ID: nht94-2.68

TYPE: Interpretation-NHTSA

DATE: May 5, 1994

FROM: John Womack -- Acting Chief Counsel, NHTSA

TO: Randolph Schwarz

TITLE: None

ATTACHMT: Attached to letter dated 9/30/93 Est. from Randolph Schwarz to John Messera (OCC-9211)

TEXT:

This responds to your letter to Mr. John Messera of NHTSA, requesting an interpretation of Federal Motor Vehicle Safety Standard No. 116; Motor vehicle brake fluids. Your letter has been referred to my office for a response. As a consumer retrofitting your vehicle with DOT 5 brake fluid, you had several questions concerning the possible effects that an ingredient in the brake fluid might have on elastomers used in brake systems. Your questions are answered below.

You described "seal swelling additives" added to DOT 5 brake fluid, that contact various elastomers in the brake system. Your first question was, when brake fluid manufacturers combine additives with brake fluid, should consumers be concerned with the c ombined fluids' compatibility with various elastomers used in braking systems?

Standard No. 116 defines, at S4. Definitions, brake fluid as a liquid designed for use in a motor vehicle hydraulic brake system where it will contact elastomeric components made of: styrene and butadiene rubber (SBR); ethylene and propylene rubber (EPR) ; polychlorophene (CR) brake hose inner tube stock; or natural rubber (NR). In order to minimize failures in hydraulic braking systems, Standard No. 116 specifies minimum performance standards for brake fluids. These performance standards include tests for styrene and butadiene rubber cups,the most common type of elastomer in a hydraulic brake system. The brake fluid manufacturer must certify that the brake fluid complies with Standard No. 116. (See S5.2.2(d).)

While DOT 5 brake fluid must meet Standard No. 116, the specific ingredients in the fluid are not regulated by the standard. However, in addition to compliance with Standard No. 116, brake fluid manufacturers must ensure that the fluid is free of safety -related defects under the National Traffic and Motor Vehicle Safety Act. Sections 151-159 of the Safety Act concern the recall and remedy of products with defects related to motor vehicle safety. In the event that the brake fluid manufacturer or NHTSA determines that the brake fluid contains a safety related defect, the brake fluid manufacturer would be responsible for notifying purchasers of the defective brake fluid and remedying the problem free of charge.

In your letter, you stated that you are retrofitting a vehicle with DOT 5 brake fluid. If your vehicle contained a brake fluid other than DOT 5 in its brake system, we recommend that the old fluid be flushed completely out of the brake system, before be ing replaced with DOT 5. This is necessary to ensure that the DOT 5 brake fluid does not mix with any other brake fluid type.

Your second question was whether DOT 5 brake fluid's compliance with

Standard No. 116 ensures compatibility with elastomers. The answer is yes, for SBR elastomers. Further, besides Standard No. 116, the brake fluid manufacturer is subject to sections 151-159 of the Safety Act, that were previously discussed. At this ti me, NHTSA is not aware of safety related defects resulting from other ingredients used with brake fluid.

Your third question was whether Standard No. 116 only addresses SBR compatibility with brake fluid. Standard No. 116, at S4, addresses brake fluid that contacts four elastomer types. However, the tests specified in the standard are only of the most com monly used SBR cups.

Your fourth question was, if Standard No. 116 only mentions SBR elastomer, would it be advisable to add other elastomers to the specification, or to discuss elastomer compatibility on the brake fluid container?

Information discussing the elastomer compatibility of the brake fluid, or other ingredients, may be voluntarily placed on brake fluid containers. Standard No. 116 specifies information that brake fluid containers must carry. However, Standard No. 116 do es not prohibit manufacturers from noting on brake fluid containers, compatibility of the silicone brake fluid, or other ingredients, with various elastomers.

Finally, you asked what Standard No. 116 specifies as the maximum viscosity for DOT 5 brake fluid, at -40 degrees Fahrenheit. Standard No. 116 specifies, at S5.1.3 (o), that the maximum viscosity is 900 centistokes (cSt).

I hope that this information is helpful. If you have any further questions, please contact Dorothy Nakama of my staff at (202) 366-2992.

ID: nht93-6.29

DATE: September 2, 1993

FROM: Donald W. Vierimaa -- Vice President-Engineering, Truck Trailer Manufacturers Association

TO: John Womack -- Acting Chief Counsel, NHTSA

COPYEE: TTMA Engineering Committee; Tank Conference Engineering Committee; The 3M Company; Reflexite

TITLE: Conspicuity

ATTACHMT: Attached to letter dated 2/7/94 from John Womack to Donald W. Vierimaa (A42; Std. 108)

TEXT:

We request three interpretations pertaining to S5.7 of FMVSS 108.

Conversion from S1 to English linear dimensions

May we consider the following nominal English dimensions equivalent for the purpose of compliance with S5.7 of FMVSS 108?

