Interpretation ID: aiam2121
Director
Automotive Safety Office
Ford Motor Company
The American Road
Dearborn
MI 48121;
Dear Mr. Eckhold: This responds to your letter of November 11, 1975, requestin confirmation that a 1976 Ford Motor Company 'deluxe continuous-loop seat belt system' satisfies the requirements of Section 7.1.1 of Standard No. 208, *Occupant Crash Protection*.; Section 7.1.1 requires adjustment of the lap belt portion of a fron outboard seat belt assembly 'by means of an emergency-locking or automatic-locking retractor' and adjustment in most cases of the upper torso portion 'by means of an emergency-locking retractor.' The language permits some single retractor, continuous loop systems as long as the single retractor does 'automatically adjust' the tension of the lap belt portion to prevent excessive slack. Because of the submarining danger of a slack lap belt, the National Highway Traffic Safety Administration (NHTSA) has restricted the acceptability of continuous loop systems under S7.1.1 in two areas.; In the NHTSA's September 25, 1972, letter to Renault to which yo refer, the level of friction in the tongue is discussed and our position is stated that it must have a sufficiently low level to qualify the lap belt portion as 'automatically adjustable.' In your recent demonstration of the tongue frictions in the Ford 1976 'standard' and 'deluxe' continuous loop seat belt systems to NHTSA personnel, we saw no evidence of design deficiency in limited use of those systems.; The other restriction concerns the use of manual and automatic tensio relieving devices on the upper portion of continuous loop systems. In our letters of March 9, 1973, and March 27, 1975 (to General Motors), June 13, 1975 (to Chrysler Corporation), and September 5, 1975 (to Takata-Kojyo), the NHTSA has limited the use of tension relieving devices to the upper torso portion of seat belt assemblies that have 'an individually adjustable lap belt.' It is our view that the 1976 Ford deluxe continuous loop system does not have 'an individually adjustable lap belt' within the meaning of Standard No. 208. In this system slack which is introduced into the continuous loop by the 'window shade' tension relief device on the upper retractor is directly transferred to the lap belt, thus increasing the risk of submarining if a crash should occur. I would like to point out that issues related to tension relief devices are, however, still outstanding in an (sic) NHTSA proposal (Docket 74-32, Notice 1).; I am enclosing a report on 'Comfort and Convenience Analysis o Advanced Restraint Systems' of August 1975. This study, conducted by the NHTSA Safety Research Laboratory on a number of different safety belt designs concludes that: 'Several aspects of the systems caused difficulties or confusion, but the single-loop 'window-shade' feature most frequently produced problems.' In light of our mutual desire to improve safety belt usage levels, I should also like to again recommend to your attention the results of the earlier NHTSA sponsored study 'Sources and Remedies for Restraint System Discomfort and Inconveniences' by Man Factors, Inc., that I sent to your company in January 1975.; Sincerely, James B. Gregory, Administrator