GB2420545A

GB2420545A - Fall arrest cable bracket

Info

Publication number: GB2420545A
Application number: GB0601373A
Authority: GB
Inventors: Bernard Raymond Warren
Original assignee: Rapid Rail International Ltd
Current assignee: Rapid Rail International Ltd
Priority date: 2005-11-28
Filing date: 2005-11-28
Publication date: 2006-05-31
Anticipated expiration: 2025-11-28
Also published as: GB2420545B; GB0601373D0; GB2420545B8

Abstract

An intermediate bracket 1 to be secured to a flange F of a tower such as a pylon and to support a cable C comprises a base member 2, a sleeve 6 to receive the cable, a tongue 9 connecting the base and sleeve and a polymer lining 21 for the sleeve may from two parts, each split to receive the cable (figure 5). The sleeve includes a cut out allowing the cable to be introduced into the sleeve, the cut out having a central transverse portion 11 and end portions 12, 14 extending from the central portion to the ends of the sleeve.

Description

A1ENT OFF1c -iT Copy FALL ARREST 2420545 The present invention relates to

a bracket for a fall arrest system particularly though not exclusively for use by linesmen working on electricity supply towers or pylons.

Conventionally, linesmen clip themselves onto a tower via bolts used for climbing the tower. This is renders the climb slow and awkward, with clipping continuously being overhead and un-clipping low down.

Fall arrest systems comprising a cable which extends continuously up the tower have been developed, a linesman clipping on at anti-climbing device level via a sliding cleat, which jams if he falls.

The cable of such a system should remain in tension. A slack cable can frap and fail due to wear and fatigue.

Usually, the cable will be so long as to require an intermediate bracket or indeed several such brackets. Frapping of the cable in an intermediate bracket is a particular problem, with long runs of the cable on both sides of the bracket. The frapping problem can be relieved by ensuring that the cable remains tensioned.

However this can lead to the further problem of aeolian vibration in the wire, i.e. resonance of the wire induced by wind currents around the tower and in particular around the corner of the tower on which the fall arrest system is installed. Usually the corner member will be of angle iron, which is particularly likely to induce uneven air flow.

The object of the present invention is to provide an improved intermediate bracket.

According to the invention there is provided an intermediate bracket for a fall arrest system, the bracket comprising: * a base member adapted to be secured to a tower; * a sleeve for receiving a cable; * a tongue connecting the sleeve to the base for allowing passage of a cleat along the wire and past the sleeve; * a polymer lining of the sleeve for spacing the cable from the sleeve; wherein the intermediate bracket further comprises the improvement of: * the sleeve being open along a cut-out, the cut-out having: * a central, transverse portion opposite from the tongue for introduction of the cable into the sleeve at an orientation transverse to the length of the sleeve and * end portions on opposite sides of the sleeve, extending from the transverse portion to the end of the sleeve for turning of the bracket about the introduced the cable for alignment of the sleeve and the cable, and * the polymer lining is comprised of two parts, each being split for positioning over the cable and introduction into the opposite ends of the sleeve.

The significant advantage of the improved intermediate bracket is that as opposed to requiring threading from the end of the cable, a tedious operation liable to cause skimping on the number of the brackets and use of unsuitable erroneously threaded brackets at the wrong position along the cable, the intermediate brackets can be installed wherever required at whatever stage in the process of installation of the fall arrest system.

Whilst the transverse portion of the cut-out could be angled towards the ends of the sleeve, it is preferably at right angles to the length of the sleeve.

The polymer lining parts could be lengths of extruded tube, either of a size to fit between the cable and sleeve and slit for opening to fit over the cable or over-size and double-slit to remove a strip so that it can be compressed to a size to fit.

Alternatively the lining parts can be injection mouldings, again either moulded to be opened for fitting or closed for fitting. In the preferred embodiment, the parts are polyamide mouldings, which are open for fitting to the cable and compressed to fit the sleeve. Also they have keys to fit the end portions of the cut-outs, mutually engaging formations to engage with each other for their retention in the sleeve and end rims for protection of the cable from the ends of the sleeve. The preferred lining parts are mutually complementarily formed so that identical parts pressed into the sleeve from opposite ends engage with each other.

The wall thickness of the lining parts is such as to give the cable negligible freedom from lateral movement.

