MANHOLE COVER FRAME WITH SELF LOCKING FUNCTION OF THE COVER AND COVER THEREFOR

Abstract: There is disclosed a manhole cover frame (8) with self-locking function of the cover (2), the manhole cover frame (8) comprising a number of locking means arranged to interact with complementarily shaped locking means of the cover, where the said locking means of the manhole cover frame are constituted by a number of curved, resilient locking members (12) which are formed in an internal side wall (10) of the manhole cover frame (8), and which at a free outer end (16) are designed with inwardly protruding locking projections (18), and that the complementarily shaped locking means of the cover are constituted by a corresponding number of upwardly open lateral recesses (14) having a lower locking face (6) which is arranged to interact with the said locking projections. By means of simple measures is hereby achieved an improved and more operation-friendly locking function which furthermore, due to the resilient locking members being situated in the side of the manhole cover frame instead of as previously normally in the cover, will be less exposed to being damaged in use. Furthermore, it will be regarded as an advantage that the dead weight of a cover according to the invention may be minimised, i.e. easier to handle.

Description: MANHOLE COVER FRAME WITH SELF-LOCKING FUNCTION OF THE COVER AND COVER THEREFORE The present invention concerns a manhole cover frame with self-locking function of the cover of the kind indicated in the preamble of claim 1. Manhole cover frames and well or manhole covers are made usually of cast iron, irrespective of the size. In most cases the dead weight of the cover will be so great that under normal conditions the cover cannot be opened by unauthorised persons. In practice, however, it has appeared to be a serious problem that even very large and heavy well or manhole covers can be sucked up at the passing of large vehicles. Therefore, in practice road authorities most often make requirements regarding a kind of locking function between cover and manhole cover frame. And of consideration to improved safety, most often self-locking manhole covers are used. Self-locking manhole covers are known in may different embodiments, such as from DK-B-154 519, CH-A-448 917, SE-B-436 050, and GB-A-2 085 946. Common to these known covers are, however, that they are cumbersome to operate and often require special tools for releasing the spring-biased lock of the cover. The invention has the purpose of indicating an improved manhole cover frame with self-locking function of cover of the kind mentioned in the introduction and which by means of simple measures makes the locking function more optimal and facilitates the operation. The manhole cover frame according to the invention is characterised in that the said locking means of the manhole cover frame are constituted by a number of curved, resilient locking members which are formed in an internal side wall of the manhole cover frame, and which at a free outer end are designed with inwardly protruding locking projections, and that the complementarily shaped locking means of the cover are constituted by a corresponding number of upwardly open lateral recesses having a lower locking face which is arranged to interact with the said locking projections. By means of simple measures is hereby achieved an improved and more operation- friendly locking function which furthermore, due to the resilient locking members being situated in the side of the manhole cover frame instead of as previously normally in the cover, will be less exposed to being damaged by use. Furthermore, it will be regarded as an advantage that the dead weight of a cover according to the invention may be minimised, i.e. easier to handle. Suitably, the manhole cover frame according to the invention may be thus designed that at the outer side of the curved, resilient locking members and spaced apart there- from it has a curved outer wall section so that a curved cavity is formed behind the resilient locking members. In a simple way is hereby also ensured optimal function of the resilient locking members as the curved cavities are only open downwardly, i.e. sand and gravel does not penetrate in behind and blocks the function of the locking members. In order to achieve a more optimal distribution of the locking force, the manhole cover frame according to the invention may advantageously be thus designed that it is formed with two resilient locking members disposed mutually diametrically opposite. Hereby is also achieved a good symmetry of the locking function so that the cover does not capsize at the handling. The invention furthermore concerns a cover for use in connection with the manhole cover frame according to the invention, the cover being characterised in that it is formed with two of the lateral recesses which are disposed diametrically opposite to each other along the periphery of the cover. The invention is explained more closely in the following in connection with the drawing on which: Fig. 1 shows a plan view from above of an embodiment of a cover with self-locking function for a manhole cover frame or manhole according to the invention, Fig. 2 shows a side sectional view of an embodiment of a manhole cover frame with self-locking function according to the invention, Fig. 3 shows a top view, partly in section, of the manhole cover frame shown in Fig. 2 according to the invention, and Fig. 4 shows an enlarged part sectional view for illustrating the locking function between manhole cover frame and manhole cover according to the invention. The manhole cover 2 shown in Fig. 1 is designed with two diametrical lateral recesses, the side profile of which comprising a lower locking surface 6 is more clearly seen in Fig. 4. An embodiment for a manhole cover frame 8 shown in Fig. 2 and 3 comprises two curved, resilient locking members 12 in a side wall 10, the members 12 being connected with the side wall 10 at 14, and which at free outer ends 16 are designed with inwardly protruding locking projections 18 which, cf. Fig. 4, interact with the lower locking surface 6 of the lateral recesses 4 of the cover 2. In Fig. 4 is furthermore illustrated how the self-locking locking function between the manhole cover frame 8 and the cover 2 is easily released by means of an outer end of an operating lever 20 by pressing back the locking projections 18 so that the curved, resilient locking members 12 are pivoted rearwards into a curved cavity 22 behind the locking members 12. This cavity 22, which has outer walls 24 and 26 have just the purpose of providing that the function of the resilient locking means 12 is not disturbed by incoming material (stones and sand etc.), why the cavity 22 is only open downwards.

Claims: CLAIMS 1. A manhole cover frame (8) with " self-locking function of the cover (2), the manhole cover frame comprising a number of locking means arranged to interact with comple- mentarily shaped locking means of the cover, characterised in that the said locking means of the manhole cover frame are constituted by a number of curved, resilient locking members (12) which are formed in an internal side wall (10) of the manhole cover frame, and which at a free outer end (16) are designed with inwardly protruding locking projections (18), and that the complementarily shaped locking means of the cover are constituted by a corresponding number of upwardly open lateral recesses (14) having a lower locking face (6) which is arranged to interact with the said locking projections. 2. A manhole cover frame according to claim 1, characterised in that at the outer side of the curved, resilient locking members (12) and spaced apart therefrom it has a curved outer wall section so that a curved cavity (22) is formed behind the resilient locking members (12). 3. A manhole cover frame according to claim 1, characterised in that it is formed with two resilient locking members disposed mutually diametrically opposite. 4. A cover for a manhole cover according to claim 1 and 3, characterised in that it is formed with two of the lateral recesses which are disposed diametrically opposite to each other along the periphery of the cover.

Inventors: SCHACK HANSEN OLE, SCHACK HANSEN, OLE
Applicants: BOETKERS TOEMMERHANDEL AS L, SCHACK HANSEN OLE, L. BOETKERS TOEMMERHANDEL A/S, SCHACK HANSEN, OLE
Application year: 2001
Main classification: E02D29
IPC codes: E02D29