IES69539B2 - Improvements relating to gully tops and manhole tops - Google Patents

Abstract

A non-fouling grating and frame assembly (1) which can be of cast iron and which can have an efficient locking means (5) comprising a locking bolt (29) mounted on the grating (3) and engagable with a complimentary lock nut (33) mounted in an integrally cast lock nut housing (32) in the frame (2). The housing (32) has a contaminant discharge passageway (41) so that contaminant materials, in normal use, flow through the passageway (41) and thus the locking means (5) and in particular the lock nut (33) and the thread of the locking bolt (29) which engage the locknut (33) are less liable to corrosion and damage. Similarly the housing (32) is less likely to disintegrate and collapse in use. .

Description

Improvements relating to aullv tops and manhole tops The invention relates to gully tops and manhole tops for vehicular and pedestrian areas as defined in European Standard EN124 and particularly made from those materials specified in that standard.

For clarity and consistency, this patent specification will refer to these as gratings and frames but this is understood to include covers and frames or gully tops as they are often called.

UK Patent Specification No. 2,284,627 relates to a manhole assembly which is manufactured by fabrication. Such manhole assemblies are generally treated after fabrication, typically by galvanising. While such assemblies have proved to be very useful, there are some limitations with them. Such manhole assemblies must be capable of withstanding the very adverse conditions of heat cycling, water (which is regularly contaminant with organic and/or inorganic chemicals) etc.. Further, the manhole assemblies are subjected to irregular forces of people, and/or vehicles passing over them.. In certain rare instances, this has led to problems though it has to be stated that these are an extremely efficient construction of manhole assembly as is evidenced by their widespread use. There are certain technical problems in using pre-fabricated assemblies for some specific uses. Indeed, it has to be said that in some instances the reason why refabricated manhole assemblies are not used is often based on aesthetic considerations rather than on sound technical and commercial considerations.

One of the major problems encountered in such gullies and manholes for vehicular and pedestrian areas is the need to secure the grating or cover within its frame to prevent S69539 >1 - 2 unauthorised tampering. The logical and obvious way to do this is to provide a threaded fastener for releasably locking the grating in the frame in order to prevent unauthorised access to the opening. One well known way of doing this is to provide an opening in a grating for reception of a bolt which engages a complementary threaded receiver nut or receiver in the frame. There are difficulties with this. A primary difficulty that can arise is that unless the grating and frame are very accurately manufactured it can, in many cases, be difficult to align and engage the bolt with the associated threaded receiver in the frame. Further, if the threaded receiver is even slightly out of alignment, the bolt head will not sit properly within the grating. Also, if the bolt and receiver are of different materials this will promote corrosion, particularly as those gratings and frames are generally located in open exposed positions. Contaminants are a major problem. Indeed, over a period of use dust, dirt and corrosion generally will cause such deterioration that what was originally a relatively easily opened and closed grating becomes almost totally inoperative.

For example, it is known to provide a relatively complicated arrangement such as disclosed in French Patent Specification No. 2 320 034 in which there is described a manhole cover locking mechanism using a bolt to draw a threaded sleeve with an arm engaging a frame underneath. Such a relatively complicated structure is provided to overcome the problems of the siting of the bolt within the threaded area. It is obviously a very complicated piece of equipment, relatively difficult to manufacture and very difficult to protect or to prevent corroding or other difficulties when coming into contact with contaminants which are often present in an around manhole covers, not just simply from the existing environment above ground, but. also because very often below ground gases and noxious fumes abound which gases and noxious fumes, while not necessarily harmful to passing traffic - pedestrians, a vehicles and the like - can be extremely harmful over a 5 long period of time to the manhole cover and associated frame, generating corrosive gases which corrosive gases over a period of time attack and damage the manhole cover.

Various proposals have been made heretofore to solve this problem and indeed one of the first solutions to the problem is described in U.K. Patent Specification No. 1 409 785 where there is described a manhole assembly of sheet metal or more correctly a prefabricated manhole and it illustrates a captive nut means which is provided on a seating, which captive nut means cooperates with a bolt ' and the captive nut is generally mounted within a housing formed from a single piece of sheet metal, usually formed by pressing. The nut housing is chosen preferably from a material not subject to corrosion, such as brass. However, such a fitting is not entirely satisfactory in practice, it requires relatively accurate fabrication and still worse, in use, suffers from the problem of the difficulty of engaging a locking bolt within the captive nut in the housing.

