ID: 1985-02.14

TYPE: INTERPRETATION-NHTSA

DATE: 04/16/85

FROM: AUTHOR UNAVAILABLE; Jeffrey R. Miller; NHTSA

TO: Mr. John L. Strickland

TITLE: FMVSS INTERPRETATION

TEXT:

Mr. John L. Strickland J.S. Welding Rt. 5 Box 496 Denham Springs, Louisiana 70726

Dear Mr. Strickland:

I am responding to your February 20, 1985 request for information regarding Federal regulation of trailer manufacturing.

There is no Federal Licensing requirement for the manufacture of trailers, which are considered motor vehicles under Federal law. As a manufacturer of a motor vehicle, however, you must submit identification information to the National Highway Traffic Safety Administration under 49 CFR Part 566, Manufacturer Identification. You must also certify that each trailer complies with all applicable Federal regulations. The procedure is specified in 49 CFR Part 567.

At this time, the only safety standards applicable to all trailers are Safety Standard No. 108, Lamps, reflective devices, and associated equipment, Safety Standard No. 120, Tire selection and rims for motor vehicles other than passenger cars, and Safety Standard No. 115, Vehicle Identification Number-Basic Requirements. The content requirements for the vehicle identification number are found at Part 565. Trailers with certain braking systems also must meet Safety Standard No. 106, Brake hoses, Safety Standard No. 116, Motor vehicle brake fluids, and Safety Standard No. 121, Air brake systems. These standards are found in Part 571 of 49 CFR.

I am enclosing an information sheet that explains how you can obtain copies of these regulations. If you have any further questions, please feel free to contact me.

Sincerely,

Original Signed By

Jeffrey R. Miller Chief Counsel Enclosure

February 20, 1985

National Hwy. Traffic Safety Admin. Office of Chief Council 400 7th Street Washington, D.C. 20590

Dear Sirs:

I need all information on what I need to obtain the necessary manufacturing license for this operation.

The trailers will range from approximately 6' long by 6' wide; 1 axle - gross weight of 750 to 1500 pounds - to 20' long by 6' 6' wide; 3 axles - gross weight of 20,000 pounds.

As it stands in our business at the present we will be building between 10 and 20 trailers a year.

We are new in this field, if you need more information please contact me.

Yours truly,

John L. Strickland J. S. Welding Rt. 5 Box 496 Denham Springs, Louisiana 70726 504 - 6644593

ID: nht87-1.94

TYPE: INTERPRETATION-NHTSA

DATE: 06/04/87

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: Ching-Hsien Huang

TITLE: FMVSS INTERPRETATION

TEXT: Ching-Hsien Huang Branch Chief Structural Analysis Department Yue Loong Motor Engineering Center P.O. Box 510 Taoyuan, Taiwan 33099 Republic of China

Dear Mr. Huang:

Thank you for your letter of May 4, 1987, asking several questions about Standard No. 210, Roof Crush Resistance, and Standard No. 208, Occupant Crash Protection. You asked whether Standard No. 216 is still in effect. The answer is yes.

You also asked whether Standard No. 216 can be substituted for the rollover test contained in the first, second, or third option of Standard No. 208. - The answer is that compliance with the roof crush resistance requirements of Standard No. 216 cannot b e substituted for compliance with the rollover test of Standard No. 208.

I would like to clarify the applicability of the rollover test requirement of Standard No. 208 for you. The only rollover test contained in Standard No. 208 is found in 54.1.2.1 of the standard. A vehicle is subject to the test only if the vehicle's manu facturer chooses to meet it instead of an alternative requirement. 54.1. 2. l(a)- provides that a manufacturer has to meet the dynamic occupant protection requirements by automatic means in a frontal/angular crash test. In addition, a manufacturer must m eet 54.1.2.1(c). 54.1.2.1 (c ) provides a manufacturer with two options. A manufacturer can either meet the requirements of 54.1.2.1 (c)(l) and provide occupant crash protection by automatic means in a literal crash test and a rollover crash test or a ma nufacturer can meet the requirements of 54. 1. 2.1 (c) ( 2) and provide a manual lap or a manual lap/shoulder below at each front designated seating position. If a manufacturer chooses to meet 54.1.2.1 (c) ( 2), the vehicle must comply with 54.1.2.1(s) a nd provide occupant crash protection by automatic means in a frontal/angular test with the manual safety belt unfastened. In addition, the vehicle must provide occupant crash protection by automatic means in a frontal/angular test with the manual safety belt fastened.

