GB2257490A - Ducting - Google Patents

Abstract

A cast or moulded duct assembly comprises a plurality of generally channel section ducts 16, 17, 18 which are interlocked end to end by generally saw toothed formations in their end walls. Additionally, lateral displacement is prevented by tongue and groove engagement of their bases. To prevent tampering with the pipes or cables within the ducting, cast or moulded lids (10, 12, 14) are interlocked with the ducting sections by means of downwardly projecting flanges 55 having projections 57 engaging undercut 62 in the side walls of the ducts. The extreme free ends of the covers are chevron shaped (68, 72). The covers cannot be removed vertically. Where two runs of ducting are joined, a connection duct having mirror image ends is used as a starting point for laying the runs of ducting and is interlocked using saw tooth formations as before. A lid having downwardly and inwardly tapered free ends is positioned over the connection duct and bolted and padlocked in place. <IMAGE>

Description

DUCTING The present invention relates to cast or moulded ducting for carrying services such as cables, water and gas.

Services such as electric power and telephone cables are frequently laid in ducting. The ducting is generally channelshaped and laid horizontally in a trench excavated from the ground. Traditionally, the ducting is cast from concrete but more recently has been moulded from plastics material.

Lengths of ducts are laid end to end in abutting relationship and covers of slabs of concrete or plastics, as the case may be, are placed over the ducts to protect the service cable or pipe installed therein. The trench is then reinstated leaving the service ducting protected below ground level.

British Patent No. 2,181,206 (ECC Quarries Limited) discloses an improved type of ducting in which the individual ducts are moulded with shaped end portions enabling adjacent ducts to be placed in end to end interlocking relationship.

However, because the covering slabs of concrete or plastics are merely placed over the ducts they are easily removed allowing unauthorised access as a result of which the service cables and pipes in the ducting may be tampered with or become relatively easy targets for thieves.

The present invention seeks to provide an improved duct assembly.

Accordingly, the present invention provides a cast or moulded channel shaped duct assembly comprising: a first duct having two end portions for placing in interlocked relationship with complementary end portions of juxtaposed ducts, one end portion having interlocking means adapted to interlock with complementary interlocking means of the second end portion of a juxtaposed duct to prevent both longitudinal and lateral relative displacement of the two ducts; and a cover for said duct, said cover having one end portion provided with interlock means adapted to interlock with complementary interlock means of said first duct for preventing vertical removal of said cover.

Said one end portion of the cover may have a downwardly extending portion defining an undercut hook formation, which forms the interlock means.

The walls of the first duct may each have an undercut hook formation adapted to receive the undercut hook formation of the downwardly extending portion of the cover.

The undercut hook formation of the first duct may be adjacent one end of the duct or between its opposite ends.

One extreme end of the cover may have a projecting chevron shaped cross-section adapted to engage a corresponding undercut cross-section of an extreme end of an adjacent cover.

Preferably, each cover has a projecting chevron shaped crosssection at one extreme end and an undercut chevron shaped cross-section at the other extreme end.

The assembly may include a pair of ducting assemblies as set out above connected by a connection duct assembly comprising a duct having a pair of end portions of mirror image formation, each including interlocking means, and a cover having a pair of generally planar downwardly and inwardly tapered free ends adapted to overlie corresponding interlock means of the adjacent covers.

The present invention is further described hereinafter by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side elevation of one complete cast concrete duct assembly and part of two adjacent duct assemblies arranged in juxtaposed relationship with the complete duct assembly; and Figure 2 is a diagrammatic side elevation of a modified form of duct assembly forming an interconnection between two of the duct assemblies of Figure 1.

Referring to Figure 1, this shows three identical duct assemblies 10, 12 and 14 of a length of ducting, each assembly having a generally channel shaped cast concrete duct 16, 18, 20, with the three ducts 16 to 20 arranged with respective ends 22, 24 and 22', 24' in juxtaposed relationship so that the ducts are both longitudinally and laterally locked together.

The end profiles 33, 35 of side walls 34 of the duct 18 are of generally saw tooth form and the corresponding side walls 30 and 38 of the ducts 16 and 20 are of complementary profile so that the respective ends are interlocked together against longitudinal movement. The duct 20 is laid before the duct 18 is lowered into position and so on.

Lateral interlocking of the ducts is achieved by a tongue 42 in the duct base which engages in a corresponding cut out of an adjacent duct.

Alternative means for longitudinal and lateral locking may be employed.

When the ducting is placed in a trench excavated from the ground the longitudinal and lateral locking ensures that the run of the ducting is in correct alignment.

The run of ducting 16, 18, 20... has a plurality of identical covers 48, 50, 52. The covers are also arranged with respective ends 54', 56 and 54, 56' in juxtaposed relationship to lock the covers together. One end of the cover 50 is formed with a laterally extending, depending and rearwardly facing flange 55 which forms a hook like projection 57, on its underside which engages in complementary, cooperating cut away portions 62 (only one of which is shown) in the side walls 34 of the associated duct 18. The portion 62 may be adjacent one end of the duct, as shown, or between opposite ends. Once the flange is engaged in the cut away portions 62 the cover cannot simply be lifted from the duct 18 but must be slid to the right as shown in Figure 1 in order to disengage the flange from the cut away portions.

However, movement of the cover 50 to the right is prevented by the adjacent end 56' of the adjacent cover 52. This also has a depending flange 66' which extends laterally of the cover 52. The side wall 70' of the flange 66' abuts against the surface profile 24'. The other side wall 68' is of chevron shape and which abuts against, and partly underneath surface 72 on the flange 54 of the end of the adjacent cover 50 to prevent lifting of the cover.

The cover 48 is positioned and slid to the left, followed by the cover 50 and so on.

The duct assembly 100 is used to connect two runs of ducting.

It has a duct 102 with side walls 104 and a cover 106. The end profiles 33' of the side walls 104 of the duct 102 are identical to the end profiles 33 of the side wall 34 of duct 18 to enable the duct 102 to mesh and lock with cooperating runs of ducts 18'. It will be seen that the duct 102 is laid before the runs 18'.

The cover 106 has two mirror-image end portions 56''. In this case, however, the side walls 68'' extend from the top of the cover and taper towards each other. This enables the cover 106 to be lowered into engagement with the ends 54'' of adjacent covers 50'. As will be appreciated, the duct assemblies laid on one side of the duct assembly 100 are simply turned through 1800 relative to the duct assemblies laid on the opposite side of the duct assembly 100.

The cover 106 is the only one which can simply be lifted from the duct 102. This allows removal of adjacent covers along the ducting for access to the services. The cover 106 can be locked in place by any suitable means, for example a metal hoop 112 moulded to the duct 102 and arranged to project through a slot in the cover 106 to allow the latter to be locked to the duct 102 by a padlock, or the like.

The duct assembly described has a reduced risk of unauthorised tampering or theft of service cables or pipes contained therein.

Claims (10)

1. A cast or moulded channel shaped duct assembly comprising: a first duct having two end portions for placing in interlocked relationship with complementary end portions of juxtaposed ducts, one end portion having interlocking means adapted to interlock with complementary interlocking means of the second end portion of a juxtaposed duct to prevent both longitudinal and lateral relative displacement of the two ducts; and a cover for said duct, said cover having one end portion provided with interlock means adapted to interlock with complementary interlock means of said first duct for preventing vertical removal of said cover.

2. A duct assembly according to claim 1 wherein said one end portion of the cover has a downwardly extending portion defining an undercut hook formation forming said interlock means.

3. A duct assembly according to claim 2 wherein the wall of said first duct each have an undercut hook formation adapted to receive the undercut hook formation of the downwardly extending portion of the cover.

4. A duct assembly according to claim 3 wherein the undercut hook formation of the first duct is adjacent one end thereof.

5. A duct assembly according to claim 3 wherein the undercut hook formation of the first duct is between opposite ends thereof.

6. A duct assembly according to any preceding claim wherein one extreme end of the cover has a projecting chevron shaped cross-section adapted to engage a corresponding undercut cross-section of an extreme end of an adjacent cover.

7. A duct assembly according to claim 6 wherein each cover has a projecting chevron shaped cross-section at one end and an undercut chevron shaped cross-section at the other extreme end.

8. A duct assembly according to any preceding claim wherein a pair of duct assemblies according to any preceding claim are provided, connected by a connection duct assembly comprising a duct having a pair of end portions of mirror image formation, each including interlocking means, and- a cover having a pair of generally planar downwardly and inwardly tapered free ends adapted to overlie corresponding interlock means of adjacent covers.

9. A duct assembly substantially as hereinbefore described with reference to and as illustrated in Figure 1 of the accompanying drawings.

10. A duct assembly substantially as hereinbefore described with reference to and as illustrated in Figure 2 of the accompanying drawings.