This second edition cancels and replaces the first edition (ISO 7642:1983), of which certain values have been altered, the previous clause 8 deleted and references updated. Specifies test methods for type approval testing of the overrun brakes that relate to mechanically and hydraulically operated braking systems. Should therefore be used in connection with the pertinent regulation. It is recommended that the regulation is studied before application of this International Standard. ISO 7642 uses only SI units.