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The invention relates to a lock, more specifically a lock for securing a manhole cover to a manhole ring.
Background of the invention, the prior art and the drawbacks thereof
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Conventional manhole covers are designed to be openable without the use of a tool, possibly by means of a digging bar or the like, which is inserted into a digging-bar hole in the manhole cover in order to lift the manhole cover from a surrounding manhole ring. This makes it easy to open the manhole cover but has the drawback of allowing the manhole covers to be opened by anybody.
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Unauthorized opening of manhole covers is an increasing problem. A removal or displacement of a manhole cover is a great safety risk as pedestrians and playing children may fall into the manhole. Car-drivers and cyclists are also known to have run into loose manhole covers or have run into manholes from which the manhole covers have been displaced or removed. Such accidents may have a considerable extent of damage, to both material and persons.
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In recent years, there have been an increased awareness of, and requirements for physical blocking of access to strategic infrastructure. Examples of such infrastructure are water mains, power cables and telecommunication cables which are often arranged in tunnels to which access is through a manhole with a manhole cover.
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Today, the securing of a manhole cover is typically done by welding the manhole cover to the manhole ring. This is a method often used at, for example, major events and state visits at which there is a risk of terror attacks. For example, 430 manhole covers were welded up when former US president Barack Obama visited Norway. This was done to prevent any possible positioning of explosives in the manholes along Mr. Obama's driving route. Afterwards, all the welds must be removed by means of a grinding tool.
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An alternative way of securing the manholes is using locks. In connection with establishing new infrastructure, it is known, outside Norway, to use manhole covers with factory-fitted locks. Such manhole covers may also replace ordinary manhole covers, but that requires replacement of both the manhole cover and the manhole ring. This is an expensive solution and is therefore seldom done on existing infrastructure.
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It is also known to have retrofittable locks. A feature common to these locks is that they comprise a pivotable locking pawl arranged to engage with a counter-element, for example a frame. The locks are arranged in a hole formed in the manhole cover and are screwed to the manhole cover. Screwing can be done with separate screws or with nuts arranged on the locking cylinder, wherein a first nut is arranged under the manhole cover and a second nut is arranged over the manhole cover. The locking pawl can be pivoted between a closed position and an open position by using a key. One drawback of prior-art retrofittable locks is that the locks become filled with dust and dirt. Further, they have a projecting portion above the top side of the manhole cover, whereupon the projecting portion is exposed to wear from vehicles and implements, for example snow-clearing equipment, running over it. Another drawback is that the locking pawl may easily become damaged if the manhole cover falls uncontrolledly onto the ground or gets an inaccurate or incorrect positioning in the manhole ring.
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Further, it is known to have devices that block access to the lifting points but that do not prevent opening of the manhole cover.
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Therefore, alternative solutions are sought to secure manhole covers, the solutions being adapted for Norwegian infrastructure, climate and road maintenance.
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The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.
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The object is achieved through the features that are specified in the description below and in the claims that follow.
General description of the invention
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The invention is defined by the independent claims. The dependent claims define advantageous embodiments of the invention.
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In a first aspect, the invention relates more specifically to a lock for a manhole cover with at least one digging-bar hole, the lock comprising a housing, a coupling portion for engaging with the manhole cover and a latch arranged to engage with an encircling manhole ring, the lock being adapted for releasable attachment in the digging-bar hole.
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By a digging-bar hole may be understood, herein, a cut-out in the manhole cover, the cut-out being arranged to receive a tool for lifting the manhole cover from the encircling manhole ring. The tool may, for example, be a digging bar, a crowbar or a rod. A manhole cover as described herein may have one or more digging-bar holes.
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By a latch may be understood a projecting element belonging to a lock, the latch being designed for engagement with a counter-element or a recess. The lock may be arranged on a first body, for example a door. The counter-element may be arranged on a second body, for example a door frame. In the invention that is described herein, the manhole cover is equivalent to the door and the manhole ring is equivalent to the door frame.
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The effect of the lock being adapted for releasable attachment in the digging-bar hole is that the lock can both lock the manhole cover to the manhole ring and block the digging-bar hole to a tool arranged to open the manhole cover. A portion of the lock may fill out a portion of the digging-bar hole.
