IES922856A2 - Cover locking device - Google Patents

Abstract

A manhole cover comprises a cast frame and a cover, the cover having been fitted with formations for receiving a bolt. The cover is convertible from non-lockable to lockable by the optional fitting of a shooting bolt into the cover formations. In use, the bolt head seats in a receiving formation in the frame to lock the cover. The bolt can be speedily assembled on the hatch, permitting easy interconversion of unlockable and lockable covers on site.

Description

COVER LOCKING DEVICE A manhole cover comprises a cast frame and a cover, the cover having been fitted with formations for receiving a bolt. The cover is convertible from non-lockable to lockable by the optional fitting of a shooting bolt into the cover formations. In use, the bolt head seats in a receiving formation in the frame to lock the cover. The bolt can be speedily assembled on the hatch, permitting easy interconversion of unlockable and lockable covers on site.

(Figure 4) S5 7 7 6 3 4/6 or o - 1 P6199.IES IE 922856 OVER LOCKING DEVICE 59228 Tfie present invention relates to a cover for underground chambers and in particular to a lockable cover for such 5 chambers.

Traditional covers for manholes, cable-joint boxes and the like comprise a frame which is placed on the underground chamber at ground level and a cover which rests in the frame. Typically, the cover is an iron casting or a steel fabrication or manufactured from concrete poured over and about steel reinforced bars. Once in place, the cover is flush with the surface of the ground.

For some applications, it is highly desirable that the cover should be lockable in place in the frame. It is not uncommon for underground chambers to be tampered with by vandals or thieves. For example, such chambers which are the property of telecommunications companies are frequently invaded by thieves who steal valuable copper wire. A thief might open two chambers in series, cut the wire in both, then pull through the intervening length of wire.

It will be appreciated that any intrusions by unauthorised 25 persons into such underground chambers is unwelcome and can result in great trouble and expense for the utility concerned. In some cases, tampering may even be dangerous for the intruder if, for example, electrical conductors are present.

Locks for such covers are known in the art and can be of a simple shooting bolt type or of a more complex design.

Unlocked covers are less expensive to produce than locked Η ί- JT' ./ 5 tUuu xLkj jNi NoMfel.......OF IE 922856 - 2 covers. Covers are generally supplied either with or without a lock, so that the utility company must stock two designs of cover. For some geographical areas, the low or non-occurrence of tampering would not justify the installation of a costlier cover fitted with a lock. Furthermore, it occasionally occurs that a previously unlocked cover need be substituted by a locked cover. Heretofore, this could be achieved only by the utility company stocking the various types of covers.

It is an object of the present invention to seek to overcome the disadvantages of known covers.

The present invention provides a cover for an access 15 chamber, the cover having an outer surface, an inner surface and a skirt depending from the inner surface, the inner surface being provided with means for retaining a locking bolt which is accessible from the outer surface by a key so as to move the bolt through an orifice in the skirt for locking engagement with a frame member secured to the access chamber.

Preferably, the cover is a metal casting, the retaining means being cast integrally with the cover.

Conveniently, the retaining means includes stop means for limiting the travel of the bolt between retracted and locking positions.

Advantageously, a locking bolt comprises at least two portions which are mutually disengageable to facilitate fitting the bolt to a cover as described above.

The invention also provides in combination a cover and a IE 922856 - 3 locking bolt as described above. Preferably, biasing means are provided for urging the bolt into a locking position.

Advantageously, the outer surface of the cover is profiled 5 so as to prevent skidding. Preferably, that portion of the outer surface over which a key travels on operation has a smooth profile to facilitate the operation of the key.

Conveniently, a key for use with a cover according to the invention comprises a cover lifting portion and a key portion, whereby rotational movement of the key operates the lock and pivotal movement of the key relative to the frame moves the cover away from the frame.

The invention will now be described more particularly with reference to the accompanying drawings, which show, by way of example only, an embodiment of an underground chamber cover according to the invention.

In the drawings: Figure 1 is a perspective view of the frame portion of the cover; Figure 2 is a plan view of the upper side of the cover; Figure 3 is a plan view of the under side of the cover, with a lock fitted; 30 Figure 4 is a perspective view of the under : side of the cover with a lock fitted; Figure 5 is a front elevational view of the locking bolt, with the spring omitted; IE 922856 - 4 Figure 6 is a sectional side view of the bolt taken along the line VI-VI in Figure 5; and Figure 7 is a perspective view of the lock opening and cover lifting key for the cover.

Referring to Figures 1 to 4, the frame 1 is cast from iron or fabricated from steel and has a shoulder 12 for receiving a cover 2. An underground chamber is normally constructed from concrete or preformed in plastics or fibreglass. The frame 1 seats on top of the walls of the chamber and is inset in the concrete. The frame may be incorporated in a preformed plastic or fibreglass chamber.

The frame 1 has an overhang 13 on two of its sides. Cover 2 has a top plate 21 and a depending skirt 22, which is provided with a cross-wall 23. Top plate 21 has a cut-out 21a on one of its sides and a step 21b on the opposing side. The cover 2 fits in place in the frame 1, with the skirt 22 resting on shoulder 12, step 21b engaged under one of the overhangs 13 and cut-out 21a passed over the other overhang 13. In this position, the upper surfaces of the cover 2 and frame 1 are normally flush.

