GB2265649A

GB2265649A - Temporary manhole cover

Info

Publication number: GB2265649A
Application number: GB9207264A
Authority: GB
Inventors: Colin Edward Staggs
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-04-02
Filing date: 1992-04-02
Publication date: 1993-10-06
Anticipated expiration: 2012-04-02
Also published as: GB2265649B; AU3764993A; GB9207264D0; WO1993020291A1

Abstract

The cover 10, preferably of plastics material, has a plate-like body 11 with adjustable struts 21 on the underside for location of the cover relative to holes of different sizes and configurations. The cover 10 has apertures 16, 23, 29, for lightening the cover and for access through the cover. <IMAGE>

Description

A Manhole Cover This invention relates to manhole covers, and in particular to manhole covers that may be used as a temporary stop-gap safety cover between operations and as secondary safety devices in addition to the normal fencing used around an open manhole.

A problem associated with manhole covers (the term manhole covers includes drain covers, inspection covers, etc.) is their mass and weight. A typical cast-iron manhole cover is a very heavy item to move and if an operator is working through a manhole then it may be necessary to remove and replace the cover serveral times during a single job so that for the sake of safety the hole is always covered when an operator is not actually working at the hole.

This constant lifting and carrying of a heavy mass tires out the operator and may even give rise to accidents and medical problems such as slipped discs in the spine.

Manholes in some areas can be extremely deep, especially so for sewage systems. In the event of a blockage in a sewage system it is not uncommon for the manholes to fill with effluent and an operative has to work from the surface to remove the blockage. This necessarily requires an operator to lean out over an open manhole to try to guide any tools to the blockage. Since essentially the operator has no support this is a dangerous operation in which the operator could fall into the filled manhole and drown. Furthermore the lack of support makes the directing of the tools difficult.

The present invention seeks to provide a solution to the above problems and increase public safety.

Accordingly there is provided a temporary manhole cover comprising a plate-like body for placing over a manhole, the body having adjustable struts for location of the cover relative to the hole.

Preferably the body has a plurality of apertures therein to lighten its mass, and conveniently at least one of the apertures is sufficiently large to allow tools to be passed through the cover. These apertures also prevent the build up of danderous effluent gases in the manhole.

Also the manhole cover comprises a plate like body which in use lies on the ground to span an open manhole, the cover being a square shape so as to span in use square, circular, and rectangular open manholes, and having adjustable means to locate the cover relative to a selected configeration of manhole.

The invention will be described by way of example and with reference to the accompanying drawing in which: Fig 1 is a plan view of a temporary manhole cover according to the invention, Fig 2 is a section on the line II-II showing the cover in use in a manhole, and Fig 3 is an illustration of the dimensions of the most common manholes shown as plan Fig 3a, and in section Fig 3b.

With reference to Fig 3, there is illustrated the most common shapes and dimensions of manholes. Circular manholes are represented by the inner circle A, having a diameter D1 of 18 inches (450mm) and the outer circle B having a diameter D2 of 24 inches (600mm). Rectangular manholes are represented by the outer square X which is 24 inches square (600mm square), the inner square Y which is 18 inches square (450mm square) and a rectangular shape Z which is 18 inches x 24 inches (450 x 600mm).

The manhole cover 10 is approximately 34 inches (850mm) square and is intended for universal use with the most common manholes. The manhole cover comprises a plate-like square body 11 having a plurality of depressions 12 spaced around its outer peripheral margin, and a further plurality of arcuate depressions 13 arranged in an annular array at the centre portion of the plate-like body 11. The depressions 12 & 13 help strengthen the essentially flat plate structure of the cover.

In the outer corners of the body 11 are four radially aligned elongated depressions 14 with through holes 15 at the outer end portions . The holes 15 are to accommodate pins or stakes 15 for holding the cover in position in use on grass or soft ground. Between the inner and outer strengthening depressions 13 and 12 respectively are arranged a pluraltity of apertures 16, which are shown as square shaped holes but could be round ovel, etc. These apertures 16 are to lighten the mass of the body 11 and to prevent the build up of effluent gases.

Arranged on the centre of the plate, is a cruciform arrangement of four adjustable struts 21. The struts are each held in cradles 22 on the underside of the body 11.

In this case the struts are of square crossbsection and the cradles 22 are square in section to accommodate the struts but other shapes could be used e.g. round struts and semi-circular cradles, etc.

