GB2267106A

GB2267106A - A system for securing manhole and pit covers

Info

Publication number: GB2267106A
Application number: GB9310086A
Authority: GB
Inventors: Grahame George Kermonde
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-05-18
Filing date: 1993-05-17
Publication date: 1993-11-24
Anticipated expiration: 2013-05-17
Also published as: GB9310086D0; SG44570A1; GB2267106B; NZ247626A

Abstract

A system for securing manhole or pit covers comprises a latch actioning means (30) and operatively connected thereto at least two spring latch arms (31). The spring latch arms are retained under compression when the manhole or pit cover is in situ. Additionally, when the manhole or pit cover is in position, the security system may include a novel device 20 comprising a first resilient means 21 and second means 22, inserted in a hole 11. The said second means, which co-operates with said first resilient means, is adapted to expand said first resilient means such that when said first resilient means is inserted into said hole or recess and said second means is actively positioned with said first resilient means, said first resilient means is substantially jammed in said hole or recess. <IMAGE>

Description

A SYSTEM FOR SECURING MANHOLE AND PIT COVERS The invention relates to a system for securing manhole and pit covers; grates, drain security covers and in particular, telecommunication covers and pit lids.

It is generally required by the Water Board, Telecom etc. to prevent the public from gaining access to the pipes, drains (either stormwater or sewage) or telecommunication equipment, for a number of reasons including the public safety policy aspect as well as in the case of telecommunication equipment, the possible damage which could occur to the expensive and important equipment stored under the manhole and pit covers.

On the issue of safety, statutory and Government bodies such as Telecom and the Water Board can arguably be held to be negligent if the covers can be removed by children and adolescent vandals and some harm comes to the children or vandals. Thus, essentially, such organisations wish to avoid any such incidents and must take steps to prevent them happening.

In respect of possible damage to telecommunication equipment with the advent of communication equipment becoming more compact, the area under manhole covers can house expensive and important equipment. As well as telecommunication cables, which any damage thereto can amount to millions of dollars in lost revenue and disruption to businesses using the same.

Some attempts have been made in the prior art to address the problems of preventing persons from obtaining entry into manholes or pits and thus minimise the damage that can occur. However, previous attempts have not been particularly effective in preventing vandals or unauthorised persons from entering the manhole or pit. The prior attempts included additional locking arrangements affixed to the manhole/pit cover, however these were generally not successful because the arrangements were apparent to the potential intruders and thus the way to enter the pit was obvious.

Whilst attempts have been made to address the problem of disguising the locking mechanisms and thus also the route to entry, the prior art attempts have generally been complex in structure. Because of the complexity of the prior art structures, they were unreliable and the cost (in the form of labour and expense) of producing the apparatus and maintaining the same in working order has been, to date, quite significant.

An example of the prior arts attempt to address the problem of security in relation to manhole covers is disclosed in US Patent No. 5,082,392. This patent discloses a locking manhole cover and key combination and in particular, discloses the use of rigid arms which are mounted upon a rotatable actuator.

The arms have attached thereon a spring mechanism to ensure that the arms are retained under tension and more importantly, according to the inventors, to ensure that the arms are retained in the "locked position". The problems with this mechanism is that because of the complexity of the arrangement and in particular, the use of a significant number of interrelated parts, the mechanism is expensive, difficult and laborious to install and maintain in working order.

Additionally, the mechanism is more prone to tampering because of its tendency to be unreliable.

Further to the issue of safety, workers for the statutory and Government bodies continuously, on their rounds, need to gain access to the manholes and pits. However, it has become a recent problem, with the increased risk of contracting AIDS, of syringes being placed in the access holes of manhole or pit covers. Workers have been stabbed by an unexpected syringe and thus there is a great need to effectively close-off access holes in manhole and pit covers as well as secure the covers themselves.

The present invention addresses some of the problems of the prior art and in particular, provides a system which is simple in design and effective in preventing the unwanted entry into manholes and pits.

The invention provides a security system for manhole or pit covers comprising a latch actioning means, and at least two spring latch arms operatively connected to said latch actioning means, wherein said spring latch arms are retained under compression when the manhole or pit cover is in position.

The latch actioning means can be actioned by a conventional manhole or pit cover key.

Preferably the spring latch arms have at least one curve, and more preferably an S-portion in their length. The spring latch arms are preferably located on the, preferably rotatable, latch actioning means such that in the locked position and, in situ, the arms are "over-centre" and thus cannot be disengaged by simply pushing on the spring latch arms.

