1、BRITISH STANDARD BS AU 210-2:1994 Drawbars for caravans and light trailers Part 2: Specification for the design of aluminium drawbars and chassis UDC 629.11-43 + 728.76:629.11.011.1BSAU210-2:1994 This British Standard, having been prepared under the directionof the Automobile Standards Policy Commit
2、tee, waspublished under the authorityof the Standards Boardand comes into effect on 15July1994 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference AUE 8 Draft for comment 92 76306 DC ISBN 0 580 22324 8 Committees responsible for this British Standard The
3、 preparation of this British Standard was entrusted by the Automobile Standards Policy Committee (AUE/-) to Technical Committee AUE/8, upon which the following bodies were represented: Association of Trailer Manufacturers British Compressed Air Society Caravan Club Department of Transport National C
4、aravan Council Limited Society of Motor Manufacturers and Traders Ltd. Coopted members Amendments issued since publication Amd. No. Date CommentsBSAU210-2:1994 BSI 11-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 Symbols 1 5 Res
5、istance calculation for drawbars 4 6 Deflection calculation 4 7 Fatigue 4 8 Mechanical design of chassis 7 9 Chassis strength 7 10 Joining of body to chassis 7 Figure 1 Drawbar reference dimensions 2 Figure 2 Curves relating maximum stress and stress ratio for 10 8life cycles 6 Table 1 Properties of
6、 aluminium alloys 3 Table 2 Permissible stresses for aluminium alloys 5 List of references Inside back coverBSAU210-2:1994 ii BSI 11-1999 Foreword This Part of BS AU210 was prepared under the direction of the Automobile Standards Policy Committee. Since the drawbar is only one part of the chassis of
7、 a caravan or light trailer, and as the chassis can be made of materials other than steel, or even be of composite construction, this Part of BS AU210 aims to set out requirements for the design of aluminium chassis for caravans and light trailers A British Standard does not purport to include all t
8、he necessary provisions of a contract. Users of British Standards are responsible 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,
9、pages1 to8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BSAU210-2:1994 BSI 11-1999 1 1 Scope This Part of BS AU210 specifies: a) a procedur
10、e for determining the mechanical strength of drawbars for caravans and light trailers where the vertical static force on the coupling head is not less than245N and not greater than735N; b) requirements for the mechanical design of the chassis for caravans and light trailers. This standard applies to
11、 aluminium chassis of caravans and light trailers provided they are not of welded construction. It also covers the aluminium elements of chassis of composite construction, again provided the aluminium parts have not been welded. NOTEThe method for calculation of the mechanical strength of steel draw
12、bars for caravans and light trailers is covered in BSAU210-1. 2 References 2.1 Normative references This Part of BS AU210 incorporates, by reference, provisions from specific editions of other publications. These normative references are cited at the appropriate points in the text and the publicatio
13、ns are listed on the inside back cover. Subsequent amendments to, or revisions of, any of these publications apply to this Part of BS AU210 only when incorporated in it by updating or revision. 2.2 Informative references This Part of BS AU210 refers to other publications that provide information or
14、guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this Part of BS AU210, the definitions given in BS8118 apply, together with the following
15、. 3.1 chassis the element, including the drawbar, between the axle assembly and the body of the caravan or light trailer 3.2 drawbar that part of the chassis which enables the connection of the caravan or light trailer to the towing vehicle 4 Symbols For the purposes of this Part of BS AU210, the fo
16、llowing symbols are used. l is the distance (in mm) from the vertical axis of the coupling device to the first point on the trailer frame (seeFigure 1). l x is the distance (in mm) from the vertical axis of the coupling device to the drawbar section corresponding to the maximum strain rate (seeFigur
17、e 1). e is the distance (in mm) from the horizontal axis of the coupling device to the drawbar neutral axis at the first fixing point on the trailer frame (seeFigure 1). e x is the distance (in mm) from the horizontal axis of the coupling device to the drawbar neutral axis at the cross section corre
