AU723023B2 - Locking apparatus for pit covers - Google Patents

Description

L_

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 a r

S

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "LOCKING APPARATUS FOR PIT COVERS" The following statement is a full description of this invention, including the best method of performing it known to us: 2 "LOCKING APPARATUS FOR PIT COVERS" THIS INVENTION relates to locking apparatus for pit covers.

Such pit covers may be utilised for a wide variety of pits such as manholes, grates, drains, telecommunication pits and the like.

A conventional locking apparatus for pit covers is described in U.S. Patent 5082392 which refers to a lockable manhole cover and key combination. This reference also discloses the use of locking bars which are mounted on a rotatable actuator. The locking bars have attached thereto a spring mechanism to ensure that the locking bars are retained in the locked position. Reference is also made to a specialised key which is engage with the rotatable actuator through a vent hole in the manhole cover wherein the key includes a first shaft portion turnable in the vent hole for rotation of the actuator and pulling the locking bars to the unlocked position and a second shaft portion which locks against turning oooo° in the vent hole thereby preventing rotation of the actuator and holding the a spring biassed locking bars away from the locked position.

Reference is also made to Australian Patent 656856 which refers to a security system for manhole or pit covers which comprises a latch actioning means in the form of a key of specialised shape and at least two spring latch arms operatively connected to the latch actioning means wherein the spring latch arms are retained under compression when the manhole or pit cover is in position. The spring latch arms are curved or S-shaped. The security system as described in Australian Patent 656856 is also designed to be installed on the underside of the pit or manhole cover as is the case with the lock assembly of U.S. Patent 5082392.

Reference may also be made to French Patent 2721955 and U.S. Patents 1458391, 2263567, 4577478, 4964755 and 4902165, which all relate to locking apparatus for pit covers which include a plurality of locking bars or locking rods which are movable from an outer locking position to an inner unlocking position by virtue of a rotatable actuator. In particular, U.S. Patent 2263567 refers to the inner ends of each locking .o bar being offset to engage in a respective mating slot in the rotatable actuator.

~The main disadvantage of the aforementioned prior art was that it was necessary to install the locking systems underneath the manhole or pit cover and thus the locking systems could not be utilised efficiently for manhole or pit covers made from concrete. In this regard, most of the conventional manhole or pit covers in everyday usage are formed from concrete to a specific design which is in accordance with the requirements of the relevant telecommunication authorities and it would be extremely desirable to have a locking system which could be utilised for new pit covers as well as existing pit covers.

Another disadvantage that follows from the above is that because the locking systems of Australian Patent 656856 and U.S. Patent 5082392 in particular, were attached to the underside of the pit covers, they required a specialised key which had to be tailor-made for their individual locking systems and thus a normal lifting tool currently in use could not be utilised.

Another disadvantage of pit covers that utilised a locking system which was attached to the underside of the pit cover was that in some cases, it was possible to insert a crowbar into a space between the pit cover and the pit surround and lever the pit cover away from the pit so as to gain access to the locking system.

~Another disadvantage of pit covers that utilised a locking system which was attached to the underside thereof was that in some cases, such locking systems were subject to corrosion especially when i the working parts of the locking system were formed from metal.

S"It therefore is an object of the invention to provide a locking apparatus for pit covers which may alleviate at least one or more of the abovementioned disadvantages.

The locking apparatus of the invention in one aspect is adapted to be encapsulated by the material which forms the pit cover and thus has the advantage that it can be applied to new pit covers or conventional pit covers that are formed from concrete or other settable material.

However, in another aspect the locking apparatus of the invention may also be housed in a pit cover made from plastics material or alternatively the locking apparatus of the invention may be attached to an underside of the pit cover.

The abovementioned aspects mean that the locking apparatus of the invention is extremely versatile in application.

