GB2391245A

GB2391245A - Manhole cover or gully grating

Info

Publication number: GB2391245A
Application number: GB0311731A
Authority: GB
Inventors: Peter Derrick Savage
Original assignee: Peter Savage Ltd
Current assignee: Peter Savage Ltd
Priority date: 2002-05-21
Filing date: 2003-05-21
Publication date: 2004-02-04
Anticipated expiration: 2023-05-21
Also published as: GB2391245B; GB0311731D0

Abstract

The manhole or gully grating comprises a frame 10 and at least one removable cover part 14 or grating part, the or each part being hinged to the frame by a hinge, the hinge comprising a boss 42 on the frame and a formation on the part to enable the part to pivot on the boss. The formation comprises an arm 68 with a lower flat surface and the boss has an upwardly facing flat that is at an acute angle to the horizontal so that when the part is pivoted up from the closed position, the part can be pulled in the direction away from the boss so that the lower surface of the part at the end rests on the upper surface of the frame and the flat surface of the arm is parallel to and slides on the flat on the boss so that the part can be removed by sliding. The flat on the boss is preferably at an angle of around 10 degrees while the lower flat surface is designed to be substantially horizontal when the cover/grating part is closed. The formation may comprise a second flat 78 at 90 degrees to the first so that when the part is in the open position the second flat lies on the flat on the boss. The formation may also include a second arm 66 to form a fork which receives the boss and the frame may include an element 46 behind which the second arm of the fork drops when the part is opened beyond vertical so as to inhibit movement back towards the closed position.

Description

1 2391245

A Manhole Cover or Gully Grating A commonly seen manhole cover has a square frame mounting two triangular cover parts which are generally in the shape of isoceles right-angle triangles. The frame has 5 a seat at each corner of the clear opening on which the corners of the cover parts rest.

Each cover part is therefore supported at the three corners and so will not rock when traffic passes over it. Rocking creates unwanted noise and can also reduce the life of the cover. The cover parts and frame are made of cast iron or ductile iron and have to withstand heavy traffic and so the cover parts and frames are very heavy. When it is 10 desired to open the manhole cover the cover parts must be removed by lifting them out, which risks injury to the operator because of the weight of the cover parts.

Another lcnown manhole cover therefore has the parts hinged to the frame to reduce the weight to be lifted and remove the possibility of the cover parts slipping sideways when lifted. The frame is square and the cover parts are hinged to opposite sides of 15 the square frame. The cover pasts rest in the open condition just past the vertical.

According to one aspect of the invention there is provided a manhole cover or gully grating comprising a frame and at least one removable cover part or grating part, the or each part being hinged to the frame by a hinge, the hinge comprising a boss on the 20 frame and a formation on the part to enable the part to pivot on the boss, the formation comprising an arm, the arm having a lower flat surface and the boss havmg an upwardly facing substantial flat which is at an acute angle to the horizontal such that when the part is pivoted up from the closed position, the part can be pulled in the direction away from the boss so that the lower surface of the part at the free end rests on the upper 25 surface of the frame and the flat surface of the arm is parallel to and slides on the flat on the boss so that the part can be removed by sliding.

In this way, the part can be removed but the operator does not have to lift the full weight of the part, unlike the known manhole cover described above. The operator 30 initially lifts half the weight of the part as Me part is lifted through a small angle, and

then pulled so that the part rests on the edge of the frame at one end along the boss at the other. Then the operator can siTnply pull the part to slide it off the frame.

Preferably, the downwardly facing portions of the part which engage the upper 5 surface of the frame as the part is removed by sliding are smooth.

The flat on the boss may be at any suitable angle to the horizontal and preferably is at 5 to 20 to the honwntal, more preferably 7 to 13 to the horizontal, most preferably about 10 to the horizontal.

10 The lower flat surface of the arm is preferably substantially horizontal when the part is closed.

The formation preferably includes a second flat at 90 to the plane of the part, so that when the part is opened to beyond the vertical the second flat of the formation is 15 parallel to and lies on the flat on the boss. The formation may include a second arm to form a fork to receive the boss. Preferably, the frame includes a member behind which one arm of the fork drops when the part is opened to beyond the vertical to thereby inhibit movement of the part in the closing direction. The end of the second arm of the fork may be angled and or rounded to form a contact surface to contact the member 20 on the frame. The member on the frame may include an angled guide surface to contact the end of the second arm of the fork.

In a preferred embodiment, the hinge consists of only two elements,the formation and the boss. The formation is preferably integral with the part, and the boss is 25 preferably integral with the frame.

In this way no separate parts are required for the hinge assembly, the manhole cover or gully grating can consist only of cover or grating parts and the Dame. Assembly is easy as the fork of the or each part is simply dropped on to the respective boss of Me 30 frame. The part or parts are often made of cast iron or ductile iron and therefore can be very heavy, but the part or parts cannot accidentally close because of the interaction

of the fork and the member of the frame. Thus the manhole cover or gully grating of the invention, although it is simple in design, and easy to manufacture, is also safe.

