ID: nht95-6.16

TYPE: INTERPRETATION-NHTSA

DATE: August 21, 1995

FROM: Hugh J. Bode -- Reminger & Reminger Co., L.P.A.

TO: John Womack -- Acting Chief Counsel, NHTSA

TITLE: Application of Federal Motor Vehicle Safety Standard No. 124

ATTACHMT: ATTACHED TO 10/26/95 LETTER FROM JOHN WOMACK TO HUGH J. BODE (REDBOOK 4; STD. 124; VSA 30118)

TEXT: Dear Mr. Womack:

The purpose of this letter is to request that NHTSA confirm that the former National Traffic and Motor Vehicle Safety Act does not require a motor vehicle to continue to comply with any applicable Federal Motor Vehicle Safety Standard after it is sold to its first retail purchaser. Specifically, we ask that NHTSA confirm that a vehicle in use is not required to comply with Federal Motor Vehicle Safety Standard No. 124; Accelerator Control Systems, 49 CFR 571.124 (hereinafter "FMVSS 124"), after the first retail sale of the vehicle.

The vehicle at issue is a 1988 Dodge Ram 50 pickup which was manufactured by Mitsubishi Motors Corporation in Japan and distributed by Chrysler Corporation in the United States. The pickup was equipped with a Mikuni Model 32-35-DIDEF-328 carburetor. When it was first sold, the 1988 Dodge Ram 50 pickup truck was certified by Mitsubishi Motors Corporation as being in compliance with all then applicable Federal Motor Vehicle Safety Standards, including FMVSS 124.

As we understand it, former @ 108(a)(1)(A) of the National Traffic and Motor Vehicle Safety Act, 49 U.S.C. @ 30112(a), prohibits any person from manufacturing, selling or introducing into commerce any new motor vehicle unless the vehicle is in conformity with all applicable FMVSS. However, the Safety Act further provides that the requirement that a vehicle comply with all applicable FMVSS does not apply after the first purchase for purposes other than resale, i.e., the first retail sale of the vehicle. Safety Act former @ 108(b)(1), 49 U.S.C. @ 30112(b)(1). After the first retail sale, the only provision in the Safety Act that affects a vehicle's continuing compliance with an applicable FMVSS is set forth in former @ 108(a)(2)(A), 49 U.S.C. @ 30122(b), which prohibits certain persons from knowingly rendering inoperative a device installed in a motor vehicle in compliance with an applicable FMVSS.

We ask that you confirm the accuracy of the foregoing general statement of the applicability of the FMVSS under the Safety Act. In addition, we ask that you address the following specific questions concerning the application of FMVSS 124 to the 1988 Dodge Ram 50 pickup:

1. We ask NHTSA to confirm that FMVSS 124 is a standard that a given vehicle must comply with only at the time of the first retail sale of the vehicle.

2. We ask NHTSA to confirm that if a carburetor installed in a 1988 Dodge Ram 50 pickup truck met all the requirements of FMVSS 124 at the time of the truck's first retail sale, but, after the sale, due to in-service conditions, corrosion developed inside the carburetor so that the carburetor would not return to idle in accordance with the requirements of S5.1, S5.2, and S5.3 of FMVSS 124, that circumstance would not render the vehicle in violation of FMVSS 124.

3. We ask NHTSA to confirm that all of the performance standards imposed by FMVSS 124 are contained in S5.1, S5.2 and S5.3 of FMVSS 124 and that S2 headed PURPOSE does not impose any separate regulatory obligation beyond those contained in S5.

4. We ask you to confirm that the performance standard set forth in FMVSS 124 does not contain any requirement relating to durability or corrosion resistance.

We thank you in advance for your assistance in confirming these points.

ID: nht95-3.93

TYPE: INTERPRETATION-NHTSA

DATE: August 21, 1995

FROM: Hugh J. Bode -- Reminger & Reminger Co., L.P.A.

