ISO 7641:2012 道路車両—最大3.5 tのトレーラー—鋼製ドローバーの機械的強度の計算 | ページ 2

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 7641 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 4, Exterior fittings of car/trailer-caravan combinations.

This first edition of ISO 7641 cancels and replaces ISO 7641-1:1983, which has been technically revised.

1 Scope

This International Standard gives a simplified procedure for the calculation of the mechanical strength of steel drawbars, whether there are welds or not, for centre-axle trailers Categories O1 and O2 as specified in the UNECE, Consolidated Resolution on the Construction of Vehicles (R.E.3). Consequently, it only applies to simple constructions that enable a calculation in bending.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms, definitions and symbols

3.1 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.2 Symbols

e	distance, in metres, from the horizontal axis of the coupling device (coupling ball centre) to the drawbar neutral fibre at the first fixing point to the trailer frame (see Figure 1)
ex	distance, in metres, from the horizontal axis of the coupling device (coupling ball centre) to the drawbar neutral fibre at the cross section corresponding to the maximum strain rate (see Figure 1)
lx	distance, in metres, from the vertical axis of the coupling device to the drawbar section corresponding to the maximum strain rate (see Figure 1)
l	distance, in metres, from the vertical axis of the coupling device to the first fixing point to the trailer frame (see Figure 1)
P	maximum manufacturer’s total mass of the trailer, in kg as defined by the trailer manufacturer, in consideration of technical elements such as materials strength, braking ability, etc.
Dlt	value, in newtons, determined by calculation, corresponding to the longitudinal forces occurring between towing vehicle and trailer:
	Dlt=
k	coefficient for a drawbar with l > 2,5 m to be determined as follows:
	k = 1,25 – (0,1 x l) with kmin = 0,6
S	vertical static force applied to the coupling device

An example of these symbols of distance can be illustrated as shown in Figure 1.

Figure 1 — Drawbar sketch

Bibliography