ID: nht72-4.21

DATE: 05/01/72

FROM: AUTHOR UNAVAILABLE; Charles H. Hartman; NHTSA

TO: Rose Manufacturing Co.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letters of March 23, 1972, and March 27, 1972, concerning our previous letter to you dated March 10, 1972.

We recognize your contribution to safety and your deep personal involvement in child harnesses. Harnesses, such as yours, offer many desirable features. The child is free to move about, and he is adequately restrained if the harness system is properly adjusted and anchored. Effective harness systems can probably be produced at modest cost.

There certainly can be no objection to the upper torso restraint provided by a good harness system. Indeed, this is a very important feature which is required because of the child's special skeletal structure.

On the other hand, restraints which are anchored to inadequate structures or which allow excessive motion of the child in a crash cannot be condoned. Actual thirty mile-per-hour, sixteen g dynamic sled tests of child harnesses anchored as you recommend have shown that a severe problem exists with the anchorage system. Quoting the University of Michigan Highway Safety Research Institute Report, Child Seat and Restraint Systems Test Program, DOT/MS-000-376, "In the test at 30 mph the adult seat back broke away due to the load imposed by the restraint system tether. This allowed the dummy to move forward far enough to cause potential contact with the vehicle interior." This test was conducted using a heavy duty Bostrom truck bucket seat and utilized only the thrity-pound, three-year-old child dummy, restrained by a Sears small harness. The present typical seat back strengths are, thus, inadequate to support a harness system which depends upon the seat back. It is our intention to encourage improvements in seat back strength for automobile production by future rule making action.

Since your harness is recommended for children up to fifty pounds and since most passenger car seats are not as strong as the test seat, we expect the situation to be even more serious in realistic usage conditions which also normally encounter appreciably higher load levels in thirty mile-per-hour crashes. This is why we object to your system of anchorage. Thus, our position is as stated in our previous letter to you.

We hope that you will consider other methods of anchoring your child harness which will prevent seat back failure and resulting excessive occupant excursions.

We appreciate your sincere interest and concern in this matter. We emphatically do believe that child harnesses play a vital role in child restraints.

ID: nht72-4.22

DATE: 03/17/72

FROM: AUTHOR UNAVAILABLE; Francis Armstrong; NHTSA

TO: Electrical Testing Laboratories, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: Thank you for your letter dated January 19, 1972, to Mr. Eugene Laskin, regarding questions you have reisting to interpretations of demonstration procedure descriptions contained in paragraphs 5.2j and 5.2k of Federal Motor Vehicle Safety Standard (FMVSS) No. 209.

The answers to your questions are as follows:

1. Paragraph S5.2j - The phrase "within a period of 50 milliseconds" refers to the rise time of the acceleration only with the webbing movement measured from start of acceleration to lockup. The movement occurring after lockup due to natural webbing elongation and webbing compaction around the retractor spool is not measured. Webbing movement exclusive of the above-mentioned compaction and elongation can be measured by using a rotary of linear potentimeter reading out on a dual channel oscilloscope or oscillograph along with the readout of the time vs acceleration trace.

2. Paragraph s5.2k - The present standard does not specify any particular sequence for performing the 10,000 lockup cycles on emergency locking retractors as part of the total 50,000 cycles. This office presently has two laboratories performing the compliance tests in the following manner.

Laboratory A - One lockup cycle out of every five using the commercial Carlson cycling apparatus.

Laboratory B - 40,000 cycles of extension and retraction followed by 10,000 lockup cycles.

3. The methods presently employed by our test laboratories in actuating the lockup mechanism is to accelerate the retractor by means of compressed air, thus effecting the lockup.

This method of lockup is employed by our laboratories because a retractor that is sensitive both to vehicle acceleration and tilting would most frequently be locked by acceleration when installed in a vehicle.

This is not to say that you are compelled to cycle your retractors by accelerating them. If the locking mechanism is the name for both modes (e.g. a (Illegible Word)), it may make little difference whether the retractors are accelerated or tilted. However, if our test disclose a cycling failure, you will be obliged to show that your method was, in fact, equivalent to ours.