The latch arms may cooperate with the wall of the pit or manhole or the ground.

The security system can be formed into the manhole cover or pit cover during the manufacture thereof or as a retrofit.

The security system may be made of metal or plastic.

Another aspect of the invention provides a device for securing a manhole or pit cover comprising a first resilient means adapted to fit into a hole or recess in the manhole or pit cover and a second means which co-operates with said first resilient means and is adapted to expand said first resilient means such that when said first resilient means is inserted into said hole or recess and said second means is actively positioned with said first resilient means, said first resilient means is substantially jammed in said hole or recess.

Preferably, said second means fits within said first resilient means. The device is preferably one single component; however, the first and second means may be separate components.

The first resilient means may act as a housing for said second means.

The device of the invention may be made of metal or plastic. In the case of the first means this may be made of any resilient material. The second means can be made of any solid material.

The device of the present invention can be used alone or in combination with other security means. The device of the present invention is preferably actioned manually or by a key and preferably unlocked by a key.

The various aspects of the invention can be used in combination with each other, even though each of the aspects can be used alone.

Advantageously, the present invention provides an effective, yet simple system of preventing access to a manhole or pit without the shortcomings of the prior art.

The invention may be further understood from the following discussion of some preferred embodiments of the invention.

Figure la - a conventional cast iron manhole cover currently in use.

Figure 1 b - another conventional cement pit cover currently in use.

Figure 2 - illustrates one aspect of the invention.

Figure 3a - illustrates a detailed aspect of the invention viewing from underneath the cover in the unlocked position.

Figure 3b - illustrates a detailed aspect of the invention viewing from underneath the cover in the locked position.

Figure 4a - illustrates an embodiment of the locking mechanism aspect of the invention from a bottom view.

Figure 4b - illustrates an embodiment of the locking mechanism aspect of the invention from the top view.

Figure 5 illustrates another aspect of the invention when made from plastic.

Figure 6a - illustrates a sample of the prior art.

Figure 6b - illustrates one embodiment of one aspect of the invention.

Figure 6c - illustrates a cross-section of Figure 6b.

Figure 6d - illustrates another embodiment of the same aspect of the invention as in Figure 6b.

Figure 6e - illustrates another embodiment of the same aspect of the invention as in Figure 6b.

Figure 6f - illustrates a variation of the embodiment of Figure 6e.

Figure 6g - illustrates another embodiment of the same aspect of the invention as in Figure 6b.

Figure 7a - illustrates a further embodiment of Figure 6b in the unlocked position.

Figure 7b - illustrates the embodiment of Figure 7a in the locked position.

Figure 8a - illustrates another embodiment of Figure 6b in the unlocked position.

Figure 8b - illustrates the embodiment of Figure 8a in the locked position.

Figure 9 illustrates an embodiment of the security system of the present invention.

Figures 1 a and 1 b illustrate typical manhole and pit covers which are used in Australia and throughout the World. Figure 1a illustrates the metal variety of manhole cover 1 0a with conventional key access hole 11 a. The conventional key (not shown) is inserted into the hole 11 a and rotated enabling the manhole cover to be lifted open. Figure 1 b illustrates the concrete variety of pit cover 1 orb also with conventional key access hole 11 b. As with the manhole cover 10a of Figure 1a, the conventional key (not shown) is inserted into the hole 11 b of pit hole cover 1 0b and rotated enabling the pit hole cover to be lifted open.

Thus, the present invention deals with limiting general access to the pit or manhole by providing a novel security system.

Figure 2 is directed to one aspect of the present invention. Pit / manhole cover 10 covers pit / manhole defined by the pit / manhole wall 40. Provided underneath the pit / manhole cover 10 is a locking/latching mechanism comprising components 30 and 31. Latch actioning means 30 is connected to spring latch arms 31. The latch actioning means 30 is preferably rotatable and in Figure 2 is attached to the underside of cover 10 via housing means 32.

Housing means 32 allows the latch actioning means 30 to rotate. Preferably, the latch actioning means 30 has a hole or recess 34 which is similarly positioned underneath a hole or recess (11) in the manhole cover (10). The hole or recess (11) can be an access hole or in the case of covers for sewage pipes etc., the hole or recess (11) can be a vent hole. Thus, advantageously, when the manhole cover (10) is viewed from above, there is no apparent security system.

To the passer-by, the manhole cover 10 appears to be unrestrained and if entry is attempted the locking mechanism is not apparent.

The spring latch arms 31 are operatively connected to the latch actioning means 30 and at their other ends cooperate with the pit / manhole wall or frame 40. The spring latch arms 31 are constructed such that they can be placed under compression. Because of the nature of the spring latch arms 31, the manhole cover 10 can be retained in situ in a recess or recess frame, even when there is a wide tolerance of size. Similarly, because of the spring arrangement, the manhole cover 10 is retained in position when subjected to severe vibration or deformation due to machinery or foot and vehicular traffic.

It can be seen from Figures 2 and 4a that the spring latch arms 31 have protrusion means 33 attached or formed on the ends thereof. In the embodiment shown, the protrusion means 33 is in the "hat" form and is placed and/or formed on the end of the spring latch arms 31. A support means 35 supports the spring latch arms 31 and protrusion means 33 on the manhole or pit "wall" side of the actual protrusions 37. The protrusion means 33 when it is in the "hat" form may have extra gripping means 38 on its wall contacting surface. Reference is now made to Figure 4b wherein another form of protrusion means 36 is illustrated.

These protrusion means 36 are protrusions on the spring latch arms 31 and function the same way as the protrusion means 33 operate. In this case gripping means (not shown) may be applied to the spring latch arms 31.

With reference to Figure 2 again, it should be noted that the protrusion means 33 / spring latch arms 31 can pressure contact the wall of the pit or manhole 40 (left-hand side of Figure 2) in the manner of a latch or be recessed into the wall 40 (right-hand side of Figure 2) thereby strongly jamming the cover or lid into position over the manhole or pit.

Figures 3a and 3b illustrate more clearly the function of the protrusion means 33. Figure 3b illustrates the locking system in the "locked" position, in situ, as in the case of Figure 2 applied to a cement cover. In the "locked" position the spring latch arms 31 are under compression and it is the force of the spring action of the latch arms 31 against the wall 40, directly or via the protrusion means 33, that holds the cover 10 in place. As can be seen in the "locked position", the protrusions 37 do not contact the support 35. It should be noted that the support 35 may be moulded (in the case of cement) or cast (in the case of metal) into the manhole or pit cover 10 or they may be a separate piece construction.

The main purpose for the protrusion means 33 (or 36) and support 35 is for the "unlocked" arrangement and when the cover 10 has been removed and is ready for re-positioning. It can be seen that in the "unlocked" position, the protrusions 37 of the protrusion means 33 are contacting the support 35. By having the protrusion means 33 and support 35, the latch actioning means 30 can only rotate back the prescribed amount, thus advantageously enabling the key to be reinserted into the access hole 11 and engage the latch actioning means 30 easily. If the protrusion means 33 and support system 35 were not present, the latch actioning means 30 would rotate to any position making the reinsertion of the key into the latch actioning means 30 in the correct position very difficult and replacing of the cover 10 in situ, would be awkward for one person to manage.

In the preferred embodiment illustrated in Figures 4a and 4b, spring latch arms 31 have a curve shape and most preferably an "S" configuration to enable the arms to act as a spring and thus enable compression of the bars. Other shapes which provide the same action can be used; however, the "S" shape is preferred. The system of the present invention is particularly simple in design, relying upon simple co-operation between spring latch arms 31 and latch actioning means 33. Installation and maintenance time and costs are reduced significantly without any loss in effectiveness in securing the manhole or pit. In fact, the spring arm arrangement of the present security system is substantially more reliable than prior art systems because of the simplicity of the system but also because it allows for more variations in the surroundings.

Also in the preferred embodiment, it can be seen from Figure 4b in particular, that the spring latch arms 31 are connected to the latch actioning means 30 in an "over-centre" arrangement. Thus, once the locking mechanism is in a locked position, the only way to release the spring latch arms 31 from their engagement with the pit / manhole wall or frame 40 is by rotating the latch actioning means 30. That is, unlike prior art mechanisms, the spring latch arms 31 cannot be disengaged from the locked position by simply pushing on the spring latch arms 31, since the latch actioning means 30 will not rotate.

Furthermore, the combination of the spring latch arms 31 and the "over centre" mechanism provides a particularly secure locking arrangement, wherein both features of "spring arms" and "over centre" prevent the latch arms 31 from being moved out of position.

The system can be made of metal or plastic and Figure 5 illustrates a plastic form of this aspect of the invention with latch actioning means 50 and latch arms 51 held onto cover 10 by support 52. This embodiment works in a similar manner to that described in relation to the embodiment described in relation to Figure 2. It is noted that latch arms 51 can also withstand being compressed, however, it is expected that for the plastic form, the latch arms 31 will be a different shape and are preferably made up of multiple arms as illustrated. Support means 55 and protrusion means 53 operate in a similar manner to support means 35 and protrusion means 33.

