ID: 09-004766 302

ID: 09-004766 Seigel 302 refrigerator

ID: NJP Engineering Letter of Interpretation FMVSS No. 121signed

October 4, 2024

Mr. Nick Paulick, PE
Owner, NJP Engineering, LLC
P.O. Box 2161
Oshkosh, WI 54903 

Dear Mr. Paulick, 

This responds to your letter, dated October 31, 2022, regarding removing the third axle from a used three axle semitrailer and reducing both the trailer’s load-carrying capacity and its braking capacity. More specifically, we understand you to be asking whether the reduction in braking capacity would violate the “make inoperative” prohibition in 49 U.S.C. § 30122 with respect to Federal motor vehicle safety standard (FMVSS) No. 121, Air Brake Systems. 

Please note that our answer below is based on our understanding of the specific information provided in your letter. This interpretation letter does not have the force and effect of law and is not meant to bind the public in any way. This letter is intended only to provide clarity regarding existing requirements under the law and represents the opinion of the agency on the questions addressed in your letter at the time of signature. 

In your letter, you stated that you are requesting an interpretation regarding the modification of semi-trailers after first sale to add or remove axles to change their load-carrying capacity and the overall capacity of a combination motor vehicle. You note that you reviewed existing interpretations (specifically, our letter to John Paul Barber on May 24, 1993) and believe that the National Highway Traffic Safety Administration (NHTSA) “is not opposed” to aftermarket modifications such as removing an axle, “so long as they are done properly and that an explanatory label is affixed, advising the user of what these changes will mean in terms of gross weight rating.” 

You ask about the specific example of a three-axle semi-trailer with each axle having a gross axle weight rating (GAWR) of 20,000 pounds and the trailer having a gross vehicle weight rating (GVWR) of 75,000 pounds. You suggest the removal of one axle from the trailer, reducing its GVWR to 65,000 pounds. You further state that a “dataplate” would be permanently affixed to the modified trailer advising the user of the revised payload capacity. Because removing an axle from the trailer also removes the brakes associated with it, you ask whether the reduced “braking capacity” of the trailer would bring the vehicle out of compliance with NHTSA’s braking standards and potentially violate the “make inoperative” prohibition. For the purposes of this letter of interpretation, we understand “braking capacity” as used in your letter to mean the ability of the vehicle to meet the stopping distance requirements in FMVSS No. 121. 

By way of background, NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS that set performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. NHTSA also investigates safety-related defects. 

Your letter indicates that the modifications occur after first sale other than for resale.1 As you correctly note, the only legal requirement that is imposed on entities that make modifications to used vehicles is that a manufacturer, distributor, dealer, rental company, or motor vehicle repair business may not knowingly make inoperative any part of a device or element of design installed in furtherance of compliance with an applicable motor vehicle safety standard. 49 U.S.C. § 30122(b). A modifier subject to this prohibition must therefore ensure that the vehicle’s brakes and other systems remain in compliance with all applicable Federal motor vehicle safety standards once the modifications are performed. Civil penalties can be imposed under 49 U.S.C.
§ 30165(a) for violations of section 30112(b). 

We assume, for the purposes of this letter, that the trailer you intend to modify is equipped with an air brake system. FMVSS No. 121 establishes requirements for vehicles equipped with air brake systems. Under S5.3.1 of FMVSS No. 121, truck tractors must meet the stopping distance requirements specified in Table II of that standard, when loaded to their GVWR and tested using an unbraked control trailer.2 We note, however, that such requirements are applicable to the truck tractor. FMVSS No. 121 contains no stopping distance requirements applicable to trailers. FMVSS No. 121 does contain other requirements applicable to trailers, such as parking brakes, and certain as-equipped requirements should the trailer axles have brakes, such as that the braked trailer axles be equipped with anti-lock braking systems and have the required air reservoirs. 

We also assume for the purposes of this letter that the entity performing the modifications is subject to the “make inoperative” prohibition. You state that NJP Engineering provides engineering services for the evaluation of new and modified cargo tank motor vehicles. From this description, it is not clear what role NJP Engineering has in the actual performance of any modifications. We also note that even if an entity not subject to the “make inoperative” prohibition modifies the vehicles, such modifications may be subject to the laws and regulations administered by the Federal Motor Carrier Safety Administration and the States in which the vehicles are operated.

