ID: nht70-1.6

DATE: 05/01/70

FROM: AUTHOR UNAVAILABLE; R. A. Diaz; NHTSA

TO: Donald B. Haaversen

TITLE: FMVSS INTERPRETATION

TEXT: Thank you for your letter of March 9, 1970, to the National Highway Safety Bureau, concerning our Federal motor vehicle tire standards.

The only tire standard promulgated to date is Federal Motor Vehicle Safety Standard No. 109, "New Pneumatic Tires-Passenger Cars" which was effective January 1, 1968. This standard specifies minimum performance for size, strength, endurance, high speed laboratory testing and labeling. For your information, I have enclosed a copy of Standard No. 109 and No. 110 with amendments.

The replies to your specific questions are as follows:

1.Question: New American made tires have DOT load ranges, load capacity and inflation pressures molded into the sidewall. Is this required (that they be permanently marked), or is it sufficient to affix a temporary marking (such as a sticker) with this same information?

Response: Section S4.3 states that this information shall be permanently molded into or onto all new passenger car tires manufactured after August 1, 1968. If the tire was manufactured between January 1, 1968 and July 31, 1968 the labeling requirements may be met by use of a label or tag.

2. Question: How is load capacity information arrived at? Is it by manufacturer certification, government conducted tests, or some other method?

Response: The load/inflation schedule is calculated by use of empirical formulas and coordinated through the various Tire and(Illegible Word) Associations as well as the Society of Automotive Engineers.

3. Question: Is it necessary that these tires be subject to safety tests? These particular tires are already imported by another organization and may already have passed the necessary tests, if any.Response: The application of the "DOT recital to a tire, is the tire manufacturers self certification that his tire conforms to all the minimum performance standards of Federal Motor Vehicle Safety Standard No. 109.

I have also enclosed for your review and information the following data:

1. U.S. Customs Regulations for Importation of Motor Vehicles and Items of Motor Vehicle Equipment.

2. Automobiles Imported Into the United States.

ID: nht74-2.23

DATE: 09/24/74

FROM: AUTHOR UNAVAILABLE; James B Grefory; NHTSA

TO: Midland-Ross Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This responds to Midland-Ross' February 8, 1974, petition for an amendment of S5.1.2.1 and S5.2.1.2 of Standard No. 121, Air brake systems, to establish separate air reservoir volume requirements for several brake chamber types generally available in the air brake component market.

The standard presently requires air reservoir volumes to be a multiple of the vehicle's brake chamber volumes. Midland-Ross also requested that S5.1.2.2 and S5.2.1.3 be amended to require that a reservoir withstand hydrostatic pressure five times greater than stated on its label without rupture, or permanent circumferential deformation exceeding one percent. The standard presently requires that an air reservoir withstand internal hydrostatic pressure of five times the vehicle compressor cutout pressure or 500 pounds, whichever is greater. The pecition also requests modifications of the trailer test rig, which were made in a recent amendment of the standard (39 FR 17563, May 17, 1974).

You suggested that our requirement for air reservoir volume as a multiple of brake chamber volume will encourage installation of smaller equipment and thereby create a safety problem. We cannot agree, in view of the standard's stopping distance requirements which in effect mandate the installation of high performance components. Indications to date are that manufacturers have in fact not reduced brake chamber volumes. A certain degree of chamber stroke standardization may occur, which the NHTSA views as favorable. For these reasons your request is denied.

With regard to the air reservoir pressure requirements of S5.1.2.2 and S5.2.1.3, you argued that a reservoir manufacturer is unable to establish the required strength of his product because he cannot control the compressor cutout pressure of the vehicle on which the reservoir is installed. It should be understood that the standard is not an equipment standard with which Midland-Ross must comply, but a vehicle standard with which the vehicle manufacturer must comply. We have determined that the reservoir should be designed to manage the pressures to which it might be exposed on the vehicle on which it is installed. The vehicle manufacturer is able to establish a compressor cutout pressure (on powered vehicles, and, based on that value, order the appropriate reservoir to meet the requirement. It is evident that commercial considerations will standard compressor cutout pressures on reasonable range of available reservoir strengths. Midland-Ross as a manufacturer of reservoirs is free to establish a range of reservoir strenghts, and label the reservoirs as described in your petition. For the reasons cited, however, your petition to mandate this is denied.

We agree the requirement that a reservoir "withstand" a certain pressure can be further specified, and we are considering a proposal to do this in the future.

