Interpretation ID: nht79-2.3
DATE: 08/30/79
FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA
TO: Freedman Seating Company
TITLE: FMVSS INTERPRETATION
ATTACHMT: Attached to 8/16/88 letter to Glenn L. Duncan from Erika Z. Jones (Redbook A32; Std. 207); Letter dated 4/28/77 to Gordon P. Cress from Frank A. Berndt (Std. 210); Letter dated 2/1/88 to Erika Z. Jones from Glenn L. Duncan; Letter dated 11/16/97 to Erika Z. Jones from Glenn L. Dunn (OCC 1278)
TEXT: This responds to your recent letter asking how much deflection or deformation of seat belt anchorages is allowed under the requirements of Safety Standard No. 210, for anchorages that are attached to or are a part of revolving pedestal seats. You mention cases in which seat bases deflect so much that the seat touches the floor before the forces required by the standard are attained.
As noted in your letter, paragraph S4.2.3 of Safety Standard No. 210 specifies that permanent deformation or rupture of a seat belt anchorage or its surrounding area is not considered to be a failure, if the required force is sustained for the specified time. Likewise, the agency has stated in the past that the force requirements of Safety Standard No. 207, Seating Systems, allow some deformation of the seats during the force test, provided structural integrity of the seats is maintained.
Although Safety Standard No. 210 would allow some deformation of the seat base for anchorages that are part of pedestal seats, the structural integrity of the seats would have to be maintained during the force test. Further, you should note that Safety Standard No. 207 requires the forces for testing seats and the forces required by Safety Standard No. 210 to be applied simultaneously for seats that have belt assemblies attached to them. Thus, the pedestal seats discussed in your letter would have to maintain their structural integrity when subjected to the combined forces required by both standards. The agency Would not consider pedestal seats to be in compliance with these requirements, if the seats are displaced to an extent that the agency determines occupant safety is threatened.
I hope this letter has clarified the agency's position regarding the force requirements of both Safety Standard No. 210 and Safety Standard No. 207.
SINCERELY,
FREEDMAN SEATING COMPANY
June 22, 1979
Office of Vehicle Safety Standards National Highway Traffic Safety Administration
Dear Sirs: This letter is a request for clarification of Federal Motor Vehicle Safety Standard No. 210.
As a seat manufacturer and supplier for the Recreational Vehicle Industry, we have developed products which are intended for use in a variety of vehicles, and therefore must certify their compliance with Motor Vehicle Safety Standards when installed in these vehicles. It has become common practice for seating companies as ourselves to test certain "seating systems" on laboratory test equipment, rather than in each vehicle, and certify that the "seating system" complies with applicable Motor Vehicle Safety Standards when installed properly. In the case of revolving seat pedestals which are designed to be "seat belt anchorages" (by definition, the provision for transferring seat belt assembly loads to the vehicle structure) this laboratory testing raises certain questions relative to interpretation of MVSS No. 210. Per MVSS 210, "permanent deformation or rupture of a seat belt anchorage or its surrounding area is not considered to be a failure, if the required force is sustained for the specified time." Since no limitations are set for seat belt anchorage deflection, many seat manufacturers have ignored this aspect totally, and tested seat bases (seat belt anchorages) to force requirements only. In some cases, the seat bases deflect so much that the front edge of the seat is touching the floor before the required force is eventually attained. (See enclosed photographs.) While it would appear obvious that these bases are not in compliance with MVSS 210 for driver application, since the seat back would have impacted the steering wheel prior to the required force being attained, (the steering column is sustaining part of the force) the bases appear to be in compliance with MVSS 210 when installed at a location in a vehicle where there is nothing to obstruct free movement of the seat.
Our request at this time is that the Department of Transportation supply us with its interpretation of MVSS 210 to the extent that it would consider seat bases of this type in compliance or not in compliance with the standard.
Secondly, with respect to the intent of the safety standards, it would appear that future consideration should be given to setting deflection limitations in Motor Vehicle Safety Standards 207 and 210. If the "seating system" or "seat belt anchorage" is able to sustain required forces only after the occupant has impacted the steering wheel or windshield, it appears that we have met a safety standard without providing the intended safety.
Your prompt attention to this matter will be appreciated.
Robert J. Wahls Chief Engineer
ENC.
Kenco Builds Stress Machine
A new stress test machine for van and motorhome seat bases has been designed and built by Kenco Engineering, Middlebury, Indiana, to meet the specifications required by the Department of Transportation (D.O.T.). The machine operates hydraulically and can exert 8,000 pounds of pull. The seat base pictured above has sustained 6,750 pounds, well over the D.O.T. requirement of 5,000 pounds for 10 seconds. Kenco will use the machine for testing seat bases, tire carriers and other products which undergo stress in use.
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