Interpretation ID: 2843o
Technical Administration Dept.
Koito Mfg. Co. Ltd.
Shizuoka Works
500, Kitawaki
Shimuzi--shi, Shizuoka-ken
JAPAN
Dear Mr. Iwase:
This is in reply to your letter of January 25, 1988, with respect to photometric values for stop lamps and taillamps on motorcycles, and the spacing required between them and turn signal lamps.
You have asked two questions with respect to two types of motorcycle rear lighting devices, which you call "Structure l" and "Structure 2". Although a single lamp located on the vertical centerline may be used to fulfill rear lighting requirements on motorcycles, each of your Structures features two bulbs, symmetrically placed on each side of the vertical centerline. Each Structure is a single lighting device, featuring a turn signal bulb at each extremity. In Structure l a chamber containing a tail/stop lamp bulb is directly inboard of the chamber containing a turn signal bulb. The two chambers on each side are separated by a central portion of the device which is decorative in nature. Unlike Structure l, Structure 2 is a three-chamber device, with separate chambers at each end for the turn signal bulbs, and a central chamber incorporating two tail/stop lamp bulbs.
With respect to each Structure and Motor Vehicle Safety Standard No. 108 you have asked:
"(a) When tail & stop lamp on either side is lighted individually, it shall be satisfied with the photometric values of lighted section '1' which are specified in Figure 11b of S4.1.1.11.
(b) When tail & stop lamp on both sides are lighted together, it shall be satisfied with the photometric values of lighted section '2' which are specified in figure 1b of S4.1.1.11."
Figure lb specifies the minimum and maximum allowable candlepower values for lighting devices with one, two, and three lighted sections. However, the number of lighted sections is calculated with respect to each lamp, not the total number of lighted sections used for a specific purpose, or lit at a given time. We consider Structure 1 to comprise two separate tail/stop lamps, each consisting of a single chamber. Similarly, Structure 2 incorporates a single tail/stop lamp consisting of a single chamber in which two bulbs are used. Therefore, for both Structures and for both (a) and (b) the lamp should be designed so that the single chambers meet the photometric values for single compartment lamps.
Your second question for each Structure is whether the specified minimum edge to edge separation distance between turn signals and tail/stop lamps is required. The answer is yes, and the separation distance you have depicted in your drawings appears to comply with this requirement.
Sincerely,
Erika Z. Jones Chief Counsel
ref:108 3/16/88