1、BRITISH STANDARD AUTOMOBILE SERIES BS AU25:1964 Supersedes S.M.M.T. StandardNo.51 Specification for Towing hook for use between trailers of514 tons gross weight and towing vehicle UDC 629.11.013.5:629.11.013.81BSAU25:1964 This British Standard, having been approved by the AutomobileIndustry Standard
2、sCommittee and endorsedby the Chairman oftheEngineering Divisional Council, was published under theauthority of the General Council of the Institution on 15June1964 BSI 02-2000 The following BSI reference relates to the work on this standard: Committee reference AUE/- ISBN 0 580 34548 3 Amendments i
3、ssued since publication Amd. No. Date CommentsBSAU25:1964 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 3BSAU25:1964 ii BSI 02-2000 Foreword This British Standard
4、, which is published under the authority of the AutomobileIndustry Standards Committee of the BSI, is based upon data-sheet SMMT51:1957 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
5、ensure 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 safe
6、ty is not impaired. This standard should be used in conjunction with BS AU29 1) . The hook has been designed to accommodate a drawbar eye of2in internal diameter and1; in stock, or3 in internal diameter and1C in stock. The standard applies to connections to trailers of514 tons gross weight. Thespeci
7、fication for a towing hook for connections to trailers of535 tons gross weight is given in BS AU27 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 fact
8、ors and tables contained in BS350, Conversion 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 respo
9、nsible for their correct application. 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
10、date) and may have had amendments incorporated. This will 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 AU27, “Towing hook for use between trailers of53
11、5 tons gross weight and towing vehicle”. 3) BS AU24, “Towing connections for trailers of25 tons gross weight”.BSAU25:1964 BSI 02-2000 1 1 Scope This British Standard specifies the basic dimensions and quality of materials for a towing hook and its mounting, for use in connections between a towing ve
12、hicle and a trailer of514 tons gross weight. The gross weights refer 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. En5(N) 3 Dimensions Dimensions shall be as shown in Figure 1 and Figure 2. NOTETh
13、e dimensions specified are based 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 ha
14、ve a similar strength. 4 Design An 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 bar1in diameter, when held vertically, may be
15、passed freely between the inside faces of the hook with the catch held back to clear(seeFigure 1). 5 Mounting The hook shall be mounted with four bolts, C in diameter, at4in 4in centres. This renders it interchangeable in mounting with certain Government department and Services standard hooks. Bolts
16、 and nuts shall comply with: i) BS1083, threaded BSF, code symbol R, or 4) ii) BS1768, threaded UNF, code symbol R 5) . 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 fol
17、lowing wording, in clear letteringB in high, raised or impressed, shall be marked on each towing hook: “TO TOW14 TONS GROSS” on one side, and on the other side “BS AU25”. 23 32 - 4) BS1083, “Precision hexagon bolts, screws and nuts”. 5) BS1768, “Unified precision hexagon bolts, screws and nuts(UNC a
18、nd UNF thread-normal series)”.BSAU25:1964 2 BSI 02-2000 All dimensions are in inches Figure 1 Towing hook, indicating safety catchBSAU25:1964 BSI 02-2000 3 All dimensions are in inches Figure 2 Towing hookBS AU25:1964 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the
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