GB2069575A - Manhole cover and frame assemblies - Google Patents

Abstract

A triangular or other manhole cover having three-point support on frame members 1 is laterally located by upstanding frame studs 7 whose side faces are engaged by the end position 8, 12, 13 of ribs 6 on the underside of the cover, the portion 8 engaging around the outer surfaces of the respective stud 7. As shown the frame members 1 are also provided, at each corner of the cover, with an L-shaped ridge 11 cooperating with the adjacent stud 7 to define seating pockets for the rib end portions 8, 12 or 13. <IMAGE>

Description

SPECIFICATION Improvements in or relating to manhole assemblies This invention relates to manhole cover and frame assemblies, within which expression is intended to be included such assemblies for road access openings for sewers drains wiring pit and conduits, for example.

It has been suggested and is known to seat the cover within the frame by means of positive location between three separate support portions spaced around the cover and three corresponding and mating separate support portions spaced around the frame, since such a three point support arrangement is naturally very resistant to rocking problems of the cover.

However where the manhole assemblies are of cast iron, which for purposes of strength is often required, normal and reasonable tolerance ranges in the casting of the assemblies can create serious difficulties in the mating of the supposedly corresponding supporting portions of the frames and the covers leading to unsatisfactory seating of the frame. This is particularly true with large size individual frames and covers e.g. those extending a length of 500 mm to 1000 mm.

It is an object of the present invention to overcome or at least substantially reduce this problem.

According to the invention there is provided a manhole assembly comprising a cover including three support portions spaced around or adjacent the periphery thereof; and a frame provided with three support portions corresponding in position to the three support portions of the cover; the support portions of the frame each comprising a generally upwardly projecting stud; the first support portion of the cover comprising a downwardly projecting rib adapted to pass around the outer peripheral side of the stud of the associated frame support portion such that at least a part of the peripheral wall of the stud directed outwardly of the assembly bears against an inner peripheral wall of the rib; and each of the second and third support portions of the cover comprising a downwardly projecting rib lying in the direction of or parallel to the direction of, the first support portion, and adapted to lie alongside an outer peripheral side of the stud with an inner peripheral wall of the rib bearing against the stud.

The ribs comprising the support portions of the cover may be part of or an extension of an array of strengthening ribs on the underside of the cover.

The upwardly projecting studs of the support portions of the frame may be of rectangular or triangular cross-section.

in this case, the rib of the first support portion may be " L" shaped (in plan section) such as to pass around the stud, whilst the ribs of the second and third support portion may be generally straight (in plan section) such as to lie alongside a planar outer peripheral side wall of the stud of the associated frame support portion.

The frame may be provided with an outer peripheral upwardly directed ridge adjacent one or more of the support portions so as to define, with the associated stud, an ''L'' shaped groove within which the rib of the associated support portion of the cover may be seated in close and positive location.

Alternatively or in addition, the upper surface of the cover may be provided with outwardly extending tabs at one or more support portions, each tab adapted to bear against a side wall of the frame so as to provide, with the associated stud at the respective support portion, a positive location for the cover.

The cover may be triangular in general plan configuration, and may be in the form of a right angled triangle. In this case the first supporting portion of the cover may be located at or adjacent to the right angle of the triangle.

The frame may comprise two or more appropriately shaped members generally of a bar-like configuration secured in use one on each side of a rectangular road access opening, for example.

A plurality of covers of right angled general plan may be located on a single pair of such frame bars.

Adjacent sides of the same frame support studs on such frame bars may be used (in this case) for the second or third support portions of adjacent lids.

In order that the invention may be more readily understood one embodiment thereof will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a perspective view of a road wiring duct frame and cover assembly and; Figure 2 is a scrap plan view of part of the embodiment shown in Fig. 1.

From Fig. 1 of the drawings it will be seen that the manhole assembly comprises a cast iron frame comprising a plurality of " L" section bars 1 set in concrete 2 of a roadway for example and disposed on both sides of a road wiring inspection pit 3, for example., A plurality of cast iron covers 4 are located above the pit 3 and are seated on the bars 1 of the frame.

The covers 4 are right angled triangular in general plan configuration, may be provided on the hypotenuse side with downwardly extending bored tabs 5 by means of bolts passing through which two lids may be loosely joined together.

The underside of each cover is provided with a network of strengthening ribs 6.

The support arrangements for the covers are perhaps best seen in Fig. 2.

