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Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 02: 1 : 23 G M T+00: 00 2006, U n trol l ed Copy, (c) BSI BRITISH STANDARD AUTOMOBILE SERIES | | | | | | | | | | | | Code of practice for Breakaway cables and secondary couplings | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | IC S 43 040 70 ; 43 0 | | | | | | | | NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW | | | | | BS AU 267:1998 Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 02: 1 : 23 G M T+00: 00 2006, U n trol l ed Copy, (c) BSI BS AU 267:1998 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical C ommittee AUE /8, Undergear for caravans and trailers, upon which the following bodies were represented: Caravan Club Department of the E nvironment, Transport and the Regions National Caravan Council Limited National Trailer and Towing Association Ltd Society of Motor Manufacturers and Traders Limited This B ritis h Standard, having b e e n p re p are d unde r the dire ctio n o f the E ngine e ring Se cto r B o ard, was p ub lishe d unde r the autho rity o f the Standards B o ard and co me s into e ffe c t o n N o ve mb e r 9 © B SI 9 Amendments issued since publication Amd No The fo llo wing B SI re fe re nce s re late to the wo rk o n this standard: C o mmitte e re fe re nc e AUE /8 D raft fo r co mme nt 6/71 576 D C ISBN 580 28203 Date Text affected Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 02: 1 : 23 G M T+00: 00 2006, U n trol l ed Copy, (c) BSI BS AU 267:1998 Contents Page Committees responsible Foreword ii Scope Terms and definitions Application Design Attachment General Trailer documentation Figure ÐDirection of test load application © BSI 1998 Inside front cover i Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 02: 1 : 23 G M T+00: 00 2006, U n trol l ed Copy, (c) BSI B S A U 267:1 998 F o re wo rd This British Standard has been prepared by Technical Committee AUE /8 As a code of practice, this British Standard takes the form of guidance and recommendations It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading E E C D irective 71 /32 0/E E C, Braking requirements and E E C Regulation No 3, requires the fitting of a breakaway cable or secondary coupling on all trailers up to a maximum gross weight of 3500 kg It is now also a requirement of the Construction and Use Regulations that such a device is positively attached to a towing vehicle A British Standard does not p urport to include all necessary provisions of a contract Users of British Standards are responsible for their correct application C o mp lianc e wi t h a B ritis h S tandard doe s not o f its e lf c o nfe r im m un it y fro m le gal o b ligatio ns S um m ary o f p age s This document comprises a front cover, an inside front cover, pages i and ii, pages and , an inside back cover and a back cover ii © B SI 9 Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 02: 1 : 23 G M T+00: 00 2006, U n trol l ed Copy, (c) BSI B S A U 67: 998 The breakaway cable should part after application of the trailer brakes either by reason of its ultimate This code of practice provides recommendations for strength breakaway cables and secondary couplings, and their purpose or by means of a weak link inserted for this attachment points, for light trailers or caravans up to a mass of 500 kg It applies to trailers which not The cable should be provided with a device capable have brakes or have overrun or inertia type braking of permitting attachment to the attachment point and withstanding the applied loads without failure unless systems only it provides the stress limit feature The breakaway cable should have sufficient length to T e rm s an d d e fin itio ns enable attachment to be made with the vehicle in any normal towing position without risk of inadvertent brake application or coming into contact with the ground In order to ensure the compatibility cable between the towing vehicle and the trailer of the breakaway cable with the braking system only including its fitments which, in the event of the trailer manufacturer's original equipment cable or separation of the main coupling, activates the equivalent should be used braking mechanism of the trailer S cope 2.1 b r e akaway c ab le S e c o n d ary c o up lin gs 2.2 s e c o n d ary c o up lin g coupling device between the trailer and towing vehicle which, upon separation of the main coupling, ensures that the two vehicles remain connected, prevents the nose of the drawbar touching the ground and provides residual steering for the trailer At t ac h m e n t 2.3 attac h m e n t p o in t fitting (e.g closed hole, loop or eyelet) provided for the attachment of a breakaway cable or secondary coupling to the towing vehicle 2.4 c o up lin g device, usually made in two parts, which connects the trailer to the towing vehicle NOTE It allows for movement, in all axes, of the two vehicles and withstands the applied static and dynamic loads during loading and operation Typical examples are a coupling head and towball or towing eye and jaw Ap p l i c at i o n Trailers with a mass of up to 500 kg should be fitted with either a breakaway cable or a secondary coupling