GB2284627A

GB2284627A - A lockable manhole assembly

Info

Publication number: GB2284627A
Application number: GB9400247A
Authority: GB
Inventors: Joseph Cavanagh; Charles Cavanagh
Original assignee: STRIVIEW DEV Ltd
Current assignee: STRIVIEW DEV Ltd
Priority date: 1993-12-10
Filing date: 1994-01-07
Publication date: 1995-06-14
Anticipated expiration: 2014-01-07
Also published as: GB2284627B; BE1005975A6; GB9400247D0

Abstract

A manhole assembly (1) has a frame (2) for mounting in the ground to define an access opening (3). A cover (4) is releasably engagable with the frame (2) to close the opening (3). Locking means (5) for the cover (4) comprises a bolt (20) on the cover (4) engagable with a complementary nut (22) which is retained in a housing (23) on the frame (2). During manufacture, after galvanising the frame and the cover (4), the bolt (20) is mounted on the cover (4) and the nut (22) is inserted into the housing (23) through an opening in the sidewall of the housing (23) and then a flap (39) is bent across the opening to retain the nut (22) within the housing (23). A lug (18) may be provided on a side of the housing (23) opposite to the nut (22) which engages with a slot (17) provided in the cover. <IMAGE>

Description

"A Manhole Assembly" INTRODUCTION The invention relates to a manhole assembly.

The invention relates particularly to a manhole assembly which is treated after fabrication, by galvinising or painting for example, the assembly of the type having a frame for mounting in the ground to define an access opening and an assocated cover with a threaded fastener for releasably locking the cover on the frame in order to prevent unauthorised access through the manhole assembly in use. The problem arises with this construction in that if the fastener is mounted on the frame and the cover prior to treatment then the coating such as zinc or paint fills into the threads of the fastener necessitating that these be subsequently cleaned after treatment. Thus, the time and expense of manufacture is increased.To prevent coating the threads of the fastener, the fastener would be fitted to the cover and frame after treatment by welding for example, however this would damage the protective coating applied to the assembly.

Further, ingress of dust and dirt to the threads of the fastener in use can block the thread.

The present invention is directed towards overcoming these problems.

STATEMENTS OF INVENTION According to the invention there is provided a manhole assembly comprising a frame for mounting in the ground to define an access opening, a manhole cover releasably engagable with the frame to close the opening, and locking means for releasably securing the cover to the frame, characterised in that the locking means comprises a locking bolt freely mounted on the cover and a complementary locking nut mounted on the frame, the nut being loosely mounted within a housing which restrains the nut from rotation, the housing having a bolt inlet opening for through passage of the bolt for engagement with the nut within the housing.

In one embodiment of the invention an opening is provided in a sidewall of the housing for insertion of the nut into the housing, the opening being closed by a flap mounted at a periphery of the opening and bent across the opening after insertion of the nut to retain the nut within the housing.

In another embodiment of the invention complementary interengagable formations are provided on the cover and on the frame for releasably retaining the cover on the frame.

In a preferred embodiment the formations comprise one or more lugs mounted on the frame releasably engagable with a complementary slot or slots on the cover.

In a particularly preferred embodiment the bolt has a nonstandard head engagable by a complementary mating key to rotate the bolt for engagement with the nut.

In another aspect the invention provides a method for manufacturing a manhole assembly as claimed in any preceding claim comprising the steps: preparing a cover and a complementary frame, the cover having a bolt receiving socket and spaced apart therefrom a slot for complementary interengagement with an associated lug of the frame, the frame having a nut housing with an opening for insertion of a locking nut associated with the bolt; inserting a nut into the nut housing and closing the opening; mounting a bolt in the bolt receiving socket such that it passes through the cover, and securing a bolt retainer on the shank of the bolt intermediate the ends of the bolt.

Preferably the cover and the frame are of steel material, the method further including the step of galvanising the frame and cover prior to mounting the bolt on the cover and the nut within the housing.

Conveniently the housing is formed with an integral flap at a periphery of the opening, said flap being bent across the opening after insertion of the locking nut for retention of the nut within the housing.

The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which : Fig. 1 is a sectional elevational view of a manhole assembly according to the invention; Fig. 2 is a detail sectional elevational view showing a locking arrangement for the manhole assembly; Fig. 3 is a plan view of a cover of the manhole assembly; Fig. 4 is a detail perspective view illustrating portion of the manhole assembly; Fig. 5 is a detail perspective view illustrating portion of the manhole assembly; Fig. 6 is a perspective view of a key for locking the manhole assembly; Fig. 7 is an underneath plan view of a head of the key; Fig. 8 is a detail sectional elevational view showing a locking nut portion of the assembly;; and Fig. 9 is a perspective view of a lock nut housing forming portion of the assembly.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, there is illustrated a manhole assembly according to the invention indicated generally by the reference numeral 1. The assembly 1 comprises a frame 2 for mounting in the ground to define an access opening 3. A manhole cover 4 is releasably engagable with the frame 2 to close the opening 3. Locking means 5 is provided for releasably securing the cover 4 on the frame 2.

The frame 2 is of inverted T-section having a flat base 10 with an upstanding wall 11 extending around the base 10 to define an enclosure for reception of the cover 4.

