1、BRITISH STANDARD AUTOMOBILE SERIES BS AU28:1964 (Supersedes S.M.M.T. Standard No.63) Specification for Towing jaw for use between trailers of535 tons gross weight and towing vehicle UDC 629.11.013.5:629.11.013.35BSAU28:1964 This British Standard, having been approved by the AutomobileIndustry Standa
2、rdsCommittee and endorsed by the Chairman of theEngineering Divisional Council, was published undertheauthority of the GeneralCouncil of the Institutionon 15June1964 BSI 02-2000 The following BSI reference relates to the work on this standard: Committee reference AUE/- ISBN 0 580 34551 3 Amendments
3、issued since publication Amd. No. Date CommentsBSAU28:1964 BSI 02-2000 i Contents Page Foreword ii 1 Scope 1 2 Materials 1 3 Dimensions 1 4 Design 1 5 Mounting 1 6 Marking 1BSAU28:1964 ii BSI 02-2000 Foreword This British Standard which is published under the authority of the Automobile Industry Sta
4、ndards Committee of the BSI, is based upon data-sheet SMMT63:1957 of the Society of Motor Manufacturers and TradersLtd. The requirements of this standard, which relate only to vehicles used on the public highways, are intended to ensure the maximum degree of interchangeability between commercial and
5、 Government department and Services standards. Towing jaws may be forged(as shown in Figure) or cast. The material specifications are for the minimum qualities acceptable, and do not exclude the use of other materials provided that these are at least equal in quality so that road safety is not impai
6、red. This standard should be used in conjunction with BS AU29 1) . The jaw has been designed to accommodate a drawbar eye of3in internal diameter and 1 5 / 8in stock. The standard applies to connections to trailers of535 tons gross weight. Thespecification for a towing jaw for connections to trailer
7、s of514 tons gross weight is given in BS AU26 2) , and for trailers of25 tons gross in BSAU24 3) . NOTEIf it is required to convert the figures in this standard from British units into metric units it is recommended that the conversion factors and tables contained in BS350, “Conversion factors and t
8、ables”, be used. Attention is drawn to BS2856, “Precise conversion of inch and metric sizes on engineering drawings”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a
9、 British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This w
10、ill be indicated in the amendment table on the inside front cover. 1) BS AU29, “Drawbar eyes and forecarriage pins for connection between trailers of535 tons gross weight and towing vehicle”. 2) BS AU26, “Towing jaw for use between trailers of514 tons gross weight and towing vehicle”. 3) BS AU24, “T
11、owing connections for trailers of25 tons gross weight”.BSAU28:1964 BSI 02-2000 1 1 Scope This British Standard specifies the basic dimensions and quality of materials for a towing jaw and its mountings, for use in connection between a towing vehicle and a trailer of535 tons gross weight. The gross w
12、eight refers to gross laden train weights where more than one trailer is drawn. 2 Materials The jaw shall be made from a material of quality not less than BS970 4) . En3A for the forged jaw, or BS592A 5)for the cast jaw, both materials to be in their normalized condition. The towing pin shall be mad
13、e from a material of quality not less than BS970 4) . En16S. 3 Dimensions Dimensions shall be as shown in the Figure. Theringed dimensions are essential for interchangeability, other dimensions apply to the forged jaw and are for guidance only. NOTEThe dimensions specified for the forged jaws have b
14、een calculated on the basis of the total yield strength being not less than two thirds of the gross weight being towed, It is necessary that any other parts not covered by this standard, connecting the coupling to the towing vehicle shall have a similar strength. 4 Design An efficient safety locking
15、 device shall be provided as indicated in the Figure to prevent accidental extraction of the towing pin from the jaw. The jaw shall be so designed that a bar1 3 / 4in diameter may be passed freely between the pin and the inside face of the jaw(seeFigure). 5 Mounting The jaw shall be mounted with fou
16、r bolts, 3 / 4in diameter, at4in 4 in centres. This renders it interchangeable in mounting with hooks specified in BS AU25 6)and BS AU27 7) , and with certain Government department and Services standard hooks. Bolts and nuts shall comply with: i) BS1083, threaded BSF, code symbol R, or 8) ii) BS1768
17、, threaded UNF, code symbol R 9) . The nuts shall be secured either by peening the end of the bolt or by fitting a positive locking device such as a safe locking nut or a slotted nut and split pin. 6 Marking The following wording, in clear lettering 3 / 8in high, raised or impressed, shall be marked
18、 on each towing jaw: “TO TOW35 TONS GROSS” on one side, and on the other side BS AU28”. 4) BS970, “Wrought steels in the form of bars, billets and forgings, up to6in ruling section, for automobile and general engineering purposes. En series”. 5) BS592, (included in BS3100) “Carbon steel castings for
19、 general engineering purposes”. 6) BS AU25, “Towing hook for use between trailers of514 tons gross weight and towing vehicle”. 7) BS AU27, “Towing hook for use between trailers of535 tons gross weight and towing vehicle”. 8) BS1083, “Precision hexagon bolts, screws and nuts”. 9) BS1768, “Unified pre
20、cision hexagon bolts, screws and nuts(UNC and UNF thread normal series)”.BSAU28:1964 2 BSI 02-2000blankBS AU28:1964 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on stan
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