Interpretation ID: nht74-2.37

DATE: APRIL 26, 1974

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: Granning Suspensions Inc.

TITLE: FMVSR INTERPRETATION

TEXT: This responds to your March 21, 1974, request for an explanation of your certification responsibilities under the National Traffic and Motor Vehicle Safety Act of 1966 as a manufacturer of liftable and "additional" axles which are installed on completed vehicles by an independent truck equipment dealer or, in some cases, by the vehicle manufacturer at the factory.

Your responsibilities under Standard 121, Air brake systems, are largely the same as your responsibility for certification of the GAWR of an axle under 49 CFR Part 567, although somewhat more complicated. It is the responsibility of the vehicle manufacturer to certify compliance with Standard 121 (49 CFR Part 567.4), and if the completed vehicle is altered, it is the responsibility of the vehicle alterer (49 CFR Part 567.7). The addition of an axle will change the GAWR-GVWR and the brake performance of the altered vehicle and will require recertification by the dealer who undertakes alteration.

A dealer is normally not equipped to recertify an altered vehicle, except on the basis of certification information supplied to him by the manufacturer of the component that is being added. A component manufacturer like yourself might issue a performance guaranty which relies on the information that is supplied to him by the manufacturer of the basic parts (e.g. brakes, axles in your case) and which is conditioned on the observance of certain limits on installation. For instance, the reservoir volume requirement (S5.1.2.1) might be exceeded if the liftable axle manufacturer did not qualify his information by stating that a certain tank volume must be provided to serve the air chambers on his axle system. Another qualification could refer to brake actuation and release time as complying only if it did not reduce the brake actuation and release timing of the vehicle as a whole. The effect of your axle on each of the requirements would have to be determined.

We do not require certification of the axle by you as its manufacturer.