FMVSS 108 English English Citation Item Metric (actual**) (nominal)

5.7.1.3(b) Length of 300 mm 11.8 inches 12 inches red or white +/- 150 mm +/- 5.9 inches +/- 6 inches block of (150 mm (5.9 inches (6 inches sheeting to 450 mm) to 17.7 in.) to 18 inches)

5.7.1.3(d) Width of Grade 50 mm min* 1.9 inches 2 inches DOT C2 sheeting

5.7.1.3(d) Width of Grade 75 mm min* 2.9 inches 3 inches DOT C3 sheeting

5.7.1.3(d) Width of Grade 100 mm min* 3.9 inches 4 inches DOT C4 sheeting

5.7.1.4(b) Edge of white 75 mm min. 2.9 inches 3 inches sheeting to any lamp

5.7.1.4(c) Edge of red 75 mm min. 2.9 inches 3 inches sheeting to an amber lamp

5.7.1.4.1(a) Height of 1.25 m 49.2 inches 49 inches horizontal sheeting on rear

5.7.1.4.1(b) Length of 300 mm min* 11.8 inches 12 inches sheeting in upper contours of trailer

5.7.1.4.2(a) Height of 1.25 m 49.2 inches 49 inches horizontal sheeting on side of trailer

5.7.1.4.2(b) Alternative 25 mm min* 0.98 inches 1 inch width of two strips of Grade DOT C2 sheeting and their separation 25 mm max 0.98 inches 1 inch

5.7.1.5 Sheeting 3 mm min 0.118 inches 1/8 (0.125) certification inch character height

5.7.1.5 Sheeting 300 mm max 11.8 inches 12 inches certification marking separation

5.7.2.2(b) Alternative 100 mm max 3.9 inches 4 inches reflex reflector center to center separation

5.7.2.3 Reflex 3 mm min 0.118 inches 1/8 (0.125) reflector inch certification character height

* Assumed to be minimum. ** Significant decimal places for comparison.

The nominal English dimensions without underlining would appear to be acceptable conversions since they exceed the minimum metric dimensions. The nominal English dimensions underlined would, however, exceed the metric maximum dimension.

SAE J1322 JUN85, "Preferred Conversion Values for Dimensions in Lighting - Inch-Pound Units/S1," describes how English units may be converted to S1 (metric) units, but does not describe how to convert S1 units to English Units.

Vertical Location of Rear and Side Sheeting Cargo tank trailers may have a "vertical" surface only at their "belt line" which may be as high as 90 inches (2.3 m) above the ground. Retroreflective sheeting could, however, be located much closer to the ground, but for some

cargo tank trailers this may place the sheeting on non-vertical surfaces. In our comment of March 31, 1992 to Docket No. 80-9; Notice 4 we stated that "it is not clear from the proposed rulemaking as to where retroreflective material should be placed on curved surfaces of tank and some dump trailers or angled surfaces of some dump trailers."

One manufacturer of retroreflective sheeting states that "the sheeting could be applied at a maximum angle of 30 degrees to the vertical." This manufacturer reports that "An angle greater than this provides less conspicuity as defined by NHTSA."

May retroreflective sheeting be located significantly higher than 1.25 m above the road surface if there is no vertical surface lower than this height without installing structure just for the sheeting?

Upper Contour Sheeting

May the horizontal and vertical sheeting to the right and left upper contours of the trailer body required per S5.7.1.4.1(b) be of the dimensions and location shown in the enclosed figures 1 through 5?

Since a number of trailer manufacturers are presently installing conspicuity treatments in accordance with S5.7 of FMVSS 108 as standard equipment or at the request of their customers, your timely response is desirable.

ID: nht93-4.4

DATE: May 19, 1993

FROM: Richard A. Zander -- Project Engineer, AlliedSignal Automotive Proving Grounds

TO: Office of Chief Council, NHTSA

TITLE: None

ATTACHMT: Attached to letter dated 3/23/94 from John Womack to Richard A. Zander (A42; Std. 105)

TEXT:

I am writing to obtain your official interpretation of the following statement in 49 CFR 57, 105 Section S5.1.4.2(a) "each vehicle with GVWR of 10,000 lbs. or less shall be capable of making 5 fade stops (10 fade stops on the second test) from 60 mph at a deceleration not lower than 15 fpsps for each stop, followed by 5 fade stops at the maximum deceleration attainable from 5 to 15 fpsps."

I am requesting your official interpretation of the phrase "at a deceleration not lower than 15 fpsps for each stop." As further reference Section S7.11.2.1 states "Attain the required deceleration within 1 second and, as a minimum, maintain it for the remainder of the stopping time."

Within the industry, I know of three different interpretations of this statement, there could by more:

1. The average deceleration for the stop must be greater than 15 fpsps. The average deceleration is calculated from one second after the stop begins to a vehicle speed of 5 mph.

