Interpretation ID: 1985-01.17

TYPE: INTERPRETATION-NHTSA

DATE: 01/24/85

FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA

TO: Mr. John S. Cucheran

TITLE: FMVSS INTERPRETATION

TEXT:

Mr. John S. Cucheran Vice President Design and Engineering Jac Products, Inc. 1901 E. Ellsworth Ann Arbor, MI 48104

Dear Mr. Cucheran:

This is in reply to your letter of November 30, 1984, to Mr. Vinson of this office asking for an interpretation of Motor Vehicle Safety Standard No. 108 Lamps, Reflective Devices, and Associated Equipment.

Figure 10 of Standard No. 108 establishes the minimum design photometrics for center high mounted stoplamps. The test procedure for this particular part of Standard No. 108 which is specified in SAE J186a, stipulates that the "lamp axis shall be taken as the horizontal line through the light source." However, I believe that you have misinterpreted the light cone that is involved. The pertinent light cone in this case has its vertex at the photometer and a cross section at the plane of the lamp which encompasses the lens areas. From Drawing A that you have provided, it appears that your rail would interfere with this light cone.

In order to determine if your rack interferes with the photometric requirements, the vehicle must be tested with the rack in position as installed on the vehicle. As the agency has noted before, the photometric requirements do not specify that the entire lens must be visible from each 5 degree down test point. Instead, they specify the intensity of light that must be visible from those points. Therefore, the requirement can be met with a lamp whose lens is partially obscured by a portion of the vehicle when viewed from some of the test points.

We hope that this interpretation is helpful to you.

Sincerely, Frank Berndt Chief Counsel November 30, 1984 Mr. Taylor Vinson U. S. Department of Transportation National Highway Traffic Safety Administration 400 Seventh Street S.W. Washington, D.C. 20590 Subject: Center Mounted Stop Light

Dear Mr. Vinson:

As you are aware, the cross rail on our deck mounted luggage racks supplied to O.E. automotive manufacturers infringes the 50 down cone requirement of Standard Number 108. This infringement will cause our products to be deleted from 1986 model vehicles equipped with center mounted stop lights with 50 cones that do not clear the rear rails.

Because we were not successful in getting a variance to allow infringement of the 5o cone on vehicles equipped with deck mounted luggage racks, our company will lose approximately 3 million dollars worth of business per year starting next summer, plus the loss of many jobs in an area already hit with some of the highest unemployment figures in the country. We are doing everything possible to adapt our products on new vehicles to save as many of our employees jobs as possible.

One thing that might make a difference on some potential 1986 business, is a clear definition of where the horizontal line, to establish the 5o cone, is taken from in the side view. I have enclosed two illustrations to clarify my request.

Illustration A shows the relationship of the light cone taken from the center of the lens, to a cross rail section. As you will notice, the light cone clears the bar.

Illustration B shows the relationship of the light cone taken from the bottom of the lens, to a cross rail section. As you will notice, the light cone is infringed by the cross rail. Mr. T. Vinson U.S. Department of Transportation November 30, 1984 Page Two

Several of our customers have taken for granted that the intent of the Standard is to establish the light path from the bottom of the lens. As you can see from our illustrations, the location of this point can mean approval or rejection of our products in cases such as this.

Your interpretation of our request, at your earliest date, would be greatly appreciated.

Very truly yours, John S. Cucheran Vice President Design and Engineering cc: Mr. Barry Felrice/Associate Administrator for Rulemaking Mr. Jack Bott/President-JAC Products Inc.