TO: John Womack -- Acting Chief Counsel, NHTSA

TITLE: Application of Federal Motor Vehicle Safety Standard No. 124

ATTACHMT: ATTACHED TO 10/26/95 LETTER FROM JOHN WOMACK TO HUGH J. BODE (REDBOOK 4; STD. 124; VSA 30118)

TEXT: Dear Mr. Womack:

The purpose of this letter is to request that NHTSA confirm that the former National Traffic and Motor Vehicle Safety Act does not require a motor vehicle to continue to comply with any applicable Federal Motor Vehicle Safety Standard after it is sold to its first retail purchaser. Specifically, we ask that NHTSA confirm that a vehicle in use is not required to comply with Federal Motor Vehicle Safety Standard No. 124; Accelerator Control Systems, 49 CFR 571.124 (hereinafter "FMVSS 124"), after the first retail sale of the vehicle.

The vehicle at issue is a 1988 Dodge Ram 50 pickup which was manufactured by Mitsubishi Motors Corporation in Japan and distributed by Chrysler Corporation in the United States. The pickup was equipped with a Mikuni Model 32-35-DIDEF-328 carburetor. When it was first sold, the 1988 Dodge Ram 50 pickup truck was certified by Mitsubishi Motors Corporation as being in compliance with all then applicable Federal Motor Vehicle Safety Standards, including FMVSS 124.

As we understand it, former @ 108(a)(1)(A) of the National Traffic and Motor Vehicle Safety Act, 49 U.S.C. @ 30112(a), prohibits any person from manufacturing, selling or introducing into commerce any new motor vehicle unless the vehicle is in conform ity with all applicable FMVSS. However, the Safety Act further provides that the requirement that a vehicle comply with all applicable FMVSS does not apply after the first purchase for purposes other than resale, i.e., the first retail sale of the vehic le. Safety Act former @ 108(b)(1), 49 U.S.C. @ 30112(b)(1). After the first retail sale, the only provision in the Safety Act that affects a vehicle's continuing compliance with an applicable FMVSS is set forth in former @ 108(a)(2)(A), 49 U.S.C. @ 301 22(b), which prohibits certain persons from knowingly rendering inoperative a device installed in a motor vehicle in compliance with an applicable FMVSS.

We ask that you confirm the accuracy of the foregoing general statement of the applicability of the FMVSS under the Safety Act. In addition, we ask that you address the following specific questions concerning the application of FMVSS 124 to the 1988 Dodge Ram 50 pickup:

1. We ask NHTSA to confirm that FMVSS 124 is a standard that a given vehicle must comply with only at the time of the first retail sale of the vehicle.

2. We ask NHTSA to confirm that if a carburetor installed in a 1988 Dodge Ram 50 pickup truck met all the requirements of FMVSS 124 at the time of the truck's first retail sale, but, after the sale, due to in-service conditions, corrosion developed insi de the carburetor so that the carburetor would not return to idle in accordance with the requirements of S5.1, S5.2, and S5.3 of FMVSS 124, that circumstance would not render the vehicle in violation of FMVSS 124.

3. We ask NHTSA to confirm that all of the performance standards imposed by FMVSS 124 are contained in S5.1, S5.2 and S5.3 of FMVSS 124 and that S2 headed PURPOSE does not impose any separate regulatory obligation beyond those contained in S5.

4. We ask you to confirm that the performance standard set forth in FMVSS 124 does not contain any requirement relating to durability or corrosion resistance.

We thank you in advance for your assistance in confirming these points.

ID: aiam1744

Dear Mr. Kennebeck: This responds to Volkswagen's December 11, 1974, request fo confirmation that the deletion of the ignition interlock requirement from Standard No. 208, *Occupant crash protection*, does not have the effect of prohibiting installation of an interlock device in a vehicle which meets the requirements of S4.1.2.; Volkswagen will utilize a passive belt system in satisfaction of th requirements of S4.1.2. Passive belts are subject to specific belt assembly requirements of S4.5.3.3. These requirements were recently modified by deletion of the requirement for a belt interlock system (39 FR 38380, October 31, 1974), and passive belt assemblies must now conform to S7.1 (Adjustment), S7.2 (Latch mechanism), and S7.3 (Seat belt warning system).; Your interpretation of these requirements is correct. The Federal moto vehicle safety standards are minimum performance requirements with which each vehicle to which they are applicable must comply. They do not, however, prohibit installation of additional safety devices. As a practical matter, of course, additional devices could not be installed if that installation had the effect of causing the required systems not to comply.; The NHTSA agrees than (sic) an interlock system is important fo ensuring use of a passive belt system.; Yours truly, Richard B. Dyson, Acting Chief Counsel