2. After 1 second the deceleration can not drop below 15 fpsps even for an instant. If the deceleration drops below 15 fpsps at any time it is considered a failure even if the average deceleration is greater than 15 fpsps. 3. The average deceleration for the stop must be greater than 15 fpsps and the deceleration must be greater than 15 fpsps for at least 75% of the stop excluding the first second of the stop.

In the "Laboratory procedures for FMVSS No. 105-83, TP-105-83-00, dated January 31, 1984, page 1.49, data sheet No. 1.16 for the fade stops, requests the following information for the deceleration "Average Sust Decel" see pages 1 and 2 of Attachment A. Therefore, it appears that NHTSA's interpretation of the statement "at a deceleration not lower than 15 fpsps for each stop" is "the average sustained deceleration."

Pages 3 & 4 of attachment A are a typical fade stops. The X axis is time and on the Y axis is deceleration and pedal force.

Interpretation ONE would consider these a pass because the average deceleration was greater than 15 fpsps and the pedal force did not exceed 150 lbs.

Interpretation TWO would consider these a fail because several data points fell below 15 fpsps. This interpretation appears to not consider the intent of the fade procedure. The intent being that a vehicle be capable of making multiple

high deceleration stops in a short period of time without drastic changes in effectiveness. Thus the recovery stops have a maximum and a minimum pedal force requirement based on the baseline check stops.

Maintaining an average deceleration of at least 15 fpsps insures adequate heat build up in the linings to determine if they will fade or drastically change effectiveness.

The deceleration could fall below 15 fpsps for short periods of time due to instrumentation noise or in stop fade which was not immediately compensated for by the driver. Interpretation THREE would consider these a pass because the average deceleration is greater than 15 fpsps and the deceleration is greater than 15 fpsps for 75% of the stop after the first one second.

Considering the intent of the fade procedure, the 75% requirement is not necessary to insure adequate heat build-up in the linings.

The NHTSA interpretation "average sustained deceleration" would also consider these a pass.

I am also requesting that you send the latest version of the test procedure for FMVSS No. 105 from the office of vehicle compliance. Please send to:

Richard Z. Zander Allied Signal Automotive Proving Grounds 3214 State Road 2 New Carlisle, IN 46552

Thank you for your time and effort to respond to my requests.

ATTACHMENT

Laboratory Procedures for Federal Motor Vehicle Safety Standard No. 105-83; TP-105-83-00; January 31, 1984. (Text omitted)

ID: nht94-6.1

DATE: May 5, 1994

FROM: John Womack -- Acting Chief Counsel, NHTSA

TO: Randolph Schwarz

TITLE: None

ATTACHMT: Attached to letter dated 9/30/93 Est. from Randolph Schwarz to John Messera (OCC-9211)

TEXT:

This responds to your letter to Mr. John Messera of NHTSA, requesting an interpretation of Federal Motor Vehicle Safety Standard No. 116; Motor vehicle brake fluids. Your letter has been referred to my office for a response. As a consumer retrofitting your vehicle with DOT 5 brake fluid, you had several questions concerning the possible effects that an ingredient in the brake fluid might have on elastomers used in brake systems. Your questions are answered below.

You described "seal swelling additives" added to DOT 5 brake fluid, that contact various elastomers in the brake system. Your first question was, when brake fluid manufacturers combine additives with brake fluid, should consumers be concerned with the combined fluids' compatibility with various elastomers used in braking systems?

Standard No. 116 defines, at S4. Definitions, brake fluid as a liquid designed for use in a motor vehicle hydraulic brake system where it will contact elastomeric components made of: styrene and butadiene rubber (SBR); ethylene and propylene rubber (EPR); polychlorophene (CR) brake hose inner tube stock; or natural rubber (NR). In order to minimize failures in hydraulic braking systems, Standard No. 116 specifies minimum performance standards for brake fluids. These performance standards include tests for styrene and butadiene rubber cups,the most common type of elastomer in a hydraulic brake system. The brake fluid manufacturer must certify that the brake fluid complies with Standard No. 116. (See S5.2.2(d).)

While DOT 5 brake fluid must meet Standard No. 116, the specific ingredients in the fluid are not regulated by the standard. However, in addition to compliance with Standard No. 116, brake fluid manufacturers must ensure that the fluid is free of safety-related defects under the National Traffic and Motor Vehicle Safety Act. Sections 151-159 of the Safety Act concern the recall and remedy of products with defects related to motor vehicle safety. In the event that the brake fluid manufacturer or NHTSA determines that the brake fluid contains a safety related defect, the brake fluid manufacturer would be responsible for notifying purchasers of the defective brake fluid and remedying the problem free of charge.

In your letter, you stated that you are retrofitting a vehicle with DOT 5 brake fluid. If your vehicle contained a brake fluid other than DOT 5 in its brake system, we recommend that the old fluid be flushed completely out of the brake system, before being replaced with DOT 5. This is necessary to ensure that the DOT 5 brake fluid does not mix with any other brake fluid type.

