Interpretation ID: aiam1830
General Motors Corporation
General Motors Technical Center
Warren
MI 48090;
Dear Mr. Martin: This responds to General Motors' January 14, 1975, request fo confirmation that a Type II seat belt assembly demonstrated to Messrs. Carter, Detrick, Hofferberth, Burgett, Hitchcock, and Herlihy of the NHTSA on December 17, 1974, 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 frictional 'D ring' buckle tongue which limits return of webbing to the lap belt portion from the torso portion when the belt assembly is in use. At the December 17 demonstration you specifically asked if the 'D ring' frictional characteristics satisfy the criterion established in a September 25, 1972, letter to Renault, Inc. (copy enclosed), 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.'; Section S7.1.1 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 retractor, 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 was set out in the Renault letter and it is the basi for your question whether the GM 'D ring' has a sufficiently low level of friction to qualify the lap portion as 'automatically adjustable.'; 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 December 17 demonstration 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 (copy enclosed). 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.' General Motors' response to that proposal and its anticipated use of a 'window shade' device in future continuous loop systems 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.; Pursuant to your request for confidential treatment of this question o a new seat belt assembly, this letter will be made public only after the introduction of the new vehicle in question.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs;