1、BRITISH STANDARDBS ISO 21069-2:2008Road vehicles Test of braking systems on vehicles with a maximum authorized total mass of over 3,5 t using a roller brake tester Part 2: Air over hydraulic and purely hydraulic braking systemsICS 43.040.40g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54
2、g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS ISO 21069-2:2008This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 August 2008 BSI 2008ISBN 978 0 5
3、80 56209 9National forewordThis British Standard is the UK implementation of ISO 21069-2:2008.The UK participation in its preparation was entrusted to Technical Committee AUE/11, Braking systems.A list of organizations represented on this committee can be obtained on request to its secretary.This pu
4、blication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. Amendments/corrigenda issued since publicationDate CommentsReference numberISO 21069-2
5、:2008(E)INTERNATIONAL STANDARD ISO21069-2First edition2008-05-01Road vehicles Test of braking systems on vehicles with a maximum authorized total mass of over 3,5 t using a roller brake tester Part 2: Air over hydraulic and purely hydraulic braking systems Vhicules routiers Essai des systmes de frei
6、nage des vhicules ayant une masse totale maximale autorise suprieure 3,5 t effectu sur banc dessai de freinage rouleaux Partie 2: Systmes de freinage hydropneumatique et purement hydraulique BS ISO 21069-2:2008ii iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Terms and definitions .1 3 Symb
7、ols 2 4 Test conditions and evaluations3 4.1 General3 4.2 Preparation of vehicle and roller brake tester 3 4.3 Calculation and evaluation of test data.3 4.4 Presentation of results6 Annex A (normative) Technical requirements of roller brake tester .8 Annex B (informative) Periodic inspection of equi
8、pment and its documentation .12 Bibliography 14 BS ISO 21069-2:2008iv 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 techni
9、cal 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 w
10、ith 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 Int
11、ernational 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 m
12、ay be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 21069-2 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 2, Braking systems and equipment. ISO 21069 consists of the following parts, under the genera
13、l title Road vehicles Test of braking systems on vehicles with a maximum authorized total mass of over 3,5 t using a roller brake tester: Part 1: Pneumatic braking systems Part 2: Air over hydraulic and purely hydraulic braking systems BS ISO 21069-2:2008vIntroduction At present, UNECE Regulation No
14、. 13 covers only some aspects of the periodic technical inspection of vehicles in use. In order to fulfil the requirements of UNECE Regulation No. 13, paragraph 5.1.4, this part of ISO 21069 is designed to cover the periodic measurement of braking performance of vehicles in service. This part of ISO
15、 21069 specifies the test method whereby a roller brake tester is used to measure, evaluate and record the braking efficiency of road vehicles of categories M2, M3, N2, N3, O3 and O4 as defined in UNECE Consolidated Resolution on the Construction of Vehicles (R.E.3.) which are equipped with full pow
16、er air over hydraulic or purely hydraulic braking systems. This part of ISO 21069 is also applicable for electronic braking systems (EBS). BS ISO 21069-2:2008blank1Road vehicles Test of braking systems on vehicles with a maximum authorized total mass of over 3,5 t using a roller brake tester Part 2:
17、 Air over hydraulic and purely hydraulic braking systems 1 Scope This part of ISO 21069 describes a procedure that generates comparable measurement results in roller brake testing, such that the efficiency of the service braking system can be assessed reliably wherever the roller brake tests are per
18、formed. The following items are covered in this part of ISO 21069: symbols and definitions; test methods; test conditions; test equipment required; accuracy of test equipment; data recording and calculation needed; presentation of results; assessment criteria for pass/fail. The procedure described i
19、n this part of ISO 21069 is not applicable to passenger cars. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 braking force force between the tyre and the rotating roller, produced at the circumference of the tyre during braking, which oppose