1 Because the trailer is a used trailer, you are not an alterer. An alterer is defined as a person who alters by addition, substitution, or removal of components (other than readily attachable components) a certified vehicle before the first purchase of the vehicle other than for resale. 49 C.F.R. § 567.3.
2 The following vehicles may meet the stopping distance requirements specified in Table IIa instead of Table II: Three-axle tractors with a front axle that has a GAWR of 14,600 pounds or less, and with two rear drive axles that have a combined GAWR of 45,000 pounds or less, that were manufactured before August 1, 2011; and all other tractors that were manufactured before August 1, 2013. For such vehicles, the analysis in this letter of interpretation is the same. 

In your letter, you state that a three-axle trailer would be modified to remove an axle and you ask about the applicability of the “make inoperative” prohibition with respect to the trailer’s braking capacity. FMVSS No. 121 does not contain stopping distance requirements applicable to trailers. Therefore, a reduction in braking capacity alone would not affect compliance with the FMVSSs and would not violate the “make inoperative” prohibition.3 Regarding other braking performance requirements applicable to trailers, such as parking brake requirements and as- equipped requirements for trailer axles, modifications to the trailer as stated must not take the trailer out of compliance with requirements that would be applicable to the modified trailer. You do not ask about, nor does this letter address, any other aspect of compliance with FMVSS No. 121, or other applicable FMVSS. 

I hope this information is helpful. If you have any further questions, please feel free to contact Eli Wachtel of my staff at (202) 366-2992.

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 10/4/24
Ref: Standard No. 121

3 You note that you intend to affix a “dataplate” indicating the revised weight capacity of the trailer. We note that such a “dataplate” is not required by our regulations; however, we believe it is appropriate to add a label to the vehicle which indicates the appropriate loaded weight of the modified vehicle in situations where certain modifications that might be made to a used vehicle (e.g., adding or deleting an axle) which could make the originally assigned GVWR inappropriate for the vehicle as modified.
 

ID: NCC-230927-001 FMVSS 135 - Telltale_ St. Pierre_ Canoo

June 7, 2024

Mr. Barry St. Pierre 

Sr. Homologation Engineer  

Canoo 

19951 Mariner Ave 

Torrance, CA 90503 

barry.st.pierre@canoo.com

Dear Mr. St. Pierre: 

I write in response to your September 12, 2023 email to the National Highway Traffic Safety Administration (NHTSA) asking for information on federal requirements for telltales in light vehicle brake systems. Please note that our answer below is based on our understanding of the specific information provided in your email correspondence. 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue Federal Motor Vehicle Safety Standards (FMVSS) setting performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. NHTSA also investigates safety-related defects. 

Your email correspondence seeks clarification of the requirement in 49 CFR § 571.135 S5.5.5(a) that visual indicators “shall have letters not less than 3.2mm (⅛ inch) high.” You state correctly that, if the telltale is the word “BRAKE,” it must meet the height requirement. You also ask about the specific proposed brake and ABS icon symbols pictured in your correspondence. In particular, you ask: (1) if a brake symbol includes the letter “P” as part of the symbol, whether it is sufficient for the symbol as a whole to meet the 3.2 mm height requirement of S5.5.5(a), or whether the letter “P” by itself must meet the height requirement; and (2) if an antilock braking system symbol includes the letters “ABS” as part of the symbol, whether it is sufficient for the symbol as a whole to meet the 3.2 mm high requirement, or whether the letters “ABS” by themselves must meet the height requirement. 

Discussion 

As you acknowledge in your correspondence, 49 CFR § 571.135 (FMVSS 135) S5.5.5(a) specifies labeling requirements for light vehicle brake systems. It states: 

Each visual indicator shall display a word or words in accordance with the requirements of Standard No. 101 (49 CFR 571.101) and this section, which shall be legible to the driver under all daytime and nighttime conditions when activated.
Unless otherwise specified, the words shall have letters not less than 3.2 mm (⅛ inch) high and the letters and background shall be of contrasting colors, one of which is red. Words or symbols in addition to those required by Standard No. 101 and this section may be provided for purposes of clarity. 

