Interpretation ID: aiam2799
Director
Bureau of Transportation
Room 4201
City Hall
Los Angeles
CA 90012;
Dear Mr. Purko: This responds to your March 10, 1978, question whether Standard No 121, *Air Brake Systems*, applies to a device that automatically applies to (sic) vehicle's service brakes when a sensing bumper mounted at the rear of the vehicle is tripped by contact with an object during backing maneuver. For purposes of your question, I assume that the vehicle, whether new or used, has been certified to comply with Standard No. 121 prior to installation of the device.; The answer to your question is no. Paragraph S3 (Applicability) o Standard No. 121 states that the standard applies to trucks, buses, and trailers equipped with air brake systems (with some specified exceptions). The standard therefore applies only to vehicles, and does not apply to motor vehicle equipment such as the braking actuator you describe. The vehicle must, of course, conform to Standard No. 121 following installation of the device, if the installation occurs prior to the first purchase in good faith for purposes other than resale.; After the first retail sale, S108(a)(2)(A) of the National Traffic an Motor Vehicle Safety Act (the Act) (15 U.S.C. S1397(a)(2)(A)) prohibits, with one exception, manufacturers, distributors, dealers, and repair businesses from knowingly rendering inoperative devices or elements of design installed in satisfaction on a safety standard such as Standard No. 121.; Sincerely, Joseph J. Levin, Jr., Chief Counsel