GB2116611A

GB2116611A - Manhole frame and cover assembly

Info

Publication number: GB2116611A
Application number: GB08205766A
Authority: GB
Inventors: Anthony Charles Elmer
Original assignee: BRICKHOUSE DUDLEY Manufacturing
Current assignee: BRICKHOUSE DUDLEY Manufacturing
Priority date: 1982-02-26
Filing date: 1982-02-26
Publication date: 1983-09-28
Also published as: GB2116611B

Abstract

A cover and frame assembly comprising a frame (11) adapted to be embedded in the ground above a manhole, sump, sewer or the like, and a cover (10) receivable by the frame (11) to close an opening afforded by the frame (11), the assembly, in use, lying in a horizontal or substantially horizontal orientation, the cover (10) comprising two cover parts (18), each cover part (18) having an edge formation (32) which, at least when the cover (10) is received in and supported solely by the frame (11), is urged into frictional engagement with a corresponding edge surface (33) of the frame (11) so that the cover (10) is inhibited from lifting from the frame (11) by virtue of said frictional engagement. <IMAGE>

Description

SPECIFICATION Improvements in or relating to cover and frame assemblies This invention relates to a cover and frame assembly hereinafter referred to as of the kind specified, comprising a frame adapted to be embedded in the ground above a manhole, sump, sewer or the like, and a cover receivable by the frame to close an opening afforded by the frame, the assembly, in use, lying in a horizontal or substantially horizontal orientation.

The cover and/or the frame may have an aperture or apertures in the side or upper surface or surfaces thereof, to permit of drainage of water through the cover and/or frame into the opening, such as where the cover comprises a grating, or may be unapertured to completely close the opening and/or be in sealing engagement with the frame, such as where the cover comprises a manhole cover.

A cover and frame assembly of the kind specified is known wherein the opening afforded by the frame is substantially square and is completely closed by a pair of heavy triangular cover parts, the frame comprising in section an L-shaped perimeter which is relatively deep to accommodate the cover part. Such an assembly has proved able to withstand the loads imposed thereon where heavy traffic passes over the assembly.

However, in order to reduce costs, it is desirable to provide a shallower lighter frame to receive lighter shallower cover parts, but such assemblies have not proved able to withstand the loads imposed thereon by heavy traffic and quickly become worn. Further, as the cover parts are lighter, there is an increased tendency for them to become worn as the movement the cover parts undergo in the frame as traffic passes over is greater than with known heavier cover parts, which movement also produces considerable noise.

Accordingly, it is an object of the present invention to provide a new or improved cover and frarne assembly of the kind specified which overcomes or reduces this problem.

According to the invention, we provide a cover and frame assembly of the kind specified comprising two cover parts, each cover part having an edge formation, the edge formation of each cover part, at least when the cover is received in and supported solely by the frame, being urged into frictional engagement with a corresponding edge surface of the frame. Thus the cover is inhibited from lifting from the frame by virtue of said frictional engagement.

The edge formation of each cover part may comprise a portion of the periphery of the cover part, and the corresponding edge surface of the frame may be provided by the inner surface of an upstanding wall of the frame.

Preferably, both said portion of the periphery of the cover part and said inner surface of the frame may be provided with a downwardly inwardly sloping surface, the surface of the frame sloping at a greater angle so as to provide a wedging action as the cover is placed in the frame.

Alternatively, said portion of the periphery of the cover part slopes downwardly and inwardly or is vertical and the inner surface of the upstanding wall is vertical or slopes downwardly inwardly respectively, to enable a wedging action to be achieved.

In either case, to remove the cover from the frame, it is merely necessary to lift the cover parts upwardly to release said frictional engagement and accordingly lifting formations such as conventional key-hole apertures may be provided in or on the cover parts.

Preferably, the cover parts have sides which lie adjacent one another, in use, and the lifting formations may be provided adjacent said sides.

Accordingly, as the cover parts are lifted, they become separated under gravity thereby facilitating release of said frictional engagement, this is known as "hogging". If required, prising slots may be provided between the cover parts and the frame to further facilitate removing the cover parts.

If desired, the cover parts may be loosely connected together, for example by bolts which extend between ribs provided on the underside of each cover part, so that as the cover parts are lifted upwardly the adjacent sides of the covers are drawn into engagement, and the cover parts relatively inclined under gravity thereby releasing said frictional engagement of the edge formation of the cover parts and the edge surfaces of the frame.

