GB2585059A

GB2585059A - Ground surface access assemblies

Info

Publication number: GB2585059A
Application number: GB1909234.5A
Authority: GB
Inventors: John Gibson Simon; Sarah Elizabeth Evans Samantha
Original assignee: Wrekin Holdings Ltd
Current assignee: Wrekin Holdings Ltd
Priority date: 2019-06-27
Filing date: 2019-06-27
Publication date: 2020-12-30
Anticipated expiration: 2039-06-27
Also published as: GB2585059A8; GB201909234D0; GB2585059B

Abstract

A ground surface access assembly (10, fig.1) comprising a base frame (12, fig.1) defining an opening (14, fig.5) and a cover (16, fig.1). The cover comprises a plurality of formations 20 extending from the cover corner 22, contacting the base corners (34, fig.5), fixing the cover relative to the base. Formations may extend outwardly from the lower part of the cover (46, fig.2) to contact the base and a gap exists between a cover upper part (42, fig.2) and an upstanding side wall of the base (18, fig.5). Formations can terminate at a taper 50 to bite or a flat end 48 to abut a corresponding corner. The cover may comprise a pair of substantially triangular cover member 28. The base may comprise a seat (32, fig.5) in each corner onto which a corresponding cover corner mount 36 sits. Stop members (38, fig.5) may extend from the seat of a pair of diagonally opposed corner portions of the base frame, configured to abut against a corresponding stop member 40 of the cover that extend from the corner mountings. There is an independent claim to a method of mounting a cover to a base frame.

Description

TITLE

Ground Surface Access Assemblies

TECHNOLOGICAL FIELD

Examples of the disclosure relate to ground surface access assemblies, and in particular ground surface access assemblies comprising a base frame defining an opening and a cover which is mountable to the base frame in the opening.

BACKGROUND

Ground surface access assemblies, such as manhole covers, comprise a base frame defining an opening and a cover which is mountable to the base frame in the opening. The cover is mounted removably to permit access to the hole.

There is a desire to prevent in use movement of the cover relative to the frame to reduce wear, and to prevent accidental disengagement of the cover. It is known to provide an interference fit between a broad area of the cover and the base frame, for instance by providing a cover which is oversize (on plan) relative to the opening defined by the base frame. Accordingly, in such examples the mating surface between the cover and base frame is considerable, and may extend substantially around the perimeter of the cover. The mating surface will feel pressure due to friction, and deformation of the base frame will be observed.

However, in such known arrangements the cover may act in an unstable manner in the base frame, for instance, because the frictional forces are insufficient to prevent the base frame elasticity from ejecting the cover.

Accordingly, there is a desire to improve cover stability in a base frame.

BRIEF SUMMARY

According to various, but not necessarily all, examples of the disclosure there is provided a ground surface access assembly, the assembly comprising: a base frame, wherein the base frame defines a base frame opening; and a cover mountable to the base frame in the base frame opening; wherein the cover comprises a plurality of formations, wherein at least one formation extends from each respective corner portion of the cover, wherein each of the plurality of formations is configured to provide a point of contact with a corresponding corner portion of the base frame to fix the position of the cover relative to the base frame when the cover is mounted to the base frame in the base frame opening.

Possibly, the base frame comprises an upstanding side wall, wherein each of the plurality of formations is configured to provide a point of contact with the upstanding side wall in the corresponding corner portion of the base frame.

Possibly, in a condition of the assembly where the cover is mounted to the base frame in the base frame opening, the formations are the only part of the cover in contact with the upstanding side wall of the base frame.

Possibly, the cover comprises an upper part defining a top face of the cover and a lower part underlying the upper part. Possibly, in a condition of the assembly where the cover is mounted to the base frame, there is a gap between the upper part of the cover and the upstanding side wall of the base frame extending around the perimeter of the upper part. Possibly, the formations extend outwardly from the lower part of the cover, and are configured to provide a point of contact with corresponding corner portions of the base frame below an upper most portion of the upstanding side wall. Possibly, the lower part comprises the corner mountings.

Possibly, in some examples each of the plurality of formation terminates in a tapered end. Possibly, in other examples some of the plurality of formations terminate in a substantially flat end, and some of the plurality of formations terminate in a tapered end. Possibly, formations with a tapered end are configured to bite into a corresponding corner portion of the base frame. Possibly, formations with a substantially flat end are configured to abut against a corresponding corner portion of the base frame.

