GB/T 37224-2018Drum brake linings for automobiles (English PDF)

1 Scope

China's national standard for automotive drum brake linings. It specifies the terms and definitions, the requirements, the test methods and the inspection rules. The drum brake has been displaced by the disc on front axles everywhere and on most rear axles, but it survives in commercial vehicles, on trailers and as a parking brake, and it does two things a disc does not. It is self-energising: the rotation of the drum drags the leading shoe harder against it, which multiplies the applied force and is why a drum needs less pedal effort or less servo. And it is enclosed, so it keeps out water and dirt and holds its parking brake force without the caliper mechanism a disc needs. Its weakness is heat, since the drum expands away from the shoes as it warms and the friction surface is buried where air cannot reach it. The lining's requirements therefore turn on how its friction coefficient holds as temperature rises, which is what fade means and what the test methods measure.

Foreword

NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA ICS 43.040.40 Q 69

# GB/T 37224-2018 # Drum brake linings for automobile

About this edition

GB/T 37224-2018 is the current edition. It was issued on 28 December 2018 and has been in force since 1 November 2019.

The interval between issue and effect is the transition period. It exists so that producers, laboratories and buyers can requalify products, revise procedures and use up documentation before the new text becomes the one that applies. The date on this page is the official one from the record of the Standardization Administration.

Classification and status

The GB/T prefix marks a recommended national standard. It is not, in itself, law: it becomes binding when a contract names it, when a regulation or a mandatory standard refers to it, or when a producer declares conformity with it. In practice that covers most of the cases in which it will be read — a purchase specification, an inspection agreement or a certification scheme.

How a Chinese national standard is set out

Chinese national standards are drafted to the rules of GB/T 1.1, which fixes the order in which a standard is set out. The document opens with a foreword recording the issuing bodies, the relationship to any previous edition and the technical committee responsible for it. Clause 1 is the scope. Clause 2 lists the normative references — the other standards that have to be applied together with this one, and without which its requirements cannot be met. Clause 3 gives the terms and definitions. The technical clauses follow: the requirements themselves, the test or measurement methods by which conformity is established, the inspection rules that say how a lot is sampled and judged, and, for a product standard, the provisions on marking, packaging, transport and storage. Annexes, normative or informative, come last.

GB/T 37224-2018 runs to 15 pages in the English translation. What is delivered is the complete document in that order: every clause, every table, every figure and every annex of the Chinese original, with the same numbering, so that a reference to a clause number in a contract or a test report points to the same place in both languages.

About this English translation

The English edition of GB/T 37224-2018 is a full translation of the official Chinese text, not a summary, an abstract or a machine rendering left unchecked. Clause and subclause numbers, table and figure numbers and annex letters are those of the original, because they are what a specification, a purchase order or a test report cites.

Technical terms are translated against the vocabulary standards of the same field, so that a term used in GB/T 37224-2018 reads the same way as in the other Chinese standards it is used beside. Where a term has an established English form in an ISO or IEC document on the same subject, that form is used; where China's term has no foreign counterpart, it is translated literally and the Chinese is kept alongside it rather than replaced by an approximation.

Quantities, units and symbols are carried over unchanged. Chinese standards use SI, so a value in the translation is the value in the original document, not a conversion, and a limit read from the English text is the limit that will be applied by a Chinese inspection body reading the Chinese one.

This page is compiled from the official publication record: the standard number and both titles, the issuing bodies, the dates of issue and effect. The requirements, limits, tables and test conditions are in the document itself.