Interpretation ID: aiam1855
8th Floor Mears Building
Scranton
PA;
Dear Mr. Laster: This responds to your March 19, 1975, question whether Standard No 121, *Air brake systems*, applies to an air-braked trailer which has a primary cargo-carrying surface that is 23 inches above the ground in the unloaded condition and has a rack-type structure which may be added to the trailer to permit carrying several boats.; I have enclosed an amendment of Standard No. 121 which excludes certai trailers from its requirements until September 1, 1976. From your description of the sides as easily removable, and from the enclosed illustration, it appears that the trailer in question qualifies as a heavy hauler trailer and would not be required to conform to Standard No. 121 until September 1, 1976.; Yours truly, Richard B. Dyson, Assistant Chief Counsel