Interpretation ID: nht71-5.35

DATE: 12/29/71

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: Hackney Bros. Body Company

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of December 6, 1971, in which you requested our opinion on the application of Standard No. 207 to swivel type pedestal seats.

Your problem arises from the method specified in S5.1.1 for the application of the force required by S4.2(a) of 20 times the weight of the seat. Although your letter does not state the problem directly, it appears that when a forward force is applied from behind the seat, as shown in the figures accompanying S5.1.1, the seat will tend to swivel. Your solution is to attach a T-shaped structure to the seat and to apply the force to the leg of the T forward of the swivel point.

The initial question raised by your letter is whether a seat that swivels under the application of a force through its back as shown in Figure 1, will be considered to fail to withstand the force and thereby fail the standard.

On the basis of our present information, we cannot say that such a swiveling action would result in a failure of the standard. The engineering staff has expressed uncertainty as to the effects on the occupant if the seat swivels in a side or angular crash, but they are not prepared to say that it would present a hazard. Since the swiveling itself is not a failure, the remaining question is one of test procedure. Our opinion is that the procedure you describe, using a T shaped structure, appears to be an acceptable means of applying the test force to the seat.