Interpretation ID: aiam3870
Chief Inspector
Internationally Agreed Safety Division
International Trade & Industry Inspection Institute
Ministry of International Trade & Industry
Japanese Government
15-1 6 Chome Ginza Chuo-ku
Tokyo
Japan;
Dear Mr. Kasagi: This is in reply to your letter of November 13, 1984, with respect t interpretations of the motorcycle headlighting requirements of Federal Motor Vehicle Safety Standard No. 108, and SAE J584.; You have asked 'whether other lighting systems than referred i S4.1.1.34, such as non-sealed beam head lamp with two bulbs, are acceptable or not.' The answer is yes. Non-sealed lamps meeting the requirements of SAE J584 are acceptable, including those with two bulbs, as the 'At- Focus Tests' paragraph of J584 is directed to 'light source or sources.'; Your next question is whether photometric compliance is judged when on light is on or two, including the maximum permissible output of 75,000 cd. The answer to this question depends on the design of the lamp, if it is designed so that both bulbs operate simultaneously, then photometrics including maximum output are determined with both bulbs operating. If the design is such that one bulb produces lower beam and the other the upper beam, then compliance is judged by that method of operation. Should one bulb produce both lower and upper beams and the other bulb perform an unregulated lighting function, then the photometric compliance would be judged with only the bulb used for the regulated function. In this case, however, the unregulated bulb must not interfere with the effectiveness of the headlamp. This also answers your final question about conduct of the out-of-focus test. It is to be conducted according to the design intent of the operation of the headlamp, i.e. the design function of each bulb or bulbs.; You have also asked about the geometrical center of a design when on of two bulbs (both with an upper beam and a lower beam filament apparently) is on. Operation of only one bulb alone would result in an assymetrical lighting display off the vehicle's centerline. This is permitted by S4.1.1.34 of Standard No. 108 for the sealed beam lighting systems specified therein. Therefore, we could not logically dissapprove (sic) of it for unsealed headlighting systems. However, if only one bulb performed both the lower beam function and the upper beam, and the other bulb performed an unregulated lighting function, then the bulb providing the lower/upper beams must be located on the vehicle's vertical centerline.; If you have any further questions, we shall be happy to answer them. Sincerely, Frank Berndt, Chief Counsel