Your second question was whether DOT 5 brake fluid's compliance with

Standard No. 116 ensures compatibility with elastomers. The answer is yes, for SBR elastomers. Further, besides Standard No. 116, the brake fluid manufacturer is subject to sections 151-159 of the Safety Act, that were previously discussed. At this time, NHTSA is not aware of safety related defects resulting from other ingredients used with brake fluid.

Your third question was whether Standard No. 116 only addresses SBR compatibility with brake fluid. Standard No. 116, at S4, addresses brake fluid that contacts four elastomer types. However, the tests specified in the standard are only of the most commonly used SBR cups.

Your fourth question was, if Standard No. 116 only mentions SBR elastomer, would it be advisable to add other elastomers to the specification, or to discuss elastomer compatibility on the brake fluid container?

Information discussing the elastomer compatibility of the brake fluid, or other ingredients, may be voluntarily placed on brake fluid containers. Standard No. 116 specifies information that brake fluid containers must carry. However, Standard No. 116 does not prohibit manufacturers from noting on brake fluid containers, compatibility of the silicone brake fluid, or other ingredients, with various elastomers.

Finally, you asked what Standard No. 116 specifies as the maximum viscosity for DOT 5 brake fluid, at -40 degrees Fahrenheit. Standard No. 116 specifies, at S5.1.3 (o), that the maximum viscosity is 900 centistokes (cSt).

I hope that this information is helpful. If you have any further questions, please contact Dorothy Nakama of my staff at (202) 366-2992.

ID: nht95-4.57

TYPE: INTERPRETATION-NHTSA

DATE: October 14, 1995

FROM: Samuel J. Dubbin -- Chief Counsel, NHTSA

TO: Bob Clement -- U.S. House of Representatives

TITLE: NONE

ATTACHMT: Attached to 10/03/95 Letter from Bob Clement to Ricardo Martinez

TEXT: Dear Congressman Clement:

Thank you for your letter of October 3, 1995, enclosing correspondence from Mr. Dale Allen Pommer concerning his attempts to have a third seat belt installed in the back seat of his 1983 Chevrolet S-10 Blazer. Mr. Pommer has been told that this cannot b e done because of safety laws. You requested comments on Mr. Pommer's letter. As explained below, there is not Federal prohibition against the modification Mr. Pommer would like done to his vehicle. However, Federal law does place some limits on how t he modification is done. The installation of additional seat belts must be done in a way that does not compromise the performance of the existing seat belts.

Some background information about the agency may be useful. NHTSA has the authority to issue federal motor vehicle safety standards applicable to new motor vehicles and new items of motor vehicle equipment. Federal motor vehicle safety standards are mi nimum standards, and may be exceeded by manufacturers. Federal law prohibits the manufacture or sale of any new motor vehicle or new item of motor vehicle equipment which does not conform to all applicable Federal motor vehicle safety standards in effect at the time of manufacture.

After the first retail sale, there is a limit on the modifications that can be made by certain businesses to vehicles. Manufacturers, distributors, dealers, and repair businesses are prohibited from "knowingly making inoperative" any device or element o f design installed on or in a motor vehicle in compliance with an applicable safety standard (49 USC @ 30122). In general, the "make inoperative" prohibition would require a business which modifies motor vehicles to ensure that it does not remove, disco nnect, or degrade the performance of safety equipment installed in compliance with an applicable safety standard.

A safety belt is an item of motor vehicle equipment and all safety belts sold in the United States must be certified as complying with Standard No. 209, Seat Belt Assemblies, regardless of whether the belts are installed as original equipment in a motor vehicle or sold as a replacement part, Standard No. 209 sets forth strength, elongation, webbing width, durability, and other requirements for seat belt assemblies. The additional belt which might be added to Mr. Pommer's vehicle must comply with the re quirements of Standard No. 209.

In addition to Standard No. 209, the agency has issued two additional safety standards which apply to new vehicles and affect safety belts: Standard No. 208, Occupant Crast Protection, which sets forth requirements for occupant protection at the various seating positions in vehicles, and Standard No. 210, Seat Belt Assembly Anchorages, which establishes strength and location requirements for seat belt anchorages. The 1983 Chevrolet S-10 Blazer would have been required to have, at a minimum, a lap belt at each rear designated seating position.

A "designated seating position" is defined by NHTSA regulations as:

any plan view location capable of accommodating a person at least as large as a 5th percentile adult female, if the overall seat configuration and design and vehicle design is such that the position is likely to be used as a seating position while the vehicle is in motion . . . Any bench or split-bench seat . . . having greater than 50 inches of hip room (measured in accordance with SAE Standard J1100(a)) shall have not less than three designated seating positions.

