Overview
ISO 7642:1991 specifies inertia bench test methods for overrun (inertia) brakes fitted to caravans and light trailers of categories 01 and 02. This second edition replaces ISO 7642:1983 and provides standardized laboratory procedures for type-approval testing of both mechanically and hydraulically operated overrun braking systems. The standard uses only SI units and is intended to be applied together with the relevant regulatory framework (for example, UN/ECE Regulation No. 13 and its annexes, which are cited in the standard).
Key topics and requirements
- Scope and applicability: Type-approval bench tests for trailers in categories 01 (single-axle up to 0.75 t) and 02 (up to 3.5 t, excluding category 01).
- Test methods: Inertia bench procedures to measure brake torque as a function of control force (mechanical) or control pressure (hydraulic).
- Measured parameters: Brake torque curves, control forces/pressures, rotational speeds, and brake temperatures. Results are recorded and processed (regression methods) to determine required torque levels.
- Prescribed torque checkpoints: The standard defines torque reference points used in test sequences (expressed relative to vehicle weight and brake radius) to verify performance at multiple loading points.
- Cold and hot tests: Specified initial drum temperature ranges, run-in (rodage) procedures, hot-efficiency measurements immediately after controlled heating cycles, and cold-efficiency checks with repeatable starting conditions.
- Resistance/durability and post-test inspection: Procedures for higher-load resistance tests, followed by dismantling and inspection - no visible damage or deformation is permitted.
- Bench setup requirements: Inertia matching, determination of bench moments of inertia from manufacturer data, and frequency/rotation control to simulate road speeds.
- SI unit usage: All measurements and documentation use SI units only.
Practical applications and users
- Trailer and caravan manufacturers - to validate overrun brake designs for type approval.
- Test laboratories and certification bodies - to perform standardized inertia bench testing for homologation.
- Regulatory authorities - to reference consistent test procedures during approval and enforcement.
- Brake system designers and QA teams - to verify brake performance, durability and compliance with regulatory requirements.
Using ISO 7642 helps ensure reproducible, comparable brake performance data for overrun brakes and supports compliance with vehicle safety regulations.
Related standards
- UN/ECE Regulation No. 13 (brake performance and test methods) - referenced in ISO 7642 (annexes cited in the standard).
- Other ISO and national automotive test standards may be used in conjunction; always apply ISO 7642 together with the pertinent vehicle regulations for type approval.
Keywords: ISO 7642, inertia bench test, overrun brakes, caravans, light trailers, type approval, brake testing, ECE R13, hydraulic brakes, mechanical brakes, SI units.
Open preview (PDF)Caravans and light trailers — Trailers of categories 01 and 02 with overrun brakes — Inertia bench test methods for brakes
