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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 + 728.76:629.11.011.1 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:08:36 GMT+00:00 2006, Uncontr
2、olled Copy, (c) BSI BS AU 210-2:1994 This British Standard, having been prepared under the direction of the Automobile Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 July 1994 BSI 11-1999 The following BSI references relate to the wor
3、k 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 preparation of this British Standard was entrusted by the Automobile Standards Policy Committee (AUE/-) to Technical Committee AUE/8, upon which the fol
4、lowing bodies were represented: Association of Trailer Manufacturers British Compressed Air Society Caravan Club Department of Transport National Caravan Council Limited Society of Motor Manufacturers and Traders Ltd. Coopted members Amendments issued since publication Amd. No.DateComments Licensed
5、Copy: London South Bank University, London South Bank University, Sat Dec 09 02:08:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 210-2:1994 BSI 11-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2References1 3Definitions1 4Symbols1 5Resistance calculation for dr
6、awbars4 6Deflection calculation4 7Fatigue4 8Mechanical design of chassis7 9Chassis strength7 10Joining of body to chassis7 Figure 1 Drawbar reference dimensions2 Figure 2 Curves relating maximum stress and stress ratio for 108 life cycles6 Table 1 Properties of aluminium alloys3 Table 2 Permissible
7、stresses for aluminium alloys5 List of referencesInside back cover Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:08:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 210-2:1994 ii BSI 11-1999 Foreword This Part of BS AU 210 was prepared under the directio
8、n of the Automobile Standards Policy Committee. Since the drawbar is only one part of the chassis of 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 AU 210 aims to set out requirements for the design of a
9、luminium chassis for caravans and light trailers 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 British Standard does not of itself confer immunity from legal oblig
10、ations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, 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 t
11、he inside front cover. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:08:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 210-2:1994 BSI 11-19991 1 Scope This Part of BS AU 210 specifies: a) a procedure for determining the mechanical strength of drawbars
12、for caravans and light trailers where the vertical static force on the coupling head is not less than 245 N and not greater than 735 N; b) requirements for the mechanical design of the chassis for caravans and light trailers. This standard applies to aluminium chassis of caravans and light trailers
13、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 drawbars for caravans and light trailers is covered in
14、 BS AU 210-1. 2 References 2.1 Normative references This Part of BS AU 210 incorporates, by reference, provisions from specific editions of other publications. These normative references are cited at the appropriate points in the text and the publications are listed on the inside back cover. Subsequ
15、ent amendments to, or revisions of, any of these publications apply to this Part of BS AU 210 only when incorporated in it by updating or revision. 2.2 Informative references This Part of BS AU 210 refers to other publications that provide information or guidance. Editions of these publications curr
16、ent 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 AU 210, the definitions given in BS 8118 apply, together with the following. 3.1 chassis the element, including the dr
17、awbar, 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 AU 210, the following symbols are used. lis the distance
18、 (in mm) from the vertical axis of the coupling device to the first point on the trailer frame (see Figure 1). lxis the distance (in mm) from the vertical axis of the coupling device to the drawbar section corresponding to the maximum strain rate (see Figure 1). eis the distance (in mm) from the hor
19、izontal axis of the coupling device to the drawbar neutral axis at the first fixing point on the trailer frame (see Figure 1). exis the distance (in mm) from the horizontal axis of the coupling device to the drawbar neutral axis at the cross section corresponding to the maximum strain rate (see Figu
20、re 1). dis the maximum deflection (in mm) at the coupling device relative to the first fixing point (see Figure 1). Pis the manufacturers total mass (in kg) of the caravan or light trailer (see ISO 7237). Dis the value determined by calculation for the longitudinal force (in N) occurring between the
21、 tractor vehicle and the trailer (see ISO 3853). Eis the modulus of elasticity (in N/mm2); its value varies according to the alloy (see Table 1). Iis the moment of inertia (in mm4) of the section. gis the acceleration due to gravity (in m/s2) (see ISO 3853). Licensed Copy: London South Bank Universi
22、ty, London South Bank University, Sat Dec 09 02:08:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 210-2:1994 2 BSI 11-1999 Figure 1 Drawbar reference dimensions Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:08:36 GMT+00:00 2006, Uncontrolled Copy, (c)
23、BSI BS AU 210-2:1994 BSI 11-19993 Table 1 Properties of aluminium alloys Alloy BS or international no.a ConditionForm Thickness0.2 % tensile proof stress Tensile strength Elongation 0.2 % compressive proof stress Bearing strength Modulus of elasticityb Density Durability ratingc Min.Max.5.65S050 mm
24、mmmmN/mm2N/mm2%N/mm2N/mm2N/mm2kg/m3 6082TF extrusions 20 20 150d 255 270 295 310 8 8 7 same as tensile 618 68 9002 710B sheet and plate 0.23.02552958 587 3.0252402958 drawn tube 6.025531077 618 6.0102403109 5083 M extrusions150d1302801211 same as tensile 556 68 9002 660A sheet3.025 O extrusions150d
25、125275 1413 118 525 sheet and plate0.2251412-16556 6063 TFextrusions150d16018587 same as tensile 386 65 5002 710B TEextrusions2511015087324 6061TFextrusions150d24028087tensile55668 9002 710B 2014A TBextrusions202303701110206664 72 400 2 800 C TF extrusions2037043576 same as tensile 772 clad sheet3.0