20、s the force generated at that interface by the roller brake tester in order to cause a rotation of the wheel 2.2 braking force imbalance difference in the braking forces, measured with running wheels, between brakes on an axle NOTE Braking force imbalance is expressed as a percentage of the higher f
21、orce. BS ISO 21069-2:20082 2.3 braking force variation difference between the maximum and minimum values of the braking force, measured over a single wheel revolution with a constant actuation force NOTE Braking force variation is expressed as a percentage of the higher force. 2.4 roller brake teste
22、r measuring machine consisting of two pairs of powered rollers used for the assessment of a vehicles braking performance NOTE The assessment is made by measuring the braking force between tyres and drive rollers for each wheel/twin wheel, either simultaneously or independently, while the wheels of t
23、he vehicle axle are being driven and supported by rollers. 3 Symbols Table 1 General symbols Symbol Definition Unit FBiextrapolated braking forces at brake actuator pressure pA,ladiN BiFsum of all FBion all axles N FHibraking force at the circumference of tyres on axle i at brake actuator pressure p
24、A,HiN Fibraking force at the circumference of tyres on axle i N FLibraking force at the circumference of tyres on axle i at brake actuator pressure pA,LiN FMtotal normal static reaction of road surface on all wheels of the individual motor vehicle, or corresponding to FiN FM,maxmaximum permissible F
25、MN FRtotal normal static reaction of road surface on all wheels of the individual trailer vehicle N FR,maxmaximum permissible normal static reaction of fully laden trailer vehicle N pAbrake actuator pressure kPa pA,Hihigh applicable brake actuator pressure on axle i kPa pA,ladidesign brake actuator
26、pressure of laden vehicle on axle i (for extrapolation purposes) kPa pA,Lilow brake actuator pressure on axle i kPRfratio at the braking force line Rpratio at the brake actuator pressure z braking rate zM,ladbraking rate of laden motor vehicle zR,ladbraking rate of laden trailer vehicle NOTE Subscri
27、pt i indicates axles 1, 2, 3, . n, respectively. BS ISO 21069-2:20083Table 2 Symbols specific to air over hydraulic (A/H) braking systems Symbol Definition Unit CFconversion factor A/H converter front CRconversion factor A/H converter rear pFpneumatic pressure at front axle Pa pHFhydraulic pressure
28、at front axle Pa pHRhydraulic pressure at rear axle Pa pRpneumatic pressure at rear axle Pa pRATIOpressure attenuation ratio of load-conscious valve Pa/axle load NOTE All measurements are made with the vehicle stationary. 4 Test conditions and evaluations 4.1 General The characteristics of roller br
29、ake testers shall be as specified in Annex A. The efficiency test for braking systems shall be carried out with reference to the following: legal requirements; data provided by the vehicle manufacturer; the instruction manual of the roller brake tester. 4.2 Preparation of vehicle and roller brake te
30、ster 4.2.1 Rollers and tyres shall be clean. 4.2.2 Tyre pressure shall be adjusted in accordance with the vehicle manufacturers recommendations. 4.2.3 Additional instrumentation may measure the static axle loading without the rollers running. 4.2.4 Braking testing, for the purposes of official vehic
31、le inspection, is to be carried out on a roller brake tester certified by the technical services. Vehicle data and the measured values shall be recorded in the forward direction. 4.3 Calculation and evaluation of test data 4.3.1 Braking efficiency calculation 4.3.1.1 General For air over hydraulic a
32、nd hydraulic braking systems, one of the major problems is to caculate the braking efficiency without using an external pressure transducer on the hydraulic brake system. There is an increased risk of leakages when measuring hydraulic systems, caused by connecting measurement devices. The braking te
33、st may be made in the fully laden state, or in a lightly laden condition at lower actuation pressures, on the assumption that braking forces increase predictably with increasing pressure. BS ISO 21069-2:20084 4.3.1.2 Provisions for air over hydraulic braking system For the front axle, if the air ove
34、r hydraulic (A/H) conversion factor (CF) supplying the hydraulic pressure is easily calculated from the measured air pressure (pF), then HF F Fp pC= (1) In this case, the calculation is similar to the other possible extrapolation methods. A prerequisite is a pneumatic measuring gauge before the A/H
35、converter. For the rear axle, the calculation is similar, but the function of load sensing valves needs to be taken into account. The characteristic of the load sensing/conscious valve shall be given in a graph or table, giving the pressure attenuation ratio against load input: HR R R RATIOppCp= (2)
