GB2388864A

GB2388864A - Manhole cover or gully grating

Info

Publication number: GB2388864A
Application number: GB0302181A
Authority: GB
Inventors: Peter Derrick Savage
Original assignee: Peter Savage Ltd
Current assignee: Peter Savage Ltd
Priority date: 2002-05-21
Filing date: 2002-08-05
Publication date: 2003-11-26
Also published as: GB0302181D0

Abstract

The manhole covers or gully gratings comprises a frame and at least one cover part or grating part. Each part is hinged to the frame by a hinge made of only two elements, a fork 52 and a boss 42, with the fork being integral with the part and the boss being integral with the frame, so that the fork is received on the boss upon which it pivots. Each fork is formed with two arms that are substantially horizontal when the part is in lowered position. The boss includes an upwardly facing substantial flat which is at a small acute angle to the horizontal. The frame is also provided with a member 46 behind which one of the arms of the fork drops when the cover part is opened to beyond the vertical so as to inhibit movement of the part back in the closing direction. The end of the aforementioned fork arm may be angled to form a contact surface to contact the frame and the fork may have a rounded surface to engage the boss. Similarly, the member on the frame may be provided with an angled guide surface to contact the arm of the fork.

Description

A Manhole Cover or Gully Grating The invention relates to a manhole cover

or gully grating.

5 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 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 10 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 desired to open the manhole cover the cover parts must be removed, which risks injury to the operator because of the weight of the cover parts.

15 Another known 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 liked. The frame is square and the cover parts are hinged to opposite sides of the square frame. The cover parts rest in the open condition just past the vertical.

20 According to the invention there is provided a manhole cover or gully grating comprising a frame and at least one cover part or grating part, the or each part being hinged to the frame by a hinge made of only two elements, a fork and a boss, the fork being integral with the part and the boss being integral with the frame, the fork receiving the boss to pivot thereon, the two arms of the fork extending substantially 25 horizontally when the part is closed, the boss including an upwardly facing substantial flat which is at a small acute angle to the horizontal, the frame including 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.

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 frame. Assembly is easy as the fork of the or each part is simply dropped on to the respective boss of the frame.

The part or parts are often made of cast iron or ductile iron and therefore can be very 5 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.

Preferably the end of said arm of the fork is angled to form a contact surface to contact 10 the member on the frame. Additionally or alternatively, said member on the frame may include an angled guide surface to contact the said arm of the fork.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: 15 Figure I is a perspective view of the manhole cover of the embodiment; Figure 2 is the view of Figure I 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; Figure 5 is an elevation in cross section at A-A of Figure 4; 20 Figure 6 is an elevation in cross section at B-B of Figure 4; Figure 7 is a fragmentary detail view of one end of a cover part in elevation; and Figures 8a to 8c are elevations showing different degrees of pivoting at the hinge.

The manhole cover 10 of the embodiment of the invention consists of a frame 12 and 25 four cover parts 14.

The frame is generally in an inverted T shape in cross section (see Figure 5) and 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

( 3 constant width. The frame 10 is generally square. The inner edge 22 of the inner flange 18 defines a central opening 24. Buttress flange webs 26 are provided between 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 comers. A further web 30 in the 5 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 arranged one in each corner and the other 36 centrally. The corner seats 34 are wider than the central seat 36. The seats 28, SO, 34, 36 are arranged with their upper support surfaces 10 at about half the height of the upright wall 16. Behind each seat 34, 36 the wall 38 is diverted outwards to form a pocket 40. Each pocket 40 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. 6).

The inner flange 18 includes an upwardly facing channel 48 which runs all the way 15 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 comer seats 28.

20 The seats 28, SO, 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).

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

25 Each cover part 14 includes two forks 52 which receive the bosses 42 to hingingly connect each cover part 14 to the wall 38 of the frame 10. Each cover part 14 is very generally triangular in plan and comprises a plate like part 54 defining an upper walking surface 56 covered in raised squares 58 to provide grip (see Figs. I and 2). A wall 60 depends from the upper plate 54 adjacent the edge of the plate 54 so that the wall 60 30 and plate 54 fomm a box which is open downwardly. Strengthening ribs 62 depend from

the plate 54 and extend inwardly from the corners of the box to meet centrally so that they form a Y shape in plan.

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 corner 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 14a, 14b cover half of the area defined by the upright wall 16. The other two cover parts 14c, 14d are mirror images of the first two. The first two cover parts 14a' 14b are loosely bolted together by means of bolts 63 through the adjacent depending walls 60 of the cover parts.

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 8c, the fork 52 consists of an arm 66 with a rounded end, and an arm 68 which tapers inwardly.

The intrusion 69 between the arms 66, 68 of the fork 52 is part circular. The boss 42 is in the form of a circular cross section peg but with a flat 70. The flat 70 is at a small acute angle to the 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 a small acute angle 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. The cover parts 14 are lowered so that the boss 42 is received in the forks 52.

The adjacent walls 60 of the first and second parts 14a, 14b are bolted together, as are 5 the adjacent walls 60 of the third and fourth parts 14c, d. The cover 10 is then ready for placement in a road or other surface in known manner. When it is desired to open the cover 10, a hook 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 10 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 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. The load can be further IS reduced by omitting the bolts 63 between the cover parts 14. In that case, the first to fourth cover parts 14 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 20 providing a tapped bore in the lug 50 so that a bolt can be screwed in to hold the cover 14 closed. Although only the fourth cover part 14d is bolted down, the bolts 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 the first cover part 14a and the second cover part 14b preventing the first cover part 14a from 25 opening as well.

When each cover part 14 is opened, it is seen that one arm of the fork rides up the curved surface of the cam 46, and at the peak, drops down, as permitted by the flat 70 on the boss 42 to lock the cover part 14 in the position shown in Figure 2. In order to 30 replace the cover part 14, the cover part must be lifted to disengage the arm and then the cover part 14 can be pivoted back again into the closed position.

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

It is seen by means of the invention a manhole cover with excellent access provided as 5 three sides of the opening are unobstructed.

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

]O Where the cover parts are bolted together, as mentioned previously they are bolted loosely and in that way some pivoting movement between the cover parts 14 can still take place. Thus, in the case of the first cover part 1 4a, for example, the cover part 1 4a 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 contact 15 to inhibit rocking. The fact that it is loosely bolted to the second cover part 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 further embodiment, a manhole cover is provided which is twice as wide as the cover of the first embodiment and in that case a further full set of cover plates identical to the first to fourth parts 14 of the first embodiment are provided.

Claims

1. A manhole cover or gully grating comprising a frame and at least one cover part or grating part, the or each part being hinged to the frame by a hinge made of only 5 two elements, a fork and a boss, the fork being integral with the part and the boss being integral with the frame, the fork receiving the boss to pivot thereon, the two arms of the fork extending substantially horizontally when the part is closed, the boss including an upwardly facing substantial flat which is at a small acute angle to the horizontal, the frame including a member behind which one arm of the fork drops when the part is 10 opened to beyond the vertical to thereby inhibit movement of the part in the closing direction.

2. A manhole cover or gully grating as claimed in claim 1, wherein the end of said arm of the fork is angled to form a contact surface to contact the member on the 1 5 frame.

3. A manhole cover or gully grating as claimed in claim I or claim 2, wherein said member on the frame includes an angled guide surface to contact the said arm of the fork.

4. A manhole cover or gully grating as claimed in any of claims 1,,2 and 3, wherein the fork has a rounded surface to engage the boss.