As can be observed, the frame bars 1 are provided with frame support portions each including an upwardly extending square section stud 7. At the right angled portion of each cover 4, the strengthening ribs 6 are shaped to provide a first support portion 8 for the cover 4, in that, in plan, the first supporting portion of the ribs is of right angled "U' configuration such as to pass around the stud and firmly locate against the outer surfaces 9 and 10 thereof. In addition a cooperating ridge 11 is provided on the bar 1 whereby the supporting portion 8 of the ribs is securely held in the "U' shaped channel between the stud 7 and ridge 11 parallel to the adjacent sides of the cover 4. The acute angled corners of the covers are provided with the second and third support portion for the cover.These take the form of straight extension rib portions 1 2 and 1 3 of the rib assembly 6 parallel to the adjacent sides of the cover and which locate securely within a respective arm of the ''L'' shaped channel formed between sides 14 and 1 5 of the stud 7 and ridge 11. It will be appreciated that the undersides of the rib portions 8, 1 2 and 1 3 and the base of the channels between studs 7 and ridges 11 may be of any convenient configuration e.g. flat, wedge shaped or semi-cylindrical.

It is to be observed that by means of the invention the assembly illustrated provides a firmly located array of covers even though these extend over a considerable length (2 metres for example) and are subject to normal casting tolerance ranges for cast iron products. Thus the positive location in two directions at the first support portion of each cover and the positive location in single directions (mutually perpendicular) at the second and third support portions of each cover provide firm location against movement, whilst the location in single directions at the second and third support portion for size variations of the cover and frames of generous tolerance ranges. At the same time this triple form of location prevents slopping or lateral movement of the cover over the frame which greatly reduces wear at the support portions and elsewhere.

Claims (11)

1. A manhole assembly comprising a cover including three support portions spaced around or adjacent the periphery thereof; and a frame provided with three support portions corresponding in position to the three support portions of the cover; the support portions of the frame each comprising a generally upwardly projecting stud; the first support portion of the cover comprising a downwardly projecting rib adapted to pass around the outer peripheral side of the stud of the associated frame support portion such that at least a part of the peripheral wall of the stud directed outwardly of the assembly bears against an inner peripheral wall of the rib; and each of the second and third support portions of the cover comprising a downwardly projecting rib lying in the direction of or parallel to the direction of, the first support portion, and adapted to lie alongside an outer peripheral side of the stud with an inner peripheral wall of the rib bearing against the stud.

2. An assembly according to Claim 1 wherein the ribs comprising the support por tions of the cover are part of or an extension of an array of strengthening ribs on the under side of the cover.

3. An assembly according to Claim 1 or 2 wherein the upwardly projecting studs of the support portions of the frame are of rectangu lar cross-section.

4. An assembly according to Claim 1 or 2 wherein the upwardly projecting studs of the support portions of the frame are of triangular cross-section.

5. An assembly according to Claim 3 or 4 wherein the rib of the first support portion is ''L'' shaped (in plan section) such as to pass around the stud, and the ribs of the second and third support portion are generally straight (in plan section) such as to lie along side a planar outer peripheral side wall of the stud of the associated frame support portion.

6. An assembly according to Claim 5 wherein the frame is provided with an outer peripheral upwardly directed ridge adjacent one or more of the support portions so as to define, with the associated stud, an ''L'' shaped groove within which the rib of the associated support portion of the cover is seated in use in close and positive location.

7. An assembly according to Claim 5 or 6 wherein the upper surface of the cover is provided with outwardly extending tabs at one or more support portions, each tab being adapted in use to bear against a side wall of the frame so as to provide with the associated stud at the respective support portion, positive location for the cover.

8. An assembly according to any one of the preceding Claims wherein the cover is triangular in general plan configuration.

9. An assembly according to Claim 8 wherein the cover is right angled triangular in general plan configuration, and the first sup porting portion of the cover is located at or adjacent the right angle of the triangle.

10. An assembly according to any one of the preceding Claims wherein the frame com prises two or more members each generally of a bar-like configuration secured in use one on each side of an opening to be covered.

11. An assembly according to Claim 10 wherein a plurality of covers of right angled general plan are located on a pair or sequence of pairs of frame bars.

1 2. An assembly according to Claim 11 wherein adjacent sides of the same frame support studs on such frames bars are used for the second or third support portions of adjacent lids.

1 3. A manhole assembly substantially as shown in and as hereinbefore described with reference to the accompanying drawings.