I hope this answers your questions, if you need further information please let me know.

Sincerely,

Erika Z. Jones Chief Counsel

ERIKA Z. JONES CHIEF COUNSEL U.S. DEPARTMENT OF TRANSPORTATION NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION MAY 4, 1987

DEAR SIR,

WE ARE THE ENGINEERING CENTER OF YUE LOONG MOTOR COMPANY IN TAIWAN. PLEASE REPLY THE FOLLOWING QUESTIONS AS SOON AS POSSIBLE. (1) HAD STANDARD NO. 216, ROOF CRUSH RESISTANCE--PASSENGER CARS, BEEN REVOKED AFTER AUGUST 15, 1977)

(2) IF THE ANSWER OF (1) IS NO, CAN STANDARD NO. 216 BE A SUBSTITUTED FOR THE ROLLOVER TEST REQUIREMENT IN THE FIRST, SECOND, OR THIRD OPTION OF STANDARD NO. 208, OCCUPANT CRASH PROTECTION, NOWADAYS?

YOUR HELP WILL BE GREATLY APPRECIATED.

SINCERELY YOURS,

CHING-HSIEN HUANG BRANCH CHIEF STRUCTURAL ANALYSIS DEPT.

ID: nht87-2.88

TYPE: INTERPRETATION-NHTSA

DATE: 09/03/87

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: Walter Mayr -- Austrian Trade Commission

TITLE: FMVSS INTERPRETATION

TEXT:

Mr. Walter Mayr The Austrian Trade Commission 1875 Connecticut Avenue, N.W. Suite 1114 Washington, D.C. 20009

This responds to your August 5, 1987 letter to my office and August 14 telephone conversation between Ms. Schott of your staff and Ms. Hom of mine, concerning our regulations for motor vehicles. You enclosed a brochure from the Austrian firm, Reformwerke Wels, describing a "public utility vehicle." Subsequently, Ms. Schott indicated in her telephone call that Reformwerke Wels has informed her that the vehicles in question have a top speed of 15.53 miles per hour (mph). Based on this information, you asked whether the vehicle is a "motor vehicle" for the purposes of our reg ulations. The answer is no.

Under a longstanding policy, the National Highway Traffic Safety Administration has regarded vehicles not to be "motor vehicles" within the meaning of the National Traffic and Motor Vehicle Safety Act, and therefore not subject to our motor vehicle safet y standards, if they (1) have an unusual body configuration which sets the vehicles apart from typical highway traffic, and (2) have a minimum attainable speed of 20 mph or less. The utility vehicles manufactured by Reformwerke Wels meet these criteria. Thus, the vehicles are not "motor vehicles" under our regulations and the manufacture of those vehicles is not regulated by this agency.

You might wish to contact the Consumer Project Safety Commission to learn if they have any Federal safety regulations applicable to the type of utility vehicle manufactured by Reformwerke Wels. Their address is: Office of the General Counsel, U.S. Consum er Product Safety Commission, 1111 18th Street, N.W., Washington, D.C. 20207. Telephone: (202) 492-6980.

Please contact us if we can be of further assistance.

Sincerely,

Erika Z. Jones Chief Counsel

Ms. Dierdre Hom Chief Counsel's Office Department of Transportation Room 5219 NHTSA 400 7th Street, S.W. Washington, D.C. 20590 August 5 1987

Dear Ms. Hom,

Further to your telephone conversation this morning with Susan Schott from our office, we enclose a brochure from the Austrian firm, Reformwerke Wels.

We appreciate your office to review this brochure which describes the tractor. I understand that if you determine that the tractor qualifies as a motor vehicle, you can advise us of the corresponding regulations.

Thank you in advance for your assistance and we look forward to hearing from you.

