Brake lining wear detector

摘要

On a brake shoe (20), mounted is an abrasion detection head (10) which includes a closed-end chamber. This closed front end is opened by abrasion with a brake drum (25) during the actuation of the brake if the wear of lining (23) reaches a critical abrasion point (23L). A pneumatic pressure is provided in the closed-end chamber of the abrasion detection head (10) from a pneumatic pressure supply circuit (30), which includes an orifice (32). Furthermore, a pressure switch (41), which detects a decrease in the pneumatic pressure of the closed-end chamber, is provided on a branch line (35) of the pneumatic pressure supply circuit (30). When the front end of the abrasion detection head (10) is worn and torn, the line pressure decreases. The pressure switch (41) detects this pressure decrease, and an alarming device (50) takes a warning action such as lighting a warning lamp (52). <IMAGE> <IMAGE>