An embodiment of the invention will now be described by way of exernple and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the manhole cover of the embodiment; Figure 2 is the view of Figure 1 with two cover parts opened; Figure 3 is a plan view of the manhole cover in the closed position; Figure 4 is a plan view of the frame with the covers removed; 10 Figure 5 is an elevation in cross section at A-A of Figure 4; Figure 6 is an elevation in cross section at B-B of Figure 4; Figure 7 is an elevation showing the frame in cross section at C-C of Figure 3; Figure 8 is the view of Figure 7 with the corner part lifted and pulled out slightly; and 15 Figure 9 is the view of Figure 7 with the coyer partinthelocked open position.

The manhole cover 10 of the embodiment of the invention consists of a frame 12 and four cover parts 14.

20 The frame is generally in an inverted T shape in cross section (see Figure 5) and I comprises an upright wall 16 and inner and outer flanges 18, 20 extending generally horizontally from the lower edge of the wall 16. The flanges 18, 20 are generally of I constant width. The frame 10 is generally square. The ironer edge 22 of the inner flange 18 defines a central opening 24. Buttress flange webs 26 are provided between 25 the outer flange 20 and the upright wall 16. A seating 28 is provided as a web between adjacent sides of the upright wall 16 in two adjacent corners. A further web 30 in the shape of an inwardly protruding trapezium is provided centrally of the section of the wall 32 between the corner webs 28. Three rectangular seats 34, 36 are provided on the wall section 38 opposite the wall section 32. The rectangular seats 34, 36 are 30 arranged one in each corner and the other 36 centrally. The corner seats 34 are wider than the central seat 36. The seats 28, 30, 34, 36 are arranged with their upper support surfaces at about half the height of the upright wall 16. Behind each seat 34, 36 the

wall 38 is diverted outwards to form apocket40. Each pocket40 includes a boss 42 above the floor 44 of the pocket 40 and a cam 46 on the floor 44 of the pocket 40 (see Fig. 61. (The cam constitutes the aforesaid "member".) 5 The inner flange 18 includes an upwardly facing channel 48 which runs all the way round the inner flange 18 adjacent the inner edge 22 (see Fig. 4) A semicircular lug 50 protrudes inwards from the upright wall 16 in a section of the upright wall 16 between the sections 32, 38 and adjacent one of the triangular 10 comer seats28.

The seats 28, 30, 34, 36 and lug 50 which protrude inwards from the upright wall 16 do not overlap the central opening 24 when the frame 12 is viewed in plan (see Figure 4).

15 Turning now to the cover parts 14, there are four cover parts 14a, b, c, d.

Each cover part 14 includes a Connation defining two forks 52 which receive the bosses 42 to hingingly connect each cover part 14 to the wall 38 of the Rame 10. Each cover part 14 is very generally triangular in plan and comprises a plate like part 54 defining 20 an upper walking surface 56 coveredin raised squares 58 to provide grip (see Figs. 1 and 2) . A wall 60 depends from the upper plate 54 adjacent the edge of the plate 54 i so that the wall 60 and plate 54 form a box which is open downwardly. Strengthening ribs 62 depend from the plate 54 and extend inwardly from the corners of the box to I meet centrally so that they fonn a Y shape in plan. The ribs 62 and walls 60 depend to; 25 the same depth at the end adjacent the forks 52, so that the downwardly facing end portions 61, 65 of the ribs 62 and walls 60 lie in the same plane parallel to the plane of the plate 54. The ribs 62 then become shorter, the downwardly facing portions 61 thereof diverting upwardly to plateau at a higher level before diverting down again to their original length near to the opposite side of the cover part 14. The walls 60 30 also change depth at the same position across the cover part 14 as the ribs 62, but they become longer, the downwardly facing portions 65 following a smooth shallow curve with its maximum half way across the cover part 14 and then continuing flat as before

to the end. The contours of the walls 60 and ribs 62 in side profile are thus symmetrical as seen in Figures 7, 8 and 9 and Figure 2.

The cover parts 14a, b, c, d are arranged in series across the frame 12.

The first cover part 14a is hinged in the pocket 40 at one corner of the frame 12 and broadens towards its free end, which is arranged to seat on the corner seat 28 and central seat 30 on the opposite wall section 32 (see Fig. 3). The next cover part 14b in the series is hinged in the comer pocket 40 and the central pocket 40. It narrows 10 towards the wall section 32 and seats on the central seat 30 on that wall. Between them, the first two cover parts 1 4a, 14b cover half of the area defined by the upright wall 16. The first two coyer parts 14a, 14b are loosely bolted together by means of bolts 63 through the adjacent depending walls 60 of the cover parts 14a, 14b. The other two cover parts 14c, 14d are mirror images of the first two.

