Interpretation ID: nht72-2.12

DATE: 08/30/72

FROM: AUTHOR UNAVAILABLE; E. T. Driver; NHTSA

TO: Albert Hammerstein

TITLE: FMVSS INTERPRETATION

TEXT: Your Broadview, Illinois, Subsidiary recently forwarded to us a copy of your December 17, 1971, letter concerning aiming adjustment tests as specified in SAE Standard J580a. A search of our files does not reveal that your letter was previously received by this Office.

Specifically, your concern is the interpretation of a requirement which is specified in SAE J580a as follows:

"2. The mechanism, including the aiming adjustment, must be so designed as to prevent the unit from receding into the lamp body or housing when an inward pressure of 50 lb is exerted on the outer surface of the lens."

Our interpretation of the above requirement is that no visible receding of the sealed beam unit is permitted when the inward pressure is applied on the outer lens surface. Testing for compliance to the requirements of FMVSS No. 108, which references SAE J580a, is conducted on the basis of this interpretation.

In the upcoming Notice of Proposed Rule Making (NPRM) on FMVSS No. 108 (Docket 69-19), we are considering the feasibility of specifying more objective type requirements on this aspect of aiming adjustment tests for headlamps. You will no doubt be interested in commenting on the proposed requirements after issuance of the NPRM.