Interpretation ID: nht73-1.50

DATE: 08/20/73

FROM: Richard B. Dyson; NHTSA

TO: Takata Kojyo Company, Ltd.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of July 31, 1973, concerning the meaning of the term "75 percent extension" as used in S5.2(j) of Motor Vehicle Safety Standard No. 209.

The 75 percent extension point used in 85.2(j) is intended to represent the belt's extension during its use in a vehicle. The measurement of extension is therefore begun with the webbing retracted as fully as the design of hardware and the size of the retractor permit. It may be that when the belt is retracted to this point a considerable amount of webbing remains outside the retractor, as shown in Figure 2 of your letter. The measurement of extension nonetheless begins at this point, so that "75 percent extension" is 75 percent of the incremental webbing length between this point and the point of fullest extension.

To refer to the figures accompanying your letter, the measurement technique shown in Figure 2 is correct. That shown in Figure 1, which is based on 75 percent of the total length of the belt, is incorrect.