Patent Description:
Covers are used as barriers to prevent inadvertent or unauthorised entry into voids, passages, pits, and the like. To prevent unauthorised entry, these covers must be secured such that an unauthorised person is not able to remove the cover. In addition, covers applied to pits or manholes housing electrical equipment may be susceptible to being violently displaced by explosions or other powerful electrical discharges applying strong upward forces caused by faulty wiring or release of explosive gases in the pits or manholes. Such displacement could result in serious injuries or fatalities. For example, <CIT> discloses a manhole cover with a locking assembly having a hook-shaped locking lever in the form of a bell crank lever which is pivoted at its fulcrum to cooperate with a projecting catch mounted to the side wall of the void to be covered. Further covers with form fitting locking levers are known from documents <CIT> and <CIT>. A further example of a system according to the state of the art is disclosed in <CIT>.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

According to the present invention, there is provided a system as defined by claim <NUM>, wherein preferred embodiments are laid down in the dependent claims. More particularly, there is provided a system comprising a cover and a locking assembly for said cover, the cover being a substantially rigid cover and configured to close off an opening to a void, the void being bounded by a side wall and the cover defining a pair of opposed sides, being an operatively top side and an opposed underside, the locking assembly comprising: a mounting arrangement mountable to the underside of the cover; a link pivotally connected to the mounting arrangement, the link defining a first end and a second, free end; a locking member carried by the second, free end of the link, the locking member being configured to frictionally engage with the side wall of the void in a locking position, in use; and an actuating member connected to the link and accessible via the operatively top side of the cover, the actuating member being operable to displace the link relative to the mounting arrangement to cause the locking member to frictionally disengage from the side wall of the void to a disengaged position.

The actuating member may be connected to the link intermediate the first end and the second end.

The link may be pivotally connected to the mounting arrangement at the first end.

The locking member may be pivotally connected to the second end of the link.

The actuating member may be at least pivotally connected to the link. In an embodiment, the actuating member may be connected to the link such that the actuating member is able to pivot and be displaced slidably relative to the link.

The actuating member may carry a stop member, the stop member being configured to abut the underside of the cover during operation of the actuating member.

The actuating member may be dimensioned to receive a tool inserted via the operatively top side of the cover, and the actuating member may be operable, by using the tool, to displace the actuating member substantially orthogonally relative to the top side of the cover, by applying a force to the link and frictionally disengaging the locking member from the side wall.

The locking member may comprise a friction pad configured to frictionally engage with the side wall.

The link may comprise a plurality of link arms arranged in spaced, parallel relationship.

In another aspect of the present disclosure, there is provided a cover which includes a cover member; and the locking assembly, as described above, carried by the cover member.

The cover member may be vented. The cover member may comprise a support arrangement and a plurality of elongate elements arranged at spaced intervals on the support arrangement, the spacing of the elongate elements providing the venting. Each elongate element may be of metal.

Embodiments of the disclosure will now be described by way of example only with reference to the accompany drawings in which:.

In the drawings, reference numeral <NUM> generally designates a locking assembly for a cover <NUM>. The cover <NUM> is a substantially rigid cover <NUM> and is configured to close off an opening <NUM> to a void <NUM>. The void <NUM> is bounded by a side wall <NUM> and the cover <NUM> defines a pair of opposed sides, being an operatively top side <NUM> (<FIG>) and an opposed underside <NUM> (<FIG>). In the exemplary embodiment, the void <NUM> is in the form of a pit or manhole <NUM> and the cover <NUM> is in the form of a pit cover or manhole cover <NUM>.

The locking assembly <NUM> includes a mounting arrangement <NUM> mountable to the underside <NUM> of the cover <NUM> (<FIG>). The mounting arrangement <NUM> comprises a pair of laterally spaced flanges <NUM>, <NUM> projecting from the underside <NUM> of the cover <NUM>. The locking assembly <NUM> further includes a link <NUM> pivotally connected between the flanges <NUM>, <NUM> of the mounting arrangement <NUM>, the link <NUM> defining a first end <NUM> and a second, free end <NUM>.