Possibly, in some examples the cover comprises a pair of cover members, each of which is substantially triangular in plan view. Possibly, each of the pair of cover members comprises a plurality of formations, wherein a formation extends from each respective corner portion of the cover member, wherein each of the plurality of formations is configured to provide a point of contact with a corresponding corner portion of the base frame to fix the position of the cover member relative to the base frame when the cover member is mounted to the base frame in the base frame opening. Possibly, each of the plurality of formations is configured to provide a point of contact with the upstanding side wall in the corresponding corner portion of the base frame.

In an assembled condition of the cover, where the pair of cover members are mounted to the base frame in the base frame opening, the cover may be substantially rectangular or square in plan view. The cover may comprise two pairs of diagonally opposite corner portions, wherein a dividing line between the pair of cover members extends through a one of the pairs of diagonally opposite corner portions. Each of the pair of diagonally opposite corner portions through which the dividing line extends may comprise a formation from each of the pair of cover members, and may comprise two formations, one from each of the pair of cover members. Each of the other pair of diagonally opposite corner portions of the cover comprises a formation from a respective cover member, and may comprise a single formation.

In other examples, the cover may comprise a single cover member which is substantially rectangular or square in plan view. The single cover member may comprise two pairs of diagonally opposite corner portions, wherein each of the corner portions comprises a single formation.

Possibly, the base frame comprises a plurality of seats, one in each corner portion of the base frame, which may extend from the upstanding side wall into the base frame opening, wherein the cover comprises a plurality of corner mountings, one on the underside of each corner portion of the cover, the corner mountings being locatable on corresponding seats of the base frame. In examples, in which the cover comprises a pair of cover members, each of which is substantially triangular in plan view, each of the pair of cover members may comprise a plurality of corner mountings, one on the underside of each of the three corner portions of the cover member, the corner mountings being locatable on corresponding seats of the base frame.

Possibly, the base frame comprises two pairs of diagonally opposite corner portions, wherein a first pair of the diagonally opposite corner portions each comprise a stop member configured to abut against corresponding stop members on each of the pair of cover members either side of a dividing line between the pair of cover members. With respect to each of the first pair of the diagonally opposite corner portions of the base frame, the stop member may extend from the seat. With respect to each of the pair of cover members, the corresponding stop member may extend from the corner mounting.

According to various, but not necessarily all, examples of the disclosure there is provided a method of mounting a cover to a base frame of a ground surface access assembly, the method comprising: mounting the cover to the base frame in a base frame opening; providing a point of contact between each of a plurality of formations of the cover and the base frame to fix the position of the cover relative to the base frame, wherein at least one formation extends from each respective corner portion of the cover, and the point of contact is with a corresponding corner portion of the base frame.

Possibly, the base frame comprises an upstanding side wall, and the method comprises providing a point of contact between each of a plurality of formations of the cover and the upstanding side wall in the corresponding corner portion of the base frame.

The ground surface access assembly and method of installing a cover to a base frame of a ground surface access assembly may comprise any of the features described in any of the preceding statements or following description.

According to various, but not necessarily all, examples of the disclosure there may be provided examples as claimed in the appended claims.

BRIEF DESCRIPTION

For a better understanding of various examples that are useful for understanding the detailed description, reference will now be made by way of example only to the accompanying drawings in which: Fig. 1 illustrates a perspective view of a ground surface access assembly; Fig. 2 illustrates a perspective view of a cover of a ground surface access assembly, and expanded views of the corner portions of the cover; Fig. 3 illustrates a perspective view of a cover member of the cover of Fig. 2, and expanded views of the corner portions of the cover member; Fig. 4 illustrates a plan view of the cover member of Fig. 3, and expanded views of the corner portions of the cover member; Fig. 5 illustrates a perspective view of a base frame of a ground surface access assembly, and expanded views of the corner portions of the base frame; Fig. 6 illustrates a plan view of a ground surface access assembly showing lines of site A-A and B-B; Fig. 7 illustrates a cross section though line A-A, and expanded views of the corner portions; and Fig. 8 illustrates a cross section though line B-B, and expanded views of the corner portions.

DETAILED DESCRIPTION

The figures illustrate a ground surface access assembly 10 according to examples of the disclosure.

