Interpretation ID: 18462.ztv

Mr. Tadashi Suzuki
Manager
Automotive Equipment
Legal & Homologation Sect.
Stanley Electric Co., Ltd.
2-9-13, Nakameguro, Meguro-ku
Tokyo 153-8636, Japan

Re: Motorcycle stop and taillamp arrangement

Dear Mr. Suzuki:

This is in reply to your letter of July 22, 1998, asking for our advice on a motorcycle stop and taillamp system that Stanley Electric Co. Ltd. is developing.

Stanley presents two hypothetical rear lamp arrangements for which it seeks an opinion on how it should decide the number of lighted sections that should be grouped for the purpose of determining photometric compliance, that is, "whether all the lighted sections of the same function (tail or stop lamp) installed on both sides should be grouped, or the lighted sections installed on each side should be grouped." Specifically, "we would like to have your advice how we should consider the number of the lamp (one lamp with four or six lighted sections spread over the rear side of the vehicle or two lamps with two or three lighted sections on each side) in such cases."

Table IV of Standard No. 108 requires a motorcycle to have one stop lamp and one taillamp but permits it to have two stop lamps and two taillamps symmetrically disposed about the vertical centerline. The stop lamps must meet the requirements of SAE Standard J586 February 1984, and the taillamps, those of SAE Standard J585e September 1977. Neither of these standards differentiate between lamps for motorcycles and lamps for other types of motor vehicles. Therefore, compliance with the photometric requirements of the two SAE standards is determined in the same manner for all motor vehicles equipped with stop lamps and taillamps.

Table 1 of each SAE Standard establishes photometric requirements for lamps with one, two, and three lighted sections. Footnote 3 to Table 1 of SAE J585e and Footnote d to Table 1 of SAE J586 refer to a "multiple device" lamp which "gives its indication by two or more separately lighted sections which may be separate lamps." The photometric values "are to apply when all sections" which provide the signal are considered as a unit except when the dimensions between optical centers exceed 560 mm for two-compartment lamps or lamp arrangements, and does not exceed 410 mm for three-compartment lamps or lamp arrangements.

Type 1 depicts a system of six combination stop/taillamps. Two lamps are mounted on each side of the motorcycle and a third lamp is mounted below the two lamps. The distance between optical centers of the innermost upper lamp and the lower tail/stop lamp is 390 mm. The distance between the optical centers of the outermost and innermost upper lamps is not specified but is less than 390 mm. The distance in optical centers between the outermost upper lamp and the lower tail/stop lamp on each side is not specified but, if the drawing is to scale, it appears to be 390 mm.

In the Type 1 arrangement, the optical centers between the innermost upper lamp and the lower stop/taillamp on each side of the motorcycle, or between the innermost upper lamps on each side of the motorcycle, are 390 mm apart. Thus, each pair comprises "multiple devices" whose photometric requirements are those that apply to single lamps with two lighted sections. However, because more than two sections exist (three or six) in this design, one must determine whether there is more than 410 mm between optical centers. The drawing indicates that the optical centers of the three combination lamps are all within 410 mm of each other. Thus, Stanley can group three lamps on each side as a single three-compartment lamp.

The drawing also shows that the distance between optical centers of the innermost upper combination lamps on either side of the motorcycle is 390 mm. However, no dimension is given for the distance between the optical centers of either of the two upper lamps on one side of the motorcycle and the lower lamp on the other side, or for the distance between the optical center of the lower combination lamps on each side of the motorcycle. If the distance is not more than 410 mm between the optical centers of any of the six lamps, Standard No. 108 permits this arrangement to be considered a single lamp with more than three compartments.

Type 2 depicts a system with two combination tail/stop lamps mounted vertically adjacent to each other on each side of the vehicle. The distance between the optical centers of the upper lamps on each side of the vehicle is 520 mm. The distance between the optical centers of the lower lamps in the two-lamp array on each side of the vehicle is not stated but appears to be at least 520 mm. Type 2 also depicts a lower mounted stop lamp whose optical center is 340 mm from the optical center of the lower combination tail/stop lamp on the same side (the distance to the optical center of the upper lamp is not stated but is less than 560 mm). The distance between the optical center of the lower stop lamps on each side is unstated, as is the distance between the optical center of the lower stop lamp on one side of the motorcycle, and the optical centers of the two combination tail/stop lamps on the other side of the vehicle. However, the distance appears to be more than 560 mm.

In the Type 2 arrangement, the two combination tail/stop lamps on either side can be considered a taillamp with two compartments, but because the optical centers of the taillamps on the right and left are greater than 410 mm apart, the four lamps do not constitute a single lamp that comprises more than three compartments. Similarly, the three stop lamps on either side can constitute a single three-compartment lamp. However, the optical centers of some of the six stop lamps are greater than 410 mm apart and this array cannot be considered a single lamp with more than three compartments.

We note that your questions pertain to the use of "all the lighted sections of the same function" in each Type and therefore we have not addressed how photometrics might be measured when less than all lighted sections of the same function are used for compliance purposes (e.g., use of the upper pairs of stop lamps in Type 2).

We hope that this explanation is responsive to your request.

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:108
d.11/20/98