49 CFR § 571.101 (FMVSS 101), in turn, includes requirements for telltales and indicators. Section 5.2.1 states, in relevant part: 

[E]ach control, telltale and indicator that is listed in column 1 of Table 1 or Table 2 must be identified by the symbol specified for it in column 2 or the word or abbreviation specified for it in column 3 of Table 1 or Table 2. If a symbol is used, each symbol provided pursuant to this paragraph must be substantially similar in form to the symbol as it appears in Table 1 or Table 2. 

Table 1 of FMVSS 101 shows the required telltales for the items for which you request clarification: brake system malfunction and anti-lock brake system malfunction. These telltales have specific words or abbreviations that must be used as identifiers. Specifically, the word “Brake” must be used to indicate brake system malfunction. The words “Antilock” or “Anti-lock,” or the abbreviation “ABS,” must be used to indicate antilock brake system malfunction for vehicles subject to FMVSS Nos. 105 or 135. Unlike certain other items, Table 1 of FMVSS 101 does not permit the use of a symbol as an alternative to words or abbreviations to indicate either a brake system malfunction or an anti-lock brake system malfunction. Further, these required words or abbreviations must comply with the 3.2 mm height requirement of FMVSS 135 S5.5.5(a). 

NHTSA understands the symbols proposed in your correspondence to be separate from and additional to the required words or abbreviations discussed above. With this understanding, the two proposed symbols pictured in your correspondence would not be subject to the word height requirement laid out in FMVSS 135 S5.5.5(a), as they would be considered additional words or symbols used for clarification purposes. Accordingly, neither the symbols, nor the letters that are part of the symbols, would be required to be at least 3.2 mm. 

However, if a vehicle does not use Table 1’s required words or abbreviations as a telltale for the item in question, and instead only uses a symbol that does not contain the required words or abbreviations, then the vehicle does not meet the requirements of FMVSS 101 S5.2.1, regardless of the height of the symbol or the letter(s) in the symbol. 

Finally, we note that, as discussed above, one permissible telltale for an anti-lock brake system malfunction is the abbreviation “ABS.” Accordingly, if the symbol pictured in your letter that includes the letters “ABS” is the only telltale used in a vehicle to indicate an antilock system brake malfunction, then the letters “ABS” in that symbol must meet the 3.2 mm minimum height requirement in FMVSS 135 S5.5.5(a). It would not be sufficient for the symbol as a whole to meet this height requirement, because S5.5.5(a) specifically requires the “words” to meet the requirement. 

I hope this information is helpful. If you have any further questions, please feel free to contact Natasha Reed of my staff at this address or at (202) 366-2992.

Sincerely,
Adam Raviv
Chief Counsel

Dated: 6/7/24
Ref: Standard No. 135

ID: NCC-250121-001 FMVSS No 135.Parking Brake Indicator-lanetta signed 11.8.25

October 8, 2025

U.S. Department of Transportation 

National Highway Traffic Safety Administration 

Office of the Chief Counsel 

1200 New Jersey Avenue SE. 

Washington, DC 20590

Ms. Christie Iannetta 

Nelson Mullins 

101 Constitution Avenue, NW 

Suite 900

Washington, DC 20001   

Dear Ms. Iannetta:

I am writing in response to your letter addressed to NHTSA dated January 15, 2025, asking the agency to reconsider an interpretation issued on October 31, 2024 ("the interpretation").1 The interpretation was issued in response to a request you submitted on behalf of an anonymous client on February 26, 2024. In the request, you asked for clarification on Federal Motor Vehicle Safety Standard (FMVSS) No. 135, "Light vehicle brake systems." Specifically, you asked about paragraph S5.5.1, which sets out requirements for when certain brake indicators must be activated. In the interpretation, the agency concluded that the parking brake system described in your letter likely would not comply with FMVSS No. 135's requirements. 

Your January 15 letter requests that we reconsider the interpretation. After considering your request and evaluating the conclusion and analysis in the interpretation, we do not believe we misunderstood your original interpretation request, and we are not reconsidering the interpretation. A detailed explanation of our reasoning follows. 

Background 

By way of background, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to ensure that their vehicles and equipment meet applicable requirements. The following represents our opinion based on the facts provided in your letter. 