According to one aspect of the invention there is provided a locking apparatus adapted for incorporation in metal, plastics and concrete pit covers, said apparatus comprising:a housing having upper and lower housing elements securable together to form a hollow lock body; a cam actuator rotatably located in said hollow lock body and actuable via an access port in said upper housing element; opposed locking rods coupled to said cam actuator and movable between an extended and retracted position, said apparatus further including tubular retaining members for said locking rods, said retaining members each being attached at one end to said lock body and extending substantially over the length of said locking rods when locking rods are in a retracted position.

The locking apparatus of the invention may also include a housing for the lock body which may be integral but more preferably o is formed by a plurality of components which are attachable to each other. Most preferably there is provided a pair of housing OO.. components. One housing component, which is the lower housing component is use, may include a recess for retention of a spring for bi8assing movement of each locking rod to an extended or operative position. The other housing component, which is the upper housing component, may incorporate a central aperture or passage through which a lifting tool may be inserted as hereinafter described. The housing may also include one or more tubular extensions for accommodation of the locking rod(s). The housing may also include a peripheral wall providing a housing interior for location of the lock body.

*o *o oooo* oooe The lock housing may also include a plurality of legs for encapsulation by the concrete or other settable material which locate the lock housing within the pit cover.

The lock body, in a preferred embodiment, is in the form of a rotatable cam which engages with the or each locking rod so as to cause linear movement of the or each locking rod from an inoperative to operative position.

The lock body may include a central aperture which is aligned with the central aperture or passage of the upper housing 10 component so as to accommodate insertion of the lifting tool. The lock ~body may also include one or more curved or arcuate cavities which may ,,accommodate a proximal end of an associated locking rod which S"functions as a cam track so as to facilitate linear movement of each locking rod from the inoperative to operative position and vice versa upon rotation of the lock body. Each cam track is suitably elliptical in shape.

Each cam track may also include an adjacent inner bearing face for engagement with the proximal end of the locking rod.

There is preferably provided a pair of retaining tubes which each may be encapsulated in concrete or other suitable material when the pit cover is formed from concrete or other settable material. Suitably, each retaining tube is attached to an associated attachment socket of the lock housing by an interference fit or snap fit which provides a seal tight engagement.

In another arrangement, the retaining tubes may be retained between upper and lower components of a cover formed from plastics material as hereinafter described. In another arrangement the retaining tubes may be attached to an underside of a cover formed from metal or plastics as hereinafter described.

Reference may now be made to a preferred embodiment of the invention as shown in the attached drawings, wherein:- FIG. 1 is an exploded perspective view of the locking apparatus constructed in accordance with the invention; FIG. 2 is a perspective view of the locking apparatus of FIG.

1 when fully assembled; FIG. 3 is a perspective view of a pit cover formed from concrete which encapsulates or incorporates the locking apparatus of the invention; FIGS. 4, 5, 6 and 7 show the various stages of rotation of the lock body from a fully locked position shown in FIG. 4; (ii) a onethird unlocked position shown in FIG. 5; (iii) a two-thirds unlocked position shown in FIG. 6 and a fully open position shown in FIG. 7; FIG. 8 is a sectional view of the locking apparatus of the invention shown in FIG. 1 when encapsulated in a pit cover in an open position; FIG. 9 is a similar view to FIG. 9 showing the locking apparatus of the invention in a locked position; FIG. 10 shows another form of pit cover to which the locking apparatus of the invention may be installed; FIGS. 11 and 12 show a perspective and sectional view of another form of locking apparatus constructed in accordance with the invention and showing the locking apparatus attached to the underside of a pit cover; and FIGS. 13 and 14 are similar views to FIGS. 11 and 12 showing the locking apparatus of FIGS. 11 and 12 interposed between moulded plastics components of a pit cover.

o* 10 The locking apparatus 10 shown in FIG. 1 includes rotatable o*o.

0ooo ~lock body 11 which functions as a cam and thus includes cam tracks 12 and adjacent curved inner bearing or cam surfaces 13. Also shown are flat bearing surfaces 13A. Each cam track 12 is arcuate as shown. The lock body 11 also includes a central aperture 14 surrounded by body portion 15 and peripheral surface 16.

