INTERNATIONAL STANDARD ISO 14791 First edition 2000-04-15 Road vehicles Heavy commercial vehicle combinations and articulated buses Lateral stability test methods Véhicules routiers Ensembles de véhicules utilitaires lourds et autobus articulés Méthodes d'essai de stabilité latérale Reference number ISO 14791:2000(E) ISO 2000
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Contents Page Foreword...iv Introduction...v 1 Scope...1 2 Normative references...1 3 Terms and definitions...1 4 Test objectives...2 5 Measuring equipment...4 5.1 Description...4 5.2 Transducer installation...4 5.3 Data processing...5 6 Test conditions...6 6.1 Test tracks...6 6.2 Tyres...6 6.3 Operating components...7 6.4 Loading conditions...7 7 Test method...7 7.1 Warm-up...7 7.2 Test speed...7 7.3 Lateral acceleration...8 7.4 Pseudo-random input...8 7.5 Single lane-change...8 7.6 Pulse input...9 8 Data analysis and presentation...12 8.1 Preliminary analysis...12 8.2 Rearward amplification...12 8.3 Offtracking...13 8.4 Zero-damping speed and yaw damping...13 8.5 Yaw-velocity ratio...14 Annex A (normative) General data sheet...16 Annex B (normative) Presentation of results...19 Annex C (informative) Technique and verification for path-following...22 Annex D (informative) Calculation of confidence interval for the rearward amplification...25 Bibliography...26 ISO 2000 All rights reserved iii
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 3. 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 International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 14791 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 9, Vehicle dynamics and road-holding ability. Annexes A and B form a normative part of this International Standard. Annexes C and D are for information only. iv ISO 2000 All rights reserved
Introduction The road-holding ability of heavy commercial vehicle combinations and articulated buses is a most important part of active vehicle safety. Any given heavy commercial vehicle combination, together with its driver and the prevailing environment, constitutes a closed-loop system that is unique. The task of evaluating road-holding ability is, therefore, very difficult because of the significant interaction of these driver/motor vehicle/trailer/road elements, each of which is in itself complex. A complete and accurate description of the behaviour of a heavy vehicle combination must necessarily involve information obtained from a number of tests of different types. Because they quantify only a small part of the whole vehicle handling field, the results of the tests specified in this International Standard can only be considered significant for a correspondingly small part of the overall handling behaviour of heavy commercial vehicle combinations and articulated buses. In addition, the results obtained from these tests apply only for combinations of identical types of vehicle units. The results will not describe the behaviour of the vehicle units separately. Moreover, insufficient knowledge is available concerning the relationship between overall vehicle dynamic properties and accident avoidance. Since the number of variants of heavy truck combinations is tremendously large, each truck combination is unique. So the measured result is valid only for the tested vehicle or combination and the transition of the results to obviously similar vehicle combinations is, especially for heavy trucks, not possible. Therefore, it is not possible to use these test methods and the test results for regulation purposes. ISO 2000 All rights reserved v
INTERNATIONAL STANDARD ISO 14791:2000(E) Road vehicles Heavy commercial vehicle combinations and articulated buses Lateral stability test methods 1 Scope This International Standard specifies test methods to determine the lateral stability of heavy commercial vehicle combinations as defined in ISO 3833, including truck centre-axle trailer combinations and articulated buses. It is applicable to trucks and trailers having a mass exceeding 3,5 t and buses having a mass exceeding 5 t, i.e. vehicle categories N2, N3, O3, O4 and M3 according to 92/53/EEC. The manœuvres specified in these test methods are not fully representative of real driving conditions, but are useful for determining the lateral stability of a heavy vehicle combination. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1176:1990, Road vehicles Masses Vocabulary and codes. ISO 3833:1977, Road vehicles Types Terms and definitions. ISO 8855:1991, Road vehicles Vehicle dynamics and road-holding ability Vocabulary. ISO 9815:1992, Passenger-car/trailer combinations Lateral stability test. EC Council Directive No. 92/53/EEC. Annex II, Definition of vehicle categories and vehicle types. 3 Terms and definitions For the purposes of this International Standard, the terms and definitions given in ISO 8855 and the following apply. 3.1 vehicle unit rigid (i.e. non-articulating) vehicle element operating alone or in combination with one or more other rigid elements joined at yaw-articulation joints EXAMPLES Tractor, semitrailer and dolly. 3.2 rearward amplification ratio of the maximum value of the motion variable of interest of a following vehicle unit to that of the first vehicle unit during a specified manœuvre ISO 2000 All rights reserved 1