The first practical solution to this problem in fabricated manhole assemblies was proposed by the present applicants which proposal is described and claimed in U.K. Patent Specification No. 2,284,627. This invention, it is important to emphasise, relates to manhole assemblies which are manufactured by fabrication. Such manhole assemblies are generally treated after fabrication by galvanising or painting for example. In this specification there is illustrated a manhole assembly comprising a frame for mounting in the ground to define an access opening, a manhole cover releasably engagable with the frame to close the opening and locking means for releasably securing the cover to the frame. In UK Patent Specification No. 2,284,627, the locking means is provided by a locking bolt freely mounted on the cover and a complementary locking nut mounted on the frame, the nut being loosely mounted within a housing which restrains the nut from rotation, the housing having a bolt inlet opening for through-passage of the bolt for engagement of the nut within the housing. As illustrated in the specification, an opening is provided in a sidewall of the housing for insertion of the nut into the housing and then the opening is closed by a flap mounted at the periphery of the opening and bent across the opening after insertion of the nut to retain the nut within the housing. This form of locking arrangement works exceptionally well for fabricated manhole covers of this type. The problems with adapting it to cast manhole assemblies are many. Firstly in the invention described in UK Patent Specification No. 2 284 627 this works because it is possible to use in the construction of the manhole, mild steel and other reasonably easily bendable metals. However, this is not possible with a cast manhole, so that heretofore what has been done has been to provide some form of locking arrangement, which locking arrangement is essentially separate from the cast manhole or simply comprises a lug mounted securely cast within the manhole cover frame which lug is drilled and threaded with the consequent problems as mentioned heretofore of location, damage to the thread, lack of ability to replace, etc. Thus, it is not possible to apply directly the invention of U.K. Patent Specification No. 2 284 627 to commonly constructed cast manhole assemblies.

There are additional problems associated with cast manholes and in particular cast manhole frames. If a mild steel manhole cover or frame is damaged during use, whether physically by means of some impact or shock or simply by corrosion caused by effluent, contaminant gases, water causing rust, spillage of corrosive liquids or the like, then the manhole cover or its frame can be easily replaced as can the locking arrangement. To be able to adopt the invention of U.K. Patent Specification No. 2 284 627 to cast manhole covers would be advantageous, however, firstly it is not possible to use locking assemblies such as is described in this U.K. Patent Specification because the ingress of moisture and contaminants onto such a locking assembly, even if it were to be cast within a manhole frame, would very quickly corrode the metal and in particular because of the slightly different metals being used, there would be a reaction between those metals and the frame being of cast iron which would cause corrosion -and deterioration of the frame.

The first attempts having been made to do this resulted in .failure with the quick deterioration of the manhole and damage thereto. It wasn't just simply that the locking assembly itself was damaged, but it was the problem of how such an assembly could be mounted within a fully cast structure which fully cast structure would not quickly deteriorate during use.

It is relatively easy to appreciate that what was required was a fastener of two part construction as described in our previous U.K. Patent Specification No. 2 284 627, which would comprise a male member mounted on a grating and a female member mounted on the base with the socket on the base for reception of the female member, which could then be formed by basically a conventional nut and bolt. However, the problem that arises and that was long appreciated was how could such a locking member not become corroded and deteriorate rapidly in use. It was appreciated therefore that what was required was some means or method of construction that would ensure that any contaminants, other than gaseous contaminants, and in particular likely to come in contact with the assembly adjacent the locking means would be quickly dissipated and would in general terms not cause severe damage.

The present invention is directed towards overcoming these problems.

According to the invention, there is provided a nonfouling cast grating and frame assembly comprising a ground-engaging cast base frame, the base frame having an opening extending through the base frame, a cast grating pivotally mounted by a hinge in the opening for movement between a closed position extending across the opening and an open position free of the opening, locking means for releasably locking the grating in the closed position on the base frame, said locking means comprising a locking bolt mounted on the grating and a complementary lock nut mounted on the base frame, the lock nut held captive within an associated lock nut housing cast with the base frame, said housing having a downwardly opening contaminant discharge passageway for delivering contaminant materials away from the housing, the housing has an outwardly open socket for reception of the lock nut, the socket of somewhat greater size than the lock nut for articulation of the lock nut within the socket while constraining the lock nut against rotation within the socket, and retaining means for blocking an inlet of the socket to retain the lock nut within the socket.