There are also shown opposed housing components 17 and 18 which when attached together form a suitable housing 19 for lock body 11. The upper component 17 includes a central passage 20 which is adapted to be closed by a cap 21 which is hinged to passage 20 by hinge 20A. Cap 21 may carry identifying indicia (not shown) in the form of colour coding or the like which is appropriate to the service system assessed by the pit (not shown) to which the pit cover is fitted. There is also provided peripheral wall 22 and channel extensions 23.

The lower component 18 also incudes a recess 24 which is adapted to contain a compression spring 25 for biassing locking rods 26 to the extended or operative position. The lower component 18 also includes legs 27 which may be utilised as a locating means to provide correct placement of the locking apparatus 10 in covers of different thicknesses. In this regard, the legs 27 may be trimmed as may be required.

The lower component 18 also includes a peripheral wall 28 which registers with peripheral wall 23 of upper component 17 to provide 10 an assembled peripheral wall 29 of the assembled housing 30 shown in *oe* :i FIG. 2. Lower component 18 also includes opposed channel extensions 31 which align with channel extensions 23A of the upper component 17 to form tubular extensions 32 of the housing The locking rods 26 have offset ends 33 which each engage 15 a respective cam track 12 as shown. Each locking rod 26 also engages with an associated retaining tube 34 which is adapted to be embedded or 0 encapsulated in a concrete or other settable material which forms a pit cover 35 shown in FIG. 3.

In operation, a conventional or standard lifting tool (not shown) is inserted in aperture 36 of pit cover 35 after pivotal movement of cap 21 to allow insertion of the lifting tool. Upon rotation of the lock body through 900, this will cause linear movement of each locking rod 26 from a locked position shown in FIG. 4 to a fully open position shown in FIG. 7. In w. ,i the locked position shown in FIG. 4, each locking rod engages the walls of the pit (not shown).

Once the open position is reached, the pit cover 10 may then be lifted from the pit by the lifting tool. The tool can only be removed by rotation of the lock body 11, usually in an anti-clockwise direction, to the closed position shown in FIG. 4. The provision of the compression spring 25 facilitates the return of the locking bars 26 to the extended or locked position shown in FIG. 4.

ooooo FIGS. 8-9 show sectional views of the pit cover to which the *g locking apparatus of the invention has been installed and illustrates the engagement of offset ends 33 of each locking rod 26 in cam tracks 12.

Each offset end 33 also engages with bearing surface 13 and overlies flats 13A of lock body 11. There is also shown retaining tubes 34 embedded in concrete 34A and which each engage in an interference fit .:.ooi with tubular extensions 32.

If desired and as more particularly shown in FIG. 9, only a single locking rod 26 may be utilised if required. To this extent, the tubular extension 32 may be plugged at 39 if desired. FIG. 9 also shows that aperture 14 is provided with a base wall 36 and surround 37 which engage with the lifting tool when required. This embodiment is appropriate in regard to certain pit covers of the type shown in FIG. 10 which refers to a pit cover 35A which is provided with apertures 36A at each end thereof.

In this embodiment, only a single locking rod 26 is utilised in regard to 11 each aperture 36A and this embodiment applies to pit covers which have relatively large dimensions and therefore may be relatively heavy requiring the insertion of two lifting tools in respective apertures 36A to lift the cover 35A from the pit.

In FIGS. 11-12 there is shown a modified locking apparatus of the invention which instead of being embedded or encapsulated in concrete as shown in FIGS. 1-10 is adapted to be screwed or bolted to the underside of a pit cover as shown in FIG. 11 or interposed between o ooi top and bottom components of a moulded plastics pit cover as shown in 10 FIG. 13. The locking apparatus 10A is provided with attachment apertures 9*g9 99.9 40 which receive bolts 40A which are adapted to engage with mating nuts 41 as shown in section in FIG. 12. Each bolt 40 has a head 42. There is also provided a pit cover 43 which may be formed from metal or plastics o*oo having a downwardly extending peripheral flange 44. The pit cover 43 is 999999 also provided with apertures 45 aligned with attachment apertures 9..