Should you require any further details or information regarding the test procedure for emergency locking retractors, please contact Mr. R. Jasinski of this office.

Thank you for your interest in auto safety.

ID: nht72-4.23

DATE: 05/12/72

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: United States Testing Company, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of April 5, 1972, in which you suggested that S4.3(d)(3) of Motor Vehicle Safety Standard No. 209 is not appropriate for buckles located between the front seats.

Although you are correct in saying that the requirement was originally developed to guard against the buckle's being opened by the pressure of the steering wheel, there is a chance that compressive forces will also affect buckles located between the seats. Even though the tests may be more difficult to administer, these buckles are not exempt under the present version of the standard, and it is not correct to say that the requirement is not applicable to them.

We do not suggest by this that the requirement could not be changed in response to an adequately supported petition. However, the requirement as it now stands applies to all buckles, wherever located.

ID: nht72-4.24

DATE: 07/20/72

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: The Standard-Triumph Motor Co., Ltd.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of June 28, 1972, in which you requested formal confirmation of the interpretation of S4.3(c) of Motor Vehicle Safety Standard No. 209 given you informally on June 22.

The requirements of S4.3(c) apply to bolts used to secure the pelvic restraint of a seat belt assembly. They do not apply to bolts used to secure the upper torso restraint. Bolts for the upper torso restraint are therefore regulated with respect to their strength only by the assembly performance requirements of S4.4(b).

The reference to "shoulder bolts" in S4.3(c) relates to the design of the bolt and not to the manner of its use. Pelvic restraints are often attached to the vehicle by such bolts, hence the reference to them.

ID: nht72-4.25

DATE: 09/18/72

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: British Standards Institution

TITLE: FMVSS INTERPRETATION

TEXT: This is in further reply to your letter of July 26, 1972, concerning the seat belt retractor test protector test procedures of section S5.2(k) of Motor Vehicle Safety Standard No. 209.

In our initial reply of August 21, we stated that the belt was to be retracted completely during the cycling, even though some vehicle installations might prevent complete retraction. After further examining the consequences of this position, we have concluded that it is in error.

The intent of the cycling sequence is to reflect the normal use of the belt over time. If the belt is designed to be installed in a vehicle in such a manner that during normal cycling a part of the webbing cannot be wound onto the retractor, a compliance test should employ the same restrictions of movement. We therefore conclude that you are correct in considering a belt to be fully retracted for purposes of Standard No. 209 when it is retracted as fully as the geometry of its installation permits.

Sincerely,

L R Schneider -- Chief Counsel, US Department of Transportation, National Highway Traffic Safety Administration

July 26, 1972

Dear Sir

F M V S S 209

We are writing as a National Test Laboratory concerned with automotive safety testing and, in particular, seat belt assemblies to your specifications. Some parts of the specification are open to interpretation and we are, of course, concerned that we should operate our test procedure in the accepted manner.

In particular, we would request that you confirm our test methods in connection with Clause S5.2(k) "Performance of retractor". In the case of emergency locking retractors, we proceed as follows:-

1) Corrosion test.

2) Manual withdrawal retraction for 25 cycles.

3) 2500 cycles from full extension to full retraction with an application of 20 lbs force at full extension.

Note (i) As this force is dynamically applied, the mass concerned is less than 20 lbs.

(ii) Full retraction is assumed to mean the full possible retraction of the assembly when installed in a motor vehicle. This will be less than the capability of the retractor, but reflects the practical conditions providing the installation data is obtained from the belt submittor.

4) Temperature resistance test.

5) 2500 additional cycles as (3)

6) Dust test.

7) Manual withdrawal and retraction for 25 cycles.

8) For emergency locking retractors, 45000 cycles operated between the limits of 50% extraction and 100% extraction.

Note (i) The stroke will therefore be half of that applied for the initial 5000 operations and will fully extract the webbing on each occasion.

(ii) Because full extraction occurs, the 20 lbs force will be applied during the 45000 operations as well as the previous 5000 operations.

9) During the initial 5000 operations, 1000 locking operations occur and during the final 45000 operations, 9000 locking operations occur. The locking operations are applied at any point between 50% extraction and 100% extraction.