A long rectangular lug 64 extends laterally from the underside of the plate 56 of the second cover part 14b to lie underneath the plate 54 of the third cover part 14c in the other half of the cover (see Figs. 2 and 3).

20 Looking now in more detail at the hinging mechanism as shown in Figs. 6 to 9, the fork 52 consists of an arm 66 with a rounded end, and an arm 68 which tapers inwardly i The intrusion 69 between the arms 66, 68 of the fork 52 is square.

The lower surface 76 of the upper arm 68 is thus flat and parallel to the plane of the 25 plate 54 so that it is horizontal when the cover part is in the closed position. The rear surface 78 of the intrusion 69 is perpendicular to the plane of the plate 54. The anns 66, 68 are both straight sided and extend horizontally when the coyer pert 14 is closed. The boss 42 is in the form of a circular cross section peg but with a flat 70. i The flat 70 is at 10 to the horizontal, facing upwardly and outwardly. The upper 30 surface of the plate 54, as well as the upper surface 74 of the frame 16 are horizontal.

One side of the cam 46 lies directly beneath the boss 42 and rises on a large radius curve centred below the floor 44 to a peak behind the boss 44 falling away as a flat surface at 10 to the vertical.

5 All of the parts will be cast in cast iron or ductile iron and it is seen that, aside from the bolts 63, no additional parts are required. Indeed, the cover 10 can be used without the bolts 63. The manhole cover 10 thus consists of the frame 12, the cover parts 14a to 1 4d and, optionally, bolts 63.

10 The cover 10 can be placed in a road or other surface in known manner. The manhole cover 10 can be opened and closed by pivoting the cover parts 14. If it is desired to remove the cover parts 14, for example, to permit access to the central opening from all sides, or because the cover parts 14 or the whole manhole cover 10 need to be removed or replaced, then that is easily achieved. From the closed position 15 shown in Figure 7, the cover parts 14 are lifted off their seats 28, 30 through ten degrees and then pulled away from the boss 42 slightly so that the lowermost portions of the cover parts 14, which are the downwardly facing end portions 61, 65 of the walls 60 and ribs 62, rest on the upper surface 74 of the wall 16 of the frame 12.

In the first part of this movement, the lifting of the cover parts, the angle between the 20 lower surface 76 of the upper ann 68 and the flat 70 on the boss 42 decreases to zero, so that the two flat surfaces 76, 70 are in facing contact. When the second movement takes place, namely to pull the cover parts 14 so that the free end of the cover parts 14 1 rests on the upper edge 74 of the frame 12, the two flat surfaces 76, 70 slide across one another as seen in Figure 8. The operator can then continue to pull the cover parts 14 25 and they will slide on the upper surface 74 of the wall 16 of the frame. As the cover parts 14 slide across, the contact area changes as the ribs 62 become shorter and the walls 60 longer so that only the walls 60 are in contact with the wall 16. The i downwardly facing portions 65 of the walls 60 follow a smooth contour which promotes sliding. The cover parts 14 can thus be removed without having to lift the 30 whole weight of them. Only half the weight is lifted initially, as the cover parts 14 are lifted through ten degrees and pulled onto the top of the wall 16 of the frame 12, then

the rest of the removal operation is achieved by sliding, rather than lifting. Indeed, if the bolts 63 are not used, the cover parts 14 can be removed singly, one by one, to further reduce the effort on the part of the operator.

5 When it is desired to pivot open the cover 10, a hook (not shown) is placed in a hole 72 in the plate 54 of the first cover part 14a. As the first cover part 14a is lifted, it will lift the second cover part 14b, because the two parts are connected by the bolts 63. The overlapping flange 64 will also cause the third cover part 14c to lift together with the second cover part 14b and as the fourth cover part 14d is bolted to the third cover part 10 14c that will also lift and all four parts 14 will be raised together. If it is desired to reduce the lifting load, then the hook can be inserted into the fourth cover part 14d and that will just lift the third and fourth cover parts 14c, d. The first and second parts 14a, b can then be lifted separately. Theload can be further reduced by omitting the bolts 63 between the cover parts 14. In that case, the first to fourth cover parts 14 15 can be lifted in turn.

Where the bolts 63 are used, the manhole cover 10 can be locked closed by providing a bore in the edge of the plate 54 of the fourth cover part 14d above the lug 50 and providing a tapped bore in the lug 50 so that a bolt can be screwed in to hold 20 the cover 14 closed. Although only the fourth cover part 14d is bolted down, the bolts i 63 to the third cover part 14c will prevent the third cover part 14c from opening, and the lug 64 will prevent the second cover part 14b from opening, the bolts 63 between I the first cover part 14a and the second cover part 14b preventing the first cover part 14a from opening as well.

