Interpretation ID: aiam1495
Chief Engineer
American Snowblast Corporation
4695 Ironton Street
Denver
CO 80239;
Dear Mr. Massy: In response to your May 13, 1974, question whether Standard No. 121 *Air brake systems*, has been delayed one year for vehicles which have 'drive on the front axle and front axle load of 18,000 pounds or more,' I would like to summarize our recent amendment of the standard.; On May 14, 1974, we delayed the effective date of the standard for al trucks and buses until March 1, 1975. Thereafter, trucks manufactured before September 1, 1975, that have a front steerable axle with a GAWR of 16,000 pounds or more, or a front steerable drive axle, need not meet certain stopping distance requirements if their brakes meet the retardation formula and values found elsewhere in the standard. These vehicles must still stay in the 12-foot lane and, during service brake stops, their wheels must not lock-up except for antilock-controlled lock-up. After September 1, 1975, the standard applies in full to this category of trucks.; There have been several additional changes in the standard which woul affect your products. They were published May 17, 1974, in the *Federal Register* (39 FR 17750).; Yours truly, Richard B. Dyson, Assistant Chief Counsel