ID: aiam2237

Dear Mr. McNiel: On February 12, 1976, this agency denied your petition to amend S4.5. of Motor Vehicle Safety Standard No. 108 to read:; >>>'The stoplamps on each vehicle shall be activated upon applicatio of the service brakes, or by other beneficial means which will not impair the lighting system or the mechanical functioning of the vehicle.'<<<; You have now re- petitioned us on February 16, 1976, to amend S4.5.4 t read:; >>>'The stoplamps on each vehicle shall be activated upon applicatio of the service brakes. This action may be supplemented by other beneficial means which will improve the performance of the stoplamps without impairing the lighting system or the mechanical functioning of the vehicle.'<<<; This petition is unnecessary, because as you have now worded you suggested amendment it essentially reflects the present requirements of the standard. We do not view S4.5.4 as prohibiting a means of stoplamp activation supplemental to activation by application of the service brakes.; Any supplemental lighting device, however, is subject to the genera prohibition of S4.1.3 against installation of motor vehicle equipment that impairs the effectiveness of lighting equipment required by Standard No. 108. For example, a positioning device that activates the stoplamps whenever the accelerator pedal is released would impair the effectiveness of the stoplamps by providing an ambiguous signal, as release of the accelerator does not always signify that the vehicle operator intends to brake.; You also questioned whether NHTSA desires to see improvements in moto vehicle stoplamp systems. Docket No. 74-5 represented a tenative (sic) effort to provide better systems on an optional basis, but on the basis of comments to the docket and our research contracts, we are re-evaluating the entire subject. Your denial must also be considered in this context, and at the present time radical changes in rear lighting are simply premature.; The remainder of your letter was also of interest. Dr. Haddon remarke that performance standards afford the private sector optimum flexibility in designing to meet the Federal standards. His comment reflected a statutory mandate which this agency continues to adhere to in its rulemaking actions. However, as I wrote you on February 12, any performance standard is design restrictive to some extent, with the restrictions ideally only as narrow as reasonably necessary to achieve the desired safety performance. In some areas (*e.g.* the occupant protection provisions for vehicle interiors in impacts, Standard No. 201) a great deal of design freedom is afforded, while others (*e.g.* the headlighting requirements of Standard No. 108) may be quite restrictive because safety-related factors such as availability of replacements, uniformity of color and location, and detection of function are more important than design freedom.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs;

ID: wakley.2.wpd

Mr. Mark Wakley
25919 25^th Lane South, Apt. E-201
Kent, WA98032

Dear Mr. Wakley:

This is in response to your several e-mails in October 2003, concerning your desire to have the daytime running lights (DRLs) on your model year 2004 Chevrolet Cavalier disconnected. I understand that you discussed this issue at length with Eric Stas and other agency staff. You stated that your vehicle is equipped with DRLs that illuminate upon vehicle start-up and that there is no manual on-off switch. You stated that despite repeated requests, General Motors is unwilling to provide a means to disable the DRLs. Further, you described problems this has engendered in your delivery operations to military bases and other federal facilities, which require extinguishment of such lighting as a security measure.

Because DRLs are not required motor vehicle equipment, we confirm that manufacturers, distributors, dealers, and motor vehicle repair businesses are free to disconnect the vehicles DRLs or to install an on-off switch, at customer request. As the vehicle owner, you are also free to disconnect the DRLs yourself. However, vehicle manufacturers are not required to provide a means to disable DRLs.

By way of background, Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, Reflective Devices, and Associated Equipment, does not require vehicle manufacturers to install DRLs on new vehicles; however, if manufacturers choose to install such devices, paragraph 5.5.11 of the standard sets forth certain performance requirements. Paragraph S5.5.11(a) provides that DRLs are to be "automatically deactivated when the headlamp control is in any on position, and as otherwise determined by the vehicle manufacturer." In the context of paragraph S5.5.11(a), "headlamp control" refers to those position(s) of the master lighting switch that cause the headlamps themselves to be turned on.

Because DRLs are not required by FMVSS No. 108, manufacturers, distributors, dealers, and motor vehicle repair businesses may disconnect DRLs or provide on-off switches without violating the statutory prohibition against knowingly making inoperative any device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard. 49 U.S.C.

30122. However, these entities may not alter the performance specifications of DRLs in a manner that would make them not comply with the performance requirements specified for DRLs under the standard.