Since the 1982 Chevrolet S-10 Blazer had a rear bench seat with 49.5 inches of hip room, that seat was required to have a minimum of two lap belts.

The "make inoperative" prohibition discussed earlier would not prohibit a business from adding a third seat belt to Mr. Pommer's vehicle. In addition, the anchorages would not have to comply with Standard No. 210. However, in adding the third seat belt , is is possible that the existing belts and anchorages would have to be relocated. The businesses contacted by Mr. Pommer may be concerned that the belts and anchorages could not be removed and replaced without "making inoperative" the compliance of th ose belts and anchorages.

I hope this information has been helpful.

ID: nht68-2.48

DATE: 09/27/68

FROM: AUTHOR UNAVAILABLE; William Haddon, Jr.; NHTSA

TO: United States Senate

TITLE: FMVSS INTERPRETATION

TEXT: Thank you for your letter of August 13, 1968, calling my attention to Mr. Paul Johnston's comments and suggestions on the requirements for school bus signal lamps as specified in Motor Vehicle Safety Standard No. 108.

As Mr. Johnston pointed out, Standard No. 108, effective January 1, 1969, provides for optional use of either the eight-lamp or four-lamp signal system. This optional provision was adopted after careful consideration of the comments and recommendations which were received in response to the Notice of Proposed Rule Making as published in the Federal Register on February 3, 1967. The "Minimum Standards for School Buses", as published by the National Conference on School Transportation, and the regulations governing minimum standards for school buses in various states were also considered during development of the optional provision for signal lamp systems. Results of our studies and investigations indicated that approximately forty states were using either the four-lamp or eight-lamp signal system. Other states were using the adopted system with only minor variations in the installation and operational requirements.

Standard No. 108, effective January 1, 1969, was published in the Federal Register on December 16, 1967. Under the procedural rules of the Federal Highway Administration, any person adversely affected by this order may petition the Administrator under Part 216, Subchapter B, Section 216.31 or Section 216.35, published in the Federal Register on November 17, 1967, a copy of which is enclosed. No petition of the adopted requirements for school bus signal lamps has been filed.

Although we do not dispute the safety benefits which Mr. Johnson claims for a six-lamp system, I must emphasize that our long-range objective is the adoption of one nationwide system. Even with the presently adopted systems, a motorist could be faced with the problem of interpreting two sets of signals during a very short time period. This problem will become more prevalent with the anticipated increase in rapid interstate traffic. To permit the use of a third optional system, six-lamp or other, would further complicate the situation.

Standard No. 108 applies only to new school buses manufactured on or after January 1, 1969. Retrofitting of buses presently in operation is not required. Since Iowa's fleet of buses is presently equipped with a six-lamp system, it appears that considerable data on the effectiveness of this system could be accumulated from this fleet during the next several years, or until such time that a single nationwide system is proposed. We will be pleased to carefully review and consider any such data which Mr. Johnson can provide in the future.

In summary, it is the position of this Bureau that the provision of Standard No. 108 permitting optional use of either the four-lamp or eight-lamp signal system is reasonable, practicable and in the interest of highway safety. Therefore, we do not believe that a change in this provision to permit optional use of a third or six-lamp system is justified.

We have reviewed our files with respect to the written and personal contacts Mr. Arthur Roberts, Director of Pupil Transportation, has had with this Bureau.

This review indicates that the correspondence from Mr. Roberts was submitted in response to the Notice of Proposed Rule Making on Standard No. 112 (subsequently combined with Standard No. 108) as published in the Federal Register on February 3, 1967. It is not the practice of the Bureau to reply individually to the numerous responses received from published rule making notices, which often run to thousands of pages. However, a summary of the comments represented by the responses and the disposition of these comments is presented in the preamble to Standard No. 108 as published in the Federal Register on December 16, 1967. With respect to Mr. Roberts visit on May 7, 1968, the topics of discussion related primarily to the technical requirements of Standard No. 108 and other information relative to the merits of converting Iowa's school buses to either the four-lamp or eight-lamp system. Our understanding was that Mr. Roberts received the information he was seeking at the time of his visit and that no follow-up correspondence was necessary on our part.

ID: nht70-2.24

DATE: 09/03/70

FROM: AUTHOR UNAVAILABLE; Douglas W. Toms; NHTSA

TO: General Motors Corporation

TITLE: FMVSR INTERPRETATION

TEXT: On August 13, 1970, you petitioned, on behalf of General Motors Corporation, for reconsideration of the amendment of 49 CFR 571.3, published on July 14, 1970 (35 F. R. 11242), which established a definition of "fixed collision barrier". The views presented in your petition have been carefully considered. For the reasons stated below, your petition is denied.