At this time the NHTSA has adopted the SAE Standard No. J10a, which specifies that there be no rupture or permanent circumferential deformation exceeding one percent.

Sincerely,

ATTACH.

PETITION FOR RECONSIDERATION

FEDERAL MOTOR VEHICLE SAFETY STANDARD 121 DOCKET 73-13 NOTICE #3

BY POWER CONTROLS DIVISION MIDLAND-ROSS CORPORATION

M. J. Denholm Director of Engineering

February 8, 1974

Midland-Ross regrets to find that several of the proposals issued under Notice 1 of Docket 73-13 have not been incorporated in the rule issued under Notice 3 of the Docket.

The purpose of this petition is to request reconsideration of outstanding petitions and comments not yet resolved or acted upon from previous notices. In addition, we wish to offer additional information to supplement our comments on Docket 70-16 and 17, Notice 3, and the petition for reconsideration of Docket 70-17, Notice 4.

Taking the sections as they appear in FMVSS 121 as amended by Docket 73-13, Notice 3, we ask for your consideration of the following:

S5.1.2.1

S5.2.1.2

On March 23, 1972, we petitioned for consideration of this section of Docket 70-16 and 70-17, Notice 3.

Quote: "The combined volume of all service brake chambers at maximum travel of the pistons or diaphragms" requires definition in that volume can be measured in more than one way resulting in significant variation in result. For example: Displacement determined by pressurizing a chamber hydrostatically to 5 psig would result in approximately 10% less volume as compared to that indicated when the same chamber is pressurized to 100 psig hydrostatically. The hydrostatic pressure would be applied using an incompressable fluid; the volume of fluid displaced being the measure of the chamber volume. We recommend the standard be revised to read as follows:

'S5.1.2.1 . . .the combined volume of all service brake chambers at maximum travel of the pistons or diaphragms when measured with 5 psig applied to the chamber.' This will eliminate the possibility of a dual standard when determining compliance."

On August 14, 1973, we petitioned again for reconsideration of this section of Docket 70-17, Notice 4; and again on July 11, 1973, against Docket 73-13, Notice 1.

Quote: "The requirement under both these sections is restrictive and not necessarily in the public interest. For example, Midland-Ross Type 30 service chambers provide 2.75 inch stroke where units of other manufacturers are as low as 2.5 inch. The long stroke provides a desirable margin for poor brake adjustment. We believe this advantage will render our product non-competitive. To become competitive a reduction in stroke, with the attendant reduction in reservoir capacity requirement will be necessary. We feel, in light of recent experience with designs to meet FMVSS, 121, Notice 4, that this is arbitrary and an unnecessarily expensive retrograde step, caused by the wording of this section. In addition, chamber displacement varies dependent upon the applied pressure.

"This is caused by ballooning of diaphragms as pressure is increased. It should be noted that a three or four axle rigid truck would require significantly larger reservoirs under this rule than would a two-axle tractor designed to tow two or three trailers. Taking into account these three factors, it is recommended that S5.1.2.1 and S5.2.1.2 be reworded as follows:

'S5.1.2.1 The combined volume of all service reservoirs and supply reservoirs shall be at least the value obtained by the following product: Buses, and tractors and trailers designed to tow air-braked vehicles:

(12) x (115%) x (Combined volume of all service brake chambers)

Trucks not designed to tow other air-braked vehicles: (8) x (115%) x (Combined volume of all service brake chambers)

The combined volume of all service brake chambers is that volume obtained at maximum travel of the pistons or diaphragms with 100 psi hydrostatic pressure applied to the chambers with the brakes adjusted as specified by the vehicle manufacturer for new, unburnished brakes.

'S5.2.1.2 The total service reservoir volume shall be at least the value obtained by the following product: (8) x (115%) x (Combined volume of all service brake chambers)

The combined volume of all service brake chambers is that volume obtained at maximum travel of the pistons or diaphragms with 100 psi hydrostatic pressure applied to the chambers with the brakes adjusted as specified by the vehicle manufacturer for new, unburnished brakes."

No action has resulted from any of these petitions. We feel both arguments are still valid. We would like to add additional argument to that furnished on August 14, 1973, as follows:

An optional method of determining reservoir volume would consist of using an established minimum working volume for each standard size of service chamber. The minimum working volume would then be used to compute the reservoir requirement in the manner stated in the standard. Using this approach, the need for the changes recommended on March 23, 1972, would be eliminated also. We therefore recommend the S5.1.2.1 be reworded as follows: S5.1.2.1 The combined volume of all service reservoirs and supply reservoirs shall be determined by adding the volumes specified in Table V, Column 1 for each air-operated service brake actuator.