I hope that this clarifies NHTSAs regulations related to DRLs. If you have any further questions regarding our regulations, please contact Eric Stas of my staff at (202) 366-2992.

Sincerely,

Jacqueline Glassman
Chief Counsel

ref:108
d.1/22/04

ID: aiam3432

Dear Mr. Biddle: This responds to your recent letter to Mr. Kratzke of my staff describing a situation in which a railroad car full of new tires caught on fire. As a result of the damage caused to the tires by the fire, Firestone's quality control staff determined that the tires could no longer be certified as safe for highway use. The railroad company has refused to pay your claim for damage to the tires unless Firestone releases the damaged tires to the railroad company. You stated that the railroad company will either sell the tires through its salvage outlets or use the tires on company vehicles. You ask whether you can rightfully withhold these tires from the railroad company.; If Firestone releases the tires and the railroad company sells th tires or uses them on the public roads, both Firestone and the railroad company would violate an express provision of the National Traffic and Motor Vehicle Safety Act of 1966, as amended (15 U.S.C. 1381 *et seq*.) ('the Safety Act'). Therefore, you can rightfully withhold the tires from the railroad company.; Your letter did not indicate whether the damaged tires were tires fo passenger cars or tires for motor vehicles other than passenger cars. In either case, the tire manufacturer is required to certify that each tire fully complies with certain marking requirements and with specified performance requirements (resistance to bead unseating, strength, endurance, and high speed performance) of Safety Standard No. 109 in the case of passenger car tires (49 CFR S571.109) or of Safety Standard No. 119 for tires other than passenger car tires (49 CFR S571.119). This certification is made by the manufacturer by molding the letters 'DOT' into the sidewall of the tire.; As a result of the damage to this particular shipment of tires, you company has determined that his certification is no longer valid. This determination obligates Firestone to remove the 'DOT' symbol from the sidewall of the tires.; Without the 'DOT' symbol, these tires would clearly not comply with th requirements of either Standard No. 109 or Standard No. 119. Section 108(a)(1)(A) of the Safety Act (15 U.S.C. 1397(a)(1)(A)) provides:; >>>No person shall manufacture for sale, sell, or offer for sale, o introduce or deliver for introduction in interstate commerce, or import into the United States, any ... item of motor vehicle equipment manufactured on or after the date any applicable Federal motor vehicle safety standard takes effect under this title unless it is in conformity with such standard ....<<<; Firestone would violate this prohibition if it were to deliver tires t the railroad company which were not certified as complying with the appropriate safety standard. The railroad company would violate this prohibition if it sold or offered to sell uncertified tires, or if uncertified tires were used by the company on the public roads (introduction in interstate commerce). Section 109 of the Safety Act (15 U.S.C. 1398) specifies penalties of up to $1000 for each violation of section 108, and each tire delivered by Firestone or sold or used by the railroad company would constitute a separate violation of section 108. Section 109 specifies that the maximum civil penalty which can be imposed for a series of related violations, which this would be, is $800,000 for each violator.; You indicated that Firestone would not release the damaged tires fo use in any case, because of the potential safety hazard. I hope that this response reinforces that position. Should you need any further information on this matter, please do not hesitate to contact me. Please show this letter to the interested railroad company so that it will realize the serious nature of its contemplated actions.; Sincerely, Frank Berndt, Chief Counsel

ID: nht90-3.16

TYPE: Interpretation-NHTSA

DATE: July 12, 1990

FROM: Michael L. Hayes

TO: James Gilkey -- NHTSA

TITLE: Re Non Compliance to Standard 213 in the Transport Incubator

ATTACHMT: Attached to letter dated 1-15-91 from Paul J. Rice to Michael L. Hayes (A37; Std. 213; FMVSS 102(4)); Also attached to letter dated 7-12-90 from Michael L. Hayes to General Curry

TEXT:

In our resent phone conversation regarding transport safety for the new born infant which is transported in incubators, I brought to your attention that the child restraint equipment used in this area does not meet Standard 213. I have enclosed a sales brochure to illustrate my point. It is anticipated that the companies involved will claim that, due to the special circumstances involved in this type of transport, Standard 213 cannot be met and, thus, is not applicable to transport incubators. In view of this objection, I have included a copy of an engineering analysis of a restraint technique showing a design that can meet Standard 213 and meet the special needs of this type of transport as well.

