Improved Service Life of Urban Transit Coach Brakes

摘要

The program was concerned with finding the causes and evaluating pragmatic solutions for observed instances of reduced brake lining wear life in newly designed Advanced Design Buses (ADB). Based on a survey of six transit authorities, ADB's exhibited an average lining life of 22,000 miles, compared with 40,000 miles exhibited by the older 'New Look' buses designed by General Motors. In-service experiments showed that the average drum temperature of the GM RTS-ADB was slightly higher (50F) than the drum temperature of the GM 'New Look' bus. The increase was determined to be sufficient to initiate higher wear rates in the asbestos-phenolic friction materials. Techniques for lowering the drum temperature in the ADB's were designed and evaluated in service. Electrical blower units reduced brake drum temperatures by an amount sufficient to cool the brake drums, but the technique was only marginally economical. The most economical solution appears to be the use of brake lining materials having better temperature-wear properties.