18、sponding to the maximum strain rate (seeFigure 1). d is the maximum deflection (in mm) at the coupling device relative to the first fixing point (seeFigure 1). P is the manufacturers total mass (in kg) of the caravan or light trailer (see ISO7237). D is the value determined by calculation for the lo
19、ngitudinal force (in N) occurring between the tractor vehicle and the trailer (see ISO3853). E is the modulus of elasticity (in N/mm 2 ); its value varies according to the alloy (seeTable 1). I is the moment of inertia (in mm 4) ) of the section. g is the acceleration due to gravity (in m/s 2 ) (see
20、 ISO3853).BSAU210-2:1994 2 BSI 11-1999 Figure 1 Drawbar reference dimensionsBS AU 210-2:1994 BSI 11-1999 3 Table 1 Properties of aluminium alloys Alloy BS or international no. a Condition Form Thickness 0.2% tensile proof stress Tensile strength Elongation 0.2% compressive proof stress Bearing stren
21、gth Modulus of elasticity b Density Durability rating c Min. Max. 5.65S 0 50 mm mm mm N/mm 2 N/mm 2 % % N/mm 2 N/mm 2 N/mm 2 kg/m 3 6082 TF extrusions 20 20 150 d 255 270 295 310 8 8 7 same as tensile 618 68 900 2 710 B sheet and plate 0.2 3.0 255 295 8 587 3.0 25 240 295 8 drawn tube 6.0 255 310 7
22、7 618 6.0 10 240 310 9 5083 M extrusions 150 d 130 280 12 11 same as tensile 556 68 900 2 660 A sheet 3.0 25 O extrusions 150 d 125 275 14 13 118 525 sheet and plate 0.2 25 14 12-16 556 6063 TF extrusions 150 d 160 185 8 7 same as tensile 386 65 500 2 710 B TE extrusions 25 110 150 8 7 324 6061 TF e
23、xtrusions 150 d 240 280 8 7 tensile 556 68 900 2 710 B 2014A TB extrusions 20 230 370 11 10 206 664 72 400 2 800 C TF extrusions 20 370 435 7 6 same as tensile 772 clad sheet 3.0 12.5 365 425 8 726 68 900 A e clad plate 12.5 25 380 440 6 5251 H3 sheet 0.2 6.0 130 200 4-8 115 463 68 900 2 690 A 5154A
24、 H2 sheet 0.2 6.0 165 245 5-8 150 494 2 670 7020 TB extrusions 25 190 300 12 10 same as tensile 600 71 700 2 800 B sheet and plate 0.2 25 170 280 560 TF extrusions 25 280 340 10 8 660 sheet and plate 0.2 25 270 320 630 a See BS 1470. b For modulus of rigidity multiply by 0.38. c See BS 8118-1:1991 c
25、lause 2.4. d For round tube and hollow sections these properties do not apply above 75 mm. e C for immersion in fresh or sea water.BSAU210-2:1994 4 BSI 11-1999 5 Resistance calculation for drawbars 5.1 The calculation for resistance for drawbars shall be carried out over the whole length l of the dr
26、awbar, taking into account distances l xand e xin order to determine the maximum strain rate. The strain rate shall be checked at the position where the maximum bending moment occurs when l = l xand e = e x . 5.2 The maximum bending moment M f(in Nmm) for the drawbar with e/l 0.15 and e x /l x 0.15
27、shall be calculated as follows. NOTEOnly flexure is taken into account for the calculation. Three bending moments M f , M fDand M fRshall be calculated and the largest value of the three shall be used for the calculation of the maximum admissible stress M fmax . For braked trailers: M f= 0.36 Pgl x
28、M fD= 0.8 De x M fR= 0.75 (M f+ M fD ) For unbraked trailers: M f= 0.24 Pgl x M fD= 1.0 De x M fR= 0.75 (M f+ M fD ) 5.4 The permissible stress rates B, calculated for the whole length of the drawbar, shall not exceed the allowed stress B bc(seeTable 2). where NOTEIt is assumed in this standard that
29、 aluminium sheet, plate or strip conforming to BS1470 or bars, extruded round tube or sections conforming to BS1474 are used. This does not prevent other, suitable and fit for purpose, aluminium alloys being used. The properties of some aluminium alloys are shown inTable 1 andTable 2. 6 Deflection c
30、alculation 6.1 The deflections d f , d fDand d fRshall be calculated, at the same time as the resistance calculation in clause5, as follows. For braked trailers: d fR= 0.75 (d f+ d fD ) For unbraked trailers: d fR= 0.75 (d f+ d fD ) The value shall not exceed that defined in6.2 NOTEBecause of the in
31、creased flexibility of aluminium compared to steel, it should not be taken for granted that the drawbar design is sufficiently stiff without performing a deflection calculation. 6.2 The permissible deflection d at the coupling device shall not exceed: to a maximum of25mm. 7 Fatigue Because of the co
32、nstraints on manufacture, all drawbars shall be considered to have type1 classification as defined in BS8118-1:1991. Using the curves inFigure 2, the fatigue life shall be predicted. NOTE I/V is the section modulus (in mm 3 ), of the drawbar cross section corresponding to the maximum bending moment.