Trailers without brakes should have a maximum mass of 750 kg and should be fitted with a secondary coupling It is recommended that trailers with brakes should be fitted with a breakaway cable D e s ign Secondary couplings used for the retention of trailers in the event of main coupling separation should be designed to have an ultimate tensile strength of equivalent to at least twice the maximum permissible mass of the trailer B re a kaway c ab le The breakaway cable should be capable of applying a sufficient load to the braking system operating mechanism to hold the trailer on at least 18 % gradient at its maximum permissible trailer mass Upon operation of the breakaway cable, the trailer should be brought to a halt without causing damage to the braking system components as a result of the application of too great an operating force © BSI 1998 5.1 G e ne ral The breakaway cable or secondary coupling should be attached to the towbar in accordance with or 5.2 5.3 NOTE The preferred method is by direct attachment, see 5.2 D ire c t at tac h m e n t The sprung hook or clip on the end of the breakaway cable or secondary coupling should be attached directly to, or through, an attachment point on the towing vehicle L o o p e d o ve r attac h m e n t The breakaway cable or secondary coupling should be fixed by forming a loop with the hook or clip on the end of the cable which is fixed back on to the cable to form a loop The loop should then be secured around the towing ball on the vehicle R e m o vab l e t o wi n g d e vi c e s When the towing device fitted to the towing vehicle is removable without the use of special tools, then the secondary coupling or breakaway cable should be attached directly to an attachment point, which should not be on, or part of, the detachable component(s) L o c atio n Attachment points for the breakaway cable or secondary coupling should be positioned so that the normal articulation and braking action of the trailer is not impaired Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 02: 1 : 23 G M T+00: 00 2006, U n trol l ed Copy, (c) BSI B S A U 67: 998 Where possible, the breakaway cable or secondary coupling attachment point(s) should not be more than 00 mm from a vertical plane passing through the longitudinal centre line of the vehicle If this is not possible, then it is essential that two attachment points are provided, equidistant from the vehicle centre line and no more than 250 mm from the vehicle centre line The breakaway cable or secondary coupling attachment point(s) should be positioned as far rearward and as high as possible and practicable P h ys ic al c h arac t e ri s t ic s When the breakaway cable or secondary coupling is attached directly to the towbar, the attachment loop, hole, eyelet or similar should be sufficiently large to allow a rigid sphere of at least mm diameter to pass freely through it S tre n gth The breakaway cable or secondary coupling attachment point should be able to withstand a static load of for s, applied along a line passing through the centre of the attachment point on a D plane parallel to the longitudinal centre line of the vehicle and inclined downwards to the rear at ° (see Figure ), without detachment or incurring a distortion of deformation that could affect the safe operation of the breakaway cable or secondary D coupling (where is defined in EC Directive 94/20 and limited to a maximum trailer mass of 500 kg) G e ne ral B re a kaway c ab le s The breakaway cable should pass through a lug, guide or similar fitting on the trailer, to ensure that, regardless of the relative angles of the trailer and towing vehicle at the time of separation of the main coupling, there is a direct, in line, pull applied to the brake linkage of the trailer B rake m e c h an i s m p ro te c tio n If necessary a skid, or other suitable means of protection should be provided to ensure that the brake operating mechanism does not foul the ground in the event of separation of the main coupling T raile r d o c um e n tatio n Clear instructions and diagrams showing the attachment of the breakaway cable or secondary coupling should be included in the trailer handbook The trailer handbook should also specify details of the rating and dimensions for spare breakaway cables and secondary couplings The secondary coupling or breakaway cable attachment point(s) should be identified on the documentation supplied for the towbar installation and operation The trailer documentation should indicate that direct attachment is the preferred method of attachment but if the cable is to be looped around the towing ball then it is essential that the user ensures that it is secure and will operate correctly F igure ± D ire c tio n o f te s t lo ad ap p lic atio n © BSI 998 Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 02: 1 : 23 G M T+00: 00 2006, U n trol l ed Copy, (c) BSI blank Li cen sed Copy: Lon d on Sou th Ban k U n i versi ty, Lon d on Sou th Ban k U n i versi ty, Sat Dec 09 02: 1 : 23 G M T+00: 00 2006, U n trol l ed Copy, (c) BSI | | | | | | | | | BSI Ð British Standards Institution | | | | | | | BSI is the independent 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