Sincerely,

Walter Mayr Trade Commissioner

Enclosure omitted

ID: nht87-3.21

TYPE: INTERPRETATION-NHTSA

DATE: 11/05/87

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: Patterson Incorporated

TITLE: FMVSS INTERPRETATION

TEXT: Mr. Barry Patterson President Patterson Incorporated 1920 Springfield Road Kelowna, B.C. VlY 7R8

Dear Mr. Patterson:

This is in reply to your letter of September 21, 1987, asking for our "acceptance and recommendation" of a safety device "endorsed" by the government of the province of Saskatchewan. This device automatically activates parking lamps, and the lower beams of headlamps "with the touch of the Brake Pedal".

The National Highway Traffic Safety Administration has no authority to accept, recommend, or endorse any item of motor vehicle equipment. We can, however, discuss the relationship of your device to U.S. Federal Motor Vehicle Safety Standard No. 109, Lamp Reflective Devices, and Associated Equipment, and the National Traffic and Motor Vehicle Safety Act ("the Act") under which the standard was issued. This standard applies to the manufacture and sale of new motor vehicles. A device such as yours is permi ssible as original vehicle equipment as long as it does not impair the effectiveness of lighting equipment required by Standard No. 108. There is no indication in your descriptive literature that the effectiveness of packing lamps, headlamps, or the stop lamps would be impaired by the installation and operation of your device. With respect to sale in the aftermarket for vehicles in use, your device is not prohibited under the Act if its installation by a person other than the vehicle owner does not rend er inoperative in whole or in part any lamps installed to comply with Standard No. 108. We see no indication that this would occur. However, such an installer should be aware of the wiring requirement in Standard No. 108 that taillamps, parking lamps, si de marker lamps, and the license plate lamp shall be activated when the headlamps are on. The rules for operation of vehicles in use are established by the individual States, and several of these may have restrictions on the use of headlamps during daylight hours. For further information on this subject you should write the American Associati on of Motor Vehicle Administrators, 1201 Connecticut Ave., N.W., Washington, D.C. 20036.

This agency has proposed that motor vehicles be equipped with daytime running lights, in a manner similar, though not identical, to the new requirement of the Canadian Ministry of Transport. If this proposal is adopted, the Act would prohibit any State f rom having a different standard than the Federal one. As of the effective date of such an amendment to Standard No. 108 daytime operation of frontal lighting should be permissible in all States. If you have any further questions we will be pleased to answer them.

Sincerely,

Erika Z. Jones Chief Counsel

ID: nht87-3.32

TYPE: INTERPRETATION-NHTSA

DATE: 11/30/87

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: D.F. Landers -- President, Mobile Products, Inc.

TITLE: FMVSS INTERPRETATION

ATTACHMT: 7/11/83 letter from Frank Berndt to D.F. Landers

TEXT:

D. F. Landers PSI Mobile Products Inc. 25 Eldredge P.O. Box 1183 Mt. Clemens, Michigan 48043

This is in response to your letter requesting confirmation of a July 11, 1983 determination by this agency that your special tow tractor vehicle is exempt from Federal motor vehicle safety standards. You indicate in your letter that you now have three si zes of tow tractors and that your market may expand to include commercial airline use as well as the Department of Defense.

Based on the information you have provided us, we confirm our previous determinations that baggage tow tractors are not subject to the Federal motor vehicle safety standards. The agency has consistently interpreted the definition of motor vehicle as excl uding vehicles such as airport runway vehicles that are intended and sold solely for off-road use and are not equipped for highway use. Further, we note that section 571.7(c) of Title 49, Code of Federal Regulations, provides that.

No standard applies to a vehicle or item of equipment manufactured for, and sold directly to, the Armed Forces of the United States in conformity with contractual specifications.

Your vehicles might become subject to the Federal motor vehicle safety standards if there is a material change in the facts regarding the intended or actual use, design or sale of your vehicles. Please remember that compliance with all Federal motor vehi cle safety standards is the obligation of each manufacturer of motor vehicles or motor vehicle equipment. We appreciate your continuing efforts at classifying correctly your vehicles.

Sincerely, Erika Z. Jones Chief Counsel

Dear Mr. Berndt:

We have requested your opinion in the past, regarding the applicability of the Federal Motor Vehicle Safety Standards to our special tow tractor vehicle. (A copy of our most recent correspondence is attached.) The purpose of this letter is to update our files and exemption position.

