Frame

Abstract

 A frame (1) for mounting to a manhole chamber liner (6) and supporting one or more manhole covers (26). The frame (1) comprises one or more formations (4) for receiving one or more packing pieces (7) via which the frame (I) can be supported on the manhole chamber liner (6) thereby enabling the vertical position of the frame (1) relative to the manhole chamber liner (6) to be adjusted. The or each formation (4) may comprise an aperture or slot in the frame (1). The frame (1) may additionally comprise one or more packing pieces (7) which, together with the or each formation (4), are configured, respectively, so that a packing piece (7) received by a formation (4) is retained relative to the formation (4).

Description

[0001] The present invention relaxes to apparatus for adjusting the vertical position of manhole covers or the like on manhole chambers.

[0002] Manhole chambers are generally recessed into the ground to provide maintenance workers with easy access to cables, pipes and other supply lines that are located underground. To ensure public safety, manhole covers are placed onto these manhole chambers to prevent any accidental or unauthorized access which may cause injury. This is achieved by placing a supporting frame on top of a liner in the manhole chamber and then mounting one or more manhole covers on the frame.

[0003] When installed, manhole covers that are not flush with the surrounding ground level may present hazards to pedestrians and vehicles. It is therefor desirable to fit these manhole frame/cover combinations so that each manhole cover is flush with the surrounding ground level. Due to the variation in manhole chamber depth and the variation of the surrounding ground level this is not always possible. Often, the solution is to adjust the vertical position of the manhole frame so that, when seated in the frame, the manhole cover is level with the surrounding ground. This adjustment is generally achieved by packing bricks and mortar between the chamber liner top and the frame. Alternatively, steel adjustment bolts fixed to the frame may be used. It is an object of the present invention to provide an apparatus that simplifies this adjustment process.

[0004] According to a first aspect of the present invention there is provided a frame for mounting to a manhole chamber liner and supporting one or more manhole covers, the Same comprising one or more formations for receiving one or more packing pieces via which the frame can be supported on the manhole chamber liner thereby enabling the vertical position of the frame relative to the manhole chamber liner to be adjusted.

[0005] By varying the number and/or size of packing pieces it is possible to adjust the vertical position of the frame relative to a manhole chamber liner on which it is supported, and hence the vertical position of the manhole cover supported on the frame relative to the surrounding ground.

[0006] The formation may comprise an aperture or slot in the frame. Preferably, there is also provided one or mote packing pieces and the or each packing piece end the or each formation of the frame are configured, respectively, so that a packing piece received by a formation is retained relative to the formation. This facilitates movement of the frame by enabling the frame to be moved without any fitted packing pieces becoming separated from the frame, or at least reduces the risk of separation.

[0007] The retention of the or each packing piece relative to the or each formation may be achieved by an interference fit. Alternatively, retention of the or each packing piece relative to the formation may be achieved by the or each packing piece and the or each formation having cooperating features. Alternatively, the or each packing piece may be retained relative to the or each formation via an adhesive. Alternatively, the or each packing piece may be retained relative to the or each formation via magnets.

[0008] In a preferred embodiment of the invention, the frame has a sheet-like portion via which it is supported, in use, by an upper surface of a manhole chamber liner and a skirt depending from the sheet-like portion of the frame and intended to extend into a manhole chamber liner on which the frame is mounted.

[0009] In this embodiment, the or each slot or aperture is preferably defined in the depending skirt of the frame. Thus, a packing piece can be inserted into a slot or aperture such that, when the frame is mounted to the manhole chamber liner, the packing piece is positioned between an upper surface 8 of the manhole chamber liner 6 and the sheet-like portion 2 of the frame 1.

[0010] In a preferred embodiment, the means for retention comprises a pair of projections on opposing sides of the packing piece designed to engage walls of the depending skirt of the frame. More preferably, the first projection of each pair is smaller than the second projection of each pair. More preferably, the distance between the two extremes of the first projections of each pair is less than the distance between the two extremes of the second projections of each pair. More preferably, the distance between the two extremes of the first and second projections respectively is greater than the width of an aperture or slot in the frame into which the packing pieces are intended to be received.

