WHY AN AIR DISC BRAKE?

A ten-year investigation of commercial vehicle disc brakes indicates that potential revenue gain due to reduced truck weight with air disc brakes is illusionary. Initial cost, service cost, service parts availability, need for high skill service labor, and extreme mechanical wear susceptibility as well as lining wear negate any savings from using air disc brakes instead of cam brakes. Air disc brakes presently provide no real improvement in overall performance or safety. With time, brake output consistency decreases and "feel" suffers. The ability of the brake to provide good life under extreme operating conditions with minimum mechanical service is doubtful. "Looseness" necessary to preclude caliper bind results in taper lining wear, and energy load transfer between dissimilar brakes on a tractor-trailer can also produce excessive wear. The apparent fade resistance of disc brakes can be a safety hazard due to sudden, unexpected brake failure. Brake type intermix aggravates this situation and also adversely affects rig stability. Air disc brakes are not currently suitable for general use because of their relatively high initial and long-term cost and marginal performance and wearability.

• Supplemental Notes:
  • Presented at the SAE Truck Meeting, Fort Wayne, Indiana, 5-8 November 1979. Also published in HS-030 384 (SAE-SP-466), "Why an Air Disc Brake for Heavy Trucks?", Warrendale, Pennsylvania, 1980, pp 5-6.
• Corporate Authors:

  Society of Automotive Engineers (SAE)

  400 Commonwealth Drive
  Warrendale, PA  United States  15096
• Authors:
  • Bueler, R C
• Publication Date: 1980

Media Info

• Pagination: 2 p.

Subject/Index Terms

• TRT Terms: Air brakes; Brakes; Braking performance; Disc brakes; Performance evaluations; Safety; Trucks; Wear
• Old TRIS Terms: Brake fade; Truck brakes
• Subject Areas: Motor Carriers; Safety and Human Factors; Vehicles and Equipment;

Filing Info

• Accession Number: 00380919
• Record Type: Publication
• Source Agency: National Highway Traffic Safety Administration
• Report/Paper Numbers: HS-030 386
• Files: HSL, USDOT
• Created Date: Jan 30 1984 12:00AM