Interpretation ID: 1984-1.17

TYPE: INTERPRETATION-NHTSA

DATE: 02/29/84

FROM: AUTHOR UNAVAILABLE; Frank Berndt; NHTSA

TO: United States Testing Company Inc.

TITLE: FMVSS INTERPRETATION

TEXT:

Mr. Frank Pepe Assistant Vice President Engineering Services Division United States Testing Company, Inc. 1415 Park Avenue Hoboken, New Jersey 07030

Dear Mr. Pepe:

This responds to your letter concerning Safety Standard No. 209, Seat Belt Assemblies. You asked several questions about the requirements applicable to Type 2 Vehicle Sensitive Emergency Locking Retractor utilizing a tension reducer device. The particular device you are concerned about is, according to your letter, activated by the vehicle door. With the door open the mechanism operates in a high tension mode; with the door closed the mechanism is in a low tension mode.

By way of background information, this agency does not grant approvals of vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act it is the responsibility of the manufacturer to certify that its vehicles or equipment comply with applicable requirements. The following represents our opinion based on the facts provided in your letter.

Safety Standard No. 209 specifies requirements concerning minimum and maximum retraction force. Requirements are specified for both initial retraction force and retraction force after a test sequence which includes lengthy retractor cycling. See sections S4.3(j), (k) and S5.2(k).

As you know, retractors have traditionally had only one rather than two tension modes. Standard No. 209 does not prohibit a design with two tension modes. However, as written, the standard's requirements do not distinguish between tension modes.

We agree with your suggestion that both tension modes should be tested for retraction force effort as specified in the standard. However, we do not agree with your suggestion that the high tension mode should only be tested for minimum retraction force and the low tension mode for maximum retraction force. Instead, because Standard No. 209 does not distinguish between tension modes, we interpret the standard to require that all of its requirements must be met in both tension modes. For example, under section S4.3(j)(6), both tension modes must exert a retractive force within the 0.2 to 1.5 pound range. For testing purposes, of course, a single retractor could only be fully tested for one of the two modes, since testing for both modes would involve twice the amount of cycling required by the standard.

Your letter states that since the high tension mode is used only for stowing the webbing and is not in operation during normal use, you believe that only cycling tests without lock-ups should be performed in testing. While we appreciate this argument, the standard, as written, does not permit that exception. Section S5.2(k) states in relevant part:

attached to upper torso restraint shall be subjected to 45,000 additional cycles of webbing withdrawal and retraction between 50 and 100 percent extension. The locking mechanism of an emergency locking retractor shall be actuated at least 10,000 times within 50 to 100 percent extension of webbing during the 50,000 cycles....

Since the standard does not distinguish between tension modes, lock-ups should be performed in testing for both the low and high tension modes.

As already noted, the retractor in question represents a new design which was not specifically considered in drafting Standard No. 209. If the standard as written creates problems, the manufacturer may wish to consider submitting a petition for rulemaking to amend the standard to establish special test procedures.

Your letter suggests that there may be a conflict between section S7.4.2 of Standard No. 208, Occupant Crash Protection, and Standard No. 209's 0.2 pound retraction force requirement (section S4.3(j)). However, section S7.4.2 of Standard No. 208 only applies to automatic belt systems, while section S5.3(j) of Standard No. 209 only applies to active belt systems. Therefore, there can be no conflict.

Sincerely,

Frank Berndt Chief Counsel

May 12, 1983

Mr. William Smith National Highway Traffic Safety Administration 400 - 7th St., S.W. Room 5320 Washington, D.C. 20590

Dear Mr. Smith:

Some questions have been raised pertaining to the requirements relating to retraction force and lock-up distance on Type 2 Vehicle Sensitive Emergency Locking Retractors utilizing a tension reducer device (comfort type mechanism). This particular device is activated by the vehicle door; with the door open the mechanism operates in a high tension mode; with the door closed the mechanism is in a low tension mode.

The purpose of measuring retraction force is to insure that two (2) separate requirements are met.

1. Retraction force is high enough to sufficiently retract the webbing to its normal stowed position (Minimum Requirement).

2. Retraction force is not so high as to cause discomfort to the user (Maximum Requirement).

Since the referenced tension reducer is activated solely by door position, and the user has no manual control of the tension reducer operation, a question is raised pertaining to retraction force requirements.

We feel that both tension modes should be tested for retraction force effort as specified in FMVSS 209. That is; High Tension Mode -minimum retraction force requirements and Low Tension Mode - maximum retraction force requirement.

However, this raises another question on FMVSS 209 minimum requirements for retractor force for Type 2 Assemblies (0.2 lbs.). In FMVSS #208 proposed requirements for Comfort and Convenience, slack is allowed to be introduced in the webbing (S7.4.2.) provided that it is cancelled when the adjacent door is opened. This appears to be in contradiction of the 0.2 lbs. retraction force requirement of FMVSS 209 when utilizing a tension reducer type of retractor. Therefore, it seems, that since the tension reducer type of retractor is designed strictly for comfort, and not to induce slack, only 50% loss in retraction effort requirement after cycling should be pertinent.

The purpose of retractor cycling is to determine if the retractor will perform satisfactorily during repeated use and that spring tension does not change significantly as well as its ability to lock-up.

Since the high tension mode is used only for stowing the webbing and is not in operation during normal use, we feel that only cycling tests without lock-ups need be performed in accordance with FMVSS #209.

The low tension mode is the portion of the retractor that will perform during impact conditions and therefore should require standard cycling with lock-ups.

Therefore, we feel an interpretation of the adequacy of the minimum retraction force requirement pertaining to Comfort and Convenience type mechanisms is necessary. Also do both tension modes have to satisfy the Retractor Performance requirement of FMVSS #209.

We would appreciate your review of the above comments and your interpretation of same.

Very truly yours,

UNITED STATES TESTING COMPANY, INC.

Frank Pepe Assistant Vice President FP/na