formed by extrusion of a metal, for example aluminium. The caps 12 and 16 also may be formed of metal by extrusion. Aluminium and brass are suitable materials for the caps.

The modified frame illustrated in Figure 3 and the modified cover of Figure 4 comprise parts corresponding to those of the frame and cover respectively shown in Figures 1 and 2. In Figures 3 and 4, such corresponding parts are identified by like reference numerals with the prefix 1. The preceding description is deemed to apply to those corresponding parts and to the frame and cover of Figures 3 and 4, except for differences hereinafter mentioned.

The sub-frame 114 shown in Figure 4 has a projection 122 which extends downwards beyond the sealing face 121 and which surrounds the sealing face entirely. This projection enters the well 123 when the cover and frame of Figures 3 and 4 are assembled together. The sub frame shown in Figure 4 comprises a further projection 130 which extends downwards beyond both the sealing face 121 and the projection 122. The projection 130 lies at the periphery of a further well defined by the sub-frame 114. The bottom of this further well is closed by the base plate 118 and the well is occupied by concrete in the completed cover.

When the cover is removed from the frame and is placed on a flat surface, the projection 130 bears on that flat surface and maintains a clearance between the sealing face 121 and the flat surface.

There are provided on the upstand 120, in addition to the outwardly projecting rib 126, a pair of inwardly projecting ribs which are spaced apart vertically. These ribs contribute to keying of the concrete infill to the sub-frame of the cover. The cover shown in Figure 4 may be fitted with a cap corresponding to the cap 16 shown in Figure 2.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (9)

CLAIMS.

1. In or for a cover and frame assembly of the kind specified, a manhole cover having at its underside at least one projection for bearing on a flat floor to support the cover thereon with the sealing face spaced from the floor.

2. A cover according to Claim 1 wherein the sealing face of the cover is formed of a relatively hard material.

3. A cover and frame assembly of the kind specified wherein the cover is a cover according to Claim 1 or Claim 2 and wherein the frame incorporates a relatively soft element on which the sealing face of the frame is formed.

4. An assembly according to Claim 3 wherein said sealing faces are spaced inwardly from a periphery of the cover and wherein releasably anchoring means for anchoring the cover to the frame is provided between the sealing faces and the periphery of the cover.

5. An assembly according to Claim 3 or Claim 4 wherein said projection extends completely around the cover between the periphery of the cover and the sealing face of the cover and wherein the frame has a well for receiving the projection and suitable for retaining a flowable composition.

6. A cover according to Claim 1 or Claim 2 or an assembly according to Claim 3, Claim 4 or Claim 5 wherein the cover comprises a sub-frame and a plurality of blocks, each block having a lifting formation for cooperation with detachable lifting means for lifting the cover, wherein each said block and the sub-frame have respective interfitting formations which cooperate to transfer gravitational load on the sub-frame to the blocks during lifting of the cover by means of the lifting formations of the blocks.

7. A cover or an assembly according to Claim 6 wherein the sub-frame includes an outer wall of the cover, a first interfitting formation of the cover is formed on the outer wall, a second interfitting formation of the cover is spaced from the outer wall and wherein the block has third and fourth interfitting formations for cooperation with the first and second interfitting formations respectively.

8. A cover and frame assembly substantially as hereindescribed with reference to the accompanying drawing.

9. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.