36、 In this case, the axle load needs to be known or measured. The calculated hydraulic pressures, pHRand pHF, can be used as pAiis used in Equations (5) and (6). The actuator pressure and brake force shall be determined simultaneously and in real time. Extrapolation of brake output forces may be used
37、to predict the laden braking rate. This may be achieved by following one of the following extrapolation methods: a minimum of 30 % of the design brake actuator pressure shall be achieved by suitable loading, dead weight of the axle or by load simulation, or the distance between the measurement point
38、s (the first point at the beginning and the second at the cut-off point) shall be as large as possible in order to ensure the correct gradient of the function of the graph (pressure versus force). NOTE If it is prescribed in the relevant national requirements, the rolling resistance can be treated a
39、ccordingly. A plan of an air over hydraulic braking system is given in Figure 1. 4.3.1.3 Provisions for purely hydraulic braking system For hydraulic braking systems, it is recommended only to proceed with the test with fully laden conditions. For partly laden conditions, a load simulation is highly
40、 recommended. One possible indication for the gradation of brake forces can also be a measurement of pedal forces with special measurement equipment which is suitable for this purpose. This measurement should not be used for calculation. 4.3.2 Determination of braking force or braking rate The braki
41、ng force or, alternatively, the braking rate (maximum braking force/vertical wheel load) shall be determined for each wheel individually, or each axle individually. BS ISO 21069-2:20085Key 1 foot valve 2 A/H converter 3 axle load 4 rear 5 vehicle Figure 1 Air over hydraulic braking system plan 4.3.3
42、 Methods of determination 4.3.3.1 Laden measurement method The braking rate shall be determined directly by measuring the braking forces for the vehicle in the laden condition. The laden braking rate calculation requires no extrapolation, being simply calculated according to Equation (3) in the case
43、 of motor vehicles, and according to Equation (4) in the case of towed vehicles: M,ladM,maxiFzF=(3) R,ladR,maxiFzF=(4) 4.3.3.2 Two-point measurement method This method is only useful if the pneumatic/hydraulic converter function and the conversion factor are correctly known. In some cases, evaluatio
44、n using direct measurement of hydraulic pressure is needed to ensure that the conversion factor is calculated precisely. BS ISO 21069-2:20086 First, the braking force shall be measured at a low brake actuator pressure slightly above the threshold point at which braking force can be measured. The sec
45、ond (main) measurement shall be performed with the highest applicable braking forces, with the corresponding brake actuator pressure beneath the locking limit of the wheels. The measured braking forces at each axle shall be extrapolated to the minimum design pressure. For a correct calculation, at l
46、east 30 % of the design brake actuator pressure is achieved by suitable loading of the axle or simulation of load. The laden braking rate on axle i corresponds to zM,lador zR,lad, or is calculated according to Equation (5) or (6): ( )B H F A,lad A,Hiii i iFFRp p=+ (5) HLFA,H A,LiiiiiFFRpp=(6) 4.4 Pr
47、esentation of results 4.4.1 General information The test report shall contain the following general information: a) manufacturer or trade mark of the vehicle; b) vehicle category; c) vehicle model and tyre; d) vehicle identification number (VIN); e) number of axles; f) axle configuration (multi-axle
48、 assembly, bogie); g) maximum authorized total mass; h) maximum static axle load; i) service braking system. 4.4.2 Test results The test report shall contain the following data from the test results: a) measured braking force total; b) reference braking forces or braking rate; c) brake actuator pres
49、sure for each wheel/axle; d) control line pressure; e) braking force imbalance across each axle; f) braking force variation on each wheel/axle; BS ISO 21069-2:20087g) outline of roller brake tester; h) model; i) software version; j) serial number. NOTE 1 Test results are rated “successful” if the minimum prescribed service braking performance, as laid down in UNECE Regulation No. 13, Annex 4, 2.1.1 (for motor vehicles) or 3.1.2.1 (for trailers), can be justifiably predicted for the laden vehicle w