S.5.2.1.2 shall read:

S5.2.1.2 Total service reservoir volume shall be determined by adding the volumes specified in Table V, Column 2 for each air operated service brake actuator.

TABLE V Reservoir Volume Required Per Actuator * Column 1 * Column 2 Actuator Trucks-Buses Trailers Type 9 Diaphragm 240 cubic inches 160 cubic inches Type 12 Diaphragm 300 cubic inches 200 cubic inches Type 16 Diaphragm 528 cubic inches 352 cubic inches Type 20 Diaphragm 612 cubic inches 408 cubic inches Type 24 Diaphragm 732 cubic inches 488 cubic inches Type 30 Diaphragm 1056 cubic inches 704 cubic inches Type 36 Diaphragm 1464 cubic inches 976 cubic inches

*Piston or Rolling 12 x volume at max. 8 x volume at max.

Diaphragm working stroke working stroke

The above revisions to S5.1.2.1 and S5.2.1.2 are requested due to the variation in design of diaphragm type service brake chambers. These chambers are of generally similar construction, but because of manufacturing tolerances and slight differences in stroke length, their maximum volumes are different by a few percentage points. The current reservoir volume requirement based on maximum displacement encourages the use of small volume chambers (to reduce required reservoir volumes). In use, however, these small volume chambers provide less reserve than larger displacement units. This is true because the larger displacement units generally have slightly longer operating strokes. This additional stroke is a safety advantage in event that brake drums expand from heat buildup or shoes are allowed to wear without brake readjustment.

The chamber volume differences caused by variations in maximum stroke length are not significant to a vehicle in normal operation. This is because either chamber design would require the same amount of air to operate a properly adjusted brake; either unit when stroked to the same distance (any value short of maximum stroke; would displace nearly the same volume of air. Chamber volume requirements per brake application would be the same for either chamber design unless the stroke exceeded the maximum stroke length of the short stroke chamber. In that case, (abnormal situation) the long stroke chamber would require more air than a short stroke unit but would produce brake torque to stop the vehicle. The short stroke unit would be stopped internally without producing brake torque.

If S5.1.2.1 and S5.2.1.2 are not revised, market pressure will force redesign of long stroke chambers to limit stroke (and maximum volume). This could be carried to an extreme whereby the redesigned chambers would have even shorter strokes than current chambers. This type unit would then have economic advantages that would encourage their use; but they would actually be inferior to current chambers from a safety point of view.

The chamber volumes proposed in Table V were arrived at by applying the current requirement of 12 times chamber volume at maximum stroke (eight times for trailers) to the maximum volume of the truck industry's most common air brake chamber. These values do not represent a change in the spirit of the law, only in its detail. The original method of determining reservoir volume would be retained for piston actuators or other devices whose stroke and displacement have not become standardized in the industry.

S5.1.2.2

S5.2.1.3

On March 23, 1972, we petitioned for reconsideration of both of these sections of Docket 70-16 and 70-17, Notice 3.

Quote: "The requirement that the reservoirs under both of these sections should 'withstand' an internal hydrostatic pressure is nondefinitive and open to interpretation. In addition, manufacturers of air brake reservoirs are not necessarily in a position to determine what the cutout pressure of the compressor will be for a particular reservoir application prior to design and development of the reservoir as required under Paragraph S5.1.2.2. In addition, there is a significant inconsistency between the requirements for reservoir strength on a truck or bus and those for reservoirs used on a trailer as both reservoirs on a combination vehicle would be pressurized by the same compressor to the same pressure levels. It would appear reasonable, in the interest of safety, to adopt a common standard. It would also appear to be advisable to use a standard which is both proven and perfectly acceptable based on long periods of experience. It is therefore recommended that Paragraphs S5.1.2.2 and S5.2.1.3 be revised as follows:

'Each reservoir shall be capable of accepting a hydrostatic pressure of not less than five times the reservoir rated working pressure for a minimum of one minute. When subjected to this pressure for this time period there shall be no rupture or permanent circumferential deformation exceeding 1%. The reservoirs meeting this requirement must be permanently identified for rated working pressure."

On August 14, 1973, we again petitioned for reconsideration of these sections of Docket 70-17, Notice 3. Comments were also made on Docket 73-13, Notice 1.