It is estimated that close to 100,000 infants are transported in this type of equipment each year. If only one half of one percent of these infants are injured due to the lack of proper protection, this represents hundreds of needless injuries and possi bly scores of deaths.

The companies involved are aware of the moldable air-bag restraint technique and its ability to vastly improve the safety of the infant. However, the belief that it would not be profitable "enough" to up grade the transport incubator with proper occupant protection has lead to the continued sales of substandard equipment. This equipment is designed and sold specifically as a "transport" incubator in that its principal purpose is the transport of the infant. It is clear that if this equipment is capabl e of meeting child transport safety standards through specifically designed occupant protection systems the compliance should be halted.

I would like to ask that you take up this project on behalf of the infant and enforce Standard 213 as it applies to "car bed" type restraints.

Attachment

Air-Shields Vickers sales brochure entitled TI-100 Infant Transport Incubator (Text omitted)

Attachment

An Engineering Analysis of a Developmental Transport Restraint System for the Neonate by Michael L. Hayes and Dr. Brent Coleman (Text and graphics omitted)

ID: 18571-a.wkm

Geffrey W. Anderson, Esq.
Howell, Dorman, Anderson, Berg & Smyer, L.L.P.
Attorneys at Law
University Center 1, Suite 110
1300 South University Drive
Fort Worth, TX 76107

Dear Mr. Anderson:

Your letter and its enclosed product addressed to Mr. James Jones of this agency was forwarded to this office for response.

Your letter enclosed a product called the Air Blow Gun (ABG), manufactured by Barjan Products of East Moline, IL. The ABG is described as a length of 11.5-foot coiled 1/4 inch vinyl tubing with brass fittings on either end and a lever-type blow gun. The ABG attaches to the vehicle's compressed air system which supplies compressed air for its air brake system. When attached to the air system, it can be used to clean various surfaces with air pressure. The ABG's container carries the notation "D.O.T. approved." You stated that your client is concerned about this product's claim that it is "D.O.T. approved," and asked whether it is in fact approved by the US Department of Transportation and whether or not such representation constitutes false advertisement.

By way of background information, the National Highway Traffic Safety Administration (NHTSA), by delegation from the Secretary of Transportation, has the statutory authority to issue Federal motor vehicle safety standards (FMVSS) applicable to new motor vehicles and new items of motor vehicle equipment (49 U.S.C. Chapter 301). That statutory scheme establishes a self-certification system under which motor vehicle and equipment manufacturers themselves certify that their products comply with all applicable FMVSSs. Most of the FMVSSs that apply to motor vehicle equipment require such equipment to be certified by the manufacturer. That certification is often shown by marking the product itself with the letters "DOT." NHTSA enforces compliance with the standards by purchasing and testing motor vehicles and equipment. The agency also investigates safety-related defects. If NHTSA or the manufacturer finds that a vehicle or item of equipment does not comply with applicable standards or is found to have a safety-related defect, the manufacturer is responsible for remedying the defect or noncompliance at no charge to the customer. Thus, NHTSA neither approves, disapproves, endorses, tests, nor grants clearances for products prior to their introduction into the retail market.

Turning now to the ABG, we would classify it as an item of motor vehicle equipment, which is defined in 49 U.S.C. 30102(a)(7)(B) as any "part or component manufactured or sold for replacement or improvement of a system, part, or component, or as an accessory or addition to a motor vehicle." The ABG would be classified as an accessory if it meets the following two tests:

a. A substantial portion of its expected uses are related to the operation and/or maintenance of a motor vehicle; and

b. It is purchased or otherwise acquired, and principally used, by ordinary users of motor vehicles.

After reviewing the product and the information on its container, we conclude that the ABG is an accessory. While the ABG is a motor vehicle accessory, NHTSA has not issued any FMVSSs establishing performance standards applicable to this particular product. Thus, it is not required to be certified or marked with the "DOT" symbol.

The notation "D.O.T. approved" appears in four places on the ABG's container. As pointed out above, NHTSA does not approve motor vehicle equipment or accessories, nor can the phrase "D.O.T. approved" be interpreted as the manufacturer's certification of compliance with applicable FMVSSs.

We appreciate your advising us of this matter. We will contact Barjan Products, the manufacturer of the ABG, with a view to resolving the situation.