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The coupling portion of the lock is arranged for releasable attachment of the lock to the manhole cover so that the lock cannot be removed from the manhole cover when the latch is in engagement with the encircling manhole ring.
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Prior-art retrofittable locks are arranged outside the digging-bar hole and typically comprise a pivotable latch arranged to engage with the manhole ring. By the lock being arranged outside the digging-bare hole, the digging-bar hole will remain open so that a tool may be placed in the digging-bar hole to prise open the lock and the manhole cover. This is not possible with the invention, as the invention both locks the manhole cover to the manhole ring and blocks the digging-bar hole.
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By the lock described herein being adapted for releasable attachment, the lock may be retrofitted to the manhole cover, and the lock may be removed from the manhole cover when it is not necessary to secure the manhole cover. The lock may be adapted for manhole covers of different designs and with differently sized digging-bar holes.
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In one embodiment, the lock may be positioned in the digging-bar hole when the manhole cover has been released from the manhole ring. In an alternative embodiment, the lock may be positioned in the digging-bar hole when the manhole cover has been released from the manhole ring or when the manhole cover is positioned in the manhole ring.
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The coupling portion may project from a lower portion of the housing.
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The effect of the coupling portion projecting from a lower portion of the housing is that the coupling portion may be positioned in an engagement portion on a bottom side of the manhole cover so that the coupling portion is not accessible from a top side, for example a street level, when the manhole cover is positioned in the manhole ring. Thereby the coupling portion will be protected from any act of vandalism from the top side of the manhole cover.
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The engagement portion may include a recess or a groove. The engagement portion may include a bow arranged to secure the position of the lock relative to the manhole cover in one or more directions.
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The latch may be movable between an open position and a closed position.
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The effect of the latch being movable, is that the lock can more easily be positioned in the digging-bar hole when the latch is in the unlocked position, and that a movable latch may be made longer than a fixed latch so that the movable latch may engage more deeply with the counter-element or the recess when the movable latch is in the locked position, compared with a non-movable latch. By a non-movable latch may be understood a fixed latch.
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By an open position may be understood an unlocked position in which the latch is positioned in the housing or under the housing. By a closed position may be understood a locked position in which the latch projects from the housing so that the latch may engage with the counter-element or the recess. By the fact that the latch may engage more deeply with the counter-element or the recess, the latch may be in engagement with the counter-element even if the lock is displaced in the digging-bar hole or if the manhole cover is displaced in the manhole ring.
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A movable latch is advantageous if one and the same lock is to be used in digging-bar holes of varying sizes and where there is a large and/or varying clearance between the manhole cover and the manhole ring. By the movable latch being positionable in the housing or under the housing, the movable latch may be longer than the fixed latch.
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The lock may comprise a locking device arranged to move the latch between the unlocked position and the locked position.
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The effect of the locking device is that the latch may be moved even if it is inaccessible to a person. The locking device may be a locking cylinder arranged to receive a key. The locking device may include a slot for receiving a tool. The key may be formed as a ring or a cylinder.
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The locking device may be replaceable.
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The locking device may have a drain.
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The effect of the drain is that particles and water can flow down through the locking device so that it does not become blocked by, for example, particles or by water freezing to ice. Drainage is particularly beneficial when the manhole cover is positioned in a street or on a pavement where both snow is being cleared and grit or salt is being spread.
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The latch may be displaceable.
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The effect of the latch being displaceable is that it may be pulled completely or partially into a slot in the housing so that the latch is protected when the lock is in the unlocked position.
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The latch may be pivotable.
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The effect of the latch being pivotable is that the latch may be arranged outside the housing, for example under the housing, so that there is less risk of the latch becoming wedged in the housing, compared with a displaceable latch which is retracted into the housing.
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An upper portion of the housing may include a threaded portion arranged to receive a plug or a tool.
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The effect of the threaded portion is that a plug or a tool with a corresponding threaded portion may be arranged for the threaded portion of the housing. The threaded portion may be an internal one.