As illustrated in Fig. 1, the assembly 10 comprises a base frame 12 defining a base frame opening 14, and a cover 16. The cover 16 is mountable to the base frame 12 in the base frame opening 14. The base frame 12 comprises an upstanding side wall 18. A flange 26 extends outwardly from the lowermost parts of the side wall 18.

As illustrated, for instance, in Fig. 2, the cover 16 comprises a plurality of formations 20. At least one formation 20 extends from each respective corner portion 22 of the cover 16.

As best illustrated in Figs. 7 and 8 with reference to Figs. 2 and 5. each of the plurality of formations 20 is configured to provide a point of contact with a corresponding corner portion 34 of base frame 12 to fix the position of the cover 16 relative to the base frame 12 when the cover is mounted to the base frame 12 in the base frame opening 14.

In the illustrated examples in use each of the plurality of formations 20 provide a point of contact with an inner surface 24 of the upstanding side wall 18 in the corresponding corner portion 34 of the base frame 12. The inner surface 24 faces into the base frame opening 14 The formations 20 provide interference fit contact points between the cover 16 and the base frame 12, i.e. a mechanical engagement. Accordingly, an interference fit between the cover 16 and base frame 12 is only provided at the selected corner locations 22, 34 defined by the points of contact between the respective formations 20 and the base frame 12.

In the illustrated example, in a condition of the assembly where the cover 16 is mounted to the base frame 12 in the base frame opening 14, the formations 20 are the only part of the cover 16 in contact with the upstanding side wall 18 of the base frame 12. There are no other points of contact in the vertical plane between the cover 16 and the upstanding side wall 18 of the base frame 12. Furthermore, there are no other points of contact in the vertical plane between the cover 16 and base frame 12.

In the illustrated examples, the cover 16 comprises a pair of cover members 28, each of which is substantially triangular in plan view. A one of the cover members 28 is illustrated in Figs. 3 and 4. The pair of cover members 28 are substantially identical. In an assembled condition of the cover 16, where the pair of cover members 28 are mounted to the base frame 12 in the base frame opening 14, the cover 16 is substantially rectangular or square in plan view.

As illustrated in Figs. 3 and 4, each of the pair of cover members 28 comprises a plurality of formations 20. A respective formation 20 extends from each respective corner portion 22 of the cover member 28. As best illustrated in Figs. 7 and 8, each of the plurality of formations 20 is configured to provide a point of contact with a corresponding corner portion 34 of the base frame 12 to fix the position of the cover member 28 relative to the base frame 12 when the cover member 28 is mounted to the base frame 12 in the base frame opening 14.

In the illustrated examples, in use each of the plurality of formations 20 provides a point of contact with an inner surface 24 of the upstanding side wall 18 in the corresponding corner portion 34 of the base frame 12. The inner surface 24 faces into the base frame opening 14 In the illustrated example, in a condition of the assembly where the cover 16 is mounted to the base frame 12 in the base frame opening 14, the formations 20 are the only part of each respective cover member 28 in contact with the upstanding side wall 18 of the base frame 12. Accordingly, there are no other points of contact in the vertical plane between each respective cover member 28 and the upstanding side wall 18 of the base frame 12. Furthermore, there are no other points of contact in the vertical plane between each respective cover member 28 and base frame 12.

In such examples, the cover 16 comprises two pairs of diagonally opposite corner portions 22, wherein a dividing line 30 between the pair of cover members 28 extends through a one of the pairs of diagonally opposite corner portions 22. Each of the pair of diagonally opposite corner portions 22 through which the dividing line 30 extends comprises a formation 20 from each of the pair of cover members 28. In the illustrated example, each of the pair of diagonally opposite corner portions 22 through which the dividing line 30 extends comprises two formations 20, one from each of the pair of cover members 28.

Each of the other pair of diagonally opposite corner portions 22 of the cover 16 comprises a formation 20 from a respective cover member 28. In the illustrated examples, each of the other pair of diagonally opposite corner portions 22 of the cover 16 comprises a single formation 20.

In other examples (not illustrated), the cover 16 may comprise a single cover member 28 which is substantially rectangular or square in plan view. The single cover member 28 comprises two pairs of diagonally opposite corner portions 22, wherein each of the corner portions 22 may comprise a single formation 20.