Through-holes 12 are provided in the base 10 for fastening the frame 2 securely in the ground.

The cover 4 has a downwardly extending peripheral rim 15 which seats on the base 10 within the walls 11.

Referring to Fig. 4, at one end of the cover 4 a slot 17 is provided for engagement with a complementary lug 18 mounted on the sidewall 11. At an opposite end of the cover 4 (Fig. 2) a locking bolt 20 passes through a hole 21 in the cover 4 for engagement with a complementary locking nut 22 retained in a lock nut housing 23 on the base 10. The housing 23 prevents rotation of the nut 22.

A spring pin 25 is mounted through a shank 26 of the bolt 20 to retain the bolt 20 on the cover 4. It will be noted that a head 27 of the bolt is mounted within a recessed pocket 28 in the cover 4.

It will also be appreciated that the head 27 of the bolt 20 is non-standard and shaped for co-operation with a key 30. The key 30 has a head 31 with a socket 32 for engagement with the head 27 of the bolt 20.

Referring in particular to Figs. 8 and 9, the housing 23 is shown in more detail. The housing 23 has a top 35 with a central through hole 36 forming a bolt inlet opening.

Downwardly depending sidewalls 37 sit on the base 10 of the frame 2 to which they are welded. At one side of the housing 23 a flap 39 extends downwardly from the top 35 to retain the nut 22 within the housing 23. As can be seen in Fig. 9, this flap 39 is initially provided in an open position to allow insertion of the nut 22 within the housing after which the flap 39 is bent downwardly as shown in Fig. 8 for retention of the nut 22.

Advantageously, in this manner the frame 2 and cover 4 can be formed and after galvanising the frame, the nut can be inserted in the housing 23 and the bolt 20 mounted on the cover 4.

In use, the cover 4 is mounted on the frame 2 engaging the slot 17 with the lug 18. The bolt 20 is then engaged with the lock 22 and tightened by means of the key 30. For subsequent release, the bolt 20 can be released by operation of the key 30.

It will be appreciated that the manhole assembly of the invention conveniently allows a manhole cover to be locked in a secure fashion to prevent unauthorised entry to an access opening.

Advantageously, as the nut housing 23 and the frame 2 are of similar material (preferably mild steel), the housing 23 can be readily easily attached to the frame 2 by welding. Further, the housing construction allows the frame, including the housing, to be galvanised prior to insertion of the lock nut 22 thus there is no difficulty with having to remove surplus zinc on the nut such as would be the case where the nut is mounted within the housing prior to galvanising.

It will be noted that while the housing prevents the nut from turning, the nut is free to move within the housing to facilitate alignment of the nut with the locking bolt.

Further, the fact that the housing is open at the corners and under the nut retaining flap and also the ability of the nut to move within the housing allows dust pass through the housing and not collect within the nut which would cause difficulties for the bolt engaging the nut.

The invention is not limited to the embodiments hereinbefore described which may. be varied in both construction and detail.

Claims

CLAINS

1. A manhole assembly comprising a frame for mounting in the ground to define an access opening, a manhole cover releasably engagable with the frame to close the opening, and locking means for releasably securing the cover to the frame, characterised in that the locking means comprises a locking bolt freely mounted on the cover and a complementary locking nut mounted on the frame, the nut being loosely mounted within a housing which restrains the nut from rotation, the housing having a bolt inlet opening for through passage of the bolt for engagement with the nut within the housing.

2. A manhole assembly as claimed in claim 1 wherein an opening is provided in a sidewall of the housing for insertion of a nut into the housing, the opening closed by a flap mounted at a periphery of the opening and bent across the opening after insertion of the nut to retain the nut within the housing.

3. A manhole assembly as claimed in claim 1 or 2 wherein complementary interengagable formations are provided on the cover and on the frame for releasably retaining the cover on the frame.

4. A manhole assembly as claimed in claim 3 wherein the formations comprise one or more lugs mounted on the frame releasably engagable with a complementary slot or slots on the cover.

5. A manhole assembly as claimed in any preceding claim wherein the bolt has a non-standard head engagable by a complementary mating key to rotate the bolt for engagement with the nut.

6. A manhole assembly substantially as hereinbefore described with reference to the accompanying drawings.

7. A method for manufacturing a manhole assembly as claimed in any preceding claim comprising the steps: preparing a cover and a complementary frame, the cover having a bolt receiving socket and spaced-apart therefrom a slot for complementary interengagement with an associated lug of the frame, the frame having a nut housing with an opening for insertion of a locking nut associated with the bolt; inserting a nut into the nut housing and closing the opening; mounting a bolt in the bolt receiving socket such that it passes through the cover, and securing a bolt retainer on the shank of the bolt intermediate the ends of the bolt.

8. A method as claimed in claim 6 wherein the cover and the frame are of steel material, the method further including the step of galvanising the frame and cover prior to mounting the bolt on the cover and the nut within the housing.

9. A method as claimed in claim 6 or claim 7 wherein the housing is formed with an integral flap at a periphery of the opening, said flap being bent across the opening after insertion of the locking nut for retention of the nut within the housing.

10. A method for manufacturing a manhole assembly substantially as hereinbefore described with reference to the accompanying drawings.

11. A manhole assembly whenever manufactured according to the method as claimed in any of claims 7 to 10.