GB/T 22311-2023Road vehicles - Brake linings - Compressive strain test method (English PDF)

Foreword

This document was issued on 28 December 2023 by the State Administration for Market Regulation; Standardization Administration of the PRC and takes effect on 1 July 2024.

It is a GB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

1 Scope

GB/T 22311-2023 covers how much a brake lining squashes under load and how that is measured — the symbols used; the principle, with method A measuring the compressive strain of a friction material sample and a further test method alongside it; the test equipment, built around a compressibility bench or a uniaxial load frame that loads the sample surface evenly; the technical requirements for the device, including the tabulated maximum contact pressure and loading rate for each method; the preparation of samples; the test methods themselves; the deflection compensation, in which the apparent movement of the machine is subtracted from the total movement so that only the sample's deformation is reported; the periodic verification of the equipment against reference samples such as calibrated springs or dynamometers; and the test report, with a form in Appendix A. A lining that compresses too much swallows pedal travel and gives a long, soft pedal, while one that is too stiff makes the brake harsh and noisy; and because a compliant machine deforms alongside the sample, an uncompensated bench reports the wrong figure and comparisons between suppliers collapse. Written for friction material manufacturers, brake and vehicle makers, and testing laboratories.

This document specifies the principle, test equipment, technical requirements for test

equipment, sample preparation, test methods, deflection compensation of test

equipment, verification of test equipment using reference samples and test report for

the compressive strain test method of brake linings of road vehicles.

This document applies to the measurement of compressive strain of cut samples of

brake lining disc brake pad assemblies, disc or drum friction materials.

2 Normative references

The following documents are referred to in the text in such a way that some or all of

their content constitutes requirements of this document. For dated references, only the

edition cited applies. for undated references, the latest edition of the referenced

document (including any amendments) applies.

GB/T 5620, Road vehicles - Vocabulary and definition for braking of automotive

vehicles and their trailers

3 Terms and definitions

Terms and definitions determined by GB/T 5620, as well as the following, are

applicable to this document.

3.1

compressibility

Change of thickness or deflection of the lining caused by uniaxial compressive load in

the direction same as the compressive force and perpendicular to the friction surface,

when the maximum test pressure is reached in the last loading cycle.

3.2

compressive strain