[0011] Preferably, the first projections are tapered. More preferably, the first projections taper off away from the second projections. More preferably, the sides of the first projections facing the second projections are arranged to resistively engage walls of the depending skirt. More preferably there is defined a channel between the projections of each pair whose width is approximately equal to the thickness of the walls of the depending skirt.

[0012] Preferably, the first projections of each pair are flexible. More preferably, the first projections are sufficiently flexible to allow the distance between the two extremes of the first projections of each pair to be made less than the width of the aperture.

[0013] Preferably, the first projections may be depressed relative to the sides of the packing piece. More preferably, the first projections are spring loaded.

[0014] Preferably, the angle between the sides of the packing piece from which the second projections extend and the side of the second projections facing the first projections is such that the sides of the second projections facing the first projections conform to the outer walls of the depending skirt.

[0015] According to a second aspect of the present invention, there is provided a packing piece for use with a frame as hereinbefore described, comprising retention means for retaining the packing piece in a formation in the frame.

[0016] Advantageously, a packing piece of desired thickness may be fixed relative to the frame such that, when the frame is being maneuvered, the packing piece does not fall out of the formation to which it is fixed.

[0017] In order that the invention may be more clearly understood, embodiments 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 frame according to the present invention which has mounted to it, a manhole cover, and which is itself mounted to a manhole chamber liner.

Figure 2

is a perspective view of a frame according to the present invention and a manhole cover which may be mounted to the frame.

Figure 3

is an exploded, out away perspective view of a flame according to the present invention together with a packing piece and a manhole chamber liner.

Figure 4

is an alternative perspective view of the apparatus shown in Figure 3.

Figure 5

is a side view of the frame and packing piece shown in Figures 3 and 4 mounted to the manhole chamber liner.

Figure 6

is a perspective view of a corner of the frame shown in Figure 3.

Figure 7

is a plan view of the packing piece shown in Figure 3.

Figure 8

is a perspective view of a packing piece shown in Figure 7.

Figure 9

is an enlarged view of a portion of the packing piece shown in Figure 7.

Figure 10

is a side view of packing pieces of different thickness.

[0018] Referring to Figure 1, a frame 1, to which is mounted two manhole covers 26, is itself mounted to a manhole chamber liner 6 which is intended to be recessed into the ground. Packing pieces (not shown) are positioned between the frame 1 and the upper surface 8 of the manhole chamber liner 6. The packing pieces are positioned such that they engage the upper surface 8 of the manhole chamber liner 6 and maintain the frame 1 in a particular position relative to the manhole chamber liner 6.

[0019] Referring to Figure 2, the frame I is substantially rectangular in shape and defines an opening 28. Two manhole covers 26 are mounted to the frame I within the boundaries of a manhole cover retention lip 5 and fixed in place with screws. Thus, when the frame 1 is mounted to a manhole chamber liner 6, access to the manhole chamber is achieved by removing the manhole covers 26 and entering via the opening 28 defined by the frame 1.

[0020] Referring to Figures 3 to 6, the manhole cover support frame 1 comprises a substantially rectangular sheet-like portion 2 having (in the orientation depicted in the drawings) upper and lower faces, and inner and outer peripheral edges. A skirt 3 depends downwardly (again in the illustrated orientation) from the inner peripheral edge of the sheet-like portion 2, extending at an angle of approximately 90° to the faces of the sheet-like portion. The frame 1 further comprises a manhole cover retention lip 5 extending a distance of about 30mm from the upper face of the sheet-like portion 2 generally at right angles to the face and about midway between the inner and outer peripheral edges of the face which acts as a boundary for a manhole cover 26 (not shown) and ensures that the manhole cover 26 is securely seated on the frame 1. There is also shown a portion of a manhole chamber liner 6 and a polypropylene packing piece 7 which is shaped and configured to fit within an aperture 4. The dimensions of the apertures 4 are such that packing pieces 7 of varying thickness may inserted.