You argued that the phrase "absorb no significant portion of the vehicle's Kinetic energy" was subjective, and therefore not in accord with the statutory requirement that standards be stated in objective terms. This argument is without merit. It appears to be based on the misconception that the purpose of the definition is to describe, or prescribe standards for, a manufacturer's test barrier, as evidenced by your statement that it "gives manufacturer no guidelines for determing whether or not he has built a barrier which complies with the definition." The Bureau does not intend that manufacturers should build barriers to "comply with the definition." As stated in the notice,

"this is not intended to be a description of an actual test barrier. It is a device used in various standards to establish required quantitative performance levels of a vehicle in a crash situation, and means simply that the vehicle must meet the requirement no matter how small an amount of energy is absorbed by the barrier."

Far from being subjective, the definition is mathematically precise. As the energy absorption of the barrier approaches zero as a limit, the performance characteristic being measured must remain at or above the minimum stated in the standard.

From a practical standpoint, the definition is an important aid in regulation, and is a help to all parties in that a potential source of controversy concerning compliance with the standards is removed. It simply means that when the Bureau crash-tests a vehicle, the vehicle must meet the requirement no matter what the energy-absorption properties of the barrier, and therefore there is no room for argument on the differing properties of the Bureau's and the manufacturer's test barriers. The purpose of the standards is to regulate vehicles and equipment, not test barriers; manufacturers may use whatever barriers or tests they wish to ensure compliance It is a reasonably simple matter to erect a barrier that absorbs only a minute fraction of an impacting vehicle's energy. A conscientious manufacturer should therefore have no difficulty in determining whether a particular design will meet a standard.

Your petition also argued that the definition was impracticable because

"there is no known method of measuring the amount of energy absorbed by a barrier. Therefore, there is no way that the manufacturer could even attempt to determine whether or not his barrier complied with the definition, and, more importantly, whether or not his vehicle when tested complied with the performance requirements of the standards."

The energy absorption of a barrier is a direct function of the movement of the barrier during the impact. To be sure, there are other properties, such as its effective mass and elasticity, that also are factors in energy absorption. But it is clear that as the barrier movement approaches zero, the energy absorption also approaches zero; and the barrier movement can be measured, as you indicated by your recommendation that a specified amount of movement be allowed. In all cases where the vehicle has a tangible margin of safety performance over the required minimum, therefor, a manufacturer will have no difficulty in determining that his vehicle complies,

If our standards "allowed" barrier movement, it would be far more difficult to establish conclusively that a given vehicle did not meet the standard, since it would always be open to the manufacturer to argue that the Bureau's barrier did not move as far, and consequently did not absorb as much energy, as the standard allowed. To the extent that there may be a small degree of uncertainty as to the variance is the vehicle test performance caused by the variance of a barrier from zero absorption, that uncertainty must rest with the manufacturer, who is free to design into his vehicles whatever margin of performance he desires.

This matter was thoroughly considered by the Bureau, and the opinions of knowledgeable members of the public were sought and carefully evaluated. For these reasons, your petition for reconsideration must be denied.

We appreciate your cooperation in the field of motor vehicle safety.

ID: nht90-1.4

TYPE: Interpretation-NHTSA

DATE: 01/01/90 EST

FROM: Stephen W.A. Pickering -- Valley Sales Inc.

TO: Stephen R. Kratzke -- Deputy Assistant Chief Counsel for Rulemaking, NHTSA

TITLE: None

ATTACHMT: Attached to 5 photos (graphics omitted); Also attached to Report on Test of Sofa Bar according to FMVSS No. 210 (text and graphics omitted); Also attached to Test Report Number 096441-89 (text and graphics omitted) (test results are available i n the file); Also attached to letter dated 9-10-90 from P.J. Rice to S. Pickering (A36; Std. 111, Std. 202, Std. 207; Std. 208; Std. 209; Std. 210)

TEXT:

Per our conversation by telephone please find enclosed photographs, drawings, descriptions, and accompanying data that I have available at this time concerning the product I am making, trade named "RUMBLE SEAT". The product is a rear facing auxilary seat ing system for Pick up trucks.

It is a unique product that I have initiated a patent application on and a product which I have designed to be as safe and comfortable as I can.

It is my wish to be in compliance with any applicable codes and standards that I am now aware of or those I become aware of at a later date.

I have used for reference the Code of Federal Regulations (CFR) Title 49 containing National Highway Traffic Safety Administration (NHTSA) Standards.

I have listed those standards that I feel may apply to my product, and those I feel I am in compliance with, Or at least those I feel I am NOT out of compliance with.

CODE 49-Standard 209 "Seat belt Assemblies"

I believe I am in compliance by the "DEFINITIONS" S3 by using a Type 1 seatbelt assembly a "LAP BELT FOR PELVIC RESTRAINT" please see enclosed test data on the seatbelts I am now using.

CODE 49 Standard 210 "Seatbelt Assembly Anchorages"

I have enclosed pictures, drawings, and test result data for you to determine compliance, I feel I comply here also.