Quote: "The requirement that the reservoirs under both of these sections should withstand an internal hydrostatic pressure is nondefinitive and open to interpretation. In addition manufacturers of air brake reservoirs are not necessarily in a position to determine what the cutout pressure of the compressor will be for a particular reservoir application prior to design and development of the reservoir as required under Paragraph S5.1.2.2. In addition, there is a significant inconsistency between the requirements for reservoir strength on a truck or bus and those for reservoirs used on a trailer. Both reservoirs on a combination vehicle would be pressurized by the same compressor to essentially the same pressure levels. It would appear reasonable, in the interest of safety, to adopt a common standard. It would also appear to be advisable to use a standard which is both proven and perfectly acceptable based on long periods of experience. It is therefore recommended that Paragraphs S5.1.2.2 and S5.2.1.3 be revised as follows:

'Each reservoir shall be capable of accepting a hydrostatic pressure of not less than five times the reservoir rated working pressure for a minimum of one minute. When subjected to this pressure for this time period, there shall be no rupture or permanent circumferential deformation exceeding 1%. The reservoirs meeting this requirement must be permanently identified for rated working pressure.'

Note: This recommendation reflects the current SAE Standard Practice (SAE J10b) in regard to reservoir certification and therefore should provide clarification without creating unnecessary hardships."

An additional point which was not specifically made in the two petitions quoted from relates to manufacturing practice and product application.

As a major reservoir manufacturer, Midland-Ross produces all reservoirs for air-braked vehicles in one of three diameters. Each diameter is engineered from differing material thicknesses to withstand a predetermined working pressure. Usually this is 150 psi. When reservoirs are supplied to the industry we have no knowledge of the compressor cutout pressure. The compressor cutout pressure is usually adjustable in service. A situation over which the reservoir manufacturer has no control. By establishing a maximum rated working pressure for the reservoir to be marked on the unit, the user then has direct knowledge of the limit to which the compressor cutout pressure can be safely adjusted. We feel that adopting this method would result in better understanding on the part of the user as this has been the standard used historically. It would eliminate the need to re-educate operators and provide a sounder basis for economic reliable manufacture and application of air brake reservoirs.

S5.3.3

S5.3.4

On March 23, 1972 we pointed out in our petition for reconsideration the inadequacies of the test standard shown in Docket 70-16 and 70-16, Notice 3, Figure 1. Partial response to this petition was exhibited in Docket 73-13, Notice 1, S6.1.12.

Docket 73-13, Notice 3, essentially returns to 70-17, Notice 3 level, thus effectively ignoring our original petition and also our comments on Docket 73-13, Notice 1, submitted to the Administration on July 11, 1973.

We ask for consideration of our updated proposal as follows:

S5.3.3 Brake actuation time. With an initial service reservoir system air pressure of 100 psi, the air pressure in each brake chamber shall reach 60 psi in not more than 0.25 second measured from the first movement of the service brake control. A vehicle designed to tow a vehicle equipped with air brakes shall be capable of meeting the above actuation time requirement with a 50-cubic-inch test reservoir connected to the control line coupler. A trailer shall meet the above requirement with its brake system connected to a trailer timing test rig as shown in Fig. 1 which meets the requirements of S5.3.3.1 and S5.3.3.2.

S5.3.3.1 The following should be added:

"The trailer test rig shown in Fig. 1 shall be constructed such that the pressure in a 50 cubic inch test volume connected to the control coupling is raised from zero to 60 psi in .063 second minimum when tested on the test rig. Time shall be measured from the first mechanical movement of the device controlling air flow to the control coupling."

S5.3.3.2 The following should be added:

"The trailer test rig shown in Figure 1 shall be constructed such that the pressure in a 50 cubic inch test volume connected to the control coupling is exhausted from 95 to 5 psi in .220 second minimum when tested on the test rig. Time shall be measured from the first mechanical movement of the device controlling air flow from the control coupling.

Figure 1 should be revised as shown:

(Graphics omitted)

S5.3.4 Brake release time. With an initial brake chamber air pressure of 95 psi, the air pressure in each brake chamber shall fall to 5 psi in not more than 0.50 second measured from the first movement of the service brake control. A vehicle designed to tow another vehicle equipped with air brakes shall be capable of meeting the above release time requirement with a 50-cubic inch test reservoir connected to the control line coupling. A trailer shall meet the above release time requirement with its brake system connected to the test rig shown in Fig. 1 and which meets the requirements of S5.3.3.1 and S5.3.3.2.

