Warning device for critical wear in vehicle drum or disc brake lining - detects critical state as opening to atmosphere of normally closed pipe protruding into lining material

摘要

The warning device contains a signal generator (5/13) operated by a pressure medium with a pressure chamber (4) subjected to reduced pressure via one line (3) during motion of the vehicle and/or whilst the engine is running. A second line (15) connects it to a closed tube (17) protruding into the lining material (18). When critical wear is reached the pipe is opened to the atmosphere. The second line opens into the first line rather than into the pressure chamber. A replaceable microfilter (22) is arranged in the first line behind the opening of the second line when viewed from the chamber. ADVANTAGE - Reliability and unambiguity of critical wear warning function are improved.