The locking apparatus 10A is also provided with downwardly extending legs 27A. There is also shown locking rods 26 encased in retaining tubes 34 which when in an extended or locking position engage with sockets 46 of pit surround 47 which also includes a retaining ledge 48 for engagement with flange 44.

In FIGS. 13-14 there is shown a pit cover 47 having a top moulded skin 46 and a bottom moulded skin 49. Top skin 48 is provided with ribs 50 and 51 which intersect at 52. Top skin 48 is also provided with 12 a central key aperture 53 and apertures 54 located in ribs 50 for passage of retaining tubes 34 which encase locking rods 26. The top skin 48 is also provided with apertures 55 aligned with apertures 40 of locking apparatus 10A. Apertures 54 are located in protrusions 56. Bottom skin 49 is provided with ribs 50A corresponding to ribs 50 and ribs 51A corresponding to ribs 51. These ribs engage with each other as shown in FIG. 14. Bottom skin 49 is also provided with apertures 55A aligned with apertures 55. In FIG. 14 there is shown bolt 57 with head 58 engaging in recess 59 of top skin 48 and nut 60 engaging in recess 61 of bottom skin 49.

In practice, the locking apparatus of the invention, by being i capable of being embedded in concrete, can be applied to pit covers of conventional design which are prescribed by the relevant telecommunication authorities. The locking apparatus of the invention is also simple in construction and effective in operation.

o..

The lock body may be suitably formed from compression moulded or injection moulded plastics material and this also applies to the housing. The locking rods are preferably formed from metal as is the compression spring.

Claims (11)

1. According to one aspect of the invention there is provided a locking apparatus adapted for incorporation in metal, plastics and concrete pit covers, said apparatus comprising:- a housing having upper and lower housing elements securable together to form a hollow lock body; a cam actuator rotatably located in said hollow lock body and actuable via an access port in said upper housing element; opposed locking rods coupled to said cam actuator and movable between an extended and retracted position, said apparatus further including tubular retaining members for said locking rods, said retaining members each being attached at one end to said lock body and extending substantially over the length of said locking rods when locking rods are in a retracted position.

2. Locking apparatus as claimed in claim 1 wherein said lock body is adapted to support the mass of a pit cover on a lifting tool when inserted in said access post and said cam actuator is rotated to retract said locking rods.

3. Locking apparatus as claimed in Claim 1 or 2 wherein the cam 20 actuator has one or more arcuate cavities which accommodate a proximal end of an associated locking rod, said cavities in use functioning as cam tracks to facilitate linear movement of each locking rod.

4. Locking apparatus as claimed in Claim 3 wherein each cam track is elliptical in shape.

Locking apparatus as claimed in Claim 3 or 4 wherein each cam track has an inner bearing face for engagement with the proximal end of each lock rod.

6. Locking apparatus as claimed in any preceding claim including a biassing means to bias said locking rods to an extended position.

7. Locking apparatus as claimed in Claim 6 wherein said biassing means comprises a spring member located within said lock body, said spring member extending between respective proximal ends of said locking rods.

8. Locking apparatus as claimed in any preceding claim wherein the lock body includes engagement sockets for engagement of a 15 respective retaining tube.

9. Locking apparatus as claimed in Claim 8 wherein said engagement sockets are tubular extensions of the housing.

Locking apparatus as claimed in any preceding claim wherein the lock body includes a plurality of locating projections extending 20 therefrom, said locating projections, in use, locating said locking apparatus in a desired position with respect to an upper surface of a pit cover.

11. Locking apparatus for pit covers substantially as herein described with reference to the accompanying drawings. DATED this Nineteenth day of June 2000. EVERHARD INDUSTRIES PTY LTD By their Patent Attorneys FISHER ADAMS KELLY *o•