The above changes to Section S5.3.3 and Figure 1, and additions to S5.3.3.1 and S5.3.3.2 are recommended in an effort to more completely define the TRAILER TEST RIG. Until this rig is defined, uniform timing will not exist on trailers built to FMVSS 121. The original Figure 1 was designed to duplicate a tractor. It did this but as a test instrument it is inadequately defined. The air delivery performance of this device (as well as the tractors it was modeled from) will vary significantly. This is unacceptable when proof of vehicle compliance to the standard depends upon tests made with this unit. The proposed Figure 1 is a black box with narrowly defined performance characteristics. Devices built to this requirement will undoubtedly exhibit performance variations when tested against one another, but their level of consistency will far exceed that obtained by a unit in the standard which is only partly defined.

ID: nht74-2.26

DATE: 07/09/74

FROM: AUTHOR UNAVAILABLE; R. L. Carter; NHTSA

TO: Wanger Electric Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your March 12, 1974, request for interpretation of the volume requirements for service brake chambers in S5.1.2.1 and S5.2.1.2 of Standard No. 121, Air Brake Systems:

S5.1.2 Total service reservoir volume shall be at least eight times the combined volume of all service brake chambers at maximum travel of the pistons or diaphragms.

You also requested the addition of language equating brake chamber volume with brake chamber displacement, based on nominal effective area and rated stroke.

In testing for compliance with S5.1.2.1 and S5.2.1.2, the NHTSA will accept a manufacturer's published "rated volume" of the brake chamber with the piston or diaphragm at maximum travel. This means that the manufacturer may specify the full stroke of the piston or diaphragm and compute the "rated volume" based on the designed volume of the chamber and the full stroke he has established. This volume may be somewhat larger than "nominal brake chamber displacement" which does not necessarily account for the void ahead of the relaxed diaphragm or piston, the so-called "pre-fill volume". This volume must be included because it must be pressurized along with the displaced volume.

In the absence of manufacturer's published ratings, the NHTSA will measure the brake chamber volume with the push rod at maximum stroke.

Your request to add explanatory language to the standard of the measurement technique is denied as unnecessary in view of this interpretation.

Sincerely,

ATTACH.

March 12, 1974

James B. Gregory, Administrator -- National Highway Traffic Safety Administration

Re: Docket 73-13; Notice 3 74-10; Notice 1 49 CFR 571.121

Petition for Reconsideration FMVSS-121, Air Brake Systems

Dear Dr. Gregory:

We were pleased to note in the March 1, 1974, Federal Register (39FR-7966) that the NHTSA needed further consideration on petitions for air tank volume before an answer would be published.

We apparently did not place adequate emphasis on this facet of FMVSS-121 compliance. Instead of a petition, we addressed a letter dated July 13, 1973, to the Director, Office of Operating Systems, for an interpretation. In that letter we asked only one question and it is quoted below:

Will the NHTSA accept the vehicle or chamber manufacturers' nominal value for maximum allowable stroke on each actuator when determining the minimum vehicle reservoir capacity required by S5.1.2.1 and S5.2.1.2?

In view of the absence of any response to a fundamental question, the manufacturers of air-braked vehicles and air brake equipment have gone in divergent directions with their own "interpretations." Apparently, it is a more profound problem than we or our competitors anticipated. In defense of our commercial position in this product area, we now find it necessary to submit this letter as a Petition.

Petition (1) We petition for an answer to the question posed in our July 13, 1973, letter (as quoted above).

In support of this petition we have attached a copy of that letter as Appendix A. The unanswered question appears on Page 4.

We will risk being a little repetitious, but our concern is that too much emphasis is being placed on finite measurements of chamber volume and reservoir volumes. From a statistical viewpoint, the case of trailer reservoir volume is a classic example of compliance or certification "overkill." S5.2.1.2 reads:

S5.2.1.2 Total reservoir volume shall be at least eight times the combined volume of all service brake chambers at maximum travel of the pistons or diaphragms.

In mathematical terms the word "eight" has a numerical equivalent of 8. For degrees of accuracy it could be 8.0, 8.00, 8.000, --- but it was just commonplace old "number eight."