Please also note that our answer below is based on our understanding of the specific information provided in your letter. This letter does not have the force and effect of law and is not meant to bind the public in any way. This letter is intended only to provide clarity regarding existing 

1 NHTSA Interpretation File Search, ID: NCC-230308-001, https://www.nhtsa.gov/interpretations/ncc-230308-001- nelsonmullinsparkingbrakeindicatorinterp.

requirements under the law and represents the opinion of the agency on the questions addressed in your letter at the time of signature. 

FMVSS No. 135 establishes requirements for light vehicle braking systems. Paragraph S5.5.1 therein requires indicators to be activated when the ignition (start) switch is in the "on" ("run") position and one or more of seven scenarios occur. Paragraph (c) of S5.5.1 requires an indicator to be activated upon "application of the parking brake." Therefore, if the parking brake is applied and the vehicle's ignition is in the "on" position, a parking brake indicator must be activated. 

You explain that your client's vehicle uses an Electronic Parking Brake (EPB) system where the parking brake can be applied manually by the driver or automatically by the system. The driver can engage the parking brake via the in-vehicle control at any time before shifting the vehicle into park, and when the parking brake is engaged by the driver, the parking brake indicator displays clearly in front of the driver. However, the EPB system can also apply the parking brake on its own, and it does so whenever the vehicle is shifted into park. If the EPB system engages the parking brake on its own, the parking brake indicator does not display. Finally, regardless of how the parking brake is engaged (by the driver or by the EPB system), the parking brake always disengages automatically once the vehicle is shifted out of park, or in some vehicles, when the brake pedal is depressed. 

In the interpretation we concluded that your client's system is likely not compliant with the requirements of FMVSS No. 135. Specifically, we explained that S5.5.l(c) requires that if a vehicle ignition is in the "on" position and the parking brake is applied, an indicator must activate to inform the driver of the status of the parking brake. You may reference the interpretation for our complete analysis on the issue. 

In your January 15 letter, you express your belief that we misunderstood an important fact about the manufacturer's parking brake system, and that we failed to consider relevant regulatory context. 

NHTSA's Response 

We adequately understood the functionality of your client's parking brake system, and we also considered all of the relevant regulatory background. 

NHTSA Did Not Misunderstand Your Client's EPB System 

You indicate that we purportedly failed to understand that it is impossible for your client's vehicle to be driven with the parking brake applied because the system is designed to disengage whenever the vehicle is shifted out of park. Your letter quotes the following line from the interpretation as evidence that we misunderstood this crucial fact about the EPB system: "nothing prevents the vehicle from driving during this engagement." (See interpretation p. 3, ID: NCC-230308-001). 

When we drafted the interpretation, we did so with a complete understanding that your client's vehicle is designed to make it impossible to drive with the parking brake activated. We considered this fact when analyzing your client's system under the requirements of paragraph S5.5.1(c). We concluded that even though your client's vehicle design may potentially address the safety concern of driving with the parking brake activated, manufacturers may not disregard FMVSS requirements because they feel they have resolved the safety issue the standard was designed to address. As we stated in the interpretation, "[I]f a manufacturer believes that it has developed technology that makes certain regulatory requirements unnecessary, it may petition the agency for a rulemaking to amend the relevant requirements." Until the standard is amended, manufacturers must certify in good faith to the current requirements. 

NHTSA Did Not Ignore Important Regulatory Context 

You assert that the stated purpose of paragraph S5.5.l(c) is to prevent drivers from driving with the parking brake on, and your client's EPB system addresses that safety concern. Not only did we consider this argument in the interpretation, but our response to this argument was a central component of the interpretation. As we stated in the interpretation:

Just because a manufacturer has designed a system that purports to resolve, through other means, a safety concern addressed in an FMVSS does not mean that it is not bound by the requirements of the FMVSS or that it may introduce noncompliant motor vehicles or motor vehicle equipment to the market. If a manufacturer believes that it has developed technology that makes certain regulatory requirements unnecessary, it may petition the agency for a rulemaking to amend the relevant requirements. 

We understood then that your client believes it has created an EPB system that addresses the stated safety purpose of paragraph S5.5.l(c)'s parking indicator requirement. As noted, manufacturers must certify compliance with the express terms of an FMVSS, and not just with its stated purpose. In this case, we believe that even if your client's system may address the stated safety purpose underlying paragraph S5.5.l(c), it does not comply with the paragraph's requirements. 