33、 B min is the minimum stress, which is the lower numerical value of the stress in a stress cycle. B max is the maximum stress, which is the higher numerical value of the stress in a stress cycle. is the stress ratio, which is the ratio of the minimum to maximum stress in a stress cycle, tensile stre
34、ss being considered positive and compressive stress negative. When these points are plotted onFigure 2a) andFigure 2b), they always occur on the curve or in the area defined as “acceptable”. d l 70 - = min max -BSAU210-2:1994 BSI 11-1999 5 Table 2 Permissible stresses for aluminium alloys Alloy BS o
35、r international no. a Condition Form Thickness Axial b Bending Shear Bearing c Min. Max. B t B c B bt B bc B q B b mm mm N/mm 2 N/mm 2 N/mm 2 N/mm 2 N/mm 2 N/mm 2 6082 TF extrusions 20 139 139 154 154 83 222 20 150 147 147 162 162 88 sheet and plate 0.2 3.0 139 139 154 154 83 212 3.0 25 132 132 147
36、147 79 drawn tube 6.0 140 140 156 156 84 222 6.0 10 134 134 149 149 80 5083 M extrusions 150 d 82 82 96 96 49 201 sheet and plate 3.0 25 80 77 94 90 48 201 O extrusions 150 d 80 77 94 90 48 201 sheet and plate 0.2 25 6063 TF extrusions 150 d 87 87 96 96 52 139 TE extrusions 25 62 62 69 69 37 117 606
37、1 TF extrusions 150 d 131 131 145 145 78 201 2014A TB extrusions 20 135 124 153 142 81 239 TF extrusions 20 154 202 154 224 108 278 clad sheet 3.0 12.5 147 199 147 220 100 261 clad plate 12.5 25 147 207 147 229 5251 H3 sheet 0.2 6.0 75 69 85 79 45 167 5154A H2 sheet 0.2 6.0 95 88 107 100 57 178 7020
38、 TB extrusions 25 111 111 126 126 67 216 sheet and plate 0.2 25 100 100 114 114 60 202 TF extrusions 25 154 154 171 171 92 238 sheet and plate 0.2 25 148 148 164 164 89 227 a See BS 1470. b Applies only when buckling is not the criterion; see BS8118-1. c Joints in single shear. d For round tube and
39、hollow sections the permissible stresses do not apply above75mm.BS AU 210-2:1994 6 BSI 11-1999 Figure 2 Curves relating maximum stress and stress ratio and 10 8life cyclesBSAU210-2:1994 BSI 11-1999 7 8 Mechanical design of chassis 8.1 Bolted joints 8.1.1 Minimum spacing between bolt holes The spacin
40、g between the centres of the bolts shall not be less than2.5 times the bolt diameter. 8.1.2 Edge distance With extruded, rolled or machined edges, the distance to the edge, measured from the centre of the bolt hole shall not be less than1.5 times the bolt diameter. If, on the beating side, it is les
41、s than2 times the bolt diameter, the permissible beating strength shall be reduced as follows: where 8.1.3 Web stiffness The web stiffness shall be demonstrated by calculation as detailed in BS8118-1:1991, by test or both. 8.1.4 Bolt material Steel bolts conforming to BS EN24014:1992 and nuts to BS
42、EN24032:1992 shall be used. Both the bolts and nuts used shall be rendered corrosion resistant by zinc plating to BS3382-2:1961. Washers shall be provided under all bolt heads and nuts and these washers shall be zinc plated to BS1706:1990 Fe/Zn8 and passivated. The length of the unthreaded part of t
43、he bolt shall be such that as far as possible no part of the thread is within the thickness of the member The thread shall project beyond the nut by a minimum of two turns. A form of locking device shall be used. NOTEOther suitable anti-corrosion coatings may be used that adequately protect the join
44、ted parts against electrolytic corrosion. 8.2 Joints with steel or cast iron (see also8.3) For such composite joints, the steel or cast iron elements shall be either: a) zinc plated to BS1706:1990 Fe/Zn 8; or b) hot dip galvanized to BS729:1971; or c) painted with priming coat with an inhibiting pig
45、ment containing not less than20% by weight of zinc chromate or other approved chromate in a suitable water resisting vehicle. The priming coat shall not contain any copper or mercury compounds, graphite or carbonaceous materials, or lead; or d) separated by the use of a continuous membrane of non-re
46、active material e.g.plastic. NOTEA joint made by any other means not detailed in this standard may be used provided that its load carrying capacity and life expectancy can be shown to be satisfactory. 8.3 Contact with timber Aluminium surfaces in contact with timber, unless the timber is fully seaso
47、ned and the environment dry and unpolluted, shall be painted. Timber in contact with aluminium shall not be treated with preservatives containing copper sulfate, zinc chloride or mercuric salts. NOTE 1Other preservatives may be used provided that it can be shown that the timber so treated is not har
48、mful to the aluminium. NOTE 2Oak, chestnut and western red cedar are likely to be harmful to aluminium particularly where there are through fastenings, unless the timber is well seasoned. 9 Chassis strength The chassis manufacturer shall demonstrate, either by test or by calculation, or both, that a
49、ll elements of the chassis are fit for their declared purpose with reference to BS8118:1991. 10 Joining of body to chassis The chassis manufacturer shall provide, in writing, instructions in respect of strength and fixing arrangements for the attachment of the caravan or light trailer body to the chassis. There shall be no fixing directly or indirectly through the top or bottom flanges of the drawbar at the foremost body fixing position. P BM is the modi