Figure 6a illustrates an example of the prior art. The plug 19 fits into the likes of access or vent holes 11 a and 11 b; however, due to its construction the plug 19 can easily be removed and the public has easy access to the lifting handle keyhole (which are also access or vent holes 11 a or 11 b) and therefore the manhole or pit.

Figures 6b and 6c illustrate one form of another aspect of the invention.

The device generally indicated 20b is comprised of a first resilient means 21b and second means 22b. The device 20b is inserted into the lifting handle keyhole (11 a and 11 b). However, to be inserted a second means 22b must be in its "loose", that is not in its "fixed" form. After the device 20b is inserted into the access hole, the second means 22b is pushed into its "fixed" position. The bottom portion of 21b is pushed outwards and thus forcing 21b up against the hole, making the removal of device 20b from the hole extremely difficult.

Figure 6d illustrates another form of the same aspect of the invention as Figure 6b. Figure 6d has a first resilient means 21d and second means 22d.

However, second means 22d is attached to first resilient means 21d via support means 23. Thus, essentially, second means 22d is hinged to the first resilient means 21d via 23. The other side of second means 22d can be "loose" or "fixed" into position such that the device 20d is fixed or otherwise into the access holes 11 a or 11 b of the manhole or pit cover.

Figures 6e and 6f illustrate other forms of the same aspect of the invention as Figure 6b. Figures 6e and 6f illustrate the device of the invention made of plastic. The first resilient means is denoted as items 21e and 21f and second means, items 22e and 22f.

In Figure 6e, in order to "fix" the device 20e in position within access holes 11 a or 11 b, second means 22e is pushed in the downwards direction. To disengage the device 20e, the second means 22e is pushed even further in the downward direction to a narrower portion of 22e.

In Figure 6f, in order to "fix" the device 20f in position within access holes 11 a or 11 b, second means 22f is pushed in the downwards direction until, the first means 21f is jammed in. To disengage the device 20f the second means 21f is pulled in the upwards direction, by the use of a key (not shown) and in a similar manner discussed in relation to Figures 8a and 8b.

Figure 6g illustrates a plastic form of the same aspect of the invention as Figure 6b. The first means 21g is shaped such that it fits into access hole 11 a.

Second means 22g operates in a similar manner to Figure 6f wherein second means 22g is pushed in a downwards direction until the first means 21g is jammed into the access hole 11 a. To remove the device, second means 22g is pulled in an upwards direction, by the use of a key (not shown) and in a similar manner discussed in relation to Figures 8a and 8b.

Figures 7a and 7b illustrate a further embodiment of this aspect of the invention, however, in this embodiment, first resilient means 721 has an opening in its upper portion to receive second means 722. As with the other embodiments in the locked position (Figure 7b) the second means 722 expands the first resilient means 721. The operation of this embodiment is similar to the embodiment illustrated in Figures 8a and 8b which is discussed below.

Figures 8a and 8b illustrate a device 820 which is very similar to the device 720 illustrated in Figures 7a and 7b but designed to fit into the cement/concrete manhole covers. Device 820 consists of first resilient means 821 and second means 822, wherein second means 822 has lug 823. In operation the worker places the device 820 (as shown in Figure 8a) in the hole (11) of the manhole cover (10) and then, with his foot or hand pushes the second means 822 into first resilient means 821, which results in substantially jamming the device 820 into the hole 11 and having the flush appearance to a passer-by as illustrated in Figure 8b. To remove the device 820 a key (not shown) is used. The key (not shown) is inserted into the small hole 824 (724 on Figures 7a and 7b) of the second means 822.The hole 824 passes through the body of the second means 822. The key (not shown) which is shaped the same as hole 824 is pushed through hole 824 until the head portion of the key has passed through hole 825 in the first resilient means 821. The key is then rotated, in this case, 180 degrees and pulled in the upward direction. Second means 822 is also pulled upwards thus unjamming the device 820. Continued pulling of the key (not shown), allows lugs 823 to act on the first resilient means 821, thus pulling the entire device 820 out of the hole 11. To reinsert the device 820, the device 820 is inserted into the hole 11 and in this case, second means 822 is trod upon. The device 820 can be removed and inserted as often as required.

