Title of Invention

"ROADAWAY MANHOLE COVER "

Abstract

Roadway manhole cover having a frame (1) in a quadrilateral shape and a plug adapted to be in closed and open positions in which it respectively blocks off and unblocks the frame, said plug having at least one first pair of triangular plates (2, 3; 12, 13) respectively joined onto first and second adjacent sides (la, 1b) if the frame (1) to leave free access in an open position of the plug to at least one third adjacent side (1c) of the frame and each plate having one free extremity, characterized in that the plates of each pair have the shape of right angle triangles and are placed side by side in the closed position of the plug via their hypotenuse (4, 15) and in that the free extremities of all the plates are mutually adjacent.

Full Text

The present invention relates to roadway manhole cover. There are many types of manhole covers already available, and these include types with a quadrilateral type of frame to which are attached complementary triangular plates of right-angled triangle shape forming a cover for closure of the opening which is formed by the frame. In the case of such known triangular-shaped manhole covers, the plates are generally heavy and difficult to lift, and in addition, are hinged on two opposite sides of the frame, making access to the frame awkward if not difficult, that is for the introduction of equipment such as piping or cables, where the aperture in the roadway is bounded by the frame. Furthermore, this invention is intended to remedy these disadvantages by providing a manhole where opening and closure of the manhole cover is particularly easy, and which, when in the open position, provides easy and immediate access through the frame to the tunnel or the manhole in the roadway, with no hindrance from the open cover. To this end, the invention concerns a manhole cover consisting of a frame of quadrilateral form, to which are hinged complementary triangular plates to form the manhole cover, with the particular characteristic that the triangular plates are hinged to two or three adjacent sides of the frame, so that in the open position of the cover, free access is provided from two sides in the first case or from one side in the second. As can readily be seen, free access to the frame will be clearly facilitated by the fact that two adjacent sides of the frame will be left clear of hinged cover plates. According to another version of the invention, the-manhole cover of this invention includes two triangular cover plates which are hinged by one of their short sides on two adjacent sides of the frame. According to another method of manufacture, this manhole cover consists of four triangular plates, in the form of two plates hinged to open one of their short sides on two opposite sides of the frame, and another two plates hinged on their short sides, side by side to one of the other sides of the frame. According to yet another version of the invention, each triangular plate hinged to the frame, except one, is fitted with at least one projecting lug which fits into the underside of an adjacent plate. A further feature of the above is that the triangular plate which is not fitted with the mentioned lug is fitted with a system for locking this plate to the frame. As can be seen from the foregoing, the existence of these lugs, locking the single plate bearing no lug will lock all of the other plates. Accordingly, the present invention relates to roadway manhole cover having a frame in a quadrilateral shape and a plug adapted to be in closed and open positions in which it respectively blocks off and unblocks the frame, said plug having at least one first pair of triangular plates respectively joined onto first and second adjacent sides of the frame to leave free access in an open position of the plug to at least one third adjacent side of the frame and each plate having one free extremity, characterized in that the plates of each pair have the shape of rightangle triangles and are placed side by side in the closed position of the plug via their hypotenuse and in that the free extremities of all the plates are mutually adjacent. However the invention has other advantages and characteristics which are more readily appreciated in the detailed description which follows, and which refers also to accompanying drawings, which as will be appreciated are for the purpose of illustration only, and in which: - figure 1 is a plan view (from above) of a frame with a cover composed of two triangular plates as per this invention, shown in the closed position. - Figure 2 is a very schematic view in perspective of the roadway manhole cover of figure 1, but shown in the open position. - Figure 