One of the immediate advantages that arises with the present invention is that what has heretofore been seen as a major problem with grating assemblies, namely, the presence of water in that most grating assemblies are out in the open and therefore they are liable to water from rainfall, etc. has been used to advantage. Further, all grating assemblies have a considerable amount of dirt that almost naturally falls on them to overcome. Now with the present .locking assembly, water, particularly rainwater, does not cause the same problems as heretofore and indeed has been found to be very useful in washing away any contaminants of a corrosive nature, namely such dust, dirt and other contaminants that might from time to time find their way through the interstices of the grating and in particular around the peripheral edge between the grating itself and the ground engaging base frame. Now, while such dust and dirt, can gather and lie within the housing, the great advantage is the natural throughput of water through the same portions of the grating assembly will cause any dirt and contaminants to be washed away from the lock nut. There is the added advantage that there is now no need to provide specially treated assemblies. Further, the use of different metals is minimised in that the whole assembly is cast in situ and since it is not subject to damage and corrosion it will not by its very nature suffer from the same physical damage and problems as heretofore. This has been the first time that it has been possible to provide a solution to what was erstwhile an insurmountable task, namely, to provide a locking assembly for cast manhole cover assemblies, which locking assembly would not in minimal use be damaged by contaminants easy to use, in that it could be easily located and operated. In other words, the present invention provides for cast assemblies all the advantages of the invention of U.K. Patent Specification No. 2 284 627 which was applied to fabricated assemblies. While on the face of it would appear to be a relatively simple modification of the previously mentioned invention, it was not by any means that obvious since there are specific problems, as mentioned already, that have been experienced with cast assemblies over and .above those experienced with fabricated assemblies.

Another major advantage of the present invention is that in the event of a spillage of a contaminant such as an acid or other corrosion liquid onto a grating assembly, it will be relatively, easily washed away and in particular will be washed away out of the socket, thus avoiding further damage to the grating assembly. It required a major change on approach to abandon the heretofore conventional wisdom still applied successfully to fabricated assemblies namely of shrouding and protecting as much as possible from water and contaminants to using the water to rid one of the contaminants.

This is the first time that there has been provided a nonfouling grating assembly that is of a construction such that what were heretofore very difficult problems in relation to the provision of adequate locking with consequent deterioration of threads, etc. have been solved by way of what is a relatively simple invention which further allows the replacement of nuts or bolts as required without any great difficulty.

In a preferred embodiment of the invention, the contaminant discharge passageway has an entrance communicating with an interior of the housing, and an exit on an exterior of the housing, the contaminant drainage passageway being downwardly inclined between the entrance and the exit. Thus, advantageously the contaminant materials are directed away from the housing preventing lodgement of the contaminant materials within the housing.

In a further embodiment, the entrance of the contaminant drainage passageway has a flared mouth for funnelling contaminant materials away from the interior of the housing towards the exit. This construction advantageously facilitates the free flow of contaminant materials away from the interior of the housing.

In another embodiment, a contaminant discharge passageway forms an enlarged bolt mounting slot on the grating for loosely mounting the bolt on the grating, this loose mounting construction advantageously prevents the lodgement of contaminant material around the bolt.

In one embodiment of the invention, the housing has a central contaminant discharge passageway extending through a bottom of the housing. This is a relatively simple construction and easily manufactured.

In a particularly preferred embodiment the frame has an upstanding side wall defining an access opening, the lock nut housing being mounted on an inner face of the side wall at a lower end of the side wall, the housing projecting inwardly of the side wall, the housing having a pair of spaced-apart substantially parallel side walls projecting inwardly from the frame side wall, a top wall of the housing extending between upper ends of the housing side walls, a through hole being provided in the top wall for reception of the locking bolt, a bottom of the housing being formed by inwardly directed flanges at a lower end of each side wall of the housing defining the central contaminant discharge passageway therebetween, a free outer end of the housing being open to provide an inlet to a lock nut receiving socket which is T-shaped in crosssection formed by an interior of the housing.

In another embodiment, a retaining nut is provided for the locking bolt to secure the locking bolt on the mounting flange, the retaining nut being mounted intermediate the ends of the shank of the locking bolt.

In a preferred embodiment, the frame has a body having upstanding side walls defining an opening therebetween, outwardly projecting webs on an outer face of one or more of the side walls, a bedding flange being mounted between outer ends of the webs.