CODE 49 Standard 571.208 "Occupant Crash Protection"

S4.1.1.3.2. "Convertibles and open body type vehicles" provides that either Type 1 or Type 2 seatbelt assemblys may be used. I am using a Type 1 belt assembly Manual Seatbelts, again, please find test data.

CODE 49 Standard S571.111 "REARVIEW MIRRORS"

My product provides seating for 2 (two) people with space between each

seat to help minimize interference with drivers "FIELD OF VIEW" When the seats are un-occupied with the headrests down there is very minimal interference with view and does not compromise, my compliance status at all.

CODE 49 Standard 571.202 "HEAD RESTRAINTS"

I feel I need HELP with interpertation and compliance here.

Because my product sets directly behind the cab, facing the rear of the pick-up bed, any adult would find the back of the head in close proximity to the outside rear of the cab.

It seemed prudent, therefore, to offer some sort of protection

While there may be several ways to attempt to accomplish this I need to settle on one that will be in compliance with the codes and standards of your bureau.

One way would be a stationary headrest in corporated in the product.

Another may be a stationary headrest permanently affixed to the cab.

Another may be an ADJUSTABLE headrest permanently affixed to the cab.

Another may be a removable headrest either on the product itself, or on the cab. (I WOULD FAVOR THIS SYSTEM)

I decided an adjustable headrest incorporated into the product would be the best way to proceed.

There is one other choice that I have considered, and I am in the opinion that I may have an easier time with compliance. I briefly describe the other system in the enclosed explaination and drawing.

I am asking you to comment as to the possibility of compliance of each system described I have outlined here.

Thank you for your consideration and I hope to be in contact with you regarding my progress in complying with any applicable standards. ANY additional suggestions you may have would be helpfull.

enclosed:

1. test results of seatbelt systems from United States Testing Co. 2. Test results for seatbelt bar anchorage system from Stoutco. 3. Photographs and drawings of product seeking compliance. 4. Possible alternate headrest mounting systems. explaination a nd drawings.

(Photos and text are omitted but are available in the file.)

ID: nht92-5.28

DATE: July 7, 1992

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Michael Love -- Manager, Compliance Porsche Cars North America, Inc.

TITLE: None

ATTACHMT: Attached to letter dated 6/10/92 from Michael Love to Paul J. Rice (OCC 7401)

TEXT:

This responds to your letter of June 10,1992, requesting concurrence by this Office in your interpretation of the requirements of Standard No. 108 for the location of center highmounted stop lamps (CHMSL). Your letter was occasioned by mine of April 27, 1992, with respect to the design presented in your letter of April 3.

To summarize our earlier correspondence, Porsche wishes to install a CHMSL on the movable spoiler of its 911 Carrera, a configuration previously approved by this Office providing that all photometric and visibility requirements are met. However, S5.3.1.8 of Standard No. 108 requires that "If the lamp is mounted below the rear window, no portion of the lens shall be lower than 6 inches below the rear window on convertibles, or 3 inches on other passenger cars." Although Porsche's intended CHMSL meets this requirement with the spoiler in the extended position (when the car reaches 45 to 55 mph and slows to 9 to 12 mph), at other times, when the spoiler is lowered, the center lamp would be 7.5 inches below the window on the coupe, and 9.5 inches for the convertible. Because the CHMSL on the Carerra would not meet the locational requirements from a state of rest up to a minimum of 45 mph, we informed you that this design would not conform to Standard No. 108.

In your latest letter, you present the possibility of equipping the Porsche with two separate CHMSLs. The CHMSL discussed in your April letter, located at the trailing edge of the spoiler, would be activated when the spoiler had risen 35% from its at-rest position, and be deactivated at the time the spoiler lowers to 35%, from the at-rest position. The second CHMSL, located on the spoiler where it abuts the vehicle body and mounted at a complying height, would be activated when the vehicle is at rest, and when the spoiler is at heights less than 35% from the at-rest position, generally at times that the other CHMSL is deactivated. You expect that all photometric and height requirements of Standard No. 108 will be met in switching from one lamp to another while the spoiler is moving, though it might be necessary to have both lamps functioning together for a short period of time in order to fulfill photometric requirements.

A manufacturer's certification of compliance to the CHMSL requirements of Standard No. 108 is based upon the normal operation of motor vehicle equipment. The additional CHMSL you posit would appear to fulfill these requirements when the vehicle is at rest, and in low speed operation. Thus, for certification purposes, we regard this CHMSL as the one for which certification is supplied.

However, it appears that the spoiler in rising may affect the photometric conformance of the certification CHMSL. Under S5.3.1.1, when a part of a vehicle prevents a stop lamp from meeting its photometric output at any

applicable group of test points, any auxiliary stop lamp that meets these requirements may be provided. We interpret this as allowing the non-certification CHMSL to perform as a surrogate to the certification CHMSL at the point that conformance of the certification CHMSL is affected.

