Interpretation ID: 17382.ztv

Tadashi Suzuki, Manager
Automotive Equipment
Legal & Homologation Sect.
Stanley Electric Co., Ltd.
2-9-13, Nakameguro, Meguro-ku
Tokyo 153,
Japan

Re: Motorcycle Headlamp Arrangement

Dear Mr. Suzuki:

This is in reply to your letter of February 17, 1998, asking for confirmation of your interpretation of the motorcycle headlamp requirements of Federal Motor Vehicle Safety Standard No. 108.

Stanley is considering developing a two-lamp motorcycle headlamp system, each of which contains an upper beam and a lower beam light source. The upper beam would be provided by the upper light source or by both light sources. The lower beam would be provided by the lower light source. The upper light source is outboard of the lower light source. You believe that this would be an acceptable arrangement because we have previously said that two headlamps with HB2 bulbs were acceptable if mounted symmetrically about the vehicle's vertical centerline.

Stanley's arrangement is permitted by Standard No. 108. Since Stanley is currently developing this system, however, we would prefer that the lower beam be provided by the upper light source, although this is not a requirement of Standard No. 108. This rearrangement of light sources would make Stanley's new system consistent with the two lamp motorcycle headlamp system permitted by S7.9.1(b) which requires a motorcycle headlighting system using half of a passenger car headlighting system to mount the lower beam as high as practicable. This is also consistent with requirements for two-lamp headlamp systems on other motor vehicles in which the lower beam is to be provided by the most outboard light source (or by all light sources) and the upper beam by the most inboard one(see S7.4(b). The reason for these specifications is that the lower beam will provide greater seeing distance at a higher and more outboard mounting location.

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:108
d.6/3/98