On its underside, cover 2 is fitted with a number of features which permit a lock to be retrospectively fitted to the cover. In the embodiment shown in the drawings, these features are cast integrally with the cover. An end stop 24 is provided in line with an aperture 23a in the cross-wall 23. On the other side of the cross-wall 23, a lock retaining and key locating bracket 25 has a key aperture 25a. Additionally, a further aperture 22a is formed in the skirt 22 adjacent the cut-out 21a.

IE 922856 - 5 The cover 2 and frame 1 comprise the basic components, for use in situations where locking of the cover into place is not required or necessary. Cast covers which conform to the loading requirements of European Standard EN124 can be readily made from any suitable material, such as steel of grade 43, and at lower cost than reinforced concrete or steel section covers. However, it will be appreciated that covers and frames can be made from any common metals such as iron or steel or any combination of these materials with reinforced concrete.

The lock for use with the cover will now be described with reference to Figures 3 to 6. As shown in Figures 5 and 6, the bolt 3 is comprised of a shoot 31 and a support shaft 32. Shoot 31 is formed with a screw-threaded plug 31a which engages within a correspondingly threaded socket 32a in shaft 32. A flange 33 is formed on shaft 32.

Assembly of the lock onto a cover, whether in the workshop or on site, is a fast and straightforward operation. A spring 34 is placed over the length of shaft 32 which lies to the side of flange 33 away from the socket 32a. Shoot 31 is disengaged from shaft 32, then shaft 32 is inserted through aperture 23a and shoot 31 is inserted through aperture 22a. Shaft 32 and shoot 31 are then re-engaged with one another. In this configuration, the shoot is in the locked position, with its end protruding past the cut-away portion 21a. When the cover is in place on the frame, the shoot 21 underlies the overhang 13, thus locking the cover in place. Shoot 31 is biased into the locked position by spring 34 acting between the cross-wall 23 and flange 33, flange 33 in turn being limited by abutment against bracket 25. The lock may be equally readily disassembled from the cover by reversing the above steps.

IE 922856 - 6 To place the cover in or remove it from the frame, the shoot 31 is retracted by means of the lifting key 4, shown in Figure 7. As shown in Figures 2, 3 and 4, the cover 2 is provided with a key slot 26 and a lifting aperture 27. The shoot is retracted by inserting the key 4 into the key slot 26 until the locating pin 41 engages in the locking apertures 25a of the bracket 25, and the tooth 42 has passed through and cleared the key slot 26. Rotation of the key 4 then brings the tooth 42 into engagement with the flange 33 and further rotation forces the shaft 32 and shoot 31 to retract, against the action of the spring 34 until the shaft 32 hits the stop 24, thus preventing further travel. With the shaft 32 and the shoot 31 in the retracted position, the key can be lifted by means of the handgrip 44. With the shaft 32 and the shoot 31 in the retracted position the lifting action of the key 4 lifts the cover clear of the frame at that end and the cover can then be pulled forward in the frame enabling complete cover removal. Aperture 27 is used with known keys to lift out unlocked covers .

The cover 2 is advantageously covered in non skid studs or other non-slip features on its upper surface (not shown).

In such cases, the travel of the key over that surface may be impaired and for that reason a smooth-surfaced arc (see 28 in Figure 2) may be fitted on the surface to allow smooth rotation of the key. The cover can also have areas (see 29 in Figure 2) for receiving proprietary and/or other information, or indeed could be cast with the information included.

Since the cover is fitted with all the necessary formations and retainers necessary for housing the bolt, the said IE 922856 - Ί cover may be installed in all locations, regardless of whether that location presently or in future requires the cover to be locked. Once the frame and cover are installed, workmen need only carry with them a key and a supply of bolts and springs. Any cover can be converted on-site and very speedily into a locked cover. Conversely, any locked covers can be very readily converted into the unlocked type, with recovery of the bolt.

The invention has been particularly described in relation to a cast cover. The casting can be made by any suitable technique, such as sand-casting, and offers the advantage that once a suitable pattern is prepared, convertible covers can be made with all the features required for accepting a locking bolt in place on all covers, at the minimal extra cost of the small amount of additional metal required. No subsequent welding, machining or any other post-production steps are required. However, a simple cover can also be made by casting or any other technique, with the bolt retaining features subsequently added, without departing from the invention.

Equipment chambers of utility companies and the like are normally sunk into the ground. However, in some cases the chambers may be above the ground level, and it will be evident that the cover of the present invention is equally suitable for use in such chambers, regardless of the disposition of the cover (for example vertical or other orientation as opposed to horizontal).

It will be appreciated that the invention is not limited to the specific details described herein and that various modifications and alterations are possible within the scope of the invention as defined in the appended claims.

IE 922856

Claims (5)

1. A cover for an access chamber, the cover having an outer surface, an inner surface and a skirt depending 5 from the inner surface, the inner surface being provided with means for retaining a locking bolt which is accessible from the outer surface by a key so as to move the bolt through an orifice in the skirt for locking engagement with a frame member secured to the access chamber.

2. A cover according to Claim 1, which is a metal casting, the retaining means being cast integrally with the cover. 15

3. A cover according to Claim 1 or Claim 2, in which the retaining means includes stop means for limiting the travel of the bolt between retracted and locking positions.

4. A locking bolt comprising at least two portions which 20 are mutually disengageable to facilitate fitting the bolt to a cover as defined in any one of Claims 1 to 3.

5. A cover according to Claim 1 in combination with a locking bolt according to Claim 4, and including biasing 25 means for urging the bolt into a locking position.