Nor is your argument about the test procedures set out in FMVSS No. 135 S7.12.2 persuasive. You note that the parking brake test procedure requires a vehicle to be put into neutral and the parking brake applied, after which the parking brake must hold the vehicle stationary for a specific amount of time. One of the steps in the test procedure (S7.12.2(m)) is for the test conductor to verify the operation of the parking brake application indicator. You assert that the parking brake indicator is only evaluated after the performance of the steps within the test procedure in S7.12.2, during which the parking brake is applied manually. 

However, nothing in the parking brake test procedure negates paragraph S5.5.l(c)'s parking brake indicator requirement. The requirements that the brake system warning indicators illuminate under specified conditions exists independent of any test procedure. The duration during which a brake system warning indicator must be displayed is addressed in paragraph S5.5.3, which provides that each warning indicator "shall remain activated as long as the condition exists, whenever the ignition ('start') switch is in the 'on' ('run') position, whether or not the engine is running." Nothing in the test procedures purports to alter or limit this requirement. Thus, your client must be able to certify in good faith that its vehicle's parking brake indicator appears in plain view of the driver whenever the parking brake is engaged. We do not believe your client is able to do so based on your description of its EPB system. We note also that the final inspection procedure in paragraph S7.17 requires inspection of "[t]he brake system indicators, for compliance with operation in various key positions, lens color, labeling, and location, in accordance with S5.5." We expect that noncompliance with the requirement of paragraph S5.5.l(c) would be observed during this final inspection. 

I hope this letter provides clarity on NHTSA's stance on this matter. If you have any further questions, please contact Mr. David Jasinski of my staff at interpretations.NHTSA@dot.gov.

Sincerely,

Peter Simshauser 

Chief Counsel

Dated: 10/8/25
Ref: FMVSS No. 135

ID: NCC-211019-002 Zorn VW EPB FMVSS 135 2024.05.31_Interp

May 31, 2024

Mr. Thomas Zorn 

Vice President 

Vehicle Safety Office 

Volkswagen Group of America 

2200 Woodland Pointe Ave. 

Herndon, VA 20171 

Dear Mr. Zorn: 

This interpretation responds to your letter asking whether Volkswagen’s new Electronic Parking Brake (EPB) system complies with Federal Motor Vehicle Safety Standard (FMVSS) No. 135, Light vehicle brake systems. Specifically, you asked (1) whether paragraph S5.2 of FMVSS No. 135 would permit an EPB system that uses a traditional friction brake combined with a mechanical drivetrain lock; and (2) whether Volkswagen may rely on the entire EPB system for compliance with the test set out in paragraph S7.12. Based on the information you have provided, our answer to both of your questions is yes. 

By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide advance approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to ensure that their vehicles and equipment meet applicable requirements. The following represents our opinion based on the facts provided in your letter. 

In addition, in responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Paragraph S5.2 of FMVSS No. 135 provides: “Each vehicle shall be equipped with a parking brake system of a friction type with solely mechanical means to retain engagement.” The term “parking brake” is defined in 49 C.F.R. Part 571.3(c) as “a mechanism designed to prevent the movement of a stationary motor vehicle.” Thus, a compliant parking brake must prevent movement of a stationary motor vehicle by means of friction. Additionally, the parking brake system must also have “solely mechanical means to retain engagement,” meaning it cannot be held in place by non-mechanical means such as fluid, air, or electricity. 

Paragraph S7.12.2 of FMVSS No. 135 describes NHTSA’s conditions and procedures for testing whether a parking brake system complies with our standard. The test procedures require a test conductor to, among other things, drive the vehicle onto a 20 percent grade, apply the 

Mr. Thomas Zorn 

Page 2 

service brake with enough force to hold the vehicle stationary, shift the transmission into neutral, engage the parking brake system, and remove all force from the service brake. After the test conductor has taken the above steps, the vehicle must then remain stationary for five minutes. If the vehicle remains stationary for the required five minutes, the test conductor then repeats the test with the vehicle facing in the opposite direction on the grade. If the vehicle once again meets the stationary time requirement, and meets all other requirements in the paragraph, the parking brake system passes the compliance test.  