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The plug may be arranged to protect the locking device, for example by preventing sand or a fluid from getting down into the locking device. The plug may include a portion arranged to receive a tool, for example a screwdriver or a spanner. The plug may be a bolt.
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The tool may be arranged to simplify the positioning of the lock in the digging-bar hole and to simplify the removal of the lock as the tool may include a handle in order to give a good grip for an operator. In one embodiment, the tool may be a screw. In an alternative embodiment, the tool may be a lever arm with a threaded portion.
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In a second aspect, the invention relates more specifically to a system for securing a manhole cover in a manhole ring, the system comprising at least two locks in accordance with the first aspect of the invention.
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The effect of the system comprising at least two locks is that the at least two locks may be arranged in at least two digging-bar holes. Thereby, locks may be positioned in all the digging-bar holes of a manhole cover so that it will not be possible to prise open the manhole cover by using a digging bar, for example.
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The system may comprise at least one lock comprising a latch which is movable between an open position and a closed position.
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The effect of the system comprising at least one lock with a movable latch is that, in a manhole cover with several digging-bar holes, one lock adapted for being removable from the digging-bar hole while the manhole cover is positioned in the manhole ring may be arranged.
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In a manhole cover with at least two digging-bar holes, a lock with a movable latch may be positioned in one digging-bar hole, for example, whereas in the other digging-bare holes, locks with fixed latches may be arranged. The locks with fixed latches may be used as guides for the manhole cover when the manhole cover is to be positioned in the manhole ring. Further, locks with fixed latches are simpler and more solid than locks with movable latches.
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The system may comprise at least one lock comprising a locking device arranged to move the latch between the unlocked position and the locked position.
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The effect of the latch being movable is that the lock can more easily be positioned in the digging-bar hole when the latch is in the unlocked position, and that a movable latch may be made longer than a fixed latch so that the movable latch may engage more deeply with the counter-element or the recess when the movable latch is in the locked position, compared with a non-movable latch. By a non-movable latch may be understood a fixed latch.
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By an open position may be understood that the latch is positioned in the housing or under the housing. By a closed position may be understood that the latch projects from the housing so that the latch may engage with the counter-element or the recess. By the latch being able to engage more deeply with the counter-element or the recess, the latch may be in engagement with the counter-element even if the lock is displaced in the digging-bar hole or if the manhole cover is displaced in the manhole ring.
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A movable latch is advantageous if one and the same lock is to be used in digging-bar holes of varying sizes and where there is a large and/or varying clearance between the manhole cover and the manhole ring. By the movable latch being retractable into, or being retractable under, the housing, the movable latch may be longer than a fixed latch.
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The system may comprise a lock, wherein the locking device has drainage.
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The effect of the drainage is that particles and water may flow down through the locking device so that it does not become blocked by, for example, sand and dirt, or by water in the lock freezing to ice. This is particularly favourable when the manhole cover is positioned in a street or on a pavement.
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The system may comprise a lock with a displaceable latch.
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The effect of the latch being displaceable is that it can be retracted completely or partially into the housing so that the latch is protected when the lock is in the unlocked position.
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The system may comprise a lock with a pivotable latch.
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The effect of the latch being pivotable is that the latch may be arranged outside the housing, for example under the housing, so that there is less risk of the latch becoming wedged in the housing, compared with a displaceable latch which is retracted into the housing.
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The system may comprise a lock in which an upper portion of the housing includes a threaded portion arranged to receive a plug or a tool.
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The effect of the threaded portion is that a plug or a tool with a corresponding threaded portion may be arranged in the threaded portion. The threaded portion may be an internal one.
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The plug may be arranged to protect the locking device, for example in order to prevent particles or fluid from getting down into the locking device. The plug may include a portion arranged to receive a tool, for example a screwdriver or a spanner arranged to tighten or loosen the plug. The plug may be a bolt.
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The tool may be arranged to simplify the positioning of the lock in the digging-bar hole and simplify the removal of the lock, as the tool may include a handle to give a good grip for a person. In one embodiment, the tool may be a bolt. In an alternative embodiment, the tool may be a lever arm with a threaded portion.
