1、BRITISH STANDARD AUTOMOBILE SERIES BS AU27:1964 (Supersedes S.M.M.T. Standard No.52) Specification for Towing hook for use between trailers of535 tons gross weight and towing vehicle UDC 629.11.013.5:629.013.81BSAU27:1964 This BritishStandard, having been approved by the AutomobileIndustry Standards
2、Committee and endorsed by the Chairman of theEngineering Divisional Council, was published undertheauthority of the GeneralCouncil of the Institutionon 15 June1964 BSI02-2000 The following BSI reference relates to the work on this standard: Committee reference AUE/- ISBN 0 580 34550 5 Amendments iss
3、ued since publication Amd. No. Date CommentsBSAU27:1964 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 1 Figure 1 Towing hook, indicating safety catch 2 Figure 2 Towing hook 3BSAU27:1964 ii BSI 02-2000 Foreword This BritishStandard, w
4、hich is published under the authority of the Automobile Industry Standards Committee of The BSI, is based upon data-sheet SMMT52:1957 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 en
5、sure the maximum degree of interchangeability between commercial and Government department and Services standards. 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
6、 is not impaired. This standard should be used in conjunction with BSAU29 1) . The hook has been designed to accommodate a drawbar eye of3 in internal diameter and1 5 / 8in stock. The standard applies to connections to trailers of535 tons gross weight. Thespecification for a towing hook for connecti
7、ons to trailers of514 tons gross weight is given in BSAU25 2) , and for trailers of25 tons gross weight 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, “Conv
8、ersion factors and tables”, 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 applicatio
9、n. Compliance with a 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 to3 and a back cover. This standard has been updated (see copyright date) and may have had amendments i
10、ncorporated. This will be indicated in the amendment table on the inside front cover. 1) BSAU29, “Drawbar eyes and forecarriage pins for connection between trailers of535 tons gross weight and towing vehicle”. 2) BSAU25, “Towing hook for use between trailers of514 tons gross weight and towing vehicl
11、e”. 3) BSAU24, “Towing connections for trailers of25 tons gross weight”.BSAU27:1964 BSI 02-2000 1 1 Scope This BritishStandard specifies the basic dimensions and quality of materials for a towing hook and its mounting, for use in connections between a towing vehicle and a trailer of535 tons gross we
12、ight. The gross weight refers to gross laden train weights where more than one trailer is drawn. 2 Materials The hook shall be made from a material of quality not less than BS970 4) . En16(R). 3 Dimensions Dimensions shall be as shown in Figure 1 and Figure 2. NOTEThe dimensions specified are based
13、upon a forged hook, and have been calculated on the basis of the total yield strength being equal to 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
14、 efficient safety catch, preferably of the automatic or semi-automatic type, shall be provided as indicated in Figure 1 to prevent accidental detachment of the drawbar from the hook. The hook shall be so designed that a bar1 23 / 32in diameter, when held vertically, may be passed freely between the
15、inside faces of the hook with the catch held back to clear (seeFigure 1). 5 Mounting The hook shall be mounted with four bolts, 3 / 4in diameter, at4 in 4 in centres. Bolts and nuts shall comply with: i) BS1083, threaded BSF, code symbol R, or 5) ii) BS1768, threaded UNF, code symbol R 6) . The nuts
16、 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 on each towing hook: “TO TOW35 TONS GROSS”
17、 on one side, and on the other side “BSAU27”. 4) BS970, “Wrought steels in the form of bars, billets, and forgings, up to6 in ruling section, for automobile and general engineering purposes. En series”. 5) BS1083, “Precision hexagon bolts, screws and nuts”. 6) BS1768, “Unified precision hexagon bolt
18、s, screws and nuts (UNC and UNF thread-normal series)”.BSAU27:1964 2 BSI 02-2000 All dimensions are in inches Figure 1 Towing hook, indicating safety catchBSAU27:1964 BSI 02-2000 3 All dimensions are in inches Figure 2 Towing hookBS AU27:1964 BSI 389 Chiswick High Road London W4 4AL BSIBritishStanda
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