GAR | GTR7-07-09

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Document Title	Discussion document: Head restraint height measurement methods
Reference Number	GTR7-07-09
Date	21 Jul 2011
Source(s)	RDW, BASt, and OICA
Rulemaking Area(s)	GTR No. 7 Head Restraints
Meeting(s)	GTR7 \| Session 7 \| 10 Jun 2011
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Excerpts from session reports related to this document
GTR7 \| Session 7 \| 10 Jun 2011		Presentation from Mr Pott on behalf of the task force (RDW, OICA, and BASt) (GTR7-07-09): Mr Pott presented an overview of progress with the definition of a test procedure to measure the effective height of head restraints for 50th percentile and 95th percentile male occupants. The proposed effective height measurement was compared with the current UNECE Regulation 17 (R17) height measurements for selected head restraints. Some rear head restraints were identified with curved front faces that meant that the R17 method includes an area of the head restraint that is unlikely to be effective. For front HR the difference between the two methods was 15-25 mm for the seats assessed, and for rear seats was 5-60 mm. The task force proposed that an effective height of 780 mm was equivalent to an R17 height of 800 mm, based on an average difference of 20 mm. Mr Pott confirmed that the task force is continuing discussion regarding an allowance for a lower height if it prevents egress from rear seats of two-door vehicles. The task force felt that height limits could be reduced for low roof lines as is currently done in Regulation 17. They felt that consideration could also be given to assuming a lower height for e.g. 3rd row occupants, for instance if taller occupants cannot fit in this row. The task force will consider further: · Consequences for head restraint design · Refinement of the proposal · Evaluation of possible interference between CRS and (rear) HR, and options for preventing conflict between rear HR and CRS requirements · Recommendation of necessary effective height for the text, e.g. allowing for the difference between the R17 and new proposed method It was noted that the SAE HADD committee had some comments on the test method. Mr Frost noted that the informal group is open and that the SAE would be welcome to contribute to the evaluation of the effective height method, or any other part of the work. Mr Ammerlaan noted that the task force had also evaluated the method based on the Hpoint, using the H-point machine. Action Effective Height Task Force to make this comparison data available to NHTSA. It was noted that the difference between the two methods would be larger for more traditional HR shapes than the one shown in the presentation.