GB2093510A

GB2093510A - Improvements in or Relating to Gratings

Info

Publication number: GB2093510A
Application number: GB8201415A
Authority: GB
Original assignee: SELFLEVEL COVERS AG; SELF LEVEL COVERS AG
Current assignee: SELFLEVEL COVERS AG; SELF LEVEL COVERS AG
Priority date: 1981-02-19
Filing date: 1982-01-19
Publication date: 1982-09-02

Abstract

A drainage grating for setting in a roadway comprises a plurality of cross-shaped apertures 10 and U- shaped apertures 17 separated by lands 19, 22, which lands define a plurality of turtuous paths between the apertures from one side edge 20 of the grating to the opposite side edge 21. Each path thus defined by the lands includes at least one portion 22 which turns back towards said one side edge 20, whereby water flowing across the grating from said side edge towards the opposite side edge 21 cannot follow any path along the whole of its length and thus passes through one of the apertures in the grating. The grating ends are formed with half-size apertures and lands for co-operation with adjacent gratings arranged in line. The specification also shows a modified grating, and the end and side components of a reversible frame therefor, the side components having recesses and projections for interlocking with the sides of the grating. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to Gratings The invention relates to gratings and particularly to gratings for setting into a roadway or similar surface for drainage of water into an underground disposal system. Such gratings normally comprise a plurality of apertures separated by lands, the lands often being in the form of straight or curved bars extending from one side edge of the grating to the other.

Such conventional gratings for drainage suffer from the disadvantage that when there is a substantial flow of water to be drained a comparatively large proportion of the water can flow across the grating, passing along the lands, without flowing into the apertures between the lands. The present invention therefore sets out to provide an improved form of grating wherein the proportion of water flowing across the grating without passing through it is reduced.

According to the invention there is provided a grating comprising a plurality of apertures separated by lands, which lands define a plurality of tortuous paths between the apertures from one side edge of the grating to the opposite side edge, each path thus defined by said lands including at least one portion which turns back towards said one side edge, whereby water flowing across the grating from said one side edge towards the opposite side edge cannot follow any path along the whole of its length and thus passes through one of the apertures in the grating.

It will be appreciated that although water flowing along the lands of a grating may follow sideways deviations in its path, it cannot normally move back against the general direction of flow.

Consequently with the arrangement defined above water cannot follow a land across the whole width of the grating and must therefore, at some point during its flow across the grating, leave the land and pass into or over an aperture in the grating. Thus the only water which can continue to flow right across the grating is that which has sufficient velocity to bridge the apertures in the grating.

Each tortuous path defined by the lands may include a generally U-shaped portion, both limbs of the U extending towards or away from said one side edge of the grating.

In a particular and preferred embodiment of the invention, the apertures separated by said lands include a row of spaced, generally cross-shaped apertures extending longitudinally of the grating, and a row of elongate apertures to either or each side of the cross-shaped apertures, each elongate aperture being at least partly disposed between the lateral limbs of two adjacent cross-shaped apertures, and overlapping the lands between the spaced ends of the longitudinal limbs of said adjacent cross-shaped apertures.

The term "lateral" is intended to mean the direction across the grating from said one side edge to the opposite side edge, and the term "longitudinal" to mean the direction at right angles thereto. However, it will be appreciated that the dimension of the grating in the "lateral" direction is not necessarily less than its dimension in the "longitudinal" direction. Also, the use of these terms is not to be taken to indicate that the grating is necessarily rectangular in overall configuration.

Preferably each cross-shaped aperture includes a laterally extending portion at each end of the longitudinally extending limb thereof.

Each side elongate aperture may be generally U-shaped, the limbs of the U extending towards the row of cross-shaped apertures. Where these two latter features are combined, the aforementioned U-shaped portion of the lands is defined between the U-shaped elongate apertures and the laterally extending portions at the ends of the longitudinal limbs of the cross-shaped apertures.

The following is a more detailed description of embodiments of the invention, reference being made to the accompanying drawings in which: Figure 1 is a plan view of a grating in accordance with the invention, Figure 2 is a perspective view of an alternative form of grating, and Figure 3 is a perspective view of part of a support frame suitable for removably mounting a grating of the kind shown in Figures 1 and 2.

Referring to Figure 1, the grating, which may for example be cast from spheroidal graphite iron, is generally rectangular in configuration and includes a central row of spaced, generally crossshaped apertures 10 extending longitudinally of the grating. Each cross-shaped aperture comprises longitudinal limbs 11 and lateral limbs 12. Laterally extending portions 13 are provided at the ends of the longitudinal limbs 11 of the apertures.