[0021] As can be seen from Figures 3, 4 and 5, the sheet-like portion of the frame 2 corresponds approximately to the upper surface 8 of the manhole chamber liner 6 both in terms of shape and dimensions such that, when mounted to the upper surface 8 of the manhole chamber liner 6, regardless of the presence of a packing piece 7, the lower face 9 of the sheet-like portion 2 would engage the upper surface 8 of the manhole chamber liner 6. In this preferred embodiment, the manhole chamber liner 6 and the frame 1 are rectangular in horizontal cross section. The depending skirt 3 which extends downwardly from the inner peripheral edge of the sheet-like portion 2 conforms to the inner walls 10 of the manhole chamber liner 6. Thus, when the frame 1 is mounted to the manhole chamber liner 6, the skirt 3 of the frame 1 retains the frame 1 laterally relative to the manhole chamber liner 6.

[0022] The apertures 4 are defined in the skirt 3 at each corner 11 (only one shown) of the frame 1. It will be appreciated, however, that, depending on the desired level of support, apertures 4 may optionally be defined in the skirt 3 at different parts of the frame 1, for instance, at intervals between each corner 11 to allow additional packing pieces 7 to be inserted.

[0023] Referring to Figures 7, 8 and 9, the packing piece 7 is rectangular in shape and comprises two pairs of outwardly extending projections, 17 and 18, and 17' and 18'. Each pair is positioned at one end 14 of the packing piece 7 and at opposite sides 15 and 16 of the packing piece. Each pair comprises a first projection 17 (and 17') and a second projection 18 (and 18') which is larger than the first. Both projections 17 and 18 taper off toward the opposing end 19 of the packing piece 7.

[0024] The first projections 17 and 17' extend out from the packing piece sides 15 and 16 such that the distance between the two extremes of each projection 20 and 20' is just greater than the width of an aperture 4. Each of the two projections 17 and 17' has a degree of flex that enables them to be urged in toward the packing piece sides 15 and 16. Thus when the packing piece 7 is inserted into a respective aperture 4, the two projections 17 and 17' are urged in toward the packing piece sides 15 and 16 which permits projections 17 and 17' to pass through the aperture to the inner side 30 of the skirt 3 of the frame 1 and snap into place. Since the two projections 17 and 17' taper off toward the opposing end 19 of the packing piece 7, when both projections 17 and 17' have passed through the aperture 4, the back sides 21 and 21'of each projection resistively engage the manhole chamber liner facing side 30 of the skirt 3. Projections 17 and 17', therefore, prevent the packing piece 7 from falling out of the aperture 4.

[0025] Referring to Figures 8 and 9. a channel 23 of width Approximately equal to the thickness, x, of the skirt 3 of the frame 1 is defined between the two projections of each pair of the packing piece 7. Thus, when the packing piece 7 is fixed in an aperture 4, the two projections of each pair, 17 and 18, and 17' and 18', engage either side of the skirt 3. When inserted into an aperture 4, the packing piece 7 is fixed so that it cannot easily fall out of the aperture 4 or slide up and down the skirt 3.

[0026] In this preferred embodiment, referring to Figure 7, the angle, θ, between the sides 15 and 16 and the tapered faces of the two respective larger projections 18 and 18' is chosen to be 135°. Since the packing piece 7 is intended to be inserted in an aperture 4 in the corner 11 of the frame 1, when inserted, the two projections 18 and 18' will conform to the outer side 25 of the skirt 3. From this example, it will be appreciated that, if the packing piece 7 was intended to be installed in an aperture defined mid way between the two corners I 1 of the frame 1, the angle, θ, would be chosen to be 90° to ensure that the two projections 18 and 18' conform to, and engage, the outer side 25 of the skirt 3. In doing so, the packing piece 7 is not permitted to pass entirely through the aperture 4 in which it is installed.