I hope this information is helpful to you. Should you have any further questions or need additional information, feel free to contact Walter Myers of my staff at this address or at (202) 366-2992, or by fax at (202) 366-3820.

Sincerely,
Frank Seales, Jr.
Chief Counsel
ref: #121#VSA
d.3/23/99

ID: 6991

AIR MAIL

Mr. Charles Danis Les Enterprises Track Test Inc. 4652 Avenue Victoria Montreal, Quebec H3W 2N1 Canada

Dear Mr. Danis:

This responds to your letter about testing related to Federal motor vehicle safety standard No. 121, Air Brake Systems, (49 CFR 571.121). You explained that your company has recently conducted a compliance test on an articulated bus manufactured by MCI Greyhound Canada. According to your letter, the buses were tested using 28 psi for the brake actuation test and 40 psi for the brake release test. While these air pressures differ from the pressures specified in S5.3.3 and S5.3.4 for brake actuation and release times, you stated that MCI was relying on a July 23, 1976 interpretation issued by the agency to Mr. J.W. Lawrence of the White Motor Corporation that permitted such brake actuation and release pressures. We note that to be consistent with that interpretation, the maximum brake chamber pressure must have been 40 psi when the service reservoir pressure was at 100 psi. Your letter was not clear on that point. You asked whether this interpretation is still valid. As explained below, the answer is yes.

In its inquiry to NHTSA, White Motor Corporation asked whether S5.3.3 and S5.3.4 of Standard No. 121 require minimum brake chamber actuation and release time pressures of 60 psi and 95 psi, respectively, or whether these air pressures are included in the sections only as "bench marks" on which to base specifications for minimum actuation and release timing. In response, the agency's July 23, 1976 interpretation letter stated in relevant part that:

Your understanding that S5.3.3 and S5.3.4 only specify the air pressures of 60 psi and 95 psi as the basis for timing requirements is correct. Neither value is intended as a requirement that the vehicle be designed to provide a certain level of brake chamber air pressure. The values were based on an understanding of the typical configuration of existing air brake systems at the time the final rule was issued.

In response to your specific question, NHTSA's July 23, 1976 interpretation letter continues to be valid.

I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992.

Sincerely,

Paul Jackson Rice Chief Counsel Enclosure

Ref: 121 d:4/3/92

ID: nht92-8.2

DATE: April 3, 1992

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Charles Danis -- Les Enterprises Track Test Inc. (Quebec)

TITLE: None

ATTACHMT: Attached to letter dated 2/7/92 from Charles Danis to Paul J. Rice (OCC 6991)

TEXT:

This responds to your letter about testing related to Federal motor vehicle safety standard No. 121, Air Brake Systems, (49 CFR S571.121). You explained that your company has recently conducted a compliance test on an articulated bus manufactured by MCI Greyhound Canada. According to your letter, the buses were tested using 28 psi for the brake actuation test and 40 psi for the brake release test. While these air pressures differ from the pressures specified in S5.3.3 and S5.3.4 for brake actuation and release times, you stated that MCI was relying on a July 23, 1976 interpretation issued by the agency to Mr. J.W. Lawrence of the White Motor Corporation that permitted such brake actuation and release pressures. We note that to be consistent with that interpretation, the maximum brake chamber pressure must have been 40 psi when the service reservoir pressure was at 100 psi. Your letter was not clear on that point. You asked whether this interpretation is still valid. As explained below, the answer is yes.

In its inquiry to NHTSA, White Motor Corporation asked whether S5.3.3 and S5.3.4 of Standard No. 121 require minimum brake chamber actuation and release time pressures of 60 psi and 95 psi, respectively, or whether these air pressures are included in the sections only as "bench marks" on which to base specifications for minimum actuation and release timing. In response, the agency's July 23, 1976 interpretation letter stated in relevant part that:

Your understanding that S5.3.3 and S5.3.4 only specify the air pressures of 60 psi and 95 psi as the basis for timing requirements is correct. Neither value is intended as a requirement that the vehicle be designed to provide a certain level of brake chamber air pressure.

The values were based on an understanding of the typical configuration of existing air brake systems at the time the final rule was issued.

In response to your specific question, NHTSA's July 23, 1976 interpretation letter continues to be valid.

I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992.