3 is a plan view (from above) of a roadway manhole cover with a cover composed of four triangular plates, in an alternative design. - Figure 4 is a very schematic view, in perspective, showing the manhole cover of figure 3, in the open position. - Figure 5 and 6 comprise a view in partial section of the hinging of a cover plate on the frame, this hinging being illustrated in the closed position of the cover in figure 5 and in its closed position in figure 6. - figures 7 and 8 represent two views in section of the lock associated with one of the cover plates, in the locked and unlocked positions respectively. Referring to the figures, we see a frame (1) designed to outline an opening made in a roadway, for example, this frame being of quadrilateral shape, and onto which are hinged complementary triangular plates of right-angled triangle form to constitute the cover closing off the frame (1). According to the design in figures 1 and 2, onto this frame (1) are hinged two triangular plates (2 and 3) of right-angled triangle shape, which lie adjacent to each other along their hypotenuses (4) when closed. According to a further essential characteristic of the invention, the two plates (2 and 3) are hinged on two adjacent sides (la and Ib) of the frame. More accurately, plate 2 is attached by two hinges (2a) to side la of frame 1 and plate 3 is attached by two hinges (3a) to side Ib of frame 1, which is adjacent to side la. As can be seen clearly from figure 2, when triangular plates 2 and 3 are open, very easy access is provided to the manhole or tunnel, since adjacent sides la and Id will be left conveniently clear. It can also be seen on figure 2 that one of the triangular plates, namely plate 2 in the example shown, has a lug (5), projecting from this plate and designed to lie below the underside, that is face 3e, of plate 3, which is also fitted with lock 6, clearly illustrated in figures 7 and 8, and which is used to lock this plate onto the frame (1). It can therefore be seen, by referring to the open position of the manhole cover as shown in figure 2, that the cover is closed by first lowering plate 2 onto frame 1, and then plate 3 which bears onto lug 5 of plate 2 which will lock the latter, after which operation of lock 6 on plate 3 will finally lock the cover composed of plates 2 and 3 onto frame 1. It can be seen that plate 3 does not have any projecting stud (5). In the design illustrated by figures 3 and 4, frame 1 is a single-piece frame created by casting (as was frame 1 in the design described above), comes in a more rectangular shape than the squarish shape of the first example. Onto frame 1 in this case are hinged four triangular plates (10, 11, 12 and 13) on three adjacent sides (1d, la and 1b) of frame 1. More accurately, plates 10 and 13 are attached respectively by hinges l0a and 13a, and by one of their short sides, to two opposite sides (1d and 1b) of frame 1. These two sides (1d and 1b) are the short sides of the rectangle forming frame 1. The other two plates (11 and 12) are attached respectively by hinges lla and 12a, by their other short side to one of the two remaining and opposite sides (la or 1c) of frame 1. Sides la and Ic are the long sides of the triangular frame. It can be seen clearly in figure 3 that plates 10 and 11 lie alongside each other along their hypotenuses (14), and that plates 12 and 13 (likewise lie together along their hypotenuses (15), while plates 11 and 12, hinged to the same side of frame 1, lie alongside each other also along short side 16. As can be seen on figure 4, plates 10, 11 and 12 are each fitted with a projecting lug (5) while plate 13, which has no such lugs, is fitted with a lock (6). Thus on the same principle as that explained earlier for figures 1 and 2, starting from the open position on figure 4, to close the manhole cover which has just been described, plates 10, 11 and 12 are closed in that order, and these self-lock by means of the lugs (5). Plate 13 is closed finally and is locked onto frame 1 thereby also locking plates 10, 11 and 12. Thus the manhole cover is closed by successive lowering of plates 10, 11, 12 and 13 in an anti-clockwise manner, and the cover is opened in a reverse manner, lifting plate 13 first, and then opening plates 12, 11 and 10 in that order. In this respect, it can be seen that opening of the plates successively in one order and closure of the plate in the reverse order will have the advantage of facilitating the work of even an untrained field operative faced with the problem of raising several cover plates. Returning to figure 4, it can be seen that in the open position, considerable clearance is made available along the long side (1c) of the rectangular