Interpretation ID: 7289
Robert Bosch GmbH
Dept K2/ELS 11
Postfach 13 42
D-4710 Reutlingen
Germany
FAX (49)7121-1792
Dear Herr Spingler:
This responds to your FAX of July 9, 1992, asking for a "quick answer" to your question regarding the aim of replaceable bulb headlamps.
Specifically, you ask whether the requirement of "a vertical aim range of +/-4 degrees and a horizontal aim range of +/- 2.5 degrees" means "that a headlamp has to meet both ranges in addition, i.e. 2.5 degrees horizontal at a full range of 4 degrees vertical and vice-versa?"
The requirements to which you refer are found in paragraphs S7.7.3 and S7.7.4 of Standard No. 108. Paragraph S7.7.3 requires in pertinent part that "When a headlamp system is tested in a laboratory, the range of its vertical aim shall be not less than +/- 4 degrees from the nominal correct aim position for the intended vehicle application." Paragraph S7.7.4 requires that "When a headlamp system is tested in a laboratory, the range of its horizontal aim shall be not less than 2.5 degrees from the nominal correct aim position for the intended vehicle application."
We call your attention to paragraph S7.7.2.2. With respect to headlamps aimed by moving the reflector relative to the lens and headlamp housing, or vice versa, the paragraph requires conformance with respect to the applicable photometrics "with the lens at any position relative to the reflector within the aim range limits of paragraph S7.7.3 and S7.7.4 or any combination." This clearly indicates that when a replaceable bulb headlamp that is aimable as provided in S7.7.2.2 is adjusted to the extreme of its range, and at all positions in between, it must continue to meet all applicable photometrics. We interpret this requirement as also applying to headlamp systems of replaceable bulbs subject to S7.7.3 and S7.7.4, but aimable in a manner outside S7.7.2 (such as movement of the entire headlamp, rather than its lens or reflector).
I hope that this answers your question. Please note that under recent amendments to Standard No. 108, paragraphs S7.7.2.2, S7.7.3, and S7.7.4 have been renumbered respectively S7.8.2.2, S7.8.3, and S7.8.4.
Sincerely,
Paul Jackson Rice Chief Counsel
ref:108 d:8/3/92