You have raised the possibility that it will be necessary to have both CHMSLs operating simultaneously for a short period of time in order to fulfill photometric requirements. While the meaning of this statement is not exactly clear, for purposes of this interpretation, it would appear to mean that simultaneous operation of both lamps might occur briefly when the rising spoiler masks the certification CHMSL at the same time the non-certification CHMSL is operating at a height below the minimum specified by Standard No. 108. Although in the past we have encouraged disabling of interior mounted CHMSLs when new ones are added to fixed spoilers, so that a vehicle will not be equipped with two permanent simultaneously operating CHMSLs, the situation here appears to differ. Under the circumstances outlined above, it does not appear that a noncompliance with Standard No. 108 would be created.

If our understanding is not correct, we would be willing to discuss the matter further.

ID: nht88-1.75

TYPE: INTERPRETATION-NHTSA

DATE: 03/17/88

FROM: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA

TO: LEON STEENBOCK -- ADMINISTRATIVE MANAGER, ENGINEERING FWD CORPORATION

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 02/10/89 FROM ERIKA Z. JONES -- NHTSA TO J. W. LAWRENCE, REDBOOK A33, STANDARD 124; LETTER DATED 10/05/88 FROM J. W. LAWRENCE TO ERIKA Z. JONES -- NHTSA, REQUEST FOR INTERPRETATION FMVSS 124 ACCELERATOR CONTROL SYSTEMS; OCC 2650

TEXT: Dear Mr. Steenbock,

This letter responds to your letter of last year asking whether it is permissible under Federal motor vehicle safety standard 124, Accelerator Control Systems (Standard 124), to install a locking hand throttle control in a new motor vehicle. I apologize for the delay in this response. The answer to your question is no.

While you do not describe what you mean by a "locking hand-throttle control" in your letter, I understood you to mean the following. Some vehicle design configurations have a hand-operated device on the steering column that connects to the throttle leve l. In most design configurations, a driver may operate this device either by a turning or push-pull action. This device is commonly referred to as a "hand-throttle control."

These hand-throttle controls have two common applications. First, vehicles designed to be operated by physically disabled persons sometimes use a hand-throttle, rather than a foot-pedal, as the means for applying the actuating force that regulates the t hrottle valves and vehicle acceleration. Second, on some commercial vehicles, a hand-throttle control can be part of a system that allows a driver to use a hand control to regulate the engine fuel supply, and so to operate a power-driven accessory such as a generator while the vehicle is stationary with the transmission out of "drive." While the intended use of a hand-throttle control in a commercial vehicle may be only to power such an accessory, a driver still could use the throttle to control vehicl e acceleration. Nothing in Standard 124 prohibits a manufacturer from installing a hand-throttle control in its vehicles.

Some hand-throttle controls have a mechanism that permits the driver to lock the throttle valves open in a position other than idle even after the driver removes the actuating force. When you asked about "locking hand-throttle controls," I understood yo u to be referring to this type of design.

2

These "locking hand throttle controls" are expressly prohibited by Standard 124. Paragraph S5.1 of that Standard requires that the throttle valves must be capable of returning to the idle position whenever the driver removes the actuating force. The pur pose of Standard 124 is to minimize the risk of accident due to ongoing runaway. (37 FR 7097, April 8, 1972.) Consequently, a locking hand-throttle control would increase the risk of the very harm Standard 124 was adopted to address.

I hope you find this information helpful. If you have further questions, please feel free to contact Joan Tilghman of my staff at (202) 366-2992.

Sincerely,

(EXCERPT FROM PRODUCT SAFETY AND LIABILITY REPORT DATED 04/02/88)

Leon Steenbock, administrative manager, FWD Corp., Clintonville, Wis., in a March 17 opinion, that it is not permissible under Standard No. 124 -- Accelerator Control Systems (Reference File, 901:0889) to install a locking hand throttle control in a n ew motor vehicle. These devices are expressly prohibited by the standard, Paragraph S5.1 of that standard requires that the throttle valves must be capable of returning to the idle position whenever the driver removes the actuating force. The purpose o f the standard is to minimize the risk of accident due to engine runaway. Consequently, a locking hand-throttle control would increase the risk of the very harm the standard was designed to reduce, Jones said.

7/1/87

Subject: FMVSS 124 Accelerator Control Systems

Attn: Erika Z. Jones:

having discussed this standard requirements with your office in the past, as they pertain to locking hand throttles controls, I was left with the interpretation that a vehicle with a locking hand throttle would not meet the requirements of this standard.

As I have never received a written opinion regarding lacking hand throttle controls would your office consider giving me a written opinion of this standard requirement in regards to the use of locking hand throttle controls.

Your earliest consideration would be appreciated.

Sincerely,

Leon Steenbock Administrative Manager, Engineering FWD Corporation