In our letter of July 13, 1973, we reproduced the SAE J813 Recommended Practice for Air Brake Reservoir Volume (see Page 2, Appendix A). A truck trailer was considered to need "not less than 4 times the actuator displacement volume at maximum travel of the piston or diaphragm." The industry has accepted this 100% improvement in stored volume. Now all we are trying to do is determine whether this gross volume can be determined by simple mathematics or will require ultra-sensitive physical measurement of the actuators and the associated reservoirs.

Not only do the simple calculations benefit the designers of vehicles and brake systems, they have an obvious benefit to the NHTSA Office of Standards Enforcement.

Does the Office of Operating Systems assign the accuracy of these measurements to four significant figures necessary to the safe operation of a trailer? We see no technical justification for this. If there is, then it should be public knowledge. This is our rationale. Again using the most popular trailer as the example: It has 2 cam brakes with type 30 (30 square inch nominal effective area) chambers for actuation. These chambers have a nominal stroke of 2 1/2 in. (one source has a 2 3/4 inch stroke).

Under SAE J813 the required reservoir volume is:

4 x (Nominal Area) x (Nominal Max. Stroke) x (No. of Chambers) = Volume or 4 (30) (2.5) (2) = 600 cubic inches.

Under S5.2.1.2 of FMVSS the simple approach is

8 (30) (2.5) (2) = 1200 cubic inches.

Now we industry specialists get concerned by public statements at NHTSA meetings that it should be easy to measure --- put it (chamber) on a table, stroke it under pressure and measure the volume.

Production tolerances may allow a maximum stroke to extend to 2.65 inches or another 8 (30) (0.15) (2) = 25 cubic inches.

A further study points out that chambers have a void ahead of the relaxed diaphragm. It is there to assure good entry of unrestricted air flow to the effective area. This pre-fill volume can be at least 5 cubic inches per chamber or (8) (5) (2) = 80 cubic inches per axle.

At full stroke the defection of the non-rigid diaphragm adds another approximate 12 cubic inches per chamber or 8 (12) (2) = 192 cubic inches per axle. It is not needed at mid-stroke. Therefore, this is a superfluous requirement. There are many other more significant factors affecting chamber/brake output if we consider brake effectiveness under such an extreme condition.

The gross addition for these three factors alone is -

25 cu. inches 80 cu. inches +192 cu. inches

297 cubic inches per axle.

Note 192 cubic inches is beyond the point of useful volume and should not be a part of this measurement anyway.

To prove compliance or non-compliance using all of the added factors would require a very sophisticated laboratory contract and allied equipment. The report would be documented by instrument calibrations and certifications traced back to the National Bureau of Standards.

Did the NHTSA really want its "doctrine of adversity" to become this costly a situation? We can't believe the task force responsible for the first issue of FMVSS-121 was that conversant with the detailed construction of chambers to recognize the disparity of viewpoints in measuring technique that have evolved. We are certain there was not one iota of data in the DOT contract files to substantiate this stringent a need. From the public meetings we recall that concern for reservoir size was subordinated in seriousness because trailers are thought to have all sorts of space for reservoirs. In some cases this is true. However, random tank placement is not possible. One other FMVSS-121 requirement makes remote tank locations impractical.

That requirement is the Brake Actuation Time found in S5.3.3. To reach 60 psi in 0.25 sec. from actuation of the test rig control requires optimum system designing --- this prohibits such luxuries as -

(a) long air lines to the chambers

(b) untested hose sizes for these line

(c) remote reservoirs to contain this superfluous volume of air.

We could not predict how essential all of this would be in 1971, but we have come a long way. It was late Spring, 1973, when we became extremely concerned about contract testing to evaluate reservoir volume. We had already acknowledged that we were part of a regulated industry. On July 13, 1973, we demonstrated our intent to act like we were being regulated and posed our "simple" question. We are disappointed that an early response was impossible to develop and furnish. We are further disappointed that the 1972 and 1973 petitions filed by a competitor on this same subject matter have not resulted in positive rulemaking actions to resolve the internal problems that must exist between the Office of Operating Systems and Office of Standards Enforcement.

Perhaps this aspect of FMVSS-121 is not as vital as decisions on the effective date, but rule content does influence ability to meet effective dates. We trust this reinforcement of open petitions will prompt immediate action.

