BRITISH STANDARD AUTOMOBILE SERIES BS AU 114b 1979 Incorporating Amendment No 1 Specification for Strength requirements of towing brackets and coupling balls for caravans and light trailers UDC 629 11[.]
BRITISH STANDARD AUTOMOBILE SERIES BS AU 114b:1979 Incorp orating Am endm ent No Specification for Strength requirements of towing brackets and coupling balls for caravans and light trailers UD C 62 1 BS AU 1 b : 979 Fore word This British Standard has been prepared under the direction of the Automobile Road vehicles — Caravans and light trailers — Towing brackets and coupling balls — Strength test” of the International Organization for Standardization Standards Committee and is technically equivalent to ISO 3853: 977 “ (ISO) 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 C o mp liance with a British S tand ard doe s not o f itse lf co nfe r immunity fro m le gal ob ligations S ummary o f p age s This document comprises a front cover, an inside front cover, pages i and ii, pages to and a back cover This standard has been updated (see copyright date) and may have had This British Standard, having amendments incorporated This will be indicated in the amendment table on been prepared under the the inside front cover direction of the Automobile Standards Committee, was published under the authority of the Executive Board on 28 February 979 © BSI 01 - 2000 The following BSI references relate to the work on this standard: Committee reference AUE/8 Draft for comment 76/73266 DC IS B N 80 Ame ndme nts issue d since p ub lication Amd No Date of issue Comments 521 October 986 Indicated by a sideline in the margin BS AU 114b:1979 Contents Page Foreword Inside front cover Scope References Field of application D efinitions General test requirements Strength criteria Marking Figure — Examples of test mountings and marking Figure — Mating surface and fixing of b all support on towing device © BSI 01 - 000 i ii blank BS AU 1 b: 979 S cope General test requirements This British Standard lays down the strength 5.1 requirements to be met by mechanical coupling having dimensional characteristics complying with devices between light trailers or caravans, and the requirements of BS AU 1 3c towing vehicles Mechanical coupling devices may 5.2 be of the following types: The strength tests described in this standard are dynamic tests to be performed on a test bed a) one- piece ball coupling; Stre ngth te st for towing de vice b) ball coupling comprising a number of parts 5.3.1 which can be dismantled NOTE The tests shall be carried out with coupling balls Tow ing b racket incorp o rating the b all as an integral p art of the cons tructio n The term “ball coupling” is used to designate a coupling device of which a coupling ball forms a part 5.3.1 Mo unting on test b ed (see examples of mounting in Figure , example ) The complete References The following standards publication is referred to in this standard BS AU 1 3c, (see Figure , example ) towing device shall be rigidly mounted on the bed in a position geometrically identical with that intended when fitted to the type of vehicle for which this towing device is designed Sp ecification for dim ensio nal characteristics of coup ling b all fo r carav ans and The fixing arrangements for the towing device on light trailers the test bed shall be those intended for its attachment to the towing vehicle Field of app lication The fixing arrangements for the towing device on This British Standard is applicable to towing the test bed shall be those intended for its brackets and coupling balls fitted to towing vehicles attachment to the towing vehicle intended for the towing of caravans or light trailers of which the maximum total weight does not exceed tonnes 1) Anchorage p oints The relative positions of the anchorage points shall be copied on the test bed In the case where, coupling In cases where the towing device manufacturer balls fitted to towing vehicles intended for the chooses not to meet the recommendations given by towing of caravans or light trailers of which the maximum total weight does not exceed tonnes 5.3.1 1) the towing vehicle manufacturer he can choose the In the case where, exceptionally, the manufacturer anchorage points which suit him but in such cases of the towing vehicle authorizes the maximum he shall accept all responsibility resulting from this permissible towed weight to be exceeded, the unrestricted choice, and in particular he shall keep corresponding towing devices are not considered in to the maximum permissible towed weight specified this standard by the towing vehicle manufacturer In all cases, the towing device shall be subj ected to the dynamic test described below D efinitions NOTE 4.1 maximum manufacture r’s total weight (towing vehicle), W M regarding the relative positions of the anchorage points 5.3.1 weight calculated by the manufacturer for specific The towing vehicle manufacturer should provide all the necessary information to the towing device manufacturer Descrip tion of tes t m ethod The assembly mounted on the test bed under the conditions operating conditions, taking into account such defined in elements as strength of materials, tyre loading test on an alternating stress tensile testing capacity, etc machine 4.2 5.3.1 3.1 manufacture r’s towe d we ight, W R towed weight calculated by the manufacturer from the characteristics of the tractor vehicle 5.3.1 and 5.3.1 shall be subj ected to a Direction of load ap p lication The test load shall be an alternating force applied at an angle of 20 ± ° relative to the horizontal in the longitudinal vertical median plane of the towing vehicle and passing through the centre of the coupling ball 1) This value is chosen to include categories 01 and 02 of trailers according to the classification of vehicles given in document E/ECE/324/Rev /Add of the Economic Commission for Europe of the United Nations This document is entitled “Agreem ent concerning the ado p tio n of uniform conditions o f ap p ro v al and recip ro cal reco gnitio n of ap p rov al for m oto r v ehicle eq uip m ent and p arts — done at GENEVA on 20 March 958 — Addendum 2: Regulation to be annexed to the Agreement: Unifo rm p ro v is ions co ncerning the ap p ro v al of v ehicles w ith regard to b raking” © BSI 01 - 2000 BS AU 1 b : 979 This angle is chosen in order to take account of the 5.4.2 vertical static load characteristics of the mating surface of the ball 5.3.1 3.2 Value of test load The minimum value of the test load to be applied in the direction specified in 5.3.1 3.1 W M = D W M shall be D (in kilonewtons × + 2) ) R M R is the maximum manufacturer’s total The assembly of the support and the is the manufacturer’s towed weight (in kN) Lo ading cycle and freq uency The value of the test load shall vary in an approximately number of cycles equal to × specified in The test shall be carried out by applying the load at 5.4.3.2 The test shall be carried out according to the requirements given in Tow ing b racket incorp orating the b all as a 3.1 In all cases, the weights of the towing vehicles and trailers to be considered for the test shall correspond to one or other of the following two categories: category : a selected frequency, not exceeding 35 Hz detachab le elem ent shall be subj ected to a test on an 5.4.1 alternating stress tensile testing machine sinusoidal manner from + D to – D for a 5.3.2.1 of coupling ball mounted according to the conditions 5.3.1 3.3 5.3.2 3.2 Description of test method 5.4.3.1 weight (towing vehicle) (in kN) W be of diameter M1 as specified in BS AU 1 3c 5.4.3 R where W support with the test bed or the towing bracket shall be those given in Figure The two bolts used shall W W When specified, the dimensional W M W R category 2: (see Figure , examples to 4) W M W R = 50 kN = 35 kN = 220 kN = 35 kN Ball couplings comprising parts which can be dismantled are principally as follows: S tre ngth criteria a) towing device plus ball For the duration of the tests carried out according to (see Figure , example 2); the requirements of this standard, the towing b) towing device plus ball on integral support, devices and their constituent parts (bracket, ball, i e “one- piece” (see Figure , example 3); support, fixings, etc ) shall not exhibit any c) towing device plus support plus ball (see Figure , example 4) 5.3.2.2 These towing devices shall be tested under the conditions given in 5.3.2.3 5.3.1 The test shall be carried out on a complete towing device but account will be taken only of the results relating to the part of the complete towing permanent deformation or visible external deterioration and there shall be no breakage Marking Devices complying with 5.3 and 5.4, and identical with the type which was tested, shall carry the marking shown in Figure and the following: device included between the anchorage points and a) the towbar manufacturer’s name; the fixing of the coupling ball support b) the towbar part number; 5.3.2.4 The strength tests on the support, and/or on the coupling ball, shall be carried out according to the requirements of 5.4 S tre ngth te st o n the b all and its sup p o rt 5.4.1 Mounting for test c) the towbar batch number; d) the notice “Consult the vehicle details for the maximum permissible trailer weight and nose load” (see examples of mounting in Figure ) The assembly of the support and the coupling ball shall be fixed rigidly on the test bed 2) kN = 01 , 972 kgf © BSI 01 - 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