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In a third aspect, the invention relates to a method for securing a manhole cover with a lock according to the first aspect of the invention, the method comprising the steps of:
- a) forming an attachment portion for the lock in the manhole cover.
- b) forming a keeper for the latch in an encircling manhole ring.
- c) positioning the manhole cover in the manhole ring.
- d) positioning a lock with a movable latch in a first digging-bar hole.
- e) adjusting the latch from the open position to the closed position.
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The method may further, before step c), include the step of:
f) positioning a lock according to the first aspect of the invention in at least one second digging-bar hole.
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The effect of the method that is described herein is that a manhole cover with a digging-bar hole may be secured by arranging a releasable lock in the digging-bar hole. In a manhole cover with several digging-bar holes, one lock may be arranged in each of the digging-bar holes.
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In a manhole cover with several digging-bar holes, a first lock comprising a movable latch may be arranged at a first digging-bar hole, and at a second and possibly more digging-bar holes, a lock with a fixed latch may be arranged.
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The lock with the fixed latch may be arranged on the manhole cover before the manhole cover is positioned in the manhole ring. When the manhole cover is being positioned, the fixed latch may be used as a guide for the manhole cover and engage with the manhole ring as the manhole cover is positioned in the manhole ring. Then a lock with a movable latch may be positioned and locked in the open digging-bar hole.
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In what follows, examples of preferred embodiments are described, which are visualized in the accompanying drawings, in which:
- Figure 1
- shows a top view of a locking system comprising a plurality of locks arranged in a plurality of digging-bar holes in a manhole cover in a manhole ring;
- Figure 2
- shows a lock with a fixed latch in perspective and on a larger scale;
- Figure 3
- shows a lock with a pivotable latch in perspective;
- Figure 4a
- shows a lock with a displaceable latch in a closed position, in perspective;
- Figure 4b
- shows the lock of figure 4a in an open position;
- Figure 5a
- shows a top view of a lock with a fixed latch positioned in the diggingbar hole;
- Figure 5b
- shows a section of figure 5a;
- Figure 6a
- shows a top view of a lock with a displaceable latch positioned in the digging-bar hole;
- Figure 6b
- shows a section of figure 6a;
- Figure 7a
- shows a top view of a lock with a pivotable latch positioned in the digging-bar hole;
- Figure 7b
- shows a section of figure 7a;
- Figure 8
- shows a perspective view of a locking cylinder;
- Figures 9a-b
- show perspective views of a key for the lock from the top side and from the bottom side;
- Figure 10
- shows a tool for installing and removing the lock in/from the digging-bar hole; and
- Figure 11
- shows a cap for the lock.
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Figure 1 shows a top view of a locking system 99 comprising a manhole cover 5 with three digging-bar holes 52, a manhole ring 7, a first lock 1a with a fixed latch 12 (figure 2) and a second lock 1b with a movable latch 12 (figures 4a, 4b).
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The second lock 1b comprises a locking cylinder (not shown) which is arranged to move the latch 12 between a closed position (figure 4a) and an open position (figure 4b).
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First locks 1a were positioned in two digging-bar holes 52 before the manhole cover 5 was positioned in the manhole ring 7. After the manhole cover 5 was positioned in the manhole ring 7, the second lock 1b was threaded into and positioned in a third digging-bar hole 52. The second lock 1b was threaded into and positioned in the digging-bar hole 52 with the latch in an open position (figure 4b). Then the latch 12 was moved 12 from the open position to the closed position. To displace the latch 12, a key (figure 9) has been used.
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When the locks 1a, 1b are positioned in the digging-bar holes 52 as shown in the figure, the manhole cover is locked to the manhole ring 7, and the locks 1a, 1b are blocking the digging-bar holes 52 so that it is not possible to arrange a digging bar or some other tool (not shown) in the digging-bar hole to open the manhole cover 5 by the digging-bar holes 52.
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Figure 2 shows a first lock 1a with a fixed latch 12. The first lock 1a comprises a housing 10, a coupling portion 11 and the fixed latch 12. The coupling portion 11 projects from a lower portion of the hosing 10. The fixed latch 12 projects from the housing 10 on an opposite side to that of the coupling portion 11. In figure 2, the first lock 1a is shown as one piece of material.