Figure 9 illustrates the security system of the invention utilising all of the aspects of the invention simultaneously. As can be seen from Figure 9, device 20 fits into access hole 11 and preferably also into the hole 34 of latch actioning means 30.

To open the manhole cover from the locked position illustrated in Figure 9, the device 20, which as illustrated is similar to device 820 of Figures 8a and 8a, is removed. A key (not shown) for the device 20 is used to lift up the second means 822 and thus unjam the device 20. Device 20 is then removed in a manner discussed in relation to Figures 8a and 8b. A conventional manhole / pit cover key (not shown) is then inserted into access hole 11 and into recess 34 of the system of the present invention. The manhole / pit cover key is shaped such that it engages with recess 34 and upon rotation similarly rotates the latch actioning means 30 and allows the spring latch bars 31 to decompress and retract. With the spring latch bars 31 retracted, the manhole / pit cover can be lifted using the same key.

When the manhole / pit cover is out of position and the key has been removed, the spring latch bars 31 are maintained under compression with the aid of protrusion means 33 (36) and support means 35. This system advantageously ensures that the recess 34 and the access hole 11 remain aligned and thus allowing the conventional key (not shown) to be easily reinserted into the access hole 11, and the recess hole 34 of the latch actioning means 30 when the manhole / pit cover 10 is to be re-locked.

Once the manhole / pit cover 10 is in position over the manhole or pit the key (not shown) is rotated, rotating the latch actioning means 30 and engaging the spring latch arms 31 in pressure contact with the pit wall 40 or a recess therein.

Thus, this particular aspect of the invention provides a secure means of protecting the contents of the pit / manhole from the public1 but to those who need to gain access provides a one step simple action using a conventional key means. Thus, no retraining of operators is required nor is there a need for any special or new tools. Additionally, due to the simple action of the mechanism, importantly, no extra time is required to release or fit the covers.

The device 20 can then be replaced in the hole 11 and if it is of the type illustrated in Figures 8a and 8b it is trod upon, leaving a flush surface.

It should be noted that in an emergency the security system can be operated from underneath and in most cases emergency keys may be provided within the pit or manhole.

The system of the present invention is cheaper than existing complicated systems to manufacture and fit, wherein the system can be economically retrofitted to existing manhole covers and pit lids in common use since no modifications to manholes or pits or frames therein are required. Similarly, the system can be cost effectively fitted at the time of manufacture of the cover or lid.

The system is particularly reliable because of its simplicity but also because of its ability to withstand large variations in the pit / manhole walls or frames and the environments thereof.

In combination, the aspects of the invention provide a simple, reliable, unique and effective security system, however, it is envisaged that each of the aspects of the invention can be used separately and still provide a more reliable and effective security system than is previously known.

Claims

14 A security system for manhole or pit covers comprising a latch actioning means, and at least two spring latch arms operatively connected to said latch actioning means, wherein said spring latch arms are retained under compression when the manhole or pit cover is in position.

2. The security system of Claim 1, wherein the latch actioning means is rotatable.

3. The security system of any one of Claims 1 or 2, wherein the spring latch arms are connected to said latch actioning means so that when the manhole or pit cover is in position, the spring latch arms are over-centre.

4. The security system of any one of Claims 1 to 39, wherein the latch actioning means is positioned underneath a hole in the manhole or pit cover.

5. The security system of Claim 4, wherein when the manhole or pit cover is in position the hole or recess in the manhole or pit cover has therein a first resilient means adapted to fit into said hole or recess and a second means which co-operates with said first resilient means and is adapted to expand said first resilient means so as to substantially jam said first resilient means in said hole or recess.

6. A device for securing a manhole or pit cover comprising a first resilient means adapted to fit into a hole or recess in the manhole or pit cover and a second means which co-operates with said first resilient means and is adapted to expand said first resilient means such that when said first resilient means is inserted into said hole or recess and said second means is actively positioned with said first resilient means, said first resilient means is substantially jammed in said hole or recess.

7. The device of Claim 6, wherein said second means fits within said first resilient means.

8. A security system for manhole or pit covers substantially as herein described with reference to, and as illustrated in, Figures 2, 3a and 3b, Figures 2, 3a, 3b, 4a and 4b, Figure 2 as modified by Figure 5, or Figure 9, of the accompanying drawings.

9. A device for securing a manhole or pit cover substantially as herein described with reference to, and as illustrated in, Figures 6b and 6c, Figure 6d, Figure 6e, Figure 6f, Figure 6g, Figures 7a and 7b, Figures 8a and 8b or Figure 9, of the accompanying drawings.