The EPB system described in your letter appears to be a parking brake of a friction type with solely mechanical means to retain engagement. You describe Volkswagen’s new EPB as a system that will “utilize a traditional friction brake combined with a mechanical lock that is automatically engaged in the vehicle drivetrain when the EPB is activated.” Based on this description, the system has a friction element combined with a mechanical drivetrain lock designed to hold the vehicle stationary. Additionally, based on the information provided in your letter, engagement of the friction element of the EPB is not retained by pneumatic or hydraulic means. To the best of our knowledge, the only ways to retain engagement of a friction type brake are by pneumatic, hydraulic, or mechanical means. Because your friction brake is not retained by pneumatic or hydraulic means, for the sake of this letter, we are assuming that engagement of the friction element of the EPB is retained by mechanical means.1 Applying that assumption, the Volkswagen EPB system described in your letter appears to meet the requirements of S5.2 of FMVSS No. 135. 2 

You also state that Volkswagen intends to rely on the entire EPB system to demonstrate compliance with paragraph S7.12 and ask whether NHTSA would conduct its compliance tests similarly. In conducting compliance testing for parking brakes, NHTSA follows the testing procedures set out in S7.12, as described above. You state that the friction element and mechanical lock are “designed to operate together only, and cannot be engaged individually by the vehicle operator.” Additionally, you indicate that it would be impossible for Volkswagen’s EPB system to engage the friction brake exclusively without the mechanical lock engaging. The testing procedure specified in S7.12 does not mandate a parking brake system hold a vehicle stationary by exclusively friction means. Accordingly, if NHTSA conducted compliance testing on the EPB described in your letter, it would follow the procedures as written in S7.12. 

I hope this answers your questions. If you have any further questions regarding this matter, please feel free to contact Mr. Matthew Filpi of my staff at (202) 366-2992. 

Sincerely,

ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 5/31/24
Ref: Standard No. 135

ID: NCC-241028-001 Interp Response - Volvo Trucks - FMVSS 121 Air Brake Reservoirs 01.16.2025

January 16, 2025

Mac Bradley Principal Engineer 

Volvo Group Trucks Technology 

Volvo Group North America LLC 

7900 National Service Road 

Greensboro, NC 27409

Re:    Interpretation of Air Brake System reservoir requirements under Standard No. 121 

Dear Mr. Bradley: 

This responds to your letter dated May 23, 2018, on behalf of Volvo Group North America LLC regarding the air brake system reservoir requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 121, S5.1.2. You describe a technology where an air dryer feeds the service reservoir directly, without the use of a separate supply reservoir or a condensate drain valve. You asked whether technology that you find to be “demonstratively more effective than a supply reservoir or automatic drain valve” may be used to comply with S5.1.2’s requirements. This letter responds to that request. 

In responding, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Section 5.1.2 requires that each truck and bus shall have:  

One or more service reservoir systems, from which air is delivered to the brake chambers, and either an automatic condensate drain valve for each service reservoir or a supply reservoir between the service reservoir system and the source of air pressure. 

S5.1.2 provides explicit reservoir requirements. Without either an automatic condensate drain valve or a supply reservoir, a vehicle would not comply with S5.1.2. The air dryer technology you suggest includes neither a condensate drain valve nor a supply reservoir. Although you suggest that this new technology is at least equally effective at removing water from compressed air, the standard is specific in its equipment requirements. We cannot by interpretation remove the requirements set forth in express terms in the regulatory text.1 

1 See, e.g., Letter to R.W. Hildebrandt, Bendix Corp. (May 30, 1980), available at www.nhtsa.gov/interpretations/nht80-241 (finding non-compliance where the air brake system may comply with the alleged intent of FMVSS No. 121 but does not comply with the standard’s technical requirements). 

The Notice of Proposed Rulemaking you cited from 1996 did propose revising FMVSS No. 121 to require a means of automatically removing moisture and contaminants from the air system and to delete the requirement for a supply reservoir. See 61 F.R. 56652 (Nov. 4, 1996). However, after consideration, NHTSA terminated that rulemaking, opting for further study of the requirements and test procedures for air drying and cleansing equipment used in air brake systems. See 63 F.R. 14674 (May 26, 1998). 

