This report presents analyses, findings and recommendations concerning the brake adjustment criteria of the North American Uniform Driver-Vehicle Inspection Criteria for heavy trucks. The study involved interviews with Motor Carrier Safety Assistance Program (MCSAP) inspectors, mechanical analyses of the influence of brake adjustment on stopping capability, statistical analyses of brake inspection data, combined statistical and mechanical analyses of the current brake adjustment criteria, and development of a procedure for estimating or predicting brake adjustment intervals. The key statistical results are derived primarily from a set of 2,146 brake inspections performed by the National Transportation Safety Board. The data indicate 936 of the 2,146 vehicles (with S-cam brakes) were placed out of service for brake adjustment. Of the 936 vehicles placed out of service, 480 vehicles had braking capability that was greater than 80% of what the braking capability would have been if the brakes were fully adjusted. These 480 vehicles represent "false positive" cases. The study presents recommendations for changes to the brake adjustment criteria in order to reduce the percentage of "false positives" during roadside inspections and a procedure motor carriers can use to estimate brake adjustment intervals.

  • Corporate Authors:

    University of Michigan Transportation Research Institute

    2901 Baxter Road
    Ann Arbor, MI  United States  48109-2150

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Fancher, P
    • Bareket, Z
    • Blower, D
    • Mink, C
    • Campbell, K
  • Publication Date: 1993-8


  • English

Media Info

  • Pagination: 249 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00675270
  • Record Type: Publication
  • Source Agency: University of Michigan Transportation Research Institute
  • Report/Paper Numbers: UMTRI-93-15, FHWA-MC-93-014
  • Contract Numbers: DTFH61-89-C-01006
  • Files: TRIS, USDOT
  • Created Date: Mar 14 1995 12:00AM