10) The 20 lbs force is applied on every cycle including the locking cycles.

We should be grateful for your assistance in this matter as a considerable quantity of test work is awaiting clarification of this particular test procedure.

Yours faithfully for Director, RAC DANDY --Senior Engineer Head of Mechanical Section

ID: nht72-4.26

DATE: 03/16/72

FROM: AUTHOR UNAVAILABLE; Robert L. Carter; NHTSA

TO: Wingard Limited

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of February 10, 1972, regarding interpretation of certain parts of Federal Motor Vehicle Safety Standard No. 209, Seat Belt Assemblies.

In regard to your question on performance of retractors, the standard specifies that "an emergency-locking retractor or a non-locking retractor attached to upper torso restraint shall be subjected to 45,000 additional cycles of webbing withdrawal and retraction between 50 and 100 percent extension." This requirement applies to all emergency-locking retractors whether attached to the pelvic or upper torso restraint and only to those non-locking retractors that are attached to the upper torso restraint.

In regard to the 45,000 additional cycles, one cycle consists of extending the webbing from 50 to 100 percent extension and return to 50 percent.

Please do not hesitate to contact us if we can be of further assistance.

ID: nht72-4.27

DATE: 01/01/72 EST.

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: British Standards Institution

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of July 26, 1972, on the subject of seat belt retractor testing under S5.2(k) of Motor Vehicle Safety Standard No. 209.

Your outline of the emergency locking retractor test procedure is essentially correct. During the initial 5,000 cycles, however, the belt is to be retracted completely, even though some vehicle installations may prevent complete retraction. The assumption in (3)(ii) of your letter is therefore incorrect.

The remaining points in your interpretation are correct.

Sincerely,

ATTACH.

British Standards Institution

L R Schneider -- Chief Counsel, U S Department of Transporatation, National Highway Traffic Safety Administration

JULY 26, 1972

Dear Sir

F M V S S 209

We are writing as a National Test Laboratory concerned with automotive safety testing and, in particular, seat belt assemblies to your specifications. Some parts of the specification are open to interpretation and we are, of course, concerned that we should operate our test procedure in the accepted manner.

In particular, we would request that you confirm our test methods in connection with Clause S5.2(k) "Performance of retractor". In the case of emergency locking retractors, we proceed as follows:-

1) Corrosion test.

2) Manual withdrawal retraction for 25 cycles.

3) 2500 cycles from full extension to full retraction with an application of 20 lbs force at full extension.

Note (i) As this force is dynamically applied, the mass concerned is less than 20 lbs.

(ii) Full retraction is assumed to mean the full possible retraction of the assembly when installed in a motor vehicle. This will be less than the capability of the retractor, but reflects the practical conditions providing the installation data is obtained from the belt submittor.

4) Temperature resistance test.

5) 2500 additional cycles as (3).

6) Dust test.

7) Manual withdrawal and retraction for 25 cycles.

8) For emergency locking retractors, 45000 cycles operated between the limits of 50% extraction and 100% extraction.

Note (i) The stroke will therefore be half of that applied for the initial 5000 operations and will fully extract the webbing on each occasion.

(ii) Because full extraction occurs, the 20 lbs force will be applied during the 45000 operations as well as the previous 5000 operations.

9) During the initial 5000 operations, 1000 locking operations occur and during the final 45000 operations, 9000 locking operations occur. The locking operations are applied at any point between 50% extraction and 100% extraction.

10) The 20 lbs force is applied on every cycle including the locking cycles.

We should be grateful for your assistance in this matter as a considerable quantity of test work is awaiting clarification of this particular test procedure.

Yours faithfully for Director

R A C DANDY -- Senior Engineering; Head of Mechanical Section

ID: nht72-4.28

DATE: 03/08/72

FROM: JOHN G. WOMACK FOR RICHARD B. DYSON -- NHTSA

TO: Volvo, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of February 23, 1972, in which you posed three questions concerning the test procedures of Standard 209.

