Interpretation ID: nht76-1.1

DATE: 12/29/76

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Chrysler Corporation

TITLE: FMVSS INTERPRETATION

TEXT:

December 29, 1976 N40-30

Mr. R. E. Weil Exterior Lighting Development Chrysler Corporation P.O. Box 1118 Detroit, Michigan 48231

Dear Mr. Weil:

This is in reply to your letter of September 16, 1976, to Mr. Brooks of this agency on photometric test requirements of multiple compartment and multiple lamp configurations. You have asked for our concurrence on two interpretations of Standard No. 108, as discussed below.

In your "example 1", on vehicles designed with a two lamp system, parking and (or taillamp) and turn signal functions are combined in each lamp of the two lamp system. You have asked whether the second lamp in this system would be treated as supplemental and need not meet the photometric requirements for required lamps.

The answer is no. As you are aware the photometric requirements of multiple lamps or multiple compartment lamps, where a tail or parking lamp is combined with the turn signal lamp, are partially determined by Note 4 to SAE Standard J588e Turn Signal Lamps. Note 4 establishes permissible ratios of intensity between functions i.e. that the intensity of the tail or parking lamps shall not be so great as to diminish the effectiveness of the turn signal function. Where two lamps are used and the distance between filament centers does not exceed 22 inches (as appears to be the case here) the combination of the lamps must be used to meet the photometric requirements for the corresponding number of lighted sections. (Paragraph 3.1 of J585d; J588e). Further, the ratio of the turn signal to the tail or parking lamps must be computed with all the lamps lighted (Note 4). With reference to those vehicles designed with a two-lamp system (your example 1), your first answer is the correct one; the lamps would be photometered together to meet the two compartment requirements for the two lamp functions performed, as specified in Table 1 of Standard No. 108.

With respect to your example 2, a multiple compartment lamp with one compartment performing turn signal and parking or tail lamp functions, and the other portion the function of parking or tail lamp only, photometric requirements for the tail lamp function are determined on the basis of the output of the two compartments. The single compartment parking lamp may, however, be treated as a "supplemental" lamp, except that the candlepower ratios (with turn signal lamp) must be met with both parking lamp compartments illuminated.

Sincerely,

Frank A. Berndt Acting Chief Counsel

SUBJECT: Request for an Interpretation of Federal Motor Vehicle Safety Standard (FMVSS) No. 108 from Chrysler Corporation

N41-2lRBr 22 OCT 1976

FROM: Director Office of Standards Enforcement Motor Vehicle Programs

To: Acting Chief Counsel National Highway Traffic Safety Administration

Attached is a letter dated September 16, 1976, from the Chrysler Corporation, requesting an interpretation of FMVSS No. 108, on the subject of: "Photometric Test Requirements of Multiple Cavity and Multiple Lamp Configurations."

The letter is being referred to you as a matter coming within your cognizance. It is requested that the reply be staffed through this office, prior to being transmitted to Chrysler.

This office does not concur with Chrysler's proposals concerning supplemental lamps, but considers that compliance must be determined by testing with each lamp function lighted in the same cavities, just as it actually operates in vehicles being used on the highway. To allow manufacturers to certify lighting functions to conditions other than those seen by drivers of nearby vehicles, would clearly be inconsistent with the basic intent of FMVSS No. 108. Thus, using the sketch attached to the Chrysler letter, the requirements of Note 4 below Table I of SAE J588e dated September 1970, referenced in Table III of FMVSS No. 108, would be determined by measuring the photometric properties of the parking lamp function at the optical center of the two cavities, with both parking lamp bulbs lighted, as they operate in the highway environment. Next, the photometric properties of the turn signal function would be determined with only tie turn signal bulb in cavity number 1, lighted. Based on these measurements, the ratios specified in Note 4 would be obtained.

Francis Armstrong

Attachment

September 16, 1976

Mr. Roman Brooks National Highway Traffic Safety Administration 400 7th Street S.W. Washington, D.C. 20591

Dear Mr. Brooks:

Subject: Photometric Test Requirements of Multiple Cavity and Multiple Lamp Configurations

Reference: 1. Telephone conversation between R. Brooks and J. B. Carrier on August 13, 1976. 2. Telephone conversation between R. Brooks and R. E. Weil on August 16, 1976.

This letter is to confirm our telephone conversations regarding the Federal Motor Vehicle Safety Standard 108 Multiple Lamp and Multiple Cavity Lighting Requirements applicable to the 1979 models.

Based on our discussions, we would like your concurrence with the interpretation of the standard as illustrated by the following examples.

Example 1

On vehicles designed with a two lamp system in which park and turn-signal or tail and turn-signal functions are combined, the requirements may be met in one of the following ways:

1. The lamps would be photometered together to meet the two cavity requirements for the park or tail and the two cavity requirements for the turn signal. The ratio of the turn signal to park or tail would be determined using the two cavity readings of both the turn signal and park or tail. In such cases the manufacturer should use the legal name on each lamp to designate that two lamps have been designed to meet the requirements, or

2. One lamp would be photometered to one cavity requirements and the ratio of the turn-signal to the park or tail would be determined for that lamp. In such cases the manufacturer should use the legal name to designate the lamp which has been designed to meet the requirements. The other lamp would be treated by NHTSA as a supplemental lamp and need not meet the photometric requirements for required lamps.

Example 2

On vehicles designed with a two cavity lamp in which only one cavity is a combination turn-signal and park or tail, the requirements may be met as follows:

The combined cavity would be photometered to single cavity requirements and the ratio of the turn-signal to park or tail would be determined using only the park or tail readings for that cavity. In such cases, the manufacturer should use the legal name to designate the cavity which has been designed to meet the requirements.

The other cavity would be treated by NHTSA as a supplemental lamp and need not meet the photometric requirements for required lamps.

Similarly for lamps with more than two cavities, the manufacturer should designate which cavities have been designed to meet the legal requirements.

We would appreciate a written confirmation of this understanding at the earliest possible date.

Yours truly,

CHRYSLER CORPORATION

R. E. Weil Exterior Lighting Development CIMS: 416-32-27

REW/ww

cc: R. O. Sornson