Interpretation ID: 1983-2.25

TYPE: INTERPRETATION-NHTSA

DATE: 07/05/83

FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA

TO: Volvo of America Corporation

TITLE: FMVSS Interpretation

TEXT: William Shapiro,. P.E. Manager, Regulatory Affairs North American Car Operations Product Planning and Development Volvo of America Corporation Rockleigh, New Jersey 07647

Dear Mr. Shapiro:

This responds to your letter of May 24, 1983, requesting an interpretation concerning the retraction force requirements to Safety Standard No. 209, Seat Belt Assemblies. You are considering a Type 2 seat belt design which includes an emergency locking retractor for continuous loop webbing and an emergency locking retractor for additional webbing at the inboard buckle portion of the system. You state that this inboard webbing is extended only if the belt is used by an extremely large occupant. You ask whether the retraction force requirements of the standard allow testing with the webbing of the entire system extended 75%, i.e., even if this mean; that no webbing is extended from the inboard retractor, so that the retraction force is actually only measured from the retractor for the continuous loop portion of the belt.

Paragraph @4.3(j) of Safety Standard No. 209 specifies that an emergency locking retractor of a Type 1 or Type 2 seat belt assembly, when tested in accordance with the procedures specified in paragraph @5.2(j) shall:

(1) expert a retroactive force of at least 0.6 pound under zero accelaration when attached only to the pelvic restraint: (5) exert a retroactive force of not less than 0.2 pound and not more than 1.1 pounds under zero acceleration when attached only to in upper torso restraint;

(6) exert a retroactive force of not less than 0.2 pound and not more than 1.5 pounds under zero acceleration when attached to a strap or webbing that restrains both the upper torso and pelvis.

The test procedures of paragraph @5.2 (j) specify that these retraction forces are to be measured with the belt webbing extended from the retractor to 75% of its length.

The requirements of @4.3(j) apply to each retractor on a Type 1 or Type 2 belt system. There is no exception in the standard for a system which includes two or more retractors which exert force on the same belt webbing. Thus, both retractors on your proposed system would have to comply with the requirements of the standard independently of one another. Under the test procedure you suggest, the retraction force of the inboard retractor would not be measured. This is contrary to the explicit language of the standard. Both retractors on your proposed system would have to comply with the force requirements of paragraph @4.3(j) (6). This is true because both retractors are attached "to a strap or webbing that restrains both the upper torso and the pelvis." Therefore, the retraction force on your inboard retractor must be not less than 0. 2 pound and not greater than 1.5 pounds when the webbing on that retractor is extended to 75% of its length. The same is true for the retractor on the continuous loop portion of the system.

I hope this has clarified any misunderstanding you might have had concerning these requirements.

Sincerely,

Frank Berndt Chief Counsel