Interpretation ID: aiam1948
Vice President
Public Responsibility and Consumer Affairs
Chrysler Corporation
P.O. Box 1910
Detroit
MI 48231;
Dear Mr. Terry: This responds to your letter of May 13, 1975, requesting confirmatio that Chrysler's new unibelt shoulder/lap belt system with a 'window shade' tension adjustment feature satisfies the requirements of S7.1.1 of Standard No. 208, Occupant Crash Protection, that the lap belt portion 'adjust by means of an emergency-locking or automatic-locking retractor.' You describe the seat belt assembly as of the single retractor, continuous loop type, with a B-pillar-mounted 'window shade' emergency-locking retractor, and a one-way locking device in the buckle tip which prevents return of webbing to the lap portion from the torso portion when the belt assembly is in use.; Section 7.1.1 requires adjustment of the lap belt portion 'by means o 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 refractor, continuous loop systems as long as the single retractor does 'automatically adjust' the tension of the lap belt portion to prevent excessive belt slack. Because of the submarining danger of a slack lap belt, the NHTSA has restricted the acceptability of continuous loop systems under S7.1.1 in two areas.; One restriction, set forth in a letter to Renault, Inc., on Septembe 25, 1972, is that 'the friction in the buckle is low enough that the normal motion of the occupant against the shoulder belt cinches up the lap belt.'; We would like to clarify that letter by emphasizing that, to conform t the requirements, the assembly must be designed by the manufacturer with a sufficiently low level of friction to qualify the lap portion as 'automatically adjustable.' Thus, it is the manufacturer who determines whether or not the particular belt is designed to satisfy the requirements of the standard. In your May 16, 1975, demonstration to Messrs. Hitchcock, Nelson, Medlin, Smith, Breedon, and Ziegler of the NHTSA, we saw no evidence of design deficiency in limited use of that continuous loop system.; The other restriction was set out in a March 9, 1973, letter to Genera Motors. It limits the use of 'comfort clips' on the upper torso portion of continuous loop systems. The letter distinguishes continuous loop systems from systems that have separate lap and shoulder belt retractors. It concludes that 'a comfort clip would be acceptable under S7.1.1 of the standard, so long as the shoulder belt is otherwise capable of adjustment as required by S7.1.1.'; This restriction has since been the subject of an NHTSA proposa (Docket 74-32, Notice 1) which would restrict the use of 'a device used to limit retractive action of an emergency-locking retractor for the comfort of the occupant' to seat belt assemblies that have 'an individually adjustable lap belt.' Chrysler's response to that proposal and stated plan to introduce a continuous loop belt system with a 'window shade' device in the new 1976 model four-door compact car assume that NHTSA intends to permit 'belt tension relief' devices on all continuous loop systems. I would like to point out that this issue is outstanding in Docket 74-32.; Sincerely, James B. Gregory, Administrator