The link <NUM> comprises a pair of laterally spaced link arms <NUM>, <NUM>, though it will be appreciated that a single link arm may be provided in alternate embodiments. The link <NUM> is pivotally connected to the mounting arrangement <NUM> by a mounting pin <NUM> of the mounting arrangement 24arranged at the first end <NUM> of the link <NUM>. The mounting pin <NUM> is held fast between the flanges <NUM>, <NUM> of the mounting arrangement <NUM>. It will be appreciated that the link <NUM> may pivotally receive the mounting pin <NUM> at various points or positions along the link <NUM>.

Each of the flanges <NUM>, 29is formed integrally, as a one piece element, with a rib <NUM> carried on the underside <NUM> of the cover <NUM>. It will be appreciated that the mounting arrangement <NUM> can take various forms, such as, for example, the exclusion of the pair of flanges <NUM>, <NUM>, thereby having the mounting pin <NUM> received within at least one of the ribs 31or between two of the ribs <NUM>.

The locking assembly <NUM> further includes a locking member <NUM> (<FIG>) carried by the second, free end <NUM> of the link <NUM>. The locking member <NUM> is configured to frictionally engage with the side wall <NUM> of the pit <NUM> in a locking position <NUM>, in use. The locking member <NUM> includes a friction pad <NUM> configured to frictionally engage with the side wall <NUM>. A pivot pin <NUM> is integrally formed with the friction pad <NUM> as a one piece element. The pivot pin <NUM> is pivotally received between the link arms <NUM>, <NUM> of the link <NUM>. It will be appreciated that, in alternate embodiments, the locking member <NUM> may be fixedly arranged relative to the link <NUM> via appropriate fabrication with the link <NUM>, welding, adhesion, or the like.

The locking assembly <NUM> further includes an actuating member <NUM> (<FIG>) connected to the link <NUM> and accessible via the operatively top side <NUM> of the cover <NUM>. The actuating member <NUM> is operable to displace the link <NUM> relative to the mounting arrangement <NUM> to cause the friction pad <NUM> of the locking member <NUM> to frictionally disengage from the side wall <NUM> of the pit <NUM> as a result of which a further upward force on the actuating member <NUM> results in raising of the cover <NUM> as will be described in greater detail below.

The cover <NUM> includes a receptacle <NUM> projecting from the underside <NUM> of the cover <NUM> into the pit <NUM>, in use. The receptacle <NUM> defines a recess in which a housing <NUM> of the actuating member is displaceably received. The housing <NUM> of the actuating member <NUM> is accessible via the operatively top side <NUM> of the cover <NUM>. The actuating member <NUM> includes a shaft <NUM> extending from an operatively under side of the housing <NUM> and through an aperture <NUM> in a floor of the receptacle <NUM> of the cover <NUM>.

A free end of the shaft <NUM> carries a transversely extending pin <NUM>. Ends of the pin <NUM> are held captive in slots <NUM>, <NUM> defined in the link arms <NUM>, <NUM>, respectively, of the link <NUM>. The pin <NUM> is thus able to pivot and be displaced slidably relative to the link <NUM> via the ends of the pin <NUM> being received in the slots <NUM>, <NUM>. The length of the slots <NUM>, <NUM> is dependent on the geometry of the locking assembly <NUM> and, the closer the pin <NUM> is to the mounting pin <NUM>, the shorter the slots <NUM>, <NUM> can be. Thus, it will be appreciated that, in some embodiments, the actuating member <NUM> may only be pivotable relative to the link <NUM>.