PSI now manufactures three sizes of tow tractors. These are sold to the Department of Defense agencies only, but may have commercial airline potential sales In the future.

The three vehicle sizes are shown on the chart enclosed along with pertinent specifications. Photographs and brochures are also enclosed for your information and files.

We would appreciate your confirmation that your previous determination that these vehicles are exempt from the Federal Motor Vehicle Safety Standards still applies.

Yours very truly, D. F. Landers President DFL/mm enclosures (See 7/11/83 letter from NHTSA to D.F. Landers)

ID: nht76-1.25

DATE: 11/04/76

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Universal Imports;

TITLE: FMVSS INTERPRETATION

TEXT: This is in response to your September 13, 1976, letter concerning "a line of racing/rally tires that are not Department of Transportation marked."

I understand from your recent telephone conversation with Mark Schwimmer of my staff that the tires with which you are concerned are of the following size designations: 165/70 HR 10 ; 225/60 HR 14 ; 225/60 HR 13 ; and 195/70 HR 13.

Section S6 of Federal Motor Vehicle Safety Standard No. 109, New Pneumatic Tires -- Passenger Cars, reads as follows:

S6. Nonconforming tires. No tire of a type and size designation specified in Table I of Appendix A that is designed for use on passenger cars and manufactured on or after October 1, 1972, but does not conform to all the requirements of this standard, shall be sold, offered for sale, introduced or delivered for introduction in interstate commerce, or imported into the United States, for any purpose. (emphasis added)

because the size designations of the tires in question all appear in Table I of Appendix A, these tires are subject to the prohibitions of S6 unless they were manufactured before October 1, 1972. "All the requirements of the standard" include both performance and labeling requirements.

Sincerely,

ATTACH.

Universal Imports

FRANK BERNDT -- ACTING CHIEF COUNSEL, National Highway Traffic Safety Association

September 13, 1976/Letter #7725

Dear Mr. Berndt:

Universal Tire and it's affiliates are involved in practically every aspect of the tire industry except retreading. The import aspect of our business has just been offered a line of racing/rally tires that are not Department Of Transportation marked.

As you are probably aware there exists today an ever growing extremely viable market for off road racing and rally oriented products.

It is our desire to approach this new market from retail, wholesale and mail order standpoints. We are especially concerned with our responsibilities with regard to selling these race/rally tires since they are not Department Of Transportation marked. Please keep in mind that we wish not only to adhere to the letter of the law but to the spirit of the law as well. Any guidance you can offer us regarding the sale of these tires would be greatly appreciated.

Again, as we see it we have three separate sets of selling circumstances: retail, wholesale and mail order (retail), and would like guidelines from you for all three.

Thanking you in advance for any assistance you might furnish, we remain

Most cordially,

William G. Mathews, III -- Division Manager

ID: nht76-2.38

DATE: 10/08/76

FROM: AUTHOR UNAVAILABLE; S. P. Wood for F. Berndt; NHTSA

TO: Trailer Manufacturers Association

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of September 9, 1976, asking for an interpretation of two provisions of Motor Vehicle Safety Standard No. 108.

You have informed us that "some manufacturers are mounting lamps using lock washers and wing nuts rather than conventional nuts to facilitate the installation of lamps when boat trailers are assembled at the dealer level." S4.3.1 of Standard No. 108 requires that lamps "shall be securely mounted . . . ." and you asked whether wing nuts, used as you described, provide a mounting that complies with S4.3.1. The answer is that this would appear to provide a secure mounting within the intent of Standard No. 108.

S4.3.1.3 requires that front side marker lamps for trailers be located as far to the front as practicable, exclusive of its tongue. You ask whether "the tongue is considered to start where the trailer frame begins to angle inward from its parallel sides . . . ." The answer is yes.

I hope this clarifies Standard No. 108 for you and your members.

YOURS TRULY,

trailer manufacturers association

September 9, 1976

Frank Berndt Acting Chief Counsel U.S. Department of Transportation NHTSA

With regard to Federal Standard No. 108, confusion has arisen concerning the definitions or interpretation of several items in the standard upon which both ourselves, in the administration of our Trailer Certification Program, and our member manufacturers need an official interpretation.

