Interpretation ID: 1985-04.40

TYPE: INTERPRETATION-NHTSA

DATE: 11/29/85

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: Mr. M. Iwase

TITLE: FMVSS INTERPRETATION

TEXT:

November 29, 1985 Mr. M. Iwase Manager, Technical Administration Dept. Koito Manufacturing Co., Ltd. Shizuoka Works 500, Kitawaki Shimizu-shi, Shizuoka-ken Japan Dear Mr. Iwase: This is in reply to your letter of September 20, 1985, to the former Chief Counsel of this agency, Frank Berndt, asking for a clarification of requirements for motorcycles equipped with two headlamps. You have informed us that your two-headlamp design complies with the photometric requirements of Motor Vehicle Safety Standard No. 108 (i.e., the at focus and out of focus tests of SAE J584) when the photometric measurements are made with reference to the photometric reference to the photometric reference axis of the individual headlamp unit. However, if this measurement is made at the combined axis, the combined maximum value of the upper beam will exceed 75,000 candela. Photometric measurements are to be made with reference to the photometric reference axis of the individual headlamp unit. Under Standard No. 108, however, the maximum candlepower of each unit on the upper beam is not to exceed 75,000. The fact that the combined maximum value of your system exceeds 75,000 candlepower. However, if the motorcycle headlamp is one consisting of two bulbs in a single housing, then the measurement is made at the combined axis of the two bulbs and the combined candlepower of this two-bulb single headlamp cannot exceed 75,000 candlepower. I hope that this answers your question. Sincerely, Original Signed By Erika Z. Jones Chief Counsel