In the arrangement shown the length of the grating is such that two complete cross-shaped apertures are provided, there being formed at each end of the grating a longitudinal limb 14, laterally extending portions 1 5 and an end recess 1 6 which combine with similar formations on an adjacent grating to form a whole cross-shaped aperture 10. Thus a number of grating of the kind shown in Figure 1 may be mounted end-to-end to form a continuous grating pattern. It will be appreciated that the same grating pattern could be made up from smaller portions of the grating shown in Figure 1.

On each side of the row of cross-shaped apertures 10 is a row of elongate generally Ushaped apertures 17. The limbs 18 of each Ushaped aperture extend towards the central row of cross-shaped apertures and are disposed between the lateral limbs 1 2 of two adjacent cross-shaped apertures and overlap the land 1 9 between the ends of the longitudinal limbs 11 of the adjacent cross-shaped apertures.

Integrally cast across the underside of the grating are a number of spaced reinforcing beams 8 and 9. Each reinforcing beam 8 extends across and beneath two of the U-shaped apertures 1 7, and the beams 9 extend beneath the grating on either side of the lateral limbs 12 of each crossshaped aperture. The beams 8 and 9 provide the grating with additional transverse rigidity.

It will be seen that the arrangement of the apertures is such that the lands between the apertures provide a plurality of tortuous paths from one side edge 20 of the grating to the opposite side edge 21. It will also be seen that no matter which tortuous path is followed across the lands from the side edge 20 to the side edge 21 it is always necessary to travel along a portion of the path which turns back towards the side edge 20, for example the land portion 22 between a limb 18 of a U-shaped aperture 17 and the adjacent aperture portion 13. Since water attempting to flow across the grating from the side edge 20 to the side edge 21 is unlikely to be able to flow back along such portions as the portion 22, the water necessarily has to pass into or across an aperture.Although a certain proportion of the water may be able to bridge an aperture, particularly if the volume flow and velocity is high, the described arrangement ensures that a large proportion of the water finds its way into the apertures in the grating.

The alternative arrangement shown in Figure 2 is similar in general configuration to the arrangement shown in Figure 1 except that the laterally extending portions 23 at the ends of the cross-shaped apertures 24 are rectangular, as are also the elongate U-shaped apertures 25.

Figures 2 and 3 also show the arrangement for mounting the grating in a support frame in a roadway or similar surface. Referring to Figure 3, the mounting frame, which is reversible, comprises longitudinal side members 26 and end frame members 27. Each frame member has a vertical wall portion 28 with an outwardly extending flange 29 at one end thereof. Inward projections 30 are formed on each wall portion 28. Each of the projections has inclined end faces, such as the faces 31, 32, 33 and 34, so that each projection is widest at the middle of the wall 28 and narrower at the upper and lower edges thereof. Thus adjacent pairs of projections 30 define recesses for reception of matching tapered lugs 35 (see Figure 2) formed on the grating which is to be fitted into the frame. When the frame is mounted with the flange 29 uppermost the lugs 35 on the grating engage with the inclined faces 33 and 34 on the projections 38, and when the frame is mounted with the flange 29 lowermost, as shown in Figure 3, the lugs 35 engage with the inclined faces 31 and 32 of the projections 30.

Claims

1. A grating comprising a plurality of apertures separated by lands, which lands define a plurality of tortuous paths between the apertures from one side edge of the grating to the opposite side edge, each path thus defined by said lands including at least one portion which turns back towards said one side edge, whereby water flowing across the grating from said one side edge towards the opposite side edge cannot follow any path along the whole of its length and thus passes through one of the apertures in the grating.

2. A grating according to claim 1, wherein each tortuous path defined by the lands includes a generally U-shaped portion, both limbs of the U extending towards or away from said one side edge of the grating.

3. A grating according to claim 1 or claim 2, wherein the apertures separated by said lands include a row of spaced, generally cross-shaped apertures extending longitudinally of the grating, and a row of elongate apertures on at least one side of the cross-shaped apertures, each elongate aperture being at least partly disposed between the lateral limbs of two adjacent cross-shaped apertures, and overlapping the lands between the spaced ends of the longitudinal limbs of said adjacent cross-shaped apertures.

4. A grating according to claim 3, wherein each cross-shaped aperture includes a laterally extending portion at each end of the longitudinally extending limb thereof.

5. A grating according to claim 3, wherein each elongate aperture is generally U-shaped, the limbs of the U extending towards the row of crossshaped apertures.

6. A grating substantially as hereinbefore described with reference to Figure 1 or Figure 2 of the accompanying drawings.

7. The combination with a grating according to any of the preceding claims of a frame adapted to support the grating at the outer periphery thereof.

8. The combination according to claim 7, wherein the outer periphery of the grating is formed with downwardly tapering outward projections which are received in correspondingly shaped recesses formed in the inner periphery of the support frame.