1. S4.3.1 provides that lamps ". . . shall be securly mounted . . ." Some manufacturers are mounting lamps using lock washers and wing nuts rather than conventional nuts to facilitate the installation of lamps when boat trailers are assembled at the dealer level. When properly used, wing nuts provide a secure fastening, yet we have, informally, heard that they may not be considered as meeting S4.3.1. Do wing nuts, used as indicated above, provide a mounting in accordance with S4.3.1?

2. S4.3.1.3 provides for the location of front side marker lights as far forward as practicable exclusive of the trailer tongue. We have heard, informally, that NHTSA considers that the tongue is considered to start where the trailer frame begins to angle inward from the parallel sides, which location sometimes is quite far to the rear on a boat trailer. If this interpretation is correct, it considerably simplifies boat trailer wiring harnesses and may eliminate the need for angle brackets to mount from side marker lights where the frame is angling inward. Is the above interpretation correct? If not what is the proper interpretation of where the tongue is considered to start?

Executive Secretary DONALD I. REED

ID: nht90-3.31

TYPE: INTERPRETATION-NHTSA

DATE: 07/25/90

FROM: JEFF CORNELL -- ENGINEERING, THE BARGMAN COMPANY

TO: TAYLOR VINSON -- LEGAL COUNSEL, NHTSA

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 8-23-90 TO J. CORNELL FROM P. J. RICE; (A36; STD. 108); ALSO ATTACHED TO DOCUMENT SEARCH REPORT (INFORMATION OMITTED)

TEXT:

My company manufactures lighting products for recreational vehicle manufacturers, OEM's. Due to recent customer requests, we are asking for a clarification on the following FMVSS 108 changes published May 15, 1990.

S5.1.1.31 (amended) states: On a motor vehicle, except a passenger car, whose overall width is 80 inches or more, measurements of the functional lighted lens area, and of the photometrics, of a multiple compartment stop lamp, and a multiple compartment turn signal lamp, shall be made for the entire lamp and not for the individual compartments.

Prior to this change, the maximum values increased as the number of lighted compartments Increased. As the new change states above, the photometric requirements are to be on the entire light, does this include the maximums also? If this is the case, a single compartment light must be less than the 300 maximum candlepower, and a 5 compartment light would also need to be less than the 300 value. This was addressed in the second full paragraph on page 20159 of the Federal Register for the minimum requirements, but there is no reference to the maximums. Please clarify.

Here is an example of another question we have:

Let's say a manufacturer is purchasing a single compartment light, that does not meet the new lens area requirement, for use in a molded bumper or fiberglass cap. If he is using 3 of these lights per side as stop lamps, and the combined area of the 3 is greater than the 75 square centimeters (from SAE J1398 MAY85), is this legal per the new requirements? Along the same line, If the vendor making these lights mounts the individual lights in a molded housing, are we correct in assuming that this would now classify as a multiple compartment lamp? If adding a housing to these lights will make it a multiple compartment lamp, then how is it different if it is installed into a molded bumper or fiberglass cap?

At the beginning of the amendment in the summary, it states that the lens area is 12 square inches, however, in the SAE standard J1398 MAY85 it states 75 square centimeters. When the two areas are converted into like units they do not match up. Which area is correct? (75 square centimeters = 11.625 square inches, 12 square inches = 77.42 square centimeters).

We would appreciate your earliest response, as we have customers waiting for answers concerning the above items.

ID: nht88-3.32

TYPE: INTERPRETATION-NHTSA

DATE: 09/02/88

FROM: R. YAMAUCHI -- NIPPON SEIKO K K

TO: NHTSA OFFICE OF VEHICLE SAFETY COMPLIANCE ENFORCEMENT

TITLE: DUAL MODE RETRACTOR (ELR MODE AND ALR MODE RETRACTOR)

ATTACHMT: ATTACHED TO LETTER DATED 06/19/88 FROM STEPHEN P. WOOD -- NHTSA TO R. YAMAUCHI; REDBOOK A33; INTERP 209

TEXT: The above retractor is an ELR which can change to ALR mode in order to fasten child seat.

Seat belt webbing of the dual mode retractor is pulled out to 100% extension position, where ELR mode changes to ALR mode. The ALR mode returns to ELR mode after specified amount of webbing is retracted. In ordinary use, that is webbing is not pulled o ut completely, ELR mode does not change and webbing moves smoothly without locking due to ALR mode.