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Figure 3 shows a second lock 1b with a movable latch 12, more particularly a pivotable latch 12. Figure 3 shows the movable latch 12 in a closed position. The latch 12 may be pivoted between the closed position and an open position by means of a key 3 (figures 9a-b). In the open position, the latch 12 is positioned under the housing 10 so that the second lock 1b can be threaded into the digging-bar hole 52 (figure 7).
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Figures 4a and 4b show a second lock 1b with a movable latch, more particularly a displaceable latch 12. The figure 4a shows the latch 12 in a closed position A. The figure 4b shows the latch 12 in an open position B. The latch 12 can be displaced between the closed position A and the open position B by means of a key 3 (figure 9).
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Figures 5a and 5b show the first lock 1a positioned in the digging-bar hole 52, seen from above (figure 5a) and in a section (figure 5b), respectively. The coupling portion 11 of the lock 1a is positioned in a coupling portion 54 on a bottom side of the manhole cover 5. A bow 55 arranged on the manhole cover 5 prevents the lock 1a from falling down.
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The latch 12 is in engagement with a keeper 71 belonging to the manhole ring 7. The first lock 1a is positioned 5 on the manhole cover 5 before the manhole cover 5 is positioned in the manhole ring 7. The latch 12 and the coupling portion 11 have lengths that make the latch 12 and the coupling portion 11 be in engagement with the manhole cover 5 and the manhole ring 7 even if there is a clearance C between the manhole cover 5 and the manhole ring 7.
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Figures 6a and 6b show the second lock 1b positioned in the digging-bar hole 52, seen from above (figure 6a) and in a section (figure 6b), respectively. In figure 6a, a locking cylinder 13 with a star-shaped engagement portion for a key (figures 9a-b) is shown. The locking cylinder 13 is connected to the latch 12 so that the latch 12 may be displaced between the closed position as shown in figures 6a and 6b and the open position shown in figure 4b. Figure 6b further shows a cap 57 which is screwed to the housing 10 via a threaded portion 56.
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Figures 7a and 7b show the second lock 1b provided with a pivotable latch 12, the second lock 1b being positioned in the digging-bar hole 52, seen from above (figure 7a) and in a section (figure 7b), respectively. In figures 7a and 7b, the latch 12 is shown in a closed position. The latch 12 can be pivoted from the closed position to an open position (not shown), wherein, in the open position, the latch 12 is positioned under the housing 10 so that the second lock 1b can be placed in the digging-bar hole 52 or be removed from the digging-bar hole 52.
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Figure 8 shows a locking device 13, shown, in the figure, as a locking cylinder 13 comprising a rotatable key portion 14 and a slide 16. The key portion 14 is triangular and is arranged to engage with a corresponding key (figures 9a-b). The slide 16 is arranged to engage with the displaceable latch 12 (figures 4a-b, 5a-b) and move the displaceable latch 12 between the open position and the closed position. The locking cylinder 13 is further provided with a drain 15 so that water and particles may run through the locking cylinder 13.
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Figures 9a and 9b show a key 3 arranged to engage with the locking cylinder 13, figure 9a showing the key 3 in perspective from above, and figure 9 showing the key 3 in perspective from the bottom side.
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Figure 10a shows a tool 60 with a handle 61, and a threaded portion 62 arranged to engage with the threaded portion 56 in the lock 1a, 1b.
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Figure 11 shows the cap 57 shown in figure 6b. The cap 57 includes an external threaded portion 62 arranged to engage with the threaded portion 56 in the lock 1a, 1b. Further, the cap 57 is provided with a slot 63 for receiving a portion of a screwdriver so that the cap 57 may be screwed to the housing 10 or released from the housing 10.
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It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative embodiments without departing from the scope of the attached claims. In the claims, reference numbers in brackets are not to be regarded as restrictive.
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The use of the verb "to comprise" and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article "a" or "an" before an element does not exclude the presence of several such elements.
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The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.