When each cover part 14 is opened, it is seen that one ann 66 of the fork 52 rides up the curved surface of the cam 46, and at the peak, drops down, as permitted by the i flat 70 on the boss 42tolock the cover partl4in the position shown inFigure2.

The plate 54 of the cover part 14 is then at 110 and the rear surface 78 of the intrusion 30 69 between the amps 66, 68 of the fork 52 is in face to face contact with the flat 70 of the boss 42. In order to pivot the cover part 14 back into the closed position, the cover part 14 must be lifted to disengage the arm 66 and then the cover part 14 can

be pivoted beck again into the closed position. In an alternative embodiment, the lower arm66is shortened or omitted, as is the cam 46. The cover part 14 is then held in place simply by engagement of the flat surfaces 70, 78 and engagement with the rear wall 80 of the pocket 40.

5 The channel 48 can receive a rubber insert to mount a secondary internal cover.

The manhole cover 10 of the embodiment provides excellent access as three sides of the opening are unobstructed.

The fact that the seats 28, 30, 34, 36 and lug 50 do not overlap the central opening 24 means that the opening is of regular shape for optimum access.

10 Where the cover parts are bolted together,as mentioned previously they are bolted loosely and in that way some pivoting movement between the cove parts 14 can sell talce place. Thus, in the ease ofthe first coyer partl4a,for example, the cover part 14a is supported on the closely adjacent bosses 42 at one end and at the corner seat 28 and central seat 30 at the other end. It is therefore effectively in close to three point 15 contact toinhibit rocking. The fact that it is loosely bolted to the second coyer pert 14b means that it is free to assume a three contact position rather than being constrained in its positioning by its connection to the next cover part.

In another embodiment (not shown) a manhole cover is provided which is 50% wider 20 than the cover 10 of the first embodiment and includes two further cover parts which are identical to either the first and second or third and fourth cover parts 14. In a still fiercer embodiment, a manhole cover is provided which is twice as wide as the cover of the first embodiment and in that case a furler full set of cover plates identical to the first to fourth parts 14 of the first embodiment are provided.

Claims

Claims

5 1. A manhole or gully grating comprising a frame and at least one removable cover part or grating part, the or each part being hinged to the frame by a hinge, the hinge comprising a boss on the frame and a formation on the part to enable the part to pivot on the boss, the formation comprising an arm, the arm having a lower flat surface and the boss having an upwardly facing substantial flat which is at an acute angle to the 10 horizontal such that when the part is pivoted up from the closed position,the pert can be pulled in the direction away from the boss so that the lower surface of the part at the free ends rests on the upper surface of the frame and the flat surface of the arm is parallel to and slides on the flat on the boss so that the part can be removed by sliding.
2. A manhole cover or gully grating as claimed in claim 1, wherein the downwardly facing portions of the part which engage the upper surface of the frame as the part is removed by sliding are smooth.

20
3. A manhole cover or gully grating as claimed in claim 1 or claim 2, wherein the flat on the boss is at S to 20 to the horizontal.
4. A manhole cover or gully grating as claimed in claun 1 or claim 2, wherein the flat on the boss is at 7 to 13 to the horizontal.
5. A manhole cover or gully grating as claimed in claim l or claim 2, wherein the flat on the boss is at 10 to the horizontal.
6. A manhole cover or gully grating as claimed in any preceding claim, wherein 30 the lower flat surface is substantially horizontal when the part is closed.
7. A manhole cover or gully grating as claimed in any preceding clann, wherein the formation includes a second flat at 90 to the plane of the part so that when the part is opened to beyond the vertical, the second flat on the formation is parallel to and lies on the flat on the boss.
8. A manhole cover or gully grating as claimed in any preceding claim wherein the formation includes a second arm to form a fork to receive the boss.
9. A manhole cover or gully grating as claimed in claim 8, wherein the frame
10 includes a member behind which the second arm of the fork drops when the part is opened to beyond the vertical to thereby inhibit movement of the part in the closing direction. 10. A manhole cover or gully grating as claimed in claim 8 or claim 9, wherein the 15 end of the second arm of the fork is angled and/or rounded to form a contact surface to contact the member on the frame.
11. A manhole cover or gully grating as claimed in claim 9 or claim 10, wherein the member on the frame includes an angled guide surface to contact the second arm of 20 the fork.
12. A manhole cova or gully grating as claimed in any preceding clann, wherein the hinge consists of only two elements, the formation and the boss.

25
13. A manhole cover or gully grating asclaimedin any preceding claim, wherein the formation is integral with the part.
14. A manhole cover or gully grating as claimed in any preceding claim, wherein the boss is integral with the flame.
15. A manhole cover or gully grating substantially as described herein and/or as shown in the accompanying drawings.