GB2195060A

GB2195060A - Adjustably-mounted anti-creepage cable clamp

Info

Publication number: GB2195060A
Application number: GB08621017A
Authority: GB
Inventors: Raws Shariff Bin B Moh Shariff
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-08-30
Filing date: 1986-08-30
Publication date: 1988-03-23
Anticipated expiration: 2006-08-30
Also published as: GB8621017D0; GB2195060B; MY100451A

Abstract

In order to prevent creepage of a cable within a duct, a clamping collar 1 is clamped on a portion of the cable outside the duct within a manhole, and a spacer assembly 2 is adjusted so as to space the collar 1 from an end of the duct and prevent movement of the clamped portion of the cable into the end of the duct. The spacer assembly 2 comprises a first spacer member 19 connected to the collar 1, a second spacer member 20 for engaging the end of the duct, and an adjustable connection arrangement, consisting of bolts 21, nuts 22 and springs 29. Interconnecting the first and second spacer members 19 and 20 and adjustable to vary the spacing between the first and second spacer members 19 and 20 in the direction of the axis of the cable. <IMAGE>

Description

SPECIFICATION Anti-creepage devices This invention relates to anti-creepage devices for preventing creepage of a cable within a duct.

It is standard practice for the telephone cables from an exchange to be routed through banks of ducts comprising polyvinyl chloride or porcelain sections laid end to end within a trench. At 100 metre intervals along the trench a manhole is constructed, with the end of each duct connected to the manhole being flush with the inner surface of the vertical wall of the manhole through which the duct passes and with the cables being exposed in the manhole. The purpose of these manholes is to enable cable "leaders" to be pulled through the ducts during installation and to minimise the length of cable which requires to be replaced in the event of a cable fault. In addition such manholes serve for the location of junctions between cables.

However a problem exists in that the internal diameter of the ducts is larger than the external diameter of the cables, and this, together with the low frictional engagement between the outer surfaces of the cables and the inner surfaces of the ducts, means that the cables are easily movable from their original axial positions. Furthermore a number of circumstances may arise whereby cables are subjected to graduai axial creepage within the ducts. For example, a portion of a cable may be caused to sag due to ground subsidence and the parts of the cable on either side of the sagging portion will be caused to shift in the direction of the sagging portion. Alternatively, where a cable is laid on a slope, the cable may tend to creep along the duct system in the direction of the slope.As a result the joint assemblies between cables may be shifted within their manholes and damaged by being brought into contact with a manhole wall. Furthermore, once a cable has shifted within a duct system, it can prove very difficult or impossible to return the cable to its intended position.

It is an object of the invention to provide a novel form of anti-creepage device which can be used to eliminate the above-mentioned problem.

According to the present invention there is provided an anti-creepage device for preventing creepage of a cable within a duct, comprising a clamping collar for clamping on a portion of the cable outside the duct, and a spacer assembly for spacing the collar from an end of the duct and preventing movement of the clamped portion of the cable into the end of the duct, wherein the spacer assembly comprises a first spacer member connected to the collar, a second spacer member for engaging the end of the duct, and adjustable connection means interconnecting the first and second spacer members and capable of being adjusted to vary the spacing between the first and second spacer members in the direction of the axis of the cable.

In order that the invention may be more fully understood, a preferred embodiment of anticreepage device in accordance with the invention will now be described, by way of example, with reference to the accompanying drawing, in which the single figure shows the device diagrammatically from one side.

Referring to the figure the device comprises a clamping collar 1 for clamping on a portion of the cable, and a spacer assembly 2 for spacing the collar 1 from an end of a cable duct. The clamping collar 1 comprises two portions 3 and 4 of semicircular cross-section made of 3 mm stainless steel plate. Each of the semicircular portions 3 and 4 has a respective rubber lining 5 or 6 having upstanding formations 7 thereon in the form of circular ridges for firmly gripping the outer casing of the cable.Along each axial edge of each of the semicircular portions 3 and 4 is a respective outwardly extending flange 8, 9, 10 or 11 provided with apertures through which there may be passed clamping bolts 12 provided with nuts 13 and associated washers 14, 15 and 16 in order to clamp the two semicircular portions 3 and 4 together along their opposite axial edges with the cable firmly clamped between the two portions 3 and 4 and contacted by the formations 7 on the linings 5 and 6. Each portion 3 or 4 is provided with a respective cut out 17 or 18, and the portions 3 and 4 are typically 140 mm in length.