[0027] The length, L, of the packing piece 7 is chosen such that, when installed in an aperture, it is sufficiently long to extend between the upper surface 8 of the manhole chamber liner 6 and the sheet-like portion 2 of the frame. Likewise, the width, W, of the packing piece 7 is chosen, first of all, to be of less width than the aperture 4 but also to provide sufficient surface area to bear the load of the frame 1. In this example, the packing piece 7 is chosen to be of length about 103mm and width about 37.5mm whilst the corresponding apertures 4 are chosen to be of width about 38mm.

[0028] Referring to Figure 10, packing pieces 7 can be of different thickness. If it is required to raise the manhole support frame I by a height of 10mm, packing pieces 7 of thickness 10mm may be installed in corresponding apertures 4 in each corner 11 of the frame 1.

[0029] In use, depending on the distance between the upper surface 8 of the manhole chamber liner 6 and the surrounding ground, packing pieces 7 of appropriate thickness are inserted into the apertures 4 of the frame 1 so that, when the frame 1 is mounted to the manhole chamber liner 6 and the manhole cover 26 is mounted to the frame 1, the manhole cover 26 is level with the surrounding ground. So, for example, if the distance between the upper surface 8 of the manhole chamber liner 6 and the surrounding ground surface is 60mm, taking into account the fact that the manhole cover retention lip 5 is of height 30mm, a packing piece 7 of thickness 30mm would be appropriate. In this case, four packing pieces 7 of the desired thickness are inserted into respective apertures 4 defined in the skirt 3 at each corner 11 of the frame 1.

[0030] The packing pieces 7 are inserted tapered side first into their respective apertures 4 so that the first projections 17 and 17' come into contact with the outer walls 25 of the skirt 3. The packing pieces 7 are inserted with sufficient pressure such that, in each case, the walls of the skirt 3 urge the two projections 17 and 17' into their respective sides 15 and 16 of the packing piece. The two projections 17 and 17' are urged toward their respective sides 15 and 16 until the distance between the two extremes 20 and 20' of each projection is less than the width of the aperture 4 thereby allowing the two projections 17 and 17' to pass beyond the wall of the skirt 3. Once the projections 17 and 17' are through the aperture 4, the two projections 17 and 17' return to their natural state whereby the back sides 21 and 21' of the projections engage the inner side 30 of the skirt 3 and prevent the packing piece 7 from falling out of the aperture 4 in which it is installed.

[0031] Since the distance between the two extremes 22 and 22' of the second projections 18 and 18' is greater than the width of the apertures 4, and they have less ability to flex than the first projections 17 and 17', the two projections 18 and 18' engage the outer wall 25 of the skirt 3 and prevent the packing piece 7 from passing entirely through the aperture 4. In this position, projections 17 and 17' and 18 and 18' firmly engage either side of the skirt 3 and maintain the packing piece 7 in a fixed position relative to the frame 1.

[0032] When a packing piece 7 of appropriate thickness is inserted into each respective aperture 4 of a corner II of the frame 1. the frame may be lowered onto the upper surface 8 of the manhole chamber liner 6. Each packing piece 7 then engages the upper surface 8 of the manhole chamber liner 6 and thus maintain the frame 1 at a vertical position above the manhole chamber liner 6. The vertical position of the frame 1 is such that, when a manhole cover is mounted onto the frame 1, within the boundaries of the manhole cover retention lip 5, the manhole cover 26 is flush with the surrounding ground level. The vertical position of the manhole cover 26 relative to the manhole chamber liner 6 is, therefore, easily and conveniently adjusted as desired.

[0033] If it becomes necessary to remove the packing pieces 7, this is achieved by pinching the two first projections 17 and 17' in towards their respective packing piece sides 15 and 16 until the distance between the two extremes of each projection 20 and 20' is less than the width of the aperture 4 in which it is installed. At this point, it is possible for the packing piece 7 to pass back through the aperture 4 and clear of the frame 1.

