Elevator Brake Shoes
Asbestos in Elevator Brake Shoes
Although they operate differently than automotive brakes, the fundamental principle behind elevator brakes is the same; a pair of brake shoes grips a cable or rod, slowing the motion of the car. Like their automotive counterparts, elevator brake shoes must be lined with some type of friction material. Since the physics of an elevator's motion is somewhat different than that of an automobile however, the friction material must be chosen with care; if the material is too efficient, the motion of the car will be uneven, but if it is not efficient enough, the brake may fail altogether.
The best solution for many years was an elevator brake shoe lining made from asbestos bonded with zinc. Elevator brake shoes made with asbestos were subject to wear, resulting in the asbestos becoming friable. In this state, asbestos fibers are released into the environment, where they were readily inhaled by maintenance workers. Precautions such as respirators were not used, as there was no perceived need at the time.
Hazards Associated with Elevator Brake Shoe Products
Elevator repairmen were the people at most risk from asbestos in elevator brake shoes, along with the workers in factories producing the shoes themselves. As asbestos risk was not fully understood, for many decades workers would repair and replace old shoes with worn and brittle asbestos fibers without using any form of respiratory protection. There was a risk of secondary asbestos exposure as these workers would take their contaminated work clothes home for laundering, and family members could easily be exposed as well when this happened.Sources
Bowker, Michael. Fatal Deception: The Untold Story of Asbestos (New York: Touchstone, 2003)
Salzman, Rhonda. "How An Elevator Works." Reports on How Things Work.
http://web.mit.edu/2.972/www/reports/elevator/elevator.html. Retrieved 3 January 2011.