Interpretation ID: 17490.ztv

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

Re: Vehicle Headlamp Aiming Device

Dear Mr. Suzuki:

This is in response to your letter of March 6, 1998, asking for confirmation of the acceptability of Stanley's aiming adjustment mechanism under Standard No. 108.

This mechanism is intended for headlamps that will be used on vehicles manufactured on and after September 1, 1998. On all such vehicles, each headlamp equipped with a vehicle headlamp aiming device (VHAD) must be manufactured with its calibration permanently fixed by its manufacturer (S7.8.5.2(c)).

The Stanley headlighting system consists of two headlamps, each equipped with two single-filament light sources. The headlamp is designed to be visually/optically aimable. Reflectors for both bulbs are integrally molded so that one aiming mechanism is sufficient to aim both the lower and upper beams. The headlamp system will be installed on a vehicle with an automatic leveling system which has a range of vertical movement of +/-2.5 degrees.

The headlamps in question that are intended for use on vehicles manufactured before September 1, 1998, are equipped with two aiming bolts to facilitate manual aiming. Bolt A is used for horizontal aiming. Both Bolts A and B are used for vertical aiming. From the drawings on Attachment 2 to your letter, it is evident that any independent movement of Bolt B also affects horizontal aim because it causes rotation around an axis that is other than horizontal. You have informed us that, with respect to vehicles manufactured on and after September 1, 1998, Stanley intends to provide headlamps that comply with S7.8.5.2(c) either by removing the VHAD from Bolt A or by permanently fixing its calibration (Stanley has not yet made its choice). With either choice, "the range of vertical adjustment by bolt B with less than 0.76 degree horizontal aim deviation is +/- 1 degree." You explain that "the automatic leveling system supplements the manual aiming system and covers the maximum variation of vehicle pitch, which depends on loading and the actual movement during driving and may exceed +/- 1 degree." We want to point out that if only Bolt B is used to adjust the lamp vertically by more than 1 degree, horizontal misaim will exceed 0.76 degree. This will result in a noncompliance, unless, pursuant to S7.8.5.2(b)(3), an advisory label is placed adjacent to the mechanism and instructions to be inserted in the vehicle operator's manual indicating that both Bolts A and B must be used to adjust vertical aim.

Alternatively, Stanley could retain the horizontal VHAD function and permanently fix its calibration. Paragraph S7.8.5.3(b) states that "there shall be no adjustment of horizontal aim unless the headlamp is equipped with a horizontal VHAD." Since the movement of either Bolt A or Bolt B affects the horizontal aim, it is not possible to use the fixed horizontal aim approach of S7.8.5.3(b) while allowing independent movements of Bolts A and B for vertical aim. Therefore, use of this alternative would require the addition of a second VHAD. In Stanley's design, finding the factory setting for horizontal aim depends on the relationship between the settings of two adjustment bolts rather than, as in the usual design, the absolute position of a single independent adjustment bolt. It would be necessary to equip both bolts with horizontal VHAD indicators with a fixed calibration so that the factory horizontal aim could be restored during the process of vertical aim adjustment. For example, having the VHAD indicators of each bolt read the same number could indicate the proper relationship for factory horizontal aim. We believe that this interpretation is consistent with the interpretation provided you on this subject by Transport Canada.

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref:108
d.6/30/98