Ideally, the grating has a fixed inner end pivotally mounted by a spindle within the opening defined by the side walls, the mounting flange for the bolt being mounted at a free end of the grating.

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:Fig. 1 is a perspective view of a grating and frame assembly according to the invention; Fig. 2 is a detailed perspective cut-away view showing locking means of the assembly; Fig. 3 is a sectional view of portion of the assembly showing the locking means; Fig. 4 is an end view of portion of a lock nut housing forming part of the frame; Fig. 5 is another sectional view showing the grating in a partially opened position; Fig. 6(a) is a detail perspective view showing an alternative housing construction; Fig. 6(b) is a sectional plan view of another housing showing an alternative construction of contaminant discharge passageway for the housing; Fig. 7 is a perspective view of an alternative construction of housing; Fig. 8 is an end elevational view of the housing of Fig. 7; and Figs. 9 to 12 are plan views of alternative constructions of contaminant discharge passageways for the housing or for mounting a locking bolt on a grating of the assembly.

Referring to the drawings, and initially to Figs. 1 to 5 thereof, there is illustrated a non-fouling cast grating and frame assembly according to the invention, indicated generally by the reference numeral 1. The assembly 1 comprises a frame 2 with a complementary grating 3 hingedly mounted on the frame 2 by a spindle 4 for movement between an open position and a closed position as illustrated in the drawings. A locking means indicated generally by the reference numeral 5, is provided for releasably locking the grating 3 on the frame 2 in the closed position.

The frame 2 comprises a body 6 formed by an upstanding front wall 7, rear wall 8 and end walls 9, 10 which define a rectangular opening 11. Projecting outwardly from the front wall 7 and each end wall 9, 10 are a number of spaced-apart upright webs 14, each having an upper sloped edge 15. A frame bedding flange 16 is supported at an outer end of each of the webs 14.

The grating 3 has a C-shaped pivot bar 20 at one end. Outwardly extending lugs 21 at each end of the pivot bar 20 have through holes 22 for rotatably engaging the spindle 4. Grating bars 24 extend outwardly of the pivot bar 20.

At a free end 26 of the grating 3, a locking flange 27 is mounted at an intersection of transverse and longitudinal grating bars 24. A through hole 28 is provided in the flange 27 for reception of a locking bolt 29 forming part of the locking means 3. The through hole 28 is an enlarged bolt mounting slot forming a contaminant discharge passageway for preventing build-up of contaminant materials about the bolt 29. The locking bolt 29 is held captive on the flange 27 by a retaining nut 30 below the flange 27 on the shank of the bolt 29 or by other means.

Associated with the locking flange 27 is a housing 32 which is integrally cast with the frame 2 and located on an end wall 9. The housing 32 is for reception of a lock nut 33 associated with the locking bolt 29 and thus forming the outer part of the locking means 5. The housing 32 has a socket 35 for reception of the lock nut 33, the socket 35 being somewhat larger than the lock nut 33 which is a loose fit in the socket 35 but restrained against turning in the socket 35 by the side walls of the socket 35. A top wall 38 of the housing 32 has a through hole 39 for through passage of the bolt 29 to engage the lock nut 33. A bottom wall 40 of the housing has a contaminant discharge passageway 41. To retain the lock nut 33 within the socket 35, a welded projection 42 (Fig. 3) is provided at an inlet 43 of the socket 35.

In use, the grating 3 is normally closed on the frame 2, the bolt 29 engaging the nut 33 to releasably retain the grating 3 on the frame 2. For access, the nut 29 can be undone and the grating 3 lifted, the retaining nut 30 securing the bolt 29 In the grating 3. Also, the nut 33 Is retained within the socket 35 of the housing 32 by the projection 42. When the grating 3 Is closed, the bolt 29 can be readily easily aligned with the nut 33 as the nut 33 is free to articulate within the socket 35 to facilitate easy alignment of the bolt 29 with the nut 33.

In use, surface water flows through the first contaminant 10 discharge passageway formed by the through hole 28 washing away contaminants from the flange 27 and locking bolt 29.

A substantial amount of the contaminant material will fall on the top wall 38 and will wash off it. Any contaminant material which flows into the through hole 39 and onto the housing 32 will be flushed out the contaminant discharge passageway 41. Accordingly, the amount of contaminant materials within the housing 32 is minimal and thus the «. risk of corrosion and damage to the locking means 5 is greatly reduced. It is difficult to over-emphasise the importance of these contaminant discharge passageways particularly for the housing 32.