As best illustrated in Fig. 5, in some examples the base frame 12 comprises a plurality of seats 32, one in each corner portion 34 of the base frame 12. Each respective seat extends from the upstanding side wall 18 into the base frame opening 14.

The cover 16 comprises a plurality of corner mountings 36, one on the underside of each corner portion 22 of the cover 16. In use, the corner mountings 36 are locatable on corresponding seats 32 of the base frame 12 when the cover 16 is mounted in the base frame opening 14.

In the illustrated example, wherein the cover comprises a pair of cover members 28, each of which is substantially triangular in plan view, each of the pair of cover members 28 comprises a plurality of corner mountings 36, one on the underside of each of the three corner portions 22 of the cover member 28 (see Fig. 3, for instance). In use, the corner mountings 36 are locatable on corresponding seats 32 of the base frame 12 when the cover member 28 is mounted in the base frame opening 14. Accordingly, in use the three corner mountings 36 of the cover member 28 locate on three corresponding seats 32 of the base frame 12, and therefore there are only three points of contact in the horizontal plane between each respective cover member 28 and the base frame 12 (stable three-point suspension principle). There are no other points of contact in the horizontal plane between each respective cover member 28 and base frame 12.

The corner mountings 36 on adjacent cover members 28 of the assembled cover 16 either side of the dividing line 30 are locatable on a common seat 32 of the base frame 12. In some examples, the corner mounting 36 on each respective cover member 28 opposite the dividing line 30 comprises a hinge means 52 to facilitate actuation of each respective cover member 28 in the seat 32 to allow access to the hole.

The corner mountings 36 of the cover 16 correspond in position and geometry to the seats 32 of the base frame 12. In use, the corner mountings 36 of the cover 16 intimately contact the seats 32 of the base frame 12. The seats 32 define seating positions for the cover 16.

As illustrated in Fig. 5, the base frame 12 comprises two pairs of diagonally opposite corner portions 34. A first pair of the diagonally opposite corner portions 34 each comprise a stop member 38. As illustrated in Fig. 8, each respective stop member 38 is configured to abut against a corresponding stop member 40 on each of the pair of cover members 28 either side of a dividing line 30 between the pair of cover members 28. The stop members 40 on each respective cover member 28 are illustrated, for instance, in Fig. 3. With respect to each of the first pair of the diagonally opposite corner portions 34 of the base frame 12, the stop member 38 extends from the seat 32. With respect to each of the pair of cover members 28, the corresponding stop member 40 extends from the corner mounting 36.

As best illustrated in Fig. 2, in examples of the disclosure the cover 16 comprises an upper part 42 defining a top face 44 or surface 44 of the cover 16, and a lower part 46 underlying the upper part 42.

As best illustrated in Figs. 7 and 8, in a condition of the assembly 10 where the cover 16 is mounted to the base frame 12, there is a gap 48, i.e. clearance between the upper part 42 of the cover 16 and the upstanding side wall 18 of the base frame 12 extending around the perimeter of the upper part 12. The formations 20 extend outwardly from the lower part 46 beyond the upper part 42. Accordingly, the formations 20 are below the surface 44 of the cover 16, i.e. below the upper part 42. In use, the formations 20 therefore provide a point of contact with corresponding corner portions 34 of the base frame 12 below the upper most portion of the upstanding side wall 18. The formations 20 are therefore all recessed below the surface 44 of the cover 16. The formations 20 define the outermost extent of the cover 16. The lower part 46 comprises the corner mountings 36. The corner mountings 36 extend downwardly in use from the lower part 46 of the cover 16.

As best illustrated in Fig. 4, in some examples a one of the plurality of formations 20 terminates in a substantially flat end 48, and the other of the plurality of formations 20 terminate in a tapered end 50.

In other examples (not illustrated), each of the plurality of formations 20 may terminate in a tapered end 50, i.e. all the formations terminate in a tapered end 50.

A tapered end 50 means that the end of the formation 20 is relatively sharp, i.e. has a relatively sharp edge compared to the base of the formation 20.

Accordingly, the formation 20 narrows as it extends horizontally outwardly from the cover 16. Formations 20 which terminate in a tapered end 50 may be partially deformable.

A substantially flat end 48 means that the end of the formation 20 does not terminate in a sharp edge compared to the base of the formation 20. Accordingly, the formation 20 as a broad or blunt end.

