Interpretation ID: nht71-5.57

DATE: 05/12/71

FROM: AUTHOR UNAVAILABLE; Robert L. Carter; NHTSA

TO: Mercedes-Benz of North America, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: Thank you for your letter of April 20, 1971, regarding an interpretation for seat belt assemblies required by Federal Motor Vehicle Safety Standard No. 208 - Occupant Crash Protection.

It is our intent that an integral (3-point) lap and shoulder belt system, with a sliding attachment, could meet the requirements of the subject standard. Since paragraph S7.1.1 requires automatic adjustment by means of an emergency-locking retractor for this type of integral system (see S7.1.1.3), the sliding attachment friction could not unduly restrict adjusting movements of the belt, however, a nominal friction is permissible and is expected.

The seat belt assembly which you submitted to Mr. Clue Ferguson's Office of Crash Worthiness has been placed in Docket 69-7. This system would appear to have a nominal friction at the sliding adjustment, however, an actual vehicle installation is necessary to enable a full evaluation.

MERCEDES-BENZ OF NORTH AMERICA, INC.

April 20, 1971

Doug W. Toms, Director National Traffic and Highway Safety Administration

Subject: Seat Belt Assemblies According to FMVSS 208

The Motor Vehicle Safety Standard 208 which will be effective January 1, 1972, requires that seat belt assemblies shall adjust to fit the occupant by means of an automatic or emergency locking retractor. The seat belt assembly being considered for installation in our vehicles has been designed to comply with the subject Safety Standard. We would, however, appreciate receiving your confirmation that the design complies with the aspect of performance described in S7.1.1 of the Standard prior to equipping our vehicles.

The subject assembly consists of a single piece of webbing permanently attached at the outboard floor anchorage, with the release/fastening mechanism at the inboard anchorage forming the pelvic restraining loop and a third anchorage behind the shoulder forming the upper torso restraint. The webbing is fed during extension by an emergency locking retractor through the upper shoulder restraint anchorage to provide freedom of movement for the occupant.

Application of this assembly around the occupant is achieved by pulling the "tongue" portion of the attachment hardware from its fully retracted position at the "3" pillar, across the occupant down to the fixed buckle or receptable at the inboard anchorage. The webbing passes loosely through a slot in the tongue to provide a sliding adjustment during this application.

We are requesting your confirmation that this sliding adjustment specifically, will not be considered in non-compliance with your requirement for adjustment by the retractor because of the small amount of friction occuring at the webbing and tongue. It is our opinion that the friction is adequately overcome by the retractor force to provide proper adjustment. Additionally, the assembly when extended for use, will be drawn across the occupant, thus a snug fit across the pelvic region will be provided upon application thereby minimizing the need for further automatic adjustment by the retractor.

A sample of an assembly incorporating this design has been left at Mr. C. Ferguson's office for further evaluation by your staff. Upon receipt of your evaluation of this design we will advise our parent company accordingly.

H. W. Gerth General Manager Product Engineering and Service

cc: Mr. Wilfert Dr. Reidelbach