Interpretation ID: nht73-2.1
DATE: 07/09/73
FROM: AUTHOR UNAVAILABLE; Lawrence R. Schneider; NHTSA
TO: Jeep Corporation
TITLE: FMVSS INTERPRETATION
TEXT: This is in reply to your letter of May 24, 1973, concerning the procedure for testing seat belt attachment bolts specified in section S5.2(c)(1) of Motor Vehicle Safety Standard No. 209.
The attachment bolts that you describe have extremely long shoulders and are installed in the vehicle by being passed through a hat section before entering the floor pan. Your question is whether(Illegible Word) test procedure of S5.2(c)(1) permite the hat section to be used in conjunction with the test fixture shown in Figure 3. It is our opinion that section S5.2(c)(1) permits some discretion in the manner in which the Figure 3 test fixture is to be used and that a hat section duplicating the section used in the vehicle would be permitted as part of the test apparatus. We therefore confirm your impression that you may use the hat section in testing your bolts.
Sincerely,
May 24, 1973
Lawrence R. Schneider-- Chief Counsel, National Highway Traffic Safety Administration, U.S. Department of Transportation
Dear Mr. Schneider:
Jeep Corporation is requesting your concurrence with our interpretation with regard to FMVSS No. 209, "Seat Belt Assemblies" More specifically, we refer to paragraph S5.2(c)(1) which pertains to the demonstration procedure for verifying the strength of seat belt attachment bolts. This paragraph contains, by reference, a drawing (Figure 3) which shows a test fixture into which the seat belt attachment bolt is threaded. In addition, the angle of pull is specified with respect to the axis of the bolt as well as the number of threads that must remain exposed, etc. We would particularly like to point out that paragraph S5.2(c)(1) states that attachment bolts can be tested "in a manner similar to that shown in Fig. 3." We interpret this to mean that the geometry of the attachment bolt "environment" as it exists in an actual vehicle can be simulated on the strength testing machine when the tensile strength of the bolt is verified. The following information explains our problem in more detail.
In one of our future model Jeep vehicles the attachment bolt "environment" is considerably unlike that portrayed in Fig. 3 of FMVSS No. 209. Our Figure 1, attached to this letter, shows a side view of the installation in this Jeep vehicle. It should be noted that the long shank of the bolt goes through a sheet metal "hat section" before being threaded into the anchorage nut. This "hat section" supports the shank of the bolt and prevents an excessive amount of bending as would occur if the long shank were fully exposed without the "hat section" being there. The anchorage plate with its attached nut is on the underside surface of the floor pan of the vehicle.
In verifying the strength of the attachment bolt we will therefore mount a section of floor pan complete with the "hat section" on the test fixture which is shown in Fig. 3 of FMVSS No. 209. Our adaptation of the floor pan section to the text fixture is shown in our attached sdetch, Figure 2. Naturally, in our strength test the attachment bolt will be "backed out" so as to expose two full threads as required in FMVSS No. 209. Also, we will obviously delete the sound insulation material which is used in the actual vehicle since it offers no lateral support whatsoever. Thus, the bolt shank would be supported in exactly the same way it is in the actual vehicle since we would be using the same thickness of metal for the floor pan and "hat section" as used in production. Finally, the diameter of the hole(s) in the "hat section" through which the attachment bolt passes would be the same as in the actual vehicle.
Your confirmation of our interpretation would be greatly appreciated.
Sincerely,
F.A. Stewart-- Vice President Safety & Reliability, JEEP CORPORATION
Att:2
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