Interpretation ID: nht72-2.25

DATE: 03/03/72

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

TO: Koito Manufacturing Company, Ltd.

TITLE: FMVSS INTERPRETATION

TEXT: This replies to your letters of January 27, February 8 and February 9, 1972, to the National Highway Traffic Safety Administration, regarding questions on headlamp mounting requirements of Federal Motor Vehicle Safety Standard No. 108.

The following comments relate to the specific questions in the letters of each date.

Question 1 - January 27, 1972

The Federal Motor Vehicle Safety Standard No. 108 and referenced SAE standards do not preclude the headlamp aiming adjustment by direct sliding contact of the headlamp back (Illegible Word) to the housing.

We're concerned however that headlamps of different manufacturers may not always (Illegible Words) properly in such an arrangement because of non-specific dimensional requirements of SAE J571 for the headlamp back envelope. Also in this arrangement pressure is applied to areas of the headlamp not designed for such mechanical pressures. This may result in a high incidence of lamp breakage particularly with some of the "thin walled" lamps.

Question 2 - January 27, 1972

The arrangement of the headlamp mounting ring as shown on Figure 3. conforms to the requirements of Federal Motor Vehicle Safety Standard No. 108.

Question 3 - January 27, 1972

The arrangement of the headlamp mounting ring as shown on Figure 4 conforms to the requirements of Federal Motor Vehicle Safety Standard No. 108.

Question 4 - January 27, 1972

The arrangement of the headlamp mounting ring as shown on Figure 5 conforms to the requirements of Federal Motor Vehicle Safety Standard No. 108.

Your letter of February 8, 1972, relates to the request of January 27 1972, and is therefore answered by the above comments.

The question in your letter of February 9, 1972, relates to a modification of the headlamp (Illegible Words) as described under question 1 in your letter of January 27, 1972, whereby you propose a single locating lug match in the headlamp retaining ring. The requirements of Federal Motor Vehicle Safety Standard No. 108 are for three-lug indexing. The retaining ring-housing as shown on Appendix - I of your letter of February 9, 1972, does not, therefore, conform to Federal Motor Vehicle Safety Standard No. 108.

This Administration has been concerned about problems of accurate headlamp aim and aim retention capabilities, and currently has a research contract titled "Stability of Headlamp Aim" contract DOT-HS-024-1-202 scheduled for completion in July 1972. In general one of the problem areas seems to relate to insufficient strength and life of headlamp aim and retention mechanisms, along with (Illegible Word) that cause field service problems by shifting or actually falling out when replacement of the headlamp is attempted. If you desire, you may contact Mr. Roger Benion of the Southeast Research Institute, (Illegible Words) Road, San Antonio, Texas, 73284, who manages our stability of headlamp Aid contract, for additional technical contracts on your proposed headlamp aiming mechanism.

We have enclosed a copy of report DOT-HS-(Illegible Words) on "Vehicle Forward Lighting Performance and Inspection Requirements" which includes preliminary research information on headlamp aim.