In a preferred embodiment, the frame affords a substantially rectangular opening, and each of the cover parts are triangular in plan view, and the edge formations of each cover part may be provided at the right angled vertex of each triangular part and the adjacent sides may comprise the hypotenuse of each cover part.

Where lifting formations are provided, these may be positioned nearer the hypotenuse than the centre of gravity of each cover part to encourage hogging.

Further, where prising slots are provided, these may also be located adjacent the vertices of the sides and hypotenuse of each cover part.

The frame may provide seatings in each corner thereof which extend inwardly of the opening, on which seatings corresponding bearing formations at each vertex of the cover parts are supported in use. The seatings may be of inverted V-shape as seen in elevation, providing two relatively inclined bearing surfaces intersecting along a line directed generally towards the centre of the opening of the frame.

The bearing formations of the cover parts may be parallel to the associated bearing surface of the frame, so that when the cover parts are received in the frame, they are urged away from one another to increase the frictional engagement between the edge formations of the cover parts and the edge surfaces of the frame.

Preferably, the bearing surfaces of the frame are inclined to the horizontal at an angle in the range to for example 300, although other angles are possible.

The invention will now be described in more detail, with reference to the accompanying drawings, wherein: FIGURE 1 is a plan view of a cover and frame assembly in accordance with the invention; FIGURE 2 is a section on the line Il-I I; FIGURE 3 is a section similar to that shown in Figure 2, showing the cover parts in a lifted position; FIGURE 4 is a section on the line IV-lV of Figure 1.

Referring to the drawings, a cover and frame assembly comprises a manhole cover 10 adapted to be received in a frame 11 to completely close an opening 11 a afforded thereby, which assembly is generally square as seen in plan view and formed as a casting in ductile iron although other materials and method of fabrication are possible.

As can be seen from Figures 2 to 4, the four sides of the square frame are each of L-shape in cross-section including an upstanding wall 12 the top of which, when the frame is placed in position in a roadway, is flush with the surface of the roadway and a flange 13, which extends outwardly from the wall 1 2. Between the upstanding wall 12 and the flange 1 3 a plurality of L-shaped strengthening portions 14 are provided which serve to brace the wall 12 and flange 13 relatively perpendicular to each other.

At each of the four corners of the square frame, a seating 1 5 is provided on which the cover 10 is supported, each seating 1 5 extending inwardly towards the centre of the frame from a position spaced well below the upper edge of the upstanding wall 12.

Each seating 1 5 is of prism shaped formation, as best shown in Figures 2 to 4, and when viewed in elevation is of inverted V-shape, the apex 1 6 of the V being defined by two bearing surfaces 17 each of which faces generally upwardly when the frame is in its horizontal position. The two bearing surfaces 17 intersect along a horizontal straight line which is directed generally towards the centre of the square frame from the corner thereof. Each inclined bearing surface is inclined to the horizontal, in the example shown, approximately 300 although other angles are possible, but preferably in the range 100 to 350.

The cover 10 comprises a pair of triangular cover parts 1 8 each having a patterned planar upper surface 1 8a when received in and supported solely by the frame 11 as shown in Figure 2. The parts 1 8 are each of right angled isosceles configuration as seen in plan view, and each is made as a casting in ductile iron, although again other methods of fabrication may be used.

Each cover part 1 8 incorporates a plurality of ribs 1 9 on the undersides thereof, the ribs 1 9 serving to strengthen the cover without having to make the cover heavy.

The cover parts 1 8 are loosely connected together by one or more bolts 30 as shown in Figures 2 and 3, which bolts 30 extend between ribs 1 9 which lie along the adjacent sides of the cover parts and have apertures 31 therein, through which the bolts 30 extend.

At the right angled vertex 20 of each cover part 1 8 on the underside thereof, there is provided a downwardly depending bearing formation 21 having two relatively inclined lower surfaces 22 which face generally downwards on an underside of the bearing formation 21 and are parallel to the bearing surfaces 1 7 of the seatings 15 of the frame. As seen in elevation in Figure 4, each bearing formation 21 has an underside of inverted V-shape, the apex 23 of the V lying at the intersection of the two above mentioned lower surfaces 22.

At each of the non-right angled vertices 24 of each triangular cover part 18, there is provided a downwardly depending bearing formation 25 having a single generally downwardly facing sloping lower surface 26 inclined at an angle of approximately 300 to the horizontal, which surface 26 is adapted to co-operate with one of the two generally upwardly facing bearing surfaces 1 7 of the prism-shaped seating 1 5 at the corresponding corner of the frame.

Thus when each triangular cover part 1 8 is placed in position within the square frame, the bearing formation 21 at the right angled vertex 20 co-operates with two bearing surfaces 1 7 of one of the prism shaped seatings 1 5 provided on the frame, while each of the bearing formations 25 at the other vertices 24 of the cover part 1 8 co-operate with only one surface of the prism shaped seating 1 5 by each adjacent corner of the square frame.

Thus the cover parts 18 are urged away from one another when received in the frame.

Referring now particularly to Figures 2 and 3, each cover part 1 8 has, at a portion of a periphery of the cover part adjacent the right angled vertex thereof, an edge formation 32 which slopes slightly downwardly inwardly of the cover part 1 8.

Further, the upstanding wall 1 2 of the frame has provided in the corresponding region an edge surface 33 which also slopes downwardly and inwardly but at a greater angle.

Thus, as each cover part is received in the frame, due to the inclined seatings the cover parts are urged away from one another to bring the edge formation 32 into frictional engagement with the edge surface 33 of the frame, thereby to inhibiting lifting of the cover from the frame.

The peripheral parts of each cover part 1 8 which lie along the hypotenuse 34 of each cover part lie adjacent to but separated slightly from one another.

However, when it is desired to remove the cover parts 1 8 from the frame 11 , the cover parts are lifted using conventional T-shaped lifting keys (not shown) which engage lifting formations 35 adjacent the hypotenuse 34 of the cover parts 1 8 to thereby bring the adjacent sides of each triangular cover part 1 8 into engagement and to release the frictional engagement between the edge formation 32 of the cover parts and the edge surfaces 33 of the frame.

It has been found that it is possible to make the frame and cover parts shallower than previously, and of a lighter ductile iron material compared to the conventional cast iron because the frictional engagement between the frame and cover parts inhibits lifting of the cover from the frame even when heavy traffic passes over, whereas in previous arrangements where there has been no such frictional engagement, and it has been necessary to rely solely on the weight of the cover to prevent lifting.

It will be appreciated that the manhole cover described above is given by way of example only and that a cover and frame assembly in accordance with this invention may alternatively be rectangular, triangular or any other suitable shape and may be provided with more than two cover parts if desired. Further, the cover parts and/or frame may be apertured to permit drainage or a sealing means may be provided between the cover and the frame if required.

Claims

1. A cover and frame assembly of the kind specified comprising two cover parts, each cover part having an edge formation, the edge formation of each cover part, at least when the cover is received in and supported solely by the frame, being urged into frictional engagement with a corresponding edge surface of the frame.

2. An assembly according to Claim 1 wherein the edge formation of each cover part comprises a portion of the periphery of the cover part.

3. An assembly according to Claim 1 or Claim 2 wherein the corresponding edge surface of the frame is provided by the inner surface of an upstanding wall of the frame.

4. An assembly according to Claim 2 or Claim 3 wherein both said portion of the periphery of the cover part and said inner surface of the frame are provided with a downwardly inwardly sloping surface, the surface of the frame sloping at a greater angle so as to provide a wedging action as the cover is placed in the frame.

5. An assembly according to Claim 2 or Claim 3 wherein said portion of the periphery of the cover part slopes downwardly and inwardly or is vertical and the inner surface of the upstanding wall is vertical or slopes downwardly inwardly respectively, to enable a wedging action to be achieved.

6. An assembly according to Claim 5 wherein lifting formations are provided in or on the cover parts.

7. An assembly according to any one of the preceding claims wherein the cover parts have sides which lie adjacent one another, in use.

8. An assembly according to Claim 7 where appendant to Claim 6 wherein the lifting formations are provided adjacent said sides.

9. An assembly according to Claim 7 or Claim 8 wherein prising slots are provided between the cover parts and the frame to further facilitate removing the cover parts.

10. An assembly according to any one of Claims 7 to 9 wherein the cover parts are loosely connected together.

11. An assembly according to Claim 10 wherein said connection is achieved by bolts which extend between ribs provided on the underside of each cover part.

12. An assembly according to any one of the preceding claims wherein the frame affords a substantially rectangular opening, and each of the cover parts are triangular in plan view.

1 3. An assembly according to Claim 12 wherein the edge formations of each cover part are provided at the right angled vertex of each triangular part and the hypotenuse of each cover part lie adjacent one another.

14. An assembly according to Claim 13 wherein the seatings are of inverted V-shape as seen in elevation, providing two relatively inclined bearing surfaces intersecting along a line directed generally towards the centre of the opening of the frame.

1 5. An assembly according to Claim 14 wherein the bearing formations of the cover parts are parallel to the associated bearing surface of the frame, so that when the cover parts are received in the frame, they are urged away from one another to increase the frictional engagement between the edge formations of the cover parts and the edge surfaces of the frame.

1 6. An assembly according to Claim 14 or Claim 1 5 wherein the bearing surfaces of the frame are inclined to the horizontal.

1 7. An assembly according to Claim 1 6 wherein the bearing surfaces are inclined at about 30".

1 8. A cover and frame assembly substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

1 9. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.

14. An assembly according to Claim 12 or Claim 1 3 where appendant to Claim 6 wherein lifting formations are positioned nearer the hypotenuse than the centre of gravity of each cover part.

1 5. An assembly according to any one of Claims 12 to 14 where appendant to Claim 9 wherein prising slots are located adjacent the vertices of the sides and hypotenuse of each cover part.

16. An assembly according to any one of Claims 12 to 1 5 wherein the frame provides seatings in each corner thereof which extend inwardly of the opening, on which seatings corresponding bearing formations at each vertex of the cover parts are supported in use.

1 7. An assembly according to Claim 16 wherein the seatings are of inverted V-shape as seen in elevation, providing two relatively inclined bearing surfaces intersecting along a line directed generally towards the centre of the opening of the frame.

1 8. An assembly according to Claim 1 7 wherein the bearing formations of the cover parts are parallel to the associated bearing surface of the frame, so that when the cover parts are received in the frame, they are urged away from one another to increase the frictional engagement between the edge formations of the cover parts and the edge surfaces of the frame.

19. An assembly according to Claim 1 7 or Claim 1 8 wherein the bearing surfaces of the frame are inclined to the horizontal.

20. An assembly according to Claim 1 9 wherein the bearing surfaces are inclined at about 300.

21. A cover and frame assembly substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

22. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.

New claims or amendments to claims filed on 12 May 1983 Superseded claims 1-22 New or amended claims:

1. A cover and frame assembly of the kind specified comprising two cover parts loosely connected together, each cover part having an edge formation which, at least when the cover is received in and supported solely by the frame, is urged into frictional engagement with a corresponding edge surface of the frame, both cover parts having sides which lie adjacent one another in use, lifting formations being provided adjacent said sides, said sides being drawn together as the cover parts are lifted, using the lifting formations, thereby releasing each edge Formation from frictional engagement with the corresponding edge surface of the frame and facilitating removal of the cover from the frame.

6. An assembly according to any one of the preceding claims wherein said lifting formations are provided in or on the cover parts.

7. An assembly according to any one of the preceding claims wherein prising slots are provided between the cover parts and the frame to further facilitate removing the cover parts.

8. An assembly according to any one of the preceding claims wherein said loose connection is achieved by bolts which extend between ribs provided on the underside of each cover part.

9. An assembly according to any one of the preceding claims wherein the frame affords a substantially rectangular opening, and each of the cover parts are triangular in plan view.

10. An assembly according to Claim 9 wherein the edge formations of each cover part are provided at the right angled vertex of each triangular part and the hypotenuse of each cover part lie adjacent one another.

11. An assembly according to Claim 10 wherein said lifting formations are positioned nearer the hypotenuse than the centre of gravity of each cover part.

12. An assembly according to Claim 10 or Claim 11 wherein prising slots are located adjacent the vertices of the sides and hypotenuse of each cover part.

13. An assembly according to any one of Claims 9 to 1 2 wherein the frame provides seatings in each corner thereof which extend inwardly of the opening, on which seatings corresponding bearing formations at each vertex of the cover parts are supported in use.