Interpretation ID: nht78-2.43

DATE: 04/13/78

FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA

TO: E. A. Santiago

TITLE: FMVSS INTERPRETATION

TEXT: This responds to Raycor Industries' March 13, 1978, question whether Standard No. 121, Air Brake Systems, applies to an air dryer that is installed in the air brake system of trucks that must comply with the standard.

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 specified exceptions). The standard therefore applies only to vehicles, and does not apply to motor vehicle equipment such as the Raycor air dryer unit. The vehicles in question must, of course, conform to Standard No. 121 following installation of the device, if the installation occurs prior to the first purchase in good faith for purposes other than resale.

A copy of Standard No. 121 is enclosed for your information.