The cradles 22 are preferably formed integrally with the body 11 but could be attached thereto by welding, adhesives, or by the use of fasteners such as nuts, bolts, rivets, etc. Above each cradle 22 are spaced rectangular apertures 23 formed in the body 11 again to lighten the mass. The inner ends 24 of the struts 21 are champfered so that the ends 24 of the struts can all nestle together when the struts are fully withdrawn into the centre position of the body. Each strut 21 has a plurality of longitudinally spaced holes 25 therein, and the body 11 has a plurality of like spaced holes 26 therein so that the struts can be adjusted to position where holes 26 in the body 11 align with holes in the struts 21 and a retaining pin 27 placed in the aligned holes. The pins 27 can be connected to the cover by safety cords 28 to prevent loss of the pins.

In use the struts 21 do not necessarily have to abut the sides of the manhole but are adjusted so that the cover cannot move to a position in which it would fall within the manhole.

Whilst the struts 21 have been described as having means of discrete step like adjustments, other forms of adjustment such as screw adjustment means could be used.

Located between the cruciform arrangement of the apertures 23 and the annular array of depressions 13 are four spaced large square apertures 29. These apertures are approximately 3" square (75 mm square) and are to accommodate tools, that is to allow the passage of tools through the cover so that an operator can work through the cover.

For example when used as a sewage system temporary cover, and operator could lie on the cover and pass a high pressure hose and tool head through the cover to remove a blockage in the sewage system.

The cover also prevents any child or other member of the public from falling in should the manhole be left unattended.

The body 11 of the cover can be made from any suitable light material such as aluminium or a plastics material.

Preferably the cover is made from rotationally cast plastics material such as high density polyuthylene with the depressions 12, 13, apertures 16, 23, 29, and cradles 22 being formed during the casting process.The struts 21 could again be formed from any suitable light weight material such as aluminimum, wood, or a foamed rigid plastics material such as formed polyuthylene.

In use , the manhole cover 10 will be placed over a manhole as a temporary replacement for a permanent cast iron manhole cover. The struts are then adjusted outwards to the edge of the manhole and set to the nearest full adjustment step. The cover can then be staked into position through the corner holes 14.

Claims

1. A temporary manhole cover comprising a plate like body for placing over a manhole, the body having adjustable struts for location of the cover relative to the hole.

2. A cover as claimed in Claim 1 wherein the plate like body has a plurality of apertures threin to decrease its mass and prevent the build up of effluent gases.

3. A cover as claimed in Claim 1 or Claim 2, wherein the body is formed with a plurality of depressions thereon for strengthening purposes.

4. A cover as claimed in Claim 3 wherein the cover has a square body with a plurality of depressions around its outer peripheral margin and a further plurality of depressions arranged in an annular array at the centre of the body.

5. A cover as claimed in any one of Claims 1 to 4 wherein the adjusting struts are arranged in cruciform.

6. A cover as claimed in Claim 5 wherein there are four struts arranged in a cruciform, all the struts being slideably mounted on the underside of the plate like body.

7. A cover as claimed in Claim 6 wherein the radially inner ends of the struts are champfered to allow said inner ends to mesh together.

8. A cover as claimed in any one of Claims 1 to 7, wherein the adjustable struts are each slideably mounted on the underside of the body by means of at least one cradle secured to the body.

9 A cover as claimed in Claim 8 wherein the cradle is formed integrally with the body.

10. A cover as claimed in any one of Claims 1 to 9 wherein the body has at least one aperture therein, in use to allow tools to pass through for performing a desired task.

11. A cover as claimed in Claim 8 or Claim 9 wherein each strut has a plurality of longitudinally spaced holes thereon, and the body has spaced holes therein, the position of the strut being selected by insertion of a pin in selected aligned holes in the body and strut.

12. A cover as claimed in any one of Claims 1 to 11 wherein there are a plurality of circumferentially spaced holes in the outer periphery of the body which in use can take pins or pegs for securing the lower in position if necessary.

13. A cover as claimed in any one of Claims 1 to 10 wherein the cover body is formed from a plastic material as a one piece rotational casing.

14. A manhole cover comprising a plate like body which lies on the ground to span an open manhole, the cover being a square shape so as to span in use square, circular, and rectangular open manholes, and having adjustable means to locate the cover relative to a selected configeration of manhole.