NHTSA cannot amend its regulations by interpretation. The appropriate vehicle to present your arguments would be a petition for rulemaking to amend FMVSS No. 121. In such a petition, you would be free to rely on the data you shared regarding the efficacy of air dryers at removing water from compressed air in support of a such petition for rulemaking. 

I hope this information is helpful. If you have any further questions, please feel free to contact Evita St. Andre of my staff at this address or (617) 494-2767. 

Sincerely,
ADAM RAVIV

Adam Raviv Chief Counsel
 

Dated: 1/16/25
Ref: Standard No. 121

ID: aiam0847

Dear Mr. Maupin: This is in reply to your letter of August 12, 1972, in which you aske which manufacturers are subject to the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 302. You also asked us for permission to include copies of FMVSS No. 302 in your promotional literature, and requested copies of any modification or supplements to the flame test.; Any manufacturer of passenger cars, multipurpose passenger vehicles trucks, or buses manufactured on or after September 1, 1972, is subject to the requirements of the standard. FMVSS No. 302 is a published Federal regulation, and you may reproduce it and distribute it in your promotional literature. I have enclosed a copy of a Notice of Proposed Rule Making, 36 F.R. 9565, which would amend the standard.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs;

ID: aiam5494

Dear Mr. Warlick: This responds to your letter asking how your compan would certify compliance with Federal Motor Vehicle Safety Standard (FMVSS) No. 302, Flammability of Interior Materials. You stated that your company manufactures motor homes and purchases interior materials from various vendors for these vehicles. These vendors provide you with letters stating that the materials comply with the FMVSS. You enclosed one such letter, which states that 'We have tested the panel ... that was made with COR63-AX-40. We used the MVSS 302 flame test, and obtained a flame rating of 0.64 inches per minute.' You ask whether this letter provides a sufficient basis for your company's certification of compliance with FMVSS No. 302. Some background information would be helpful. As you know, since Standard 302 applies to motor homes and other vehicles, Four Winds, as the vehicle manufacturer, is required to certify compliance with the standard. In the event NHTSA were to find an apparent noncompliance with Standard 302 when testing your vehicle to the requirements of the standard, Four Winds would be asked to show the basis for its certification that the vehicle complies with the standard. If in fact there is a noncompliance, Four Winds would be subject to civil penalties unless it can establish that it exercised 'reasonable care' in the design and manufacture of the product (through actual testing, computer simulation, engineering analysis, or other means) to ensure compliance, and did not have reason to know that the vehicle or item of equipment did not in fact comply with the safety standards (49 U.S.C. 30112(b)(2)(A)). With regard to your specific question, we cannot tell you at this time whether Four Winds' s reliance on a letter from its vendor would constitute 'reasonable care' on the part of your company in making its certification to Standard 302. NHTSA is unable to judge what efforts constitute 'reasonable care' outside of the course of a specific enforcement proceeding. What constitutes 'reasonable care' in a particular case depends on many factors, including such things as the limitations of current technology, the availability of test equipment, the size of the manufacturer, and above all, the diligence exercised by the manufacturer. In the situation you present, your vendor indicated that the burn rate of its material (0.64 inch per minute) is well within the limits of Standard 302 (not more than four inches per minute). The difference between the actual performance of a material and the required performance is a factor NHTSA would consider in making a determination of whether a manufacturer exercised reasonable care in making its certification. Another factor is whether the manufacturer should have determined whether the vendor's assurances were bona fide. Among other things, the expertise, reliability and experience of the vendor would be relevant for that issue. I hope you find this information helpful. If you have any other questions, please contact Marvin Shaw of my staff at this address or by phone at (202) 366-2992. Sincerely, Philip R. Recht Chief Counsel;

ID: aiam0911

Dear Mr. Madigan: Your letter of October 30, 1972, to Mr. James H. Wakelin, Jr. regarding a flammability test cabinet, was forwarded to us for reply.; Federal Motor Vehicle Safety Standard (FMVSS) No. 302 specifies cabinet for flammability testing with the test specimens in a horizontal position. There is no FMVSS for a vertical test method. A copy of FMVSS No. 302 is enclosed.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs;