GB2385876A

GB2385876A - Frame for manhole cover or gully grating

Info

Publication number: GB2385876A
Application number: GB0206998A
Authority: GB
Inventors: Peter Derrick Savage
Original assignee: Peter Savage Ltd
Current assignee: Peter Savage Ltd
Priority date: 2002-02-28
Filing date: 2002-03-25
Publication date: 2003-09-03
Also published as: GB0204733D0; GB0206998D0

Abstract

The frame 10 is formed with at least part of the edge 20 of the flange 16 of the frame shaped to provide secure fixing against lateral movement in suitable bedding mixture. The or each part of the edge of the flange may be shaped to increase the surface area of the edge of the flange and the frame may be shaped with corners with the shaped portions not covering the corners or alternatively the whole edge of the frame may be shaped to provide secure fixing. The or part of the edge of the flange may define at least one lateral intrusion or protrusion 26/30 and the inner portions 28 of intrusions/protrusions may be curved. The intrusions may be semicircular in plan and the protrusions may be rectangular or square in plan. The or each part of the flange may have a plurality of intrusions or protrusions which are in a regular arrangement and are all of the same general shape and size. The spacings between the intrusion or protrusions may be of the same order of width as the width of the intrusions/protrusions themselves. The edge of the flange may be upright and of a constant thickness and the edge of the flange may have a generally smooth outline to minimise stress. Also claimed are a frame for a manhole cover or gully grating in which at least one region of the flange adjoining the edge of the flange is of a reduced thickness in comparison to the main part of the flange, a frame for a manhole cover or gully grating that includes at least one upwardly facing ledge to seat at least one cover, the or each ledge covering at least 50% of the periphery of the central opening, a frame for a manhole cover or gully grating includes a continuous ledge around the entire periphery of the clear opening of the frame to seat at least one cover, a frame for a manhole cover or gully grating in which the flange includes at least one length thereof defining at least one aperture, the aperture or apertures occupying at least one third of the area of said length in plan, and a frame for a manhole cover or gully grating that is rectangular and has a flange on three or four sides, each straight section of flange defining a row of rectangular apertures.

Description

A Frame for a Manhole Cover or Gully Grating The invention relates to a frame for a manhole cover or gully grating A known frame for a manhole cover is shown in Fig. 1. The frame 10 is generally rectangular in plan and has an upright wall 12 defining a central rectangular opening 14.

The frame has a generally horizontal flange 16 extending outwardly from the lower part of the wall 12 all around the wall 12. The edge 20 of the flange 16 in the known frame 10 forms the shape of a square with rounded comers in plan, the edge 20 being plain and upright.

According to a first aspect of the invention there is provided a frame for a manhole cover or gully grating in which at least part of the edge of the flange of the frame is of a shape to provide secure fixing against lateral movement in suitable bedding material.

By means of the invention, then, the frame of a manhole cover or gully grating has an edge shape which provides improved keying to suitable bedding/fixing material acting to inhibit movement laterally under the stresses and strains resulting from traffic passing over the manhole cover or gully grating.

The or each part of the edge of the flange may be of a shape to increase the surface area of the shape of the flange.

The frame may be of any desired shape in plan, and where the frame is in a shape having comers the or each said part of the edge of the frame may not be of the comers. The greatest strength is required at the comers and so the comers may be left of known, conventional construction of which the strength is also known. In an alternative embodiment, the whole of the edge of the frame may be shaped to provide secure fixing with suitable bedding mixture against lateral movement.

The or each part of the edge of flange preferably defines at least one lateral protrusion or intrusion.

Where at least one protrusion is provided, the root of the or each protrusion may be curved. This reduces the stress concentration which would be caused by a sharp comer at the root of the protrusion. Similarly, where at least one intrusion is provided, the interior surface of the intrusion may be curved. Indeed, in one embodiment, the or each intrusion is semicircular in plan. In an alternative embodiment, the or each protrusion or intrusion may be rectangular or square in plan.

Preferably, the or each part of the edge of the flange has a plurality of lateral protrusions or intrusions. The protrusions or intrusions in each part are preferably in a regular arrangement. The protrusions or intrusions are preferably all of the same size and/or shape. The spaces between the intrusions or protrusions in one embodiment are of the same order as the width of the intrusions or protrusions themselves.

The edge of the flange is preferably upright and may be of constant thickness.

According to another aspect of the invention there is provided a frame for a manhole cover or gully grating, in which at least one region of the flange adjoining the edge of the flange is of reduced thickness in comparison with the main part of the flange.

This increases the surface area presented.

The reduced thickness may be achieved in any suitable way but in a preferred embodiment there is a step to the or each region. The step may be in the upper side of the flange but preferably is in the underside of the flange, in which case the upper surface of the or each region is preferably flush with the upper surface of the remainder of the flange. In a particularly preferred embodiment there is a single region which extends around the whole of the flange.

The aforementioned known frame has small rectangular webs across the comers of the central rectangular opening 14 to act as seatings 24 for two triangular covers 50 shown in phantom in Figure 1. As each cover rests on three of the seatings 24, it will not rock in use. Rocking creates noise in use as well as undesirable impact stresses upon the seatings. The known frame is conventionally sandcast from cast iron or ductile iron. The finish is therefore within a fairly broad tolerances. Because of the three point mounting however this is not a problem.

According to another aspect of the invention there is provided a frame for a manhole cover or gully grating, the frame including at least one upwardly facing ledge to seat at least one cover, the or each ledge occupying at least 50% of the periphery of the central clear opening.

Preferably the upwardly facing surface of the or each ledge is machined flat. In this way, there is no problem with rocking, and the frame can still be sandcast.

According to a further aspect of the invention there is provided a frame for a manhole cover or gully grating, the frame including a continuous ledge around the entire edge of the periphery of the clear opening of the frame to seat at least one cover.

The upwardly facing surface of the ledge is preferably machined flat.

According to another aspect of the invention there is provided a frame for a manhole cover or gully grating in which the flange includes at least one length thereof defining at least one aperture, the aperture or apertures occupying at least a third of the area of the said length in plan.

The aperture or apertures allow weight saving, but more importantly they provide improved keying with suitable bedding/fixing material. The bedding material, when wet, will ooze through the apertures and set providing good keying. The very high volume of the apertures aids keying and of course weight reduction.

In a preferred embodiment, the aperture or apertures occupy at least 40% of the or each said length.

The or each aperture may be of any desired shape but in a preferred embodiment is rectangular, preferably square. There may be a single aperture in each said length, but preferably there are a plurality of apertures in the or each length. The apertures may be all of the same general shape and may be all of the same general size. The apertures are preferably spaced along the length and preferably are in a single row in each length.

The apertures are preferably spaced apart by a distance less than the width of the apertures.

The frame may be of any suitable shape and may be round, but preferably is in a shape having comers and straight sections. The or each said length is preferably in a straight section. The or each length may constitute at least 50% of its respective straight section and preferably constitutes at least two thirds of its respective straight section. The or each said length is preferably in a straight section. In a preferred embodiment the frame is rectangular. The frame then preferably has an apertured length in at least three of its four straight sections.

According to another aspect of the invention there is provided a frame for a manhole cover or gully grating, the frame being rectangular and having a flange on three or four sides, each straight section of flange defining a row of rectangular apertures.

Preferably the apertures are square. The apertures in each row are preferably all of the same size.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a plan view of a known frame for a manhole cover; Figure 2 is a plan view of a frame for a manhole cover in a first embodiment of the invention;

Figure 3 is a plan view of a frame for a manhole cover in a second embodiment of the invention; Figure 4 is a plan view of a frame for a manhole cover in a third embodiment of the invention; Figure 5 is a plan view of a frame for a manhole cover in a fourth embodiment of the invention with the outline of the frame of Figure 1 superimposed in phantom; Figure 6 is a plan view of a frame for a manhole cover in a fifth embodiment of the invention; and Figure 7 is a plan view of a frame for a manhole cover in a sixth embodiment of the invention.

Figure 8 is a plan view of a frame for a manhole cover in a seventh embodiment of the invention; Figure 9 is an underneath plan view of the frame of Figure 8; Figure 10 is a cross-section of the frame of Figure 8 at X-X; and Figure 11 is a plan view of a frame for a manhole cover in an eighth embodiment of the invention.

The known frame 10 shown in Figure 1 has an upright wall 12 defining a central opening 14. A flange 16 extends outwardly all around the wall 12 and is generally horizontal. The flange 16 is of a constant width. The width is in accordance with British Standard BS 7903, which recommends that the distance"d"from the inside surface 18 of the clear opening 14 to the outside edge 20 of the flange 16 should be 75 mm, and that the flange 16 should be solid.

Buttress flange webs 22 are provided between the flange 16 and upright wall 12 adjacent each comer of the frame 10. A seating 24 is provided as a web between adjacent sides of the upright wall 12 bridging each comer. The cover (not shown) sits on the seating 24. The flange 16 has a plain, upright edge 20 and the flange is of constant thickness.

Figure 2 shows the frame of the first embodiment of the invention. The frame of the first embodiment is similar to the frame of Figure 1 and only the differences from the

known frame will be described. Equivalent features will be given the same reference numerals.

The frame 10 of the first embodiment is identical to the frame of Figure 1 except for the addition of a plurality of teeth 26 extending outwardly from the flange 16 all around the flange 16. This frame 10 also meets the British Standard BS 7903 as there is a solid flange of the required width. The teeth 26 merely form an addition to the frame 10 beyond the 75 mm distance. The teeth 26 are equispaced along the straight parts of the flange 16 and are also equispaced around the comers of the flange 16. Teeth 26 which form protrusions, are curved at the root 28, so that the intrusions 30 formed between each pair of teeth 26 has a semicircular inner surface 32 leading to parallel walls 34 leading to the outermost extent of the tooth 26. The teeth or protrusions 26 are of the same general width (i. e. the dimension in the longitudinal direction of the part of the flange from which they extend) as each adjacent intrusion 30.

It is seen that the edge 36 of the flange now takes on a scalloped or castellated appearance which increases the surface area and presents additional surface for keying as well as additional surface to resist lateral movement of the frame, therefore prolonging the life of the frame in situ in a road.

The frame of the second embodiment is similar to the frame of the first embodiment and only the differences will be described. The same reference numerals will be used for equivalent features.

The frame of the second embodiment differs from the frame of the first embodiment in that the teeth 26 are not present on the comers of the flange 16. The comers of the flange are therefore of the same shape as the known frame 10 of Figure 1. The teeth 26 terminate adjacent the flange web 22 which is also at the same distance along the side of the frame as the beginning of the seating 24.

The frame of the third embodiment is shown in Figure 4. The frame of the third embodiment is similar to the frame of the first embodiment and only the differences will be described. The same reference numerals will be used for equivalent features.

Like the second embodiment, the frame of the third embodiment does not have teeth 26 around the comers of the frame 10. Unlike the second embodiment however the flange 16 is extended at the comers so that a notional line across the ends of the teeth 36 and around the comers follows the same shape as the edge of the known frame of Figure 1 but in a larger size. While the embodiment of Figure 3 is perhaps most readily seen as a flange with protruding teeth 26, the flange of Figure 4 is perhaps more readily seen as a frame with a plurality of intrusions 30, although in fact the teeth 26 in the frames are the same and the only difference between the two frames is in the comers rather than in the teeth 26 themselves.

The frame of the embodiment of Figure 5 is identical to that of Figure 4 except that the inner surface 38 of the intrusions 30 is squared off so that the teeth 40 are square and the intrusions 42 are square being of generally the same size and dimensions. The outline of the frame of Figure 1 is shown in phantom 44.

Figures 6 and 7 show flanges of equivalent shape to Figures 2 and 3 but with square teeth 40 replacing the teeth 26 of those Figures. The square teeth 40, with square intrusions 42, give a further increase in the surface area of the edge of the flange 16.

The frames 10 of each of the embodiments and the frame of Figure 1 can be conventionally sandcast from cast iron or ductile iron.

The flange webs 22 need not be positioned as shown but can be at any desired position along the side of the frame 10.

The sides of the frame 10 may be of any desired width. Thus they may be narrower than shown, in which case they may not comply with BS 7903, or they may be wider, as desired.

Figures 8,9 and 10 show a further embodiment of the invention. The embodiment of Figures 8,9 and 10 has similarities with the known frame shown in Figure 1 and the

same reference numerals will be used for equivalent features. Only the differences from the known frame will be described.

The frame of Figures 8,9 and 10 does not have the comer seatings 24 of the frame of Figure 1 and instead the lower part of the frame is thickened to form a ledge 52 which is upwardly facing and extends around the whole of the wall 12.

The frame 10 may be sandcast from cast iron or ductile iron and the ledge 52 may subsequently be machined flat.

The ledge 52 will support the covers 50. As it is machined flat, the covers will not rock.

As shown in Figures 9 and 10, the flange 16 includes a short lateral extension 54 all the way round. The extension 54 is not as thick as the main part of the flange 16. The upper surface 56 of the extension 54 is flush with the upper surface 58 of the main part of the flange 16. There is thus a right angle step 60 on the underside of the flange 16 between the main part of the flange 16 and the extension 54.

The main part of the flange 16 includes eight rebates or pockets 62 recessed into the underside 64 thereof. The frame 10, being square, consists of four straight sections 66 and four comers 68. There are two pockets 62 in each straight section 66. The pockets 62 are rectangular being elongate along the axis of the straight section and arranged symmetrically along the length of the straight sections 66.

In use, a bed of mortar or other suitable fixing material will be laid, and the frame 10 will be placed on the bed. The bedding material will enter the pockets 62. The fixing material will also enter the step 60 under the extension 54. Fixing material is then added on top of the flange and surfacing material is brought up to the wall 12. The pockets 62 improve keying with the fixing material and also aid in resisting lateral movement due to the passage of traffic over the cover. The extension 54 resists movement in a vertical direction and again improves keying. The extension 54 and

pockets 62 together provide significantly improved keying over the frame of Figure 1 and considerably improve resistance to movement both laterally and vertically.

Figure 11 shows a further embodiment. This embodiment is again similar to the known frame of Figure 1 and only the differences from the known frame will be described.

The same reference numerals will be used for equivalent features.

In the embodiment of Figure 11, the distance"d"from the inside surface 18 of the clear opening 14 to the outside edge 20 of the flange 16 is 120 mm, rather than 75 mm. Each straight section 66 of the flange 16 of the frame 10 includes a row of large closely spaced square apertures 70. The apertures are about 50 mm square and are centrally and symmetrically arranged in a row spaced apart by about 10 mm. There are eight apertures 70 in each row.

The presence of the apertures 70 means that the frame 10 of this embodiment is not in accordance with British Standard BS 7903. However, because of the increase in the distance"d"there is a significant amount of extra material at the comers of the frame so that the frame 10 is strong.

In use, the frame 10 will be placed onto a bed of mortar or other fixing material, and more mortar will then be laid over the top of the flange, followed by the surfacing material for the road or the like in which the frame is then placed. The mortar will ooze through the apertures 70 and will"wrap around"the spars 72 separating adjacent apertures 70 and also around the part 74 of the frame between each aperture 70 and the edge 20. The frame 10 is thus extremely well bonded with the fixing material and is well suited to placement in roads where a high level of traffic is expected. The frame of the embodiment will have a considerably improved service life over the known frame of Figure 1.

Claims

Claims 1. A frame for a manhole cover or gully grating in which at least part of the edge of the flange of the frame is of a shape to provide secure fixing against lateral movement in suitable bedding mixture.
2. A frame as claimed in claim 1, wherein the or each part of the edge of the frame is of a shape to increase the surface area of the edge of the flange.
3. A frame as claimed in claim 1 or claim 2, wherein the frame is in a shape having comers and the or each said part of the edge of the flange is not at a comer.
4. A frame as claimed in claim 1 or claim 2, wherein the whole of the edge of the frame is of a shape to provide secure fixing with suitable bedding material against lateral movement.
5. A frame as claimed in any preceding claim wherein the or each part of the edge of the flange defines at least one lateral protrusion or intrusion.
6. A frame as claimed in claim 5, wherein, where at least one protrusion is provided, the root of the or each protrusion is curved.
7. A frame as claimed in claim 5 or claim 6, wherein, where at least one intrusion is provided, the interior surface of the intrusion is curved.
8. A frame as claimed in claim 7, wherein the or each intrusion is semicircular in plan.
9. A frame as claimed in claim 5, wherein the or each intrusion or protrusion is rectangular in plan.

