Interpretation ID: aiam2364
Chief Engineer
MOTAC Inc.
8400 East Slauson Ave.
Pico Rivera
CA 90660;
Dear Mr. Johnson: This responds to Motac's June 24, 1976, request to know why a traile with a flat cargo-carrying surface that is not more than 40 inches above the ground is considered a 'heavy hauler trailer' (as defined in Standard No. 121, *Air Brake Systems*), while a trailer with an inclined cargo-carrying surface that is more than 40 inches above the ground over the fifth wheel attachment point is not considered a heavy hauler trailer. You also request confirmation that the period for exclusion of heavy hauler trailers from the standard has been extended to September 1, 1977.; At the time that the 'heavy hauler trailer' exclusion was implemented the agency considered and rejected the addition of trailers with inclined beds to the excluded category. I have enclosed a copy of the notice that implemented the exclusion, which states 'The NHTSA has concluded that trailers with beds higher than 40 inches (including trailers whose beds are below 40 inches over the wheels but higher than 40 inches over the fifth wheel) can accommodate the new larger brake packages available at this time.' Of course, the exclusion was intended to and does apply to the traditional trailer with a gooseneck and a flat cargo-carrying surface that is not more than 40 inches above the ground. The 'double-drop semi', the 'stock drop frame flat-bed', and the '40 '-0' single axle drop frame platform semi' you describe appear to qualify as heavy hauler trailers.; I have enclosed a copy of the amendment of Standard No. 121 tha extends the date for exclusion of heavy hauler trailers to September 1, 1977.; Yours truly, Frank Berndt, Acting Chief Counsel