The fact that the nut 33 is loosely located within the socket 35 facilitates alignment of the bolt 29 with the nut 33. It will also be appreciated that the bolt 29 and nut 33 can be readily easily replaced if necessary.

The grating 3 and the frame 2 are preferably manufactured from graphite cast iron. The bolt 29 and nut 33 are of similar material, preferably ferrous material but, in some cases, they may be of some other material.

Referring now to Fig. 6(a), an alternative construction of lock nut housing 50 is shown. In this case, the housing has contaminant discharge passageways 51,52 in both a top wall and a bottom wall of the housing 50.

Fig. 6(b) shows a housing 60 having an alternative construction of contaminant discharge passageway 61 of castellated construction. This provides adequate support for the lock nut while at the same time, it is of a more open construction for shedding contaminant materials from the housing 60.

Referring now to Figs. 7 and 8, another housing 70 is shown. In this case, a contaminant discharge passageway in a bottom wall of the housing 70 has a flared mouth at an entrance to the passageway 71 for funnelling contaminant materials away from the interior of the housing. Again, the locking nut is adequately supported when released from the locking bolt while the flared construction facilitates drainage of contaminant materials from the housing 70.

Figs. 9 to 12 show various configurations of contaminant discharge passageways 80,81,82, and 83 for use with either the housing or with the mounting flange for the locking bolt. The discharge passageway 80 being oval in shape will ensure discharge adequate drainage. The discharge passageway 81 being of open slot construction will ensure the removal of contaminants of significant particulate size. The radially slotted arrangement of the discharge passageway 82 is particularly advantageous, while the elongated slot-like arrangement of the discharge passageway 83 is particularly useful in providing a considerable clearance around the bolt while still retaining the bolt.

The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail in so far as it is within the scope of the monopoly claimed.

Claims (4)

claims

1. A non-fouling cast grating and frame assembly comprising a ground-engaging cast base frame, the base frame having an opening extending through the base frame, a cast grating pivotally mounted by a hinge in the opening for movement between a closed position extending across the opening and an open position free of the opening, locking means for releasably locking the grating in the closed position on the base , frame, said locking means comprising a locking bolt mounted on the grating and a complementary lock nut mounted on the base frame, the lock nut held captive within an associated lock nut housing cast with the base frame, said housing having a downwardly opening contaminant discharge passageway for delivering contaminant materials away from the housing, said contaminant discharge passageway having an entrance communicating with an interior of the housing and an exit on an exterior of the housing, the contaminant discharge passageway being downwardly inclined between the entrance and the exit, the housing has an outwardly open socket for reception of the lock nut, the socket of somewhat greater size than the lock nut for articulation of the lock nut within the socket while constraining the lock nut against rotation within the socket, and retaining means for blocking an inlet of the socket to retain the lock nut within the socket.

2. An assembly as claimed in claim 1, wherein the entrance of the contaminant discharge passageway has a flared mouth for funnelling contaminant materials away from the interior of the housing towards the exit of the contaminant discharge passageway and in which the contaminant discharge passageway forms an enlarged bolt mounting slot on the grating for loosely mounting the bolt on the grating and the nut retaining means is a welded ridge at an inlet of the socket. 5

3. An assembly as claimed in claim 1 or 2 wherein the frame has an upstanding side wall defining an access opening, the lock nut housing being mounted on an inner face of the side wall at a lower end of the side wall, the housing projecting inwardly of the 10 side wall, the housing having a pair of spaced-apart substantially parallel side walls projecting inwardly from the frame side wall, a top wall of the housing extending between upper ends of the housing side walls, a through hole being provided in the top wall 15 - for reception of the locking bolt, a bottom of the housing being formed by inwardly directed flanges at a lower end of each side wall of the housing defining the central contaminant discharge passageway therebetween, a free outer end of the housing being 20 open to provide an inlet to a lock nut receiving socket which is T-shaped in cross-section formed by an interior of the housing.

4. An assembly as claimed in any preceding claim wherein the frame has a body having upstanding side walls 25 defining an opening therebetween, outwardly projecting webs on an outer face of one or more of the side walls, a bedding flange being mounted between outer ends of the webs and in which the grating has a fixed inner end pivotally mounted by a 30 spindle within the opening defined by the side walls, the mounting flange for the bolt being mounted at a free end of the grating.