Interpretation ID: nht76-4.22

DATE: 08/02/76

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: MOTAC Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This responds to Motac's June 24, 1976, request to know why a trailer 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 that extends the date for exclusion of heavy hauler trailers to September 1, 1977.

Yours truly,

Enclosures

ATTACH.

June 24, 1976

Frank Berndt -- Acting Chief Counsel, DEPT. OF TRANSPORTATION

Subject: Clarification regarding installation of FMVSS-121 brakes on "Low Bed Heavy Hauler Trailers."

Dear Sir,

We would appreciate further clarification if FMVSS-121 brakes are required or are exempt on the Drop Frame Platform Semi-Trailer per our attached drawing SK-7229-W3. This Drop Frame Platform Semi-Trailer is also made with Tandem axles and a platform height of 39".

In accordance with my letter of Aug. 7, 1975 addressed to Mr. James B. Gregory and his reply "N40-30 of Sept. 8, 1975 (copies attached) I interpret that this type of trailer is exempt from the S-121 brakes as it complies to the definition of a Low Platform Heavy Hauler Trailer."

We also received from T.T.M.A., a copy of your letter, file No. N40-30 RFBPI (copies attached) with two sketches of similar type trailers, stating that they do not qualify for exemption of the S-121 brake system.

Since the greater majority of the load is carried on the main deck, which I interpret as the "Primary Cargo Carrying Surface" and only a small portion of the load can be carried on the gooseneck platform, I analyze that this complies with your definition of Low Platform Heavy Hauler Trailers.

Also please advise if your Docket No. 75-16, Notice 5 has become effective to extend the installation of the S-121 brake system on Heavy Hauler Trailers until Sept. 1, 1977 as I do not have a confirming copy in my files.

Yours very truly,

Jack A. Johnson -- Chief Engineer, MOTAC, INC.

Enc.