ISO 14512 pdf download.Passenger cars — Straight-ahead braking on surfaces with split coefficient of friction — Open-loop test method
1 Scope
This International Standard describes an open-loop test method for determining vehicle reactions during a straight- line braking manoeuvre on a surface having a split coefficient of friction. It applies to passenger cars as defined in ISO 3833. The method is valid for all braking efforts up to full ABS operation for vehicles so equipped, or just up to the locking limit of the wheels on the high-friction surface for vehicles without ABS.
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 61 1 :1 994, Road vehicles — Braking of automotive vehicles and their trailers — Vocabulary . ISO 1 1 76:1 990, Road vehicles — Masses — Vocabulary and codes . ISO 3833:1 977, Road vehicles — Types — Terms and definitions . ISO 8855:1 991 , Road vehicles — Vehicle dynamics and road-holding ability — Vocabulary . ISO 1 5037-1 :1 998, Road vehicles — Vehicle dynamics test methods — Part 1 : General conditions for passenger cars.
3 Terms, definitions and symbols
3.1 Terms and definitions For the purposes of this International Standard, the terms and definitions given in ISO 61 1 and ISO 8855 apply. 3.2 Symbols For the purposes of this International Standard, the symbols given in Table 1 apply.
4 Principle
The objective of this test method is to determine the effects on course-holding and directional behaviour of a vehicle produced by a braking manoeuvre on a straightaway having a low coefficient of friction on one side. Test results are strongly influenced by friction coefficients as well as the difference in friction between the left and right side of the course. Other test track surface characteristics (roughness, ice or synthetic materials); which are not quantified by the friction coefficient alone, exert an important influence on the test results. For this reason, it is not possible to describe the surface conditions in a reproducible way. A large difference in the left- and right-side friction conditions is desirable and an interpretation of the test results is only useful in a comparison, for instance with a “reference-vehicle” used in the same test. The initial condition for the test is driving in a straight line at constant velocity. The position of the steering wheel and accelerator are held as steady as possible in the initial state. The steering wheel continues to be held fixed after the braking manoeuvre is initiated. During the test, the operating functions and vehicle responses are measured and recorded. Characteristic values are determined from the measured signals. The variables of motion used to describe the effect of braking on course holding and directional behaviour of the vehicle relate to the intermediate axis system X, Y, Z (see ISO 8855). The location of the origin of the vehicle axis system (X V , Y V , Z V ), being the reference point, is independent of the loading condition. It is fixed in the longitudinal plane of symmetry at half wheel base and at the same height above the ground as the centre of gravity of the vehicle at complete vehicle kerb mass (see ISO 1 1 76).