The spacer assembly 2 comprises first and second spacer members 19 and 20 interconnected by threaded bolts 21 and adjustment nuts 22. The first spacer member 19 comprises two plates 23 and 24 each of which is integral with a respective one of the portions 3 and 4 of the clamping collar 1. Furthermore the second spacermember 20 comprises two plates 25 and 26 of 3 mm stainless steel plate provided with layers 27 and 28 of rubber for engaging different parts of the periphery of the end of the duct. Each of the plates 23, 24, 25 and 26, and hence also the layers 27 and 28, has a curved inner profile corresponding to the internal cross-section of the portions 3 and 4 and the outer surface of the cable, but is generally rectangular in shape if the recess exhibiting this curved profile is excluded from consideration.The plates 23 and 25 are connected together by two bolts 21 integral with the plate 25 and passing through holes in the plate 23, and the plates 24 and 26 are connected together by two bolts 21 integral with the plate 26 and passing through holes in the plate 24. The first and second spacer members 19 and 20 are kept apart by anti-vibration compression springs 29 surrounding the bolts 21, and the plates 23 and 24 are secured on the bolts 21 by nuts 22. All the nuts, bolts, washers and springs used in the device are of stainless steel.

In order to install the device on a portion of cable projecting from the end of a duct within a manhole, the two portions 3 and 4 of the clamping collar 1, with their respective spacer assembly portions attached thereto and with the nuts 22 fully screwed down so as to compress the springs 29, are placed one above and one below the projecting portion of the cable in a position such that the rubber layers 27 and 28 of the spacer assembly 2 are spaced approximately 2 cm away from the wall of the manhole in which the duct end is set. The clamping collar 1 is then firmly clamped on the cable by securing together the portions 3 and 4 by means of the bolts 12 and nuts 13 and associated washers 14, 15 and 16.Finally the nuts 22 of the spacer assembly 2 are loosened so as to cause the rubber layers 27 and 28 to firmly engage the end of the duct and thereby prevent creepage of the cable within the duct. The nuts 22 can be adjusted so as to vary the antivibration properties of the springs 29 enabling slight movements of the clamped portion of the cable in the direction towards the end of the duct.

Various modifications of the above-described device are possible within the scope of the invention. For example the form of the various parts of the device may be modified to accommodate cables of different cross-sections, for example of rectangular or oval cross-sections, or even so as to accommodate more than one cable at a time. In addition those parts which are described above as being made of stainless steel may be made of other materials, for example of high carbon steel, cast iron or a plastics material. Whilst the described devices are particularly applicable to telecommunication cables, they can also be used on gas pipelines.

Claims

1. An anti-creepage device for preventing creepage of a cable within a duct, comprising a clamping collar for clamping on a portion of the cable outside the duct, and a spacer assembly for spacing the collar from an end of the duct and preventing movement of the clamped portion of the cable into the end of the duct, wherein the spacer assembly comprises a first spacer member connected to the collar, a second spacer member for engaging the end of the duct, and adjustable connection means interconnecting the first and second spacer members and capable of being adjusted to vary the spacing between the first and second spacer members in the direction of the axis of the cable.

2. A device according to claim 1, wherein the adjustable connection means comprises one or more threaded bolts and associated nuts capable of being tightened or loosened on the bolts to decrease or increase the axial spacing between the first and second spacer members.

3. A device according to claim 1 or 2, wherein the spacer assembly also includes anti-vibration means in the form of one or more resilient members acting to take up slight movements of the clamped portion of the cable in the direction towards the end of the duct.

4. A device according to claim 3, wherein the or each resilient member comprises a compression spring disposed between the first and second spacer members with its axis parallel to the axis of the cable.

5. A device according to any preceding claim, wherein the second spacer member comprises a rigid base plate and a layer of resilient material on the base plate for engaging the end of the duct.

6. A device according to any preceding claim, wherein the second spacer member comprises two separate portions spaced transversely with respect to the axis of the cable and provided to engage different parts of the periphery of the end of the duct.

7. A device according to any preceding claim, wherein the clamping collar comprises two portions of substantially semicircular cross-section and clamping means for clamping the two semicircular portions together along opposite axial edges with the cable therebetweeen.

8. A device according to claim 7, wherein the clamping means comprises a plurality of nuts and bolts, and apertured flanges are provided along the opposite axial edges of the semicircular portions for accommodating the nuts and bolts.

9. A device according to any preceding claim, wherein the clamping collar incorporates an inner lining of resilient material for engaging the outside of the cable.

10. A device according to claim 9, wherein the inner lining incorporates a plurality of upstanding formations for engaging the outside of the cable.

11. An anti-creepage device for preventing creepage of a cable within a duct, substantially as hereinbefore described with reference to the accompanying drawing.