GB2243638A - Restraining lateral movement of manhole cover - Google Patents

Abstract

A ground surface access assembly includes a cover (4, 5) mounted for turning for opening purposes about a hinge at or adjacent one side (6, 7) of the cover, and provided with a separate support at a position (8, 9) remote from the hinge across the opening in the frame by engagement of the cover at that position with a seating arrangement adapted to restrain horizontal movement of the cover thereat, and the cover being provided, at a position (25, 26) remote from the support position, with at least one surface engaging with at least one surface of the frame adapted to restrain horizontal movement of the cover thereat in the direction of the line of the hinge. <IMAGE>

Description

around Surface Access Assemblies This invention relates to ground surface access assemblies by which is meant covers and frames such as manhole assemblies for openings in pavement, road or flooring, or similar surfaces serving as access openings to water hydrants, sewers, access pits, wiring conduits, and other below surface cavities and installations.

More especially but not exclusively, the invention relates to access assemblies comprising a rectangular frame within which is situated a purality of generally triangular covers, such that an appropriate number of standard size and configuration of cover can be adapted to fit within an extensive range of lengths of rectangular frames, thereby providing flexibility of use of such covers.

More generally however the invention relates to surface access assemblies each including a cover hingedly mounted with respect to its frame on one side so as to be capable of being turned about its hinge upwardly to an open disposition for access through the assembly, and supported in its closed position along or adjacent the hinge, and at a position remote from the hinge across the frame opening.

Commonly such covers are of generally triangular disposition and turn about a hinge along or close to one side of the triangular cover1 and are additionally supported at the corner remote from that side.

A problem with such covers is the difficulty of trying to ensure support by the frame to prevent or limit horizontal motion of the cover when closed, caused by the movement of traffic across the cover, in any direction.

It is the object of the present invention to overcome, or at least substantially reduce the abovementioned difficulty.

In accordance with the invention there is provided a ground surface access assembly including a cover mounted for turning for opening purposes about a hinge at or adjacent one side of the cover, and provided with a separate support at a position remote from the hinge across the opening in the frame by engagement of the cover at that position with a seating arrangement adapted to restrain horizontal movement of the cover thereat, and the cover being provided, at a position remote from the support position, with at least one surface engaging with at least one surface of the frame adapted to restrain horizontal movement of the cover thereat in the direction of the line of the hinge.

In a preferred embodiment the cover of the invention comprises a triangular cover hinged along or adjacent to one side of the cover and provided with a support at a position at or adjacent to the apex of the triangular frame opposite the hinge side, the additional horizontal movement restraining surfaces being provided on the cover and adjacent frame at or adjacent the hinged side of the cover.

In one embodiment the separate support comprises supporting surfaces at the support position which may comprise surfaces inclined to the vertical associated both with the frame and the cover, urging, upon closing the cover, at that position against other frame surfaces to prevent movement of the cover thereat in any horizontal direction. By this means closure of the cover inhibits movement of any part of the cover in a direction at right angles to hinge line. Similarly surfaces inclined to the vertical of the frame and cover at or adjacent the hinge side of the cover can be arranged to restrain movement thereat in the direction of the hinge line, without which a horizontal movement somewhat similar to an arc like movement about the separate support position would be possible.

By providing an appropriately sharply angled set of inclined surfaces at the support position, and by ensuring, as the invention does, that the separate support position is remote from the hinge position, no interference of the relative incline surfaces occur when lifting the support position apart during opening of the cover so that easy disengagement is possible.

In order that the invention may be more readily understood one embodiment thereof may now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a plan view of a road surface access assembly according to the invention incorporating two generally triangular covers in a generally rectangular frame; Figure 2 is a section on line A-A of Figure 1; Figure 3 is an enlarged plan view of one corner of the assembly of figure 1; Figure 4 is an isometric section on the line B-B of Figure 3; and Figures 5 and 6 show the components of Figure 4 in a separated configuration.

Referring now to the drawings it will be seen that the assembly comprises frame 1 of generally rectangular form, but having recesses 2 and 3 at opposed corners to accommodate one extended corner of each of the triangular covers 4,5.