We believe this dual mode retractor should be treated as ELR because ALR mode is voluntary act. Dual mode retractor, therefore, has to meet ELR performance requirement, and does not have to meet ALR performance requirement.

FMVSS 209 paragraph S5.2(k) specifies as follows. "---- An emergency locking retractor or a nonlocking retractor attached to upper torso restraint shall be subjected to 45,000 additional cycles of webbing withdrawal and retraction between 50 and 100 per cent extension. ----" If the dual mose retractor may be treated as ELR, the above testing will be applied. However, there is a problem. After webbing is fully pulled out, webbing locks at the above 50% extension position due to ALR mode. (In this case, the mode does not change to ELR unless much more amount of webbing is retracted.) To stop the webbing withdrawal just before the fully pulled out position might be able to prevent the change to ALR mode. But it will be in vain because 9 Kg load at that position will extend the webbing to the 100% extended position.

Retractor durability testing of the dual mode retractor can be conducted between 100% extended position and any ELR mode position, where more than specified amount has been retracted. As a test for this retractor, we request cycles of webbing withdrawal and retraction between 0 and 100% extension. We think this test cause no problem because requirement of S5.2(k) is less strict than that of this cycle test.

Please answer the following questions.

Q1 - Is dual mode retractor regarded as ELR? If so, is only the ELR requirement required?

Q2 - We requested 45,000 cycle test after dust should be conducted between 0 and 100% extension length. Is this correct? If not, how do we test the retractor.

We would appreciate if you would answer our questions.

Very truly yours,

ID: nht88-3.41

TYPE: INTERPRETATION-NHTSA

DATE: 09/12/88 EST

FROM: ERIKA Z. JONES -- CHIEF COUNSEL; NHTSA

TO: DAVIS THEKKANATH -- SR. SUPERVISING ENGINEER, OSHKOSH TRUCK CORPORATION

ATTACHMT: MEMO DATED 11-18-87, SUBJECT: FMVSS 121, TO NHTSA, FROM DAVIS THEKKANATH -- OSHKOSH TRUCK CORPORATION

TEXT: This responds to your letter requesting an interpretation of Safety Standard No. 121, Air Brake Systems. Section S5.1.1 of the standard requires trucks and buses to have an air compressor of sufficient capacity to bring the pressure in the supply and se rvice reservoirs from 85 psi to 100 psi within a specified time. You inquired about the meaning of this requirement in the context of a truck with a trailer behind it. You particularly asked whether the air compressor capacity requirement includes the volume of service reservoirs for the trailer. As discussed below, only the truck reservoirs need to be considered for this requirement.

By way of background information, the National Highway Traffic Safety Administration does not provide approvals for motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manuf acturer to ensure that its vehicles and equipment meet applicable standards. The following represents our opinion based on the facts provided in your letter.

Section S5.1 and S5.1.1 of Standard No. 121 read as follows:

S5.1 Required equipment -- trucks and buses. Each truck and bus shall have the following equipment:

S5.1.1 Air Compressor. An air compressor of sufficient capacity to increase air pressure in the supply and service reservoirs from 85 pounds per square inch (p.s.i.) to 100 p.s.i. when the engine is operating at the vehicle manufacturer's maximum rec ommended r.p.m. within a time, in seconds, determined by the quotient

(Actual reservoir capacity x 25)/Required reservoir capacity.

The reference in section S5.1.1 to "supply and service reservoirs" refers only to the supply and service reservoirs in the truck or bus subject to the requirement. Similarly, the term "actual reservoir capacity" refers only to the actual reservoir capac ity of that truck or bus, and the term "required reservoir capacity" refers only to the reservoir capacity required for that truck or bus. Thus, for a truck designed to tow an air-braked trailer, only the truck's reservoirs need to be considered for this requirement. For purposes of testing, the towing vehicle protection system would be activated.

While Standard No. 121 does not specify air compressor capacity for towing vehicles in terms which address towed vehicles, we assume that manufacturers of vehicles designed to tow air-braked vehicles will design them to have sufficient air compressor cap acity to ensure safe braking performance under conditions of reasonably foreseeable use, including when they are towing air-braked vehicles.