The handbook is intended for use by drivers of tractor-trailers equipped with the new braking systems brought about by Federal Motor Vehicle Safety Standard (FMVSS) 121. The computer-controlled antilock feature of the new brake system frees the driver from the necessity to pump the brakes while making a sudden stop; the new system feels more aggressive to the user. Other new features of these truck brakes include larger size, new front axles, dual air systems with many plumbing changes and new valving, as well as changes in air reservoirs, wheels, drums, and axles. The red monitor light signals low air, and the yellow light indicates that the antilock feature has been lost. The new brakes help reduce the chance of jackknifing that is caused by wheel lock-up in braking situations. Quick-check procedures to be followed before driving are described, and maintenance guidelines are given. Only linings recommended by the maker of the truck, tractor, or trailer should be used; only linings specifically mentioned as being compatible with 121 brakes should be used, and 121 components should never be mixed with non-121 components. Test kits are available for checking antilock brakes.

  • Corporate Authors:

    Heavy Duty Trucking

    Box W
    Newport Beach, CA  United States  92663
  • Publication Date: 0

Media Info

  • Pagination: 24 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00399207
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: HS-025 728U
  • Files: HSL, USDOT
  • Created Date: Oct 31 1985 12:00AM