Brake Maintenance Procedure Case Study on Asbestos

Findings

Real-time data were collected on nine different operators performing brake maintenance on 10 vehicles. The general brake maintenance procedure was:

1) Remove the wheel's lug bolts and wheel;

2) Remove the brake drum;

3) Thoroughly wash the drum, brake shoes, and brake support plate;

4) Inspect the brake shoes; if they do not need replacing, reinstall the drum and wheel;

5) Remove brake shoes needing replacement;

6) Install the new brake shoes and brake drum, remount the wheel, and tighten the lug bolts.

To interpret the real-time data, the instrument background level (the internal noise level of the Apple/HAM combination was 0.05 millivolts) was used as the reference level. Asbestos values above this level were used to identify dust sources and determine their magnitude.

Brief elevations of dust were detected during the removal of the lug bolts and the drum, and during the reinstallation of the lug bolts.