Interpretation ID: nht75-3.39

DATE: 09/10/75

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Duo-matic Importers LTD.

TITLE: FMVSS INTERPRETATION

TEXT: This responds to Duo-matic's August 19, 1975, question whether Standard No. 121, Air Brake Systems, applies to an air brake coupler device that connects air brake hoses from a truck to the trailer it tows.

The answer to your question is no. Paragraph S3 (Applicability) of Standard No. 121 states that the standard applies to trucks, buses, and trailers equipped with air brake systems (with some stated exceptions). The standard therefore applies only to vehicles, and does not apply to motor vehicle equipment such as the Duo-matic coupler device.

SINCERELY,

August 19, 1975

Richard B. Dyson Assistant Chief Council Office of the Chief Council Federal Highway Administration

Refer to: A: Your letter N-40-30(MIS) dated 6-3-75

B: Motor Vehicle Safety Standard #121 as amended S5.3.3 Brake Actuation Time. With attached amendments of 11-12-74, 1-7-75, 1-17-75, 3-4-75, 3-21-75, 3-26-75, 5-15-75, and 6-11-75.

C: Duo-Matic Double Quick Release Coupling for Semi-Trailers (452-803)

D: Duo-Matic Double Quick Release Coupling for Towing Trailers (452 802)

The question is if Reference B above applies to our Wabco Westinghouse Duo-Matic coupler, which replaces the Glad Hand coupling now in use.

Your interpretation would be very much appreciated. We have enclosed two copies each of references C & D.

H. Melvin Strand, President