26、12.53654258 72668 900Ae clad plate12.5253804406 5251H3sheet0.26.01302004-8115463 68 900 2 690 A 5154AH2sheet0.26.01652455-81504942 670 7020 TB extrusions25190300 1210 same as tensile 600 71 7002 800B sheet and plate0.225170280560 TF extrusions25280340 108 660 sheet and plate0.225270320630 a See BS 1
27、470. b For modulus of rigidity multiply by 0.38. c See BS 8118-1:1991 clause 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. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:08:36 GM
28、T+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 210-2:1994 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 drawbar, taking into account distances lx and ex in order to determine the maximum strain
29、rate. The strain rate shall be checked at the position where the maximum bending moment occurs when l = lx and e = ex. 5.2 The maximum bending moment Mf (in Nmm) for the drawbar with e/l 0.15 and ex/lx 0.15 shall be calculated as follows. NOTEOnly flexure is taken into account for the calculation. T
30、hree bending moments Mf, MfD and MfR shall be calculated and the largest value of the three shall be used for the calculation of the maximum admissible stress Mfmax. For braked trailers: Mf = 0.36 Pglx MfD = 0.8 Dex MfR = 0.75 (Mf + MfD) For unbraked trailers: Mf = 0.24 Pglx MfD = 1.0 Dex MfR = 0.75
31、 (Mf + MfD) 5.4 The permissible stress rates B, calculated for the whole length of the drawbar, shall not exceed the allowed stress Bbc (see Table 2). where NOTEIt is assumed in this standard that aluminium sheet, plate or strip conforming to BS 1470 or bars, extruded round tube or sections conformi
32、ng to BS 1474 are used. This does not prevent other, suitable and fit for purpose, aluminium alloys being used. The properties of some aluminium alloys are shown in Table 1 and Table 2. 6 Deflection calculation 6.1 The deflections df, dfD and dfR shall be calculated, at the same time as the resistan
33、ce calculation in clause 5, as follows. For braked trailers: dfR = 0.75 (df + dfD) For unbraked trailers: dfR = 0.75 (df + dfD) The value shall not exceed that defined in 6.2 NOTEBecause of the increased flexibility of aluminium compared to steel, it should not be taken for granted that the drawbar
34、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 of 25 mm. 7 Fatigue Because of the constraints on manufacture, all drawbars shall be considered to have type 1 classification as defined in
35、 BS 8118-1:1991. Using the curves in Figure 2, the fatigue life shall be predicted. NOTE I/Vis the section modulus (in mm3), of the drawbar cross section corresponding to the maximum bending moment. Bminis the minimum stress, which is the lower numerical value of the stress in a stress cycle. Bmaxis
36、 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 stress being considered positive and compressive stress negative. When these points are plotted on Figure 2a)
37、and Figure 2b), they always occur on the curve or in the area defined as “acceptable”. d l 70 - -= min max - - Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:08:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 210-2:1994 BSI 11-19995 Table 2 Permissible s
38、tresses for aluminium alloys Alloy BS or international no.a ConditionForm ThicknessAxialbBendingShearBearingc Min.Max.BtBcBbtBbcBqBb mmmmN/mm2N/mm2N/mm2N/mm2N/mm2N/mm2 6082TF extrusions 2013913915415483 222 2015014714716216288 sheet and plate 0.23.013913915415483 212 3.02513213214714779 drawn tube 6
39、.014014015615684 222 6.01013413414914980 5083 M extrusions150d8282969649201 sheet and plate 3.0258077949048201 O extrusions150d 8077949048201 sheet and plate 0.225 6063 TFextrusions150d8787969652139 TEextrusions256262696937117 6061TFextrusions150d13113114514578201 2014A TBextrusions20135124153142812
40、39 TF extrusions20154202154224108278 clad sheet3.012.5147199147220 100261 clad plate12.525147207147229 5251H3sheet0.26.07569857945167 5154AH2sheet0.26.0958810710057178 7020 TB extrusions2511111112612667216 sheet and plate 0.22510010011411460202 TF extrusions2515415417117192238 sheet and plate 0.2251
41、4814816416489227 a See BS 1470. b Applies only when buckling is not the criterion; see BS 8118-1. c Joints in single shear. d For round tube and hollow sections the permissible stresses do not apply above 75 mm. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02
42、:08:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS AU 210-2:1994 6 BSI 11-1999 Figure 2 Curves relating maximum stress and stress ratio and 108 life cycles Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:08:36 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A
43、U 210-2:1994 BSI 11-19997 8 Mechanical design of chassis 8.1 Bolted joints 8.1.1 Minimum spacing between bolt holes The spacing between the centres of the bolts shall not be less than 2.5 times the bolt diameter. 8.1.2 Edge distance With extruded, rolled or machined edges, the distance to the edge,
44、measured from the centre of the bolt hole shall not be less than 1.5 times the bolt diameter. If, on the beating side, it is less than 2 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 calcula
45、tion as detailed in BS 8118-1:1991, by test or both. 8.1.4 Bolt material Steel bolts conforming to BS EN 24014:1992 and nuts to BS EN 24032:1992 shall be used. Both the bolts and nuts used shall be rendered corrosion resistant by zinc plating to BS 3382-2:1961. Washers shall be provided under all bo
46、lt heads and nuts and these washers shall be zinc plated to BS 1706:1990 Fe/Zn 8 and passivated. The length of the unthreaded part of the 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
47、 turns. A form of locking device shall be used. NOTEOther suitable anti-corrosion coatings may be used that adequately protect the jointed parts against electrolytic corrosion. 8.2 Joints with steel or cast iron (see also 8.3) For such composite joints, the steel or cast iron elements shall be eithe
48、r: a) zinc plated to BS 1706:1990 Fe/Zn 8; or b) hot dip galvanized to BS 729:1971; or c) painted with priming coat with an inhibiting pigment containing not less than 20 % by weight of zinc chromate or other approved chromate in a suitable water resisting vehicle. The priming coat shall not contain
49、 any copper or mercury compounds, graphite or carbonaceous materials, or lead; or d) separated by the use of a continuous membrane of non-reactive 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 seasoned and the environment dry and unpolluted, shall be
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