The housing <NUM> of the actuating member <NUM> defines a socket <NUM> accessible via the operatively top side <NUM> of the cover <NUM>. The socket <NUM> is dimensioned to receive a lifting tool (not shown) inserted via the operatively top side <NUM> of the cover <NUM>. The lifting tool is of the type having a T-shaped end that, once received in the socket <NUM> of the housing <NUM>, is rotated by <NUM>° to be received, in a locking and lifting orientation in opposed recesses <NUM> defined in the side wall of the housing <NUM>. This then allows the lifting tool to be used to operate the actuating member <NUM> in an authorised manner and, in so doing, raising the cover <NUM> from the opening of the pit <NUM>.

The actuating member <NUM> also carries a stop member, in the form of a collar <NUM>, fixed to the shaft <NUM> of the actuating member <NUM> and configured to abut an operatively outer surface of a bottom of the receptacle <NUM>. The collar <NUM> restricts movement of the actuating member <NUM> relative to the receptacle <NUM> of the cover <NUM> during operation of the actuating member <NUM> and facilitates raising of the cover <NUM> from the opening of the pit <NUM>. The collar <NUM> is fixed to the shaft <NUM> by welding but, in other embodiments, could be formed with the shaft <NUM> integrally as a one piece element. In other embodiments the stop member could be a split pin, a pair of lock nuts, or the like.

The cover <NUM> is vented and is in the form of a metal grate. More particularly, the cover <NUM> comprises a cover member <NUM> comprising a support arrangement <NUM> and a plurality of elongate elements <NUM> arranged at spaced intervals on the support arrangement <NUM>, the spacing of the elongate elements <NUM> providing the venting.

The support arrangement <NUM> includes a plurality of spaced support bars <NUM> (<FIG>) orthogonally overlying a plurality of the spaced ribs <NUM>. The elongate elements <NUM> are provided, in turn, orthogonally over the support bars <NUM> to define the vented grate. Each elongate element may, conveniently, be in the form of a length of Vee-Wire®. (Vee-Wire is a Registered Trade Mark of Johnson Screens, Inc. , of <NUM> St. James Place, Houston, TX, <NUM>, USA.

<FIG> show the locking assembly <NUM> in use. When an attempt is made to lift the cover <NUM>, with the installed locking assembly <NUM>, using a lifting force <NUM> via any means other than by operating the actuating member <NUM>, the lifting force <NUM> is transferred to the mounting pin <NUM> of the mounting arrangement 24as shown in <FIG>. The frictional engagement between the friction pad <NUM> of the locking member <NUM> and the side wall <NUM> of the pit <NUM> increases and, as a result, inhibits frictional disengagement of the friction pad <NUM> of the locking member <NUM> from the side wall <NUM> of the pit <NUM>, effectively locking the cover <NUM> in place. This arises due to the link <NUM> rotating relative to the substantially stationary locking member <NUM> causing an anticlockwise moment <NUM> about the pivot pin 33of the locking member <NUM>. The link <NUM> is dimensioned such that, as the link <NUM> rotates about the pivot pin <NUM>, the force applied to the side wall <NUM> by the friction pad <NUM> increases, thus strengthening the frictional engagement between the friction pad <NUM> and the side wall <NUM> and further securing the locking position <NUM>.

To remove the cover <NUM> in an authorised manner, the lifting tool is inserted into the socket <NUM> of the housing <NUM> and is rotated through <NUM>° to engage the opposed recesses <NUM> of the housing <NUM>. Pulling on the lifting tool thus raises the actuating member <NUM> substantially orthogonally relative to the top side <NUM> of the cover <NUM>, as shown by force arrow <NUM>. Raising the shaft <NUM> of the actuating member <NUM> in the direction of the arrow <NUM>, causes a clockwise moment <NUM> about the mounting pin <NUM> of the mounting arrangement <NUM>. This causes a releasing force <NUM> to be applied at the locking member <NUM> in a direction away from the side wall <NUM> of the pit <NUM> which, in turn, causes the friction pad <NUM> of the locking member <NUM> to frictionally disengage from the side wall <NUM>. Further upward movement of the shaft <NUM> of the actuating member <NUM> causes the ends of the pin <NUM> to slide in the slots <NUM>, <NUM> of the link arms <NUM>, <NUM> of the links releasing the locking member <NUM> fully from the side wall. The collar <NUM> eventually abuts the bottom of the receptacle <NUM> of the cover <NUM> allowing the cover <NUM> to be lifted out of the opening of the pit <NUM> using the lifting tool.

It will be appreciated that, in alternate embodiments, the actuating member <NUM> may be connected between the first end <NUM> of the link <NUM> and the mounting pin <NUM> so that the mounting pin <NUM> is arranged intermediate the mounting of the actuating member <NUM> to the link <NUM> and the locking member <NUM>. In this configuration, the required force <NUM> applied to the actuating member <NUM> by using the tool, must be applied in an operatively downward direction to cause the link <NUM> to rotate relative to the mounting pin <NUM> of the mounting arrangement <NUM> to move the locking assembly <NUM> to the disengaged position.

Advantageously, the likelihood of success of unauthorised persons attempting to gain access to the pit <NUM> by attempting to lift the cover <NUM> will be reduced due to the lifting force <NUM> being transferred to the mounting arrangement <NUM>, thereby maintaining the frictional engagement between the locking member <NUM> and the side wall <NUM> of the pit <NUM>. In some embodiments, this frictional engagement is further strengthened by the unauthorised persons applying the lifting force <NUM> and causing the anticlockwise moment <NUM> applied at the locking member <NUM> to increase, thereby further reducing the likelihood of the unauthorised persons removing the cover <NUM>. It is an aim of the present disclosure that only authorised users using the lifting tool to apply the lifting force <NUM> to the actuating member <NUM> will be able to cause the locking assembly <NUM> to move to the disengaged position, thereby allowing such authorised users to lift the cover <NUM> to gain access to the pit <NUM>. In this way, the locking assembly <NUM> reduces occurrences of unauthorised entry into voids such as pits, manholes, passages, and the like.

Further, since the cover <NUM> is vented, potentially explosive gases are able to escape to atmosphere minimising the chances of explosions causing the cover <NUM> to be blown off the pit <NUM>. The locking member <NUM> will, however, assist in retaining the cover <NUM> in position in the event of unexpected disturbances of the cover <NUM> from beneath the cover <NUM>.

Claim 1:
A system comprising:
a cover (<NUM>), the cover (<NUM>) being a substantially rigid cover and configured to close off an opening (<NUM>) to a void (<NUM>) having a side wall (<NUM>), and the cover (<NUM>) defining a pair of opposed sides (<NUM>, <NUM>), being an operatively top side (<NUM>) and an opposed underside (<NUM>); and
a locking assembly (<NUM>) for the cover (<NUM>), the locking assembly (<NUM>) comprising:
a mounting arrangement (<NUM>) mounted to the underside (<NUM>) of the cover (<NUM>);
a link (<NUM>) pivotally connected to the mounting arrangement (<NUM>), the link (<NUM>) defining a first end (<NUM>) and a second, free end (<NUM>);
a locking member (<NUM>) carried by the second, free end (<NUM>) of the link (<NUM>), the locking member (<NUM>) being configured to frictionally engage with the side wall (<NUM>) of the void (<NUM>) in a locking position, in use, wherein such frictional engagement of the locking member (<NUM>) with the side wall (<NUM>) of the void (<NUM>) in the locking position, in use, locks the cover (<NUM>);
an actuating member (<NUM>) connected to the link (<NUM>) and accessible via the operatively top side (<NUM>) of the cover (<NUM>), the actuating member (<NUM>) being operable to displace the link (<NUM>) relative to the mounting arrangement (<NUM>) to cause the locking member (<NUM>) to frictionally disengage from the side wall (<NUM>) of the void (<NUM>) to a disengaged position, characterized in that the actuating member (<NUM>) is at least pivotally connected to the link (<NUM>).