[0034] The two projections 17 and 17' can be spring loaded to the packing piece sides 15 and 16. Alternatively, the two projections 17 and 17' can be hinged to the packing piece sides 15 and 16. Alternatively, projections 17 and 17' may comprise material of higher elasticity than the rest of the packing piece 7. Alternatively, the aperture may comprise protections that fit within recesses in the sides of the packing piece such that, when the packing piece is inserted in the aperture, the projections of the apertures fit into the recesses in the packing piece sides and retain the packing piece relative to the aperture.

[0035] It is of course to be understood that the above embodiments have been described by way of example only and that many variations are possible without departing from the scope of the invention.

Claims

1. A frame (1) for mounting to a manhole chamber liner (6) and supporting one or more manhole covers (26), the frame (1) comprising one or more formations (4) for receiving one or more packing pieces (7) via which the frame (1) can be supported on the manhole chamber liner (6) thereby enabling the vertical position of the frame (1) relative to the manhole chamber liner (6) to be adjusted.

2. A frame as claimed in claim 1, wherein the formation (4) comprises an aperture or slot in the frame (1).

3. A frame as claimed in claim 1 or 2, wherein the frame (1) further comprises one or more packing pieces (7) and the or each packing piece (7) and the or each formation (4) are configured, respectively, so that a packing piece (7) received by a formation (4) is retained relative to the formation (4).

4. A frame as claimed in claim 3, wherein the or each packing piece (7) may be retained relative to the or each formation (4) by an interference fit.

5. A frame as claimed in claim 3, wherein the or each packing piece (7) may be retained relative to the or each formation (4) by the or each packing piece (7) and the or each formation (4) having cooperating features.

6. A frame as claimed in claim 3, wherein the or each packing piece (7) may be retained relative to the or each formation (4) by magnets.

7. A frame as claimed in any preceding claim, wherein the frame (1) has a sheet-like portion (2) via which it is supported, in use, by an upper surface (8) of a manhole chamber liner (6) and a skirt (3) depending from the sheet-like portion (2) of the frame (1) and intended to extend into the manhole chamber liner (6) on which the frame (1) is mounted.

8. A frame as claimed in claim 7 when dependent directly or indirectly upon claim 2, wherein the or each slot or aperture is defined in the depending skirt (3) of the frame (1).

9. A frame as claimed in claim 7 or 8 when dependent directly or indirectly upon claim 5, wherein the means for retention comprises a pair of projections (17), (18) and (17'), (18') on opposing sides of the packing piece (7) designed to engage walls of the depending skirt (3) of the frame (1).

10. A frame as claimed in claim 9, wherein the first projection (17), (17') of each pair is smaller than the second projection (18), (18') of the pair.

11. A frame as claimed in claim 10, wherein the distance between the two extremes (20), (20') of the first projections (17), (17') of each pair is less than the distance between the two extremes (22), (22') of the second projections (18), (18') of each pair.

12. A frame as claimed in claim 11 when dependent indirectly upon claim 2, wherein the distance between the two extremes (20), (20') and (22), (22') of the first and second projections (17), (17') and (18), (18') respectively is greater than the width of an apertures or slot (4) in the frame (1) into which the packing pieces (7) are intended to be received.

13. A frame as claimed in any of claims 9 to 12, wherein the first projections (17), (17') taper away from the second projections (18), (18'), the sides (21), (21') of the first projections facing the second projections are arranged to resistively engage walls of the depending skirt (3) and there is defined a channel between the projections of each pair whose width is approximately equal to the thickness of the walls of the depending skirt (3).

14. A frame as claimed in any of claims 9 to 13, wherein the first projections (17), (17') of each pair are sufficiently flexible to allow the distance between the two extremes (20), (20') of the first projections (17), (17') of each pair to be made less than the width of the aperture or slot (4).

15. A packing piece for use with a frame as defined by any preceding claim, the packing piece (7) comprising retention means (17), (17') and (18), (18') for retaining the packing piece in a formation (4) in the frame (1).

Drawing