Your first question concerns the passage in S5.2(j) which states that the retractor is subjected to an acceleration of 0.70 within a period of 50 milliseconds. . . . ' Your question is whether the measurement of withdrawal begins at the caset of acceleration or at the point at which an acceleration of 0.70 is achieved. Our answer is that the measurement begins at the onset of acceleration. The withdrawal that occurs within the 50 millisecond rise time will be included in determining whether the 1 inch limit has been exceeded.

Your second question concerns the sequence in which the retractor locking mechanism will be activated under S5.2(k). It is your understanding that the 10,000 locking cycles will be evenly distributed among the total 50,000 cycles. Because the standard is silent as to the sequence of testing, an even distribution is not the only test method that could be used. At the present time, the agency has one contractor who is testing in this manner and one who is testing with 40,000 cycles of extension and retraction followed by 10,000 lockup cycles. If it should prove that the latter method is more severe, however, due to the excessive wear on the same spot that you anticipated, we would (Illegible Word) to use that method and conduct our tests by evenly distributing the lockup cycles.

Your third question concerns the manner in which lockup is to be achieved during the cycling test for retractors that lock either by acceleration or by tilting. The intent of the cycling procedures is to duplicate the usage actually encountered by a retractor in a vehicle. If the retractor is sensitive to webbing withdrawal and to the acceleration of the vehicle, then the lockup mode that would be (Illegible Word) often stressed over the retractor's lifetime would be the webbing withdrawal mode and the 10,000 cycles would be cycles of lockup through webbing withdrawal. If the retractor is sensitive only to vehicle acceleration and to tilting,the most frequent cause of lockup would be vehicle acceleration and our tests will be conducted by accelerating the retractor. This is not to say that you are compiled to cycle year retractor by accelerating them. If the locking mechanism is the same for both modes (e.g. a pendulum), it may make little difference whether the retractors are accelerated or tilted. However, if our tests disclose a cycling failure, you will be obliged to show that your method was in fact equivalent to ours.

ID: nht72-4.29

DATE: 09/12/72

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: Cody Chevrolet Inc.

TITLE: FMVSR INTERPRETATION

TEXT: This is in reply to your letter of August 1, 1972, to the attention of Mr. Jerome Palist of our White Plains, New York Office, concerning certification requirements for a vehicle which you describe and indicate will be used by a college to transport ball teams and school personnel, but will not be equipped with flashing lights or other special school bus equipment. You apparently wish to know whether you must consider this vehicle as a school bus for purposes of certification to Federal requirements.

"School bus" is defined in the motor vehicle safety standards to mean a bus "designed primarily to carry children to and from school, but not including buses operated by common carriers in urban transportation of school children" (49 CFR 571.3). Based upon the description you provide, the NHTSA would not consider the vehicle you describe to be a school bus. For purposes of certification to Federal requirements (49 CFR Parts 567 and 568), therefore, "gross vehicle weight rating" should not be computed under the minimum values specified for school buses. In addition, the requirement that vehicle type be inserted on the certification label should be met by inserting, "BUS."

This letter should not be construed to mean that the NHTSA takes a position as to whether this vehicle need, under State law, conform to requirements for school buses. The State must determine the scope and application of its own laws.

ID: nht72-4.3

DATE: 09/20/72

FROM: AUTHOR UNAVAILABLE; Lawrence R. Schneider; NHTSA

TO: Docket 69-7

TITLE: FMVSS INTERPRETATION

TEXT: SUBJECT: Interpretation of Dummy Placement for Crash Test Requirements of S4.1.2.3.1(d) and (e).

A Ford Motor Company representative has informally noted that Docket 69-7, Notice 16, published February 24, 1972, does not clearly indicate whether, in S4.1.2.3.1(d) and (e), three dummies are simultaneously placed in all front seating positions for a single crash test, or whether two separate crashes are conducted, with two dummies in the outboard front seats for a S4.1.2.3.1(d) crash and a single dummy in the center front seat for a S4.1.2.3.1(e) crash.

Although a manufacturer may choose, for reasons of convenience, to conduct a combined crash test or individual crash tests for S4.1.2.3.1(d) and (e), the test intended by S4.1.2.3.1 is a combined test and the NHTSA will therefore conduct its compliance tests with dummies simultaneously placed in all front seating positions.