To help understanding of the invention, a specific embodiment thereof will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an intermediate bracket of a fall arrest system in accordance with the invention; Figure 2 is plan view sleeve memb er of the intermediate bracket of Figure 1; Figure 3 is a side view of the sleeve member; Figure 4 is a front view of the sleeve member; Figure 5 is a perspective view of a polyamide liner for the sleeve member; and Figure 6 is a view similar to Figure 4 showing two liners fitted to the sleeve member.

With reference to the drawings, the intermediate bracket I is fixed to a flange F of a corner angle iron of a pylon or tower by means of a climbing bolt B. The bracket has a base member 2 comprised of stainless steel rod bent to U-shape. A welded-on cross bar 3 holds the U against spreading and provides a positioning stop for the bracket. Outwards from the rod, the arms 4 of the U are bent 5 to bring a cable C of the fall arrest system (otherwise un-illustrated) into the bisector plane of the two flanges F,Ffofthe angle iron. A sleeve member 6 is secured by screws 7 through a lug 8 into the ends of the arms 4. The member has a tongue 9 integral with the lug and a sleeve 10 as such.

The sleeve is cut open (in practice, the sleeve member is likely to be made in finished configuration by sintering), by a transverse cut 11 and longitudinal cuts 12,14 on opposite sides from the transverse cut to respective ends of the sleeve. This allows the cable to be introduced into the sleeve by turning the bracket with respect to the cable or vice versa.

The cable is centred in the sleeve by moulded polyamide inserts 21, which are moulded over size diametrically, with a longitudinal slot 22 sized to receive the cable and yet be closed with edges abutting when introduced into the sleeve. The inserts also have rims 23 which abut the ends of the sleeve and extend out to the diameter of the sleeve, thus protecting the cable from touching the ends of the sleeve. The inserts have antirotation swellings 24 which occupy the cuts 12,14. Also they have detents 25 on the inside of the swellings and opposite, complementary openings 26. These engage with each other when the inserts are pushed into the sleeve from opposite ends and abut in the middle.

With the inserts in place, the cable is fully located in the centre of the sleeve.

Claims

CLAIMS: 1. An intermediate bracket for a fall arrest system, the bracket

comprising: * a base member adapted to be secured to a tower; * a sleeve for receiving a cable; * a tongue connecting the sleeve to the base for allowing passage of a cleat along the wire and past the sleeve; * a polymer lining of the sleeve for spacing the cable from the sleeve; wherein the intermediate bracket further comprises the improvement of: * the sleeve being open along a cut-out, the cut-out having: * a central, transverse portion opposite from the tongue for introduction of the cable into the sleeve at an orientation transverse to the length of the sleeve and * end portions on opposite sides of the sleeve, extending from the transverse portion to the end of the sleeve for turning of the bracket about the introduced the cable for alignment of the sleeve and the cable, and * the polymer lining is comprised of two parts, each being split for positioning over the cable and introduction into the opposite ends of the sleeve.
2. An intermediate bracket as claimed in claim 1, wherein the transverse portion of the cut-out is angled towards the ends of the sleeve.
3. An intermediate bracket as claimed in claim 1, wherein the transverse portion of the cut-out is at right angles to the length of the sleeve.
4. An intermediate bracket as claimed in claim 1, claim 2 or claim 3, wherein the polymer lining parts are lengths of extruded tube slit for opening to fit over the cable.
5. An intermediate bracket as claimed in claim 1, claim 2 or claim 3, wherein the polymer lining parts are injection mouldings having a longitudinal slot sized to receive the cable.
6. An intermediate bracket as claimed in claim 5, wherein the mouldings are polyamide mouldings, which are open for fitting to the cable and compressed to fit the sleeve.
7. An intermediate bracket as claimed in claim 5 or claim 6, wherein the mouldings have: * keys to fit the end portions of the cut-outs, * mutually engaging formations to engage with each other for their retention in the sleeve and * end rims for protection of the cable from the ends of the sleeve.
8. An intermediate bracket as claimed in claim 7, wherein the mouldings are mutually complementarily formed so that identical parts pressed into the sleeve from opposite ends engage with each other.
9. An intermediate bracket as claimed in any preceding claim, wherein the wall thickness of the mouldings is such as to give the cable negligible freedom from lateral movement.