Each cover 4,5 is hingedly connected to the frames along sides 6,7 for upward movement to open the lids to gain access through the assembly. The extended corners 8,9 of the generally triangular covers are adapted for restraint of horizontal movement at their support surfaces. Reference to Figures 3 to 6 show that at these extended corners, downardly extending ribs 10 and 11 of the covers have inclined surfaces 12,13 which engage on similarly inclined surfaces 14,15 of a retaining block 16 mounted on the frame 1. The surfaces 12,14 and 13,15 engage when the cover 8 is closed, causing the edges 17,18 of the corner to engage firmly with side walls 19,20 of the frame and thereby preventing at this corner of each of the covers, movement both parallel to sides 6,7, and, across the covers totally, at right angles to sides 6,7.

So as to ensure that no horizontal movement of the covers 4,5 occurs remote from corners 8,9 in the direction of the sides 6,7 (in the form of an arc like movement about corners 8,9, rather similar to a pendulum) protrusions 21,22 of the frame near to the right-angled corners 23,24 thereof engage with matching surfaces 25,26 of the cover, the interengaging surfaces of the prostrusions being so inclined to the vertical as to force cover protrusions 25,26 into the corners 23,24 of the frame 1.

The present invention is based upon placing the hinge system of the covers such that the individual half covers 4,5 hinged in a vertical plane about a line along the sides 6,7 so that the kinematic locating support corner 8,9 of the half covers traverses over the largest physical distance possible when the two half covers are open. In some instances this could be increased providing hinges behind the lines of sides 6,7.

Although in the embodiment illustrated the kinematic restraint comprises surfaces inclined to the horizontal at the supports of corners 8 and 9, these could be provided by other means such as pins within close-fitting holes or a ball or near ball-like surface mating within a corresponding socket profile. Whether the kinematic arrangement is designed with surfaces somewhat inclined to the vertical of an interlocking nature or some other arrangement, the action obtained about the vertical hinge system with the support at corners 8 and 9 can readily be arranged such as to allow easy disengagement during opening of the half covers about the hinges in what is very near to a vertical direction. Similarly this arrangement enables the provision at the kinematic location points in corners 8 and 9 of location surfaces allowing the cover to be realigned in its proper position during each closing action.

By means of invention as disclosed the kinematic location at corners 8 and 9 serve as a totally restrained position on the covers in the horizontal direction both parallel sides 6,7 and at right-anlges thereto. In addition by virtue of the hinge arrangement correct location of corners 8 and 9 of the cover effectively prevents any movement of the covers in a direction at right-angles to the hinge sides 6 and 7. To prevent any movement about the corners 8 and 9 in the horizontal plane (as though it were the centre of a horizontal pendulum or fulcrum) the surfaces 21,22,24 and 25 at the corners of the sides 6,7 of the covers and frames restrain motion in the direction of the sides 6,7. By this means therefore the covers are totally restrained from any movement whatsoever in the horizontal plane. It is to be noted that the surfaces 21,22,24 and 25 or similar surfaces restraining motion could be placed anywhere within or without the frame dimension, provided they are sited away from corners 8,9.

It is to be understood that the foregoing is merely exemplary of access assemblies in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention.

Claims (6)

1. A ground surface access assembly including a cover mounted for turning for opening purposes about a hinge at or adjacent one side of the cover, and provided with a separate support at a position remote from the hinge across the opening in the frame by engagement of the cover at that position with a seating arrangement adapted to restrain horizontal movement of the cover thereat, and the cover being provided, at a position remote from the support position, with at least one surface engaging with at least one surface of the frame adapted to restrain horizontal movement of the cover thereat in the direction of the line of the hinge.

2. An assembly as claimed in Claim 1 wherein the cover comprises a triangular cover hinged along or adjacent to one side of the cover and provided with a support at a position at or adjacent to the apex of the triangular frame opposite the hinge side, the additional horizontal movement restraining surfaces being provided on the cover and adjacent frame at or adjacent the hinged side of the cover.

3. An assembly as claimed in Claim 1 or Claim 2 wherein the separate support comprises supporting surfaces at the support position which may comprise surfaces inclined to the vertical associated both with the frame and the cover, urging, upon closing the cover, at that position against other frame surfaces to prevent movement of the cover thereat in any horizontal direction.

4. As assembly as claimed in Claim 1, 2 or 3 wherein the additional restraining surfaces comprise surfaces of the frame and cover inclined to the vertical.

5. An assembly as claimed in any one of the preceding Claims wherein the additional restraining surfaces are disposed at or adjacent to the hinge side of the cover.

6. A ground surface access assembly substantially as shown in and as hereinbefore described with reference to the accompanying drawings.