The formations 20 may be referred to as teeth or pips. In the illustrated examples, the formations 20 (with a tapered end 50 or with a substantially flat end 48) taper downwardly in a vertical direction. Accordingly, the formations 20 are substantially wedge-shaped.

In some examples in which the cover 16 comprises a pair of cover members 28, each of which is substantially triangular in plan view, each corner portion 22 of a respective cover member 28 comprise a formation 20 which terminates in a tapered end 50. Accordingly, there are three contact points (defined by a single formation 20 at each respective corner portion 22 of the cover member 28) all of which terminate in a tapered end 50. Accordingly, when the cover 16 is mounted to the base frame 12 a very high contact stress is applied to the local surface of the adjoining base frame 12, thereby plastically deforming the base frame 12 surface at the location of the formation 20 very slightly resulting in mechanical interlocking between the cover 16 and the base frame 12. This mechanical interlock (surface engagement) acts as a non-return feature to unintended vertical cover 16 dislodgement.

In other examples (and as illustrated) in which the cover 16 comprises a pair of cover members 28, each of which is substantially triangular in plan view, two of the corners portions 22 of a respective cover member 28 comprise a formation 20 which terminates in a tapered end 50 and one of the corner portions 22 comprises a formation 20 which terminates in a substantially flat end 48. Accordingly, there are three contact points (defined by a single formation 20 at each respective corner portion 22 of the cover member 28) two of which terminate in a tapered end 50 and one of which terminates in a substantially flat end 48. In such examples, no surface plastic deformation is induced in the adjoining base frame 12 at the location of the formation 20 with a substantially flat end 48. However, and as before, surface plastic deformation is induced in the adjoining base frame 12 at the locations of the two formations 20 which terminate in a tapered end 50.

In each case, possibly formations 20 which terminate in a tapered end 50 deform against the surface of the base frame 12, whereas formations 20 which terminate in a substantially flat end 48 do not deform against the surface of the base frame 12.

With regard to examples in which the cover 16 comprises a pair of cover members 28, each of which is substantially triangular in plan view, wherein two of the corners portions 22 of a respective cover member 28 comprise a formation 20 which terminates in a tapered end 50 and one of the corner portions 22 comprises a formation 20 which terminates in a substantially flat end 48, the formations 20 prevent movement of each respective cover member principally in two directions in a horizontal plane. The movement prevented in the horizontal plane is a sliding movement of the cover 16 relative to the base frame 12.

The first direction of movement prevented is between the corner portions 34 of the base frame 12 either end of the dividing line 30. In this case, the formation 20 at one end of the cover 16 has a substantially flat end 48 and the formation 20 at the other end of the cover 16 has a tapered end 50. Accordingly, in use the formation 20 with the tapered end bites into its corresponding corner portion 34 of the base frame 12, and the formation 20 at the other end is urged up against its corresponding corner portion 34 of base frame 12 (without biting into the surface).

The second direction of movement is between the corner portion 34 of the base frame 12 opposite the dividing line 30 and the two stop members 38 of the base frame 12. Accordingly, in use the formation 20 with the tapered end bites into its corresponding corner portion 34 of the base frame 12, and the two respective stop members 40 of the cover member 28 are urged up against the corresponding two respective stop members 38 of the base frame 12.

The first direction is therefore perpendicular to the second direction.

In examples in which all the formations 20 of the cover member 28 terminate in a tapered end 50, the first direction of movement is prevented when formations 20 at either end of the dividing line 30 respectively bite into the corresponding corner portions 34 of the base frame 12.

Accordingly, in the illustrated examples, formations 20 with a tapered end 50 are configured to bite into the upstanding side wall 18 in a corresponding corner portion 34 of the base frame 12. Formations 20 with a substantially flat end 48 are configured to abut against, i.e. to urge up against, the upstanding side wall 18 in a corresponding corner portion 34 of the base frame 12.

In examples (not illustrated) where the cover comprises a single cover member 28 which is substantially rectangular or square in plan view, there are four contact points (defined by, for example, a single formation 20 at each respective corner portion 22 of the cover member 28 engageable with the corresponding four corner portions 34 of the base frame 12). In such examples, each corner portion 22 of the single cover member 28 may comprise a formation 20 which terminates in a tapered end 50. Alternatively, a one of the corner portions may comprise a formation which terminates in a substantially flat end 48, with the other three corners comprising a formation 20 which terminates in a tapered end 50.

In some examples, a split or splits may be provided in the upstanding side wall 18 of one or more of the respective corner portions 34 of the base frame 12. In use, when the cover 16 is mounted to the base frame 12 and a respective formation 20 (for instance terminating in a tapered end) is urged against the upstanding side wall 18 comprising the split or splits, the base frame 12 flexes to a greater extent at these specific locations than would otherwise be the case without the split or splits. This may further improve the mechanical interlock (surface engagement) and/or facilitate mounting of the cover 16 in the base frame 12.

The figures also illustrate a method of mounting a cover 16 to a base frame 12 of a ground surface access assembly 10. The method comprises mounting the cover 16 to the base frame 12 in a base frame opening 14. The method also comprises providing a point of contact between each of a plurality of formations 20 of the cover 16 and the base frame 12 to fix the position of the cover 16 relative to the base frame 12. At least one formation 20 extends from each respective corner portion 22 of the cover 16, and the point of contact is with a corresponding corner portion 34 of the base frame 12.

Examples of the disclosure provide a number of advantages as detailed above and as follows. For instance, the formations 20 provide active restraint of the cover 16 relative to the base frame 12 at the stable corner seating positions 22, 34. The stable corner seating positions 22, 24 are provided by the interaction of the corner mountings 36 of the cover 16 with the corresponding seats 32 of the base frame 12. This limits wear between the cover 16 and the frame 12 at the stable corner seating positions 22, 34, and prevents accidental disengagement.

Furthermore, active restraint can contribute to cover safety during trafficking by preventing collision between adjoining covers 16 and subsequent cover 16 ejection.

The formations 20 partially indent the base frame 12 surface at the specific locations described above, and therefore the cover 16 is essentially locked in place, i.e. it requires a prising operation to remove the cover 16 from the base frame 12.

Furthermore, because the points of contact with the base frame 12 provided by the formations 20 are narrow they can be located accurately just at the most stable corner portions 34 of the base frame 12. This means that even in a worst-case scenario of the base frame 12 supporting the cover 16 entirely though the formations 20, the cover 16 will still behave in a stable manner under traffic load.

Furthermore, the cover 16 only contacts the base frame 12 in the respective corner portions 34. Furthermore, each respective cover member 28 only contacts the base frame 12 in the respective corner portions 34, and therefore examples of the disclosure are in accordance with the stable three-point suspension principle, which provides stability for each respective cover member 28 during trafficking.

Accordingly, in examples of the disclosure there is not continuous contact between the cover 16 (or each respective cover member 28) and the base frame 12.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, the assembly 10 may be formed from any suitable material, for example, instead of ductile cast iron, the assembly 10 could be formed of plastics. For example, the base frame 12 may comprise vertical slots adjacent the corner portions 34 to reduce the elasticity of the base frame 12, and thus the tendency for the base frame 12 to eject the cover 16.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

The term "comprise" is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising Y indicates that X may comprise only one Y or may comprise more than one Y. If it is intended to use "comprise" with an exclusive meaning then it will be made clear in the context by referring to "comprising only one..." or by using "consisting".

In this brief description, reference has been made to various examples. The description of features or functions in relation to an example indicates that those features or functions are present in that example. The use of the term "example" or "for example" or "may" in the text denotes, whether explicitly stated or not, that such features or functions are present in at least the described example, whether described as an example or not, and that they can be, but are not necessarily, present in some of or all other examples. Thus "example", "for example" or "may" refers to a particular instance in a class of examples. A property of the instance can be a property of only that instance or a property of the class or a property of a subclass of the class that comprise some but not all of the instances in the class. It is therefore implicitly disclosed that features described with reference to one example but not with reference to another example, can where possible be used in that other example but does not necessarily have to be used in that other example.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