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10. A frame as claimed in claim 9, wherein the or each intrusion or protrusion is square in plan.
11. A frame as claimed in any of claims 5 to 10, wherein the or each part of the edge of the flange has a plurality of lateral protrusions or intrusions.
12. A frame as claimed in claim 11, wherein the protrusions or intrusions in the or each part are in a regular arrangement.
13. A frame as claimed in claim 11 or claim 12, wherein the intrusions or protrusions in the or each part are all of the same general shape.
14. A frame as claimed in claim 11,12 or 13, wherein the intrusions or protrusions in the or each part are all of the same general size.
15. A frame as claimed in any of claims 11 to 14, wherein the spacings between the intrusions or protrusions are of the same order as the width of the protrusions or intrusions themselves.
16. A frame as claimed in any preceding claim wherein the edge of the flange is upright.
17. A frame as claimed in any preceding claim wherein the edge is of constant thickness.
18. A frame as claimed in any preceding claim wherein the or each part of the edge

of the flange is of a generally smooth outline to minimise stress concentration. tn
19. A frame for a manhole cover or gully grating, the frame being substantially as described herein with reference to or as shown in any of Figures 2 to 7 of the accompanying drawings.

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20. A frame for a manhole cover of gully grating, in which at least one region of the flange adjoining the edge of the flange is of reduced thickness in comparison with the main part of the flange.
21. A frame as claimed in claim 20, wherein there is a step to the or each region.
22. A frame as claimed in claim 21, wherein the step is in the underside of the flange.
23. A frame as claimed in claim 22, wherein the upper surface of the or each region is flush with the upper surface of the remainder of the flange.
24. A frame as claimed in any of claims 20 to 23, wherein there is a single region which extends around the whole of the flange.
25. A frame for a manhole cover or gully grating, the frame including at least one upwardly facing ledge to seat at least one cover, the or each ledge occupying at least 50% of the periphery of the central clear opening.
26. A frame as claimed in claim 25, wherein the upwardly facing surface of the or each ledge is machined flat.
27. A frame for a manhole cover or gully grating, the frame including a continuous ledge around the entire edge of the periphery of the clear opening of the frame to seat at least one cover.
28. A frame as claimed in claim 27, wherein the upwardly facing surface of the ledge is machined flat.
29. A frame for a manhole cover or gully grating in which the flange includes at least one length thereof defining at least one aperture, the aperture or apertures occupying at least a third of the area of the said length in plan.

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30. A frame as claimed in claim 29, wherein the aperture or apertures occupy at least 40% of the or each said length.
31. A frame as claimed in claim 29 or claim 30, wherein the or each aperture is rectangular.
32. A frame as claimed in any of claims 29,30 and 31, wherein the or each aperture is square.
33. A frame as claimed in any of claims 29 to 32, wherein there are a plurality of apertures in the or each length.
34. A frame as claimed in claim 33, wherein the apertures are all of the same general shape.
35. A frame as claimed in claim 33 or claim 34, wherein the apertures are all of the same general size.
36. A frame as claimed in any of claims 33,34 and 35, wherein the apertures are spaced along the or each length.
37. A frame as claimed in claim 36, wherein the apertures are in a single row in the or each length.
38. A frame as claimed in claim 36 or claim 37, wherein the apertures are spaced apart by a distance less than the width of the apertures.
39. A frame as claimed in any of claims 29 to 38, wherein the frame is in a shape having comers and straight sections, the or each said length being in a straight section.
40. A frame as claimed in claim 39, wherein the or each length constitutes at least 50% of its respective straight section.

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41. A frame as claimed in claim 39, wherein the or each length constitutes at least two thirds of its respective straight section.
42. A frame as claimed in any of claims 39,40 and 41, wherein the frame is rectangular.
43. A frame as claimed in claim 42, wherein the frame has an apertured length in at least three of its four straight sections.
44. A frame for a manhole cover or gully grating, the frame being rectangular and having a flange on three or four sides, each straight section of flange defining a row of rectangular apertures.
45. A frame as claimed in claim 44, wherein the apertures are square.
46. A frame as claimed in 44 or claim 45, wherein the apertures in each row are all of the same size.
47. A frame as claimed in claim 44,45 or 46, wherein the apertures are spaced apart by a distance less than the width of the apertures.
48. A frame substantially as described herein with reference to or as shown in Figures 8,9 and 10 of the accompanying drawings.
49. A frame substantially as described herein with reference to or as shown in Figure 11 of the accompanying drawings.