frame, so that access to the manhole or the tunnel, and introduction of equipment through the frame, will be particularly easy and rapid. Hinging of the triangular plates, in the shape of right-angled triangles, into frame 1, whether it concerns the plates in the version of figure 1 or the variant of figure 2, is of a type which is known as such, and will be described briefly with reference to figures 5 and 6. Each plate, such as plate 2 for example, is fitted with an ear or similar (20) which accepts a pin (21) attached to frame 1. Ear 20 has a beak (22) which, in the open position of plate 2 (figure 6) can fir into a cut¬out or similar (23) in frame 1. Thus starting from the closed position of plate 2 as shown in figure 5, the plate is opened by pivoting it in the direction of the arrow (F), whereupon beak 22 lodges in cut-out 23, holding plate 2 positively in the open position. To close plate 2, slightly lifting the later releases beak 22 from cut-out 23, and it will then fold against the frame moving the direction opposite to that of arrow F. The feet or similar of plate 2 have been shown already, allowing this plate to rest on frame 1 in the closed position. The locking system (5) associated with the only cover plate of frame 1 which is not fitted with lug 5, that is plate 3 as shown in figures 1 and 2, plate 13 as shown in figures 3 and 4, will also be described in a concise manner. In figures 7 and 8, it can be seen that lock 6 associated with the aforementioned plate, plate 3 for example, is composed in essence of a rotor (30) mounted to rotate on plate 3, and held by a spring (31). This rotor (30) is associated with a bolt or similar (32) which is designed to fit into a rib (33) on frame 1. Starting from the locked position shown in figure 7, a key (34) is used to turn rotor (30) through a quarter turn for example to draw bolt (32) clear of frame 2, thus releasing plate 3, as can be seen clearly in figure 8. Of course the invention is not limited to the methods of manufacture described and illustrated, as these have been given as an example only. In this manner, triangular plates in the shape of right-angled triangles can be used in numbers other than those described, on condition that these plates are hinged to certain adjacent sides of the frame, so that the other side or sides of the frame are left clear in the open position. This invention therefore covers all equivalent techniques associated with the system described, and their combination, as long as these are included in the following claims. WE CLAIM: 1. Roadway manhole cover having a frame (1) in a quadrilateral shape and a plug adapted to be in closed and open positions in which it respectively blocks off and unblocks the frame, said plug having at least one first pair of triangular plates (2, 3; 12, 13) respectively joined onto first and second adjacent sides (la, 1b) of the frame (1) to leave free access in an open position of the plug to at least one third adjacent side (1c) of the frame and each plate having one free extremity, characterized in that the plates of each pair have the shape of rightangle triangles and are placed side by side in the closed position of the plug via their hypotenuse (4, 15) and in that the free extremities of all the plates are mutually adjacent. 2. Roadway manhole cover as claimed in claim 1, wherein the plug has a second pair of triangular plates (10, 11) respectively joined onto the first and onto a fourth adjacent side (la, 1d) of the frame (1) and in that the first and second pairs of plates have respective adjacent plates (11, 12) placed side by side in the closed position of the plug via one (16) of their right sides. 3. Roadway manhole cover as claimed in claim 1 or 2, wherein each triangular plate is joined onto the frame (1) except one plate (13) is fitted with at least one projecting tab (5) that fits with the bottom of an adjacent plate. 4. Roadway manhole cover as claimed in claim 3, wherein the triangular plate (13) without said tab (5) is fitted with a locking system (6) for locking said plate on the frame (1). 5. Roadway manhole cover substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

Documents:

1381-del-1997-abstract.pdf

1381-del-1997-claims.pdf

1381-DEL-1997-Correspondence-Others-(19-04-2010).pdf

1381-del-1997-correspondence-others.pdf

1381-del-1997-correspondence-po.pdf

1381-del-1997-description (complete).pdf

1381-del-1997-drawings.pdf

1381-del-1997-form-1.pdf

1381-del-1997-form-13.pdf

1381-del-1997-form-19.pdf

1381-del-1997-form-2.pdf

1381-del-1997-form-4.pdf

1381-del-1997-form-6.pdf

1381-DEL-1997-GPA-(19-04-2010).pdf

1381-del-1997-gpa.pdf

1381-del-1997-petition-137.pdf

1381-del-1997-petition-138.pdf