Interpretation ID: 7023
Head, Crash Avoidance Standards (ASFBE)
Road Safety and Motor Vehicle Regulation
Transport Canada
FAX: 613-998-1965
Dear Mr. White:
This responds to your FAX of February 18, 1992, to Richard Van Iderstine of this agency, who has asked this office to respond to your question 1.a.
That question is: "Is Koito correct in stating that FMVSS 108 does not require the 'O' point on IHAD (sic) indicators to be marked by the numeral '0'"? In the letter from Koito that you furnished, Koito had remarked that the requirement in S7.7.5.2(a)(1) and (2) of Standard No. 108 "to have a zero mark" did "not necessarily mean a mark of figure 'O', but may be just a reference mark."
Koito is incorrect. S7.7.5.2 On-vehicle aiming specifies requirements for Vehicle Headlamp Aiming Devices (VHADs). VHADs provide for headlamp aim inspection in both the vertical and horizontal axes. S7.7.5.2(a)(2) Horizontal aim states that "An 'O' mark shall be used to indicate alignment of the headlamps relative to the longitudinal axis of the vehicle." This clearly establishes the requirement for use of the figure "0" as the mark, and not use of a reference mark. You will note that S7.7.5.2(b) references setting the VHAD "at 'O' vertical and 'O' horizontal." This means at the "O" mark.
Both S7.7.5.2(a)(1) Vertical aim and (a)(2) reference the necessity to provide "an equal number of graduations from the 'O' position representing angular changes in the axis." These graduations are not required to be marked. The presence of the "O" mark will assist the person aiming the headlamp to ensure that the VHAD is set at the junction of the horizontal and vertical axes, rather than at one of adjacent, unmarked graduations.
Sincerely,
Paul Jackson Rice Chief Counsel
ref:109 d:3/5/92