CLAIMS1. A ground surface access assembly, the assembly comprising: a base frame, wherein the base frame defines a base frame opening; and a cover mountable to the base frame in the base frame opening; wherein the cover comprises a plurality of formations, wherein at least one formation extends from each respective corner portion of the cover, wherein each of the plurality of formations is configured to provide a point of contact with a corresponding corner portion of the base frame to fix the position of the cover relative to the base frame when the cover is mounted to the base frame in the base frame opening.
2. An assembly according to claim 1, wherein the base frame comprises an upstanding side wall, wherein each of the plurality of formations is configured to provide a point of contact with the upstanding side wall in the corresponding corner portion of the base frame.
3. An assembly according to claim 2, wherein in a condition of the assembly where the cover is mounted to the base frame in the base frame opening, the formations are the only part of the cover in contact with the upstanding side wall of the base frame.
4. An assembly according to claims 2 or 3, wherein the cover comprises an upper part defining a top face of the cover and a lower part underlying the upper part, and wherein in a condition of the assembly where the cover is mounted to the base frame, there is a gap between the upper part of the cover and the upstanding side wall of the base frame extending around the perimeter of the upper part.
5. An assembly according to claim 4, wherein the formations extend outwardly from the lower part of the cover, and are configured to provide a point of contact with corresponding corner portions of the base frame below an upper most portion of the upstanding side wall.
6. An assembly according to any of the preceding claims, wherein each of the plurality of formation terminates in a tapered end.
7. An assembly according to any of claims 1 to 5, wherein some of the plurality of formations terminate in a substantially flat end, and some of the plurality of formations terminate in a tapered end.
8. An assembly according to claims 6 or 7, wherein formations with a tapered end are configured to bite into a corresponding corner portion of the base frame.
9. An assembly according to claim 7, wherein formations with a substantially flat end are configured to abut against a corresponding corner portion of the base frame.
10. An assembly according to any of the preceding claims, wherein the cover comprises a pair of cover members, each of which is substantially triangular in plan view.
11. An assembly according to claim 10, wherein each of the pair of cover members comprises a plurality of formations, wherein a formation extends from each respective corner portion of the cover member, wherein each of the plurality of formations is configured to provide a point of contact with a corresponding corner portion of the base frame to fix the position of the cover member relative to the base frame when the cover member is mounted to the base frame in the base frame opening.
12. An assembly according to claim 11 when dependent on claim 2, wherein each of the plurality of formations is configured to provide a point of contact with the upstanding side wall in the corresponding corner portion of the base frame.
13. An assembly according to any of claims 10 to 12, wherein the cover comprises two pairs of diagonally opposite corner portions, wherein a dividing line between the pair of cover members extends through a one of the pairs of diagonally opposite corner portions.
14. An assembly according to claim 13, wherein each of the pair of diagonally opposite corner portions through which the dividing line extends comprises a formation from each of the pair of cover members, and wherein each of the other pair of diagonally opposite corner portions of the cover comprises a formation from a respective cover member.
15. An assembly according to any of the preceding claims, wherein the base frame comprises a plurality of seats, one in each corner portion of the base frame, wherein the cover comprises a plurality of corner mountings, one on the underside of each corner portion of the cover, the corner mountings being locatable on corresponding seats of the base frame.
16. An assembly according to claim 15, wherein the respective seats extend from the upstanding side wall into the base frame opening. 15
17. An assembly according to claim 15 or 16 when dependent on any of claims 10 to 14, wherein each of the pair of cover members comprises a plurality of corner mountings, one on the underside of each of the three corner portions of the cover member, the corner mountings being locatable on corresponding seats of the base frame.
18. An assembly according to any preceding claims when dependent on claim 13, wherein the base frame comprises two pairs of diagonally opposite corner portions, wherein a first pair of the diagonally opposite corner portions each comprise a stop member configured to abut against corresponding stop members on each of the pair of cover members either side of a dividing line between the pair of cover members.19. An assembly according to claim 18, wherein with respect to each of the first pair of the diagonally opposite corner portions of the base frame, the stop member extends from the seat.
19. An assembly according to claims 18 or 19, wherein with respect to each of the pair of cover members, the corresponding stop member extends from the corner mounting.
20. A method of mounting a cover to a base frame of a ground surface access assembly, the method comprising: mounting the cover to the base frame in a base frame opening; providing a point of contact between each of a plurality of formations of the cover and the base frame to fix the position of the cover relative to the base frame, wherein at least one formation extends from each respective corner portion of the cover, and the point of contact is with a corresponding corner portion of the base frame.
21. A method according to claim 20, wherein the base frame comprises an upstanding side wall, and the method comprises providing a point of contact between each of a plurality of formations of the cover and the upstanding side wall in the corresponding corner portion of the base frame.20 25 30