ISO 16234 pdf download – Heavy commercial vehicles and buses一 Straight-ahead braking on surfaces with split coefficient of friction一Open-loop test method.
7.3.1 Tyres
The tyre conditions shall be In accordance with ISO 15037-2:2002.
7.3.2 Safety equipment
An anti-jack-knife device should be used when executing tests with heavy vehicle combinations. For vehicles
with a risk of rollover, outriggers should be used and reported in Annex A.
7.3.3 LoadIng conditions
Tests may be performed at the minimum, maximum or other loading conditions as specified in
ISO 15037-2:2002.
7.3.4 CondItion of thi brak.s
Prior to testing, the brakes of the test vehicle shal be burnished The method of burnishing the brakes shall be reported in Annex A.
The brakes of the test vehicle shall not be contaminated with foreign material.
NOTE If brake burmsSng or teslng are conducted on roads that have been treated Mlh salt or other materials for
melting i, dust from the dried malenal may be present In the brakes and may change mew frlctn properties
8 Test method
8.1 Condition and temperature of the brakes
The user shall identity an acceptable range for initial brake temperature. Prior to each individual run, the brakes shall be warmed up or allowed to cool as required such that the initial brake temperatures are within this range. The initial temperature of the brakes shall be reported in the General Data (Annex A).
NOTE Typical initial temperatures of disc brakes awe from 50’C to 200 C and for drum brakes from 50 C to 150 C
8.2 Initial driving conditions
The tnitial driving conditions for the test shall be driving straight ahead as specified in ISO 15037.2:2002 with the addition that the steering wheel be held fixed within ± 3 during the time Interval from t to 2’
For safety reasons, the first test runs should be conducted with an initial longitudinal velocity of 30 kmTh. The initial longitudinal velocity, i. of subsequent tests should be increased in increments of 10 kn,Th up to the maximum velocity of interest.
8.3 Performance of the braking procedure
The test track should be approadied in such a way that the border between high- and low-friction surfaces is located in the X.Z plane of synirnetry of the vehicle.
After reaching the initial driving conditions, the steering wheel shall be held fixed by the test driver or by a mechanical device, and the accelerator pedal shall be released and the brakes applied as quickly as possble to 100 % of full brakiig and maintained during the period of evaluation defied ii 8.4.4. For air brake systems, full braking corresponds to 100 % of the full stroke of the brake pedal, and for hydraulic brake systems full braking corresponds to 100 % of the brake-pedal force, i.e. no less than 500 N.
9.2 Validity criteria
9.2.1 Braking action
To ensure that the acceleration is achieved, the time between the time t and the time r, shall not exceed 0,2 a. Once the brake pedal has reached its maxrum position. it shall be held in that position for the remainder of the manoeuvre.
9.2.2 Split-p condItion
To correctly determine the characteristic values, it is necessary that the vehicle be in split-p condition throughout the period of evaluation, The transition of a front wheel to high-p is revealed by a clear increase in longitudinal deceleration; the transition of a rear wheel to low-p is revealed by a clear increase in yaw acceleration
9.3 TIme history
For every test run, time histories of the variables listed in CLause 6 shall be presented. Apart from their evaluation purposes, the time histories serve to monitor correct test performance and functioning of the transducers (see Figure 6.1, Annex B).
9.4 Characteristic values
9.4.1 General
For each set of Initial conditions, the characteristic values listed below shall be calculated and plotted. The mean values are obtained from llnew approximations of the time h,stones In the period of evaluatiort Three linear curve fits of these time histories shall be made. The method of curve fitting shall be reported. The correlation coefficient of each curve fit Is used as a quality measure.
ISO 16234 pdf download – Heavy commercial vehicles and buses一 Straight-ahead braking on surfaces with split coefficient of friction一Open-loop test method