In summary, we believe an affirmative reply to our July 13, 1973, question will not adversely affect vehicle safety. If there is any suspicion in the Office of Standards Enforcement that the vehicle manufacturers or chamber manufacturers would falsify their nominal stroke or nominal areas for these components to avoid "proper" sizing of reservoirs, then that should be a subject for docket comment. We are already charged with honest manufacturing recommendations for brake adjustment, air compressor capacity, interpretation of "controlled lockup," option choices for parking brake mode, transmission gear range, tire inflation pressure, gross vehicle weight rating, gross axle weight ratings, burnish options and others not mentioned.

Our conclusion is that the following petition will reflect a simple means for calculations:

Petition (2) We petition for the addition of this sentence to S5.2.1.2 (see Page 2): "For purposes of establishing reservoir volumes, brake chamber displacement is equal to the product of the nominal effective area and nominal rated stroke."

It may be that the relative ease of chamber and reservoir measurements makes them good "compliance targets," but if the enforcement of FMVSS-121 is reduced to such attack, the goal of the NHTSA and the efforts of the industry to attain these goals will be unjustly inhibited in future vehicle safety programs.

Very cordially yours,

WAGNER ELECTRIC CORPORATION; John W. Kourik -- Chief Engineer, Automotive Products

Attachment: Appendix A

WAGNER ELECTRIC CORPORATION WAGNER DIVISION

July 13, 1973

Elwood T. Driver, Code 41-30 -- Director, Office of Operating Systems, NHTSA

Gentlemen:

As a manufacturer of brakes and air brake actuating system components, Wagner Electric Corporation is desirous of consistent and accurate interpretations of all applicable Federal Motor Vehicle Safety Standards. We are encountering an increasing amount of confusion in the industry regarding the method or procedure to be used in establishing the air reservoir capacity for air brake vehicles as required by FMVSS-121 (Section 5.1.2.1 and Section 5.2.1.2). We are, therefore, requesting interpretation and/or clarification of these sections with regard to the wording ". . . the combined volume of all service brake chambers at maximum travel of the pistons or diaphragms . . ." as found in Sections 5.1.2.1 and 5.2.1.2.

While the method of measurement of brake actuator volume may seem insignificant, in some cases it has become a major concern to decide whether an existing reservoir volume can be used or whether a new air reservoir must be made up with a slightly larger capacity. The determining factor is how the brake actuator volume requirements are measured. Therefore, a prompt response would be most appreciated so that the design and specification of air system components required to meet FMVSS-121 can be finalized.

Prior to Docket 70-17 and Docket 70-16 work by the NHTSA the recommendation for air brake reservoir volume used by some of the vehicle manufacturers was SAE J813.

AIR BRAKE RESERVOIR VOLUME

AIR BRAKE RESERVOIR VOLUME -- SAE J813

SAE Recommended Practice

Report of Brake Committee approved November 1961

Scope -- This recommended practice establishes minimum volume requirements for air reservoirs for automotive vehicles using compressed air systems essentially for the actuation of the brake. Accessories that utilize compressed air for their operation are not included in the conventional air brake system and, therefore, additional volume must be provided for their requirements. Where air operated accessories are used, a check valve or equivalent device will be required to provide protection to the brake system.

These recommendations for minimum reservoir volumes in air brake systems are based on past experience and are intended as a guide in selecting the proper size reservoirs to assure an adequate source of braking power under normal level operating conditions.

General -- The volume of the brake actuators in the air brake system, commonly referred to as brake cylinders, brake chambers, or roto-chambers, varies with the diameter and travel of the piston or diaphragm. The reservoir volume depends upon the size and number of the actuators on the vehicle and the type of vehicle service. Recommended volumes are calculated in Table 1 by multiplying the total volume of all actuators by an experience factor. Depending on traffic conditions and terrain, reservoir volumes, greater than the minimum values, should be considered.

(Illegible Table)

This recommended practice had also been endorsed in the Final Report of the Consolidated Brake Task Force of the Joint AMA-TIMA Brake Committee dated October 28, 1965. SAE J813 was reproduced above to simplify the evaluation of the comments which follow for those individuals who were not acquainted with previous (and current) recommended practice. Note that trucks or truck-tractors required only eight (8) times the actuator displacement volume and truck-trailers only four (4) times the actuator volume. We know from our experience that the maximum travel used throughout the industry in determining actuator displacement was the nominal value for the stroke of the actuator and that there was no attempt to incorporate production variations due to manufacturing tolerances. When we compare the values for the volume in J813 with the requirements of S5.1.2.1 (trucks and buses) and S5.2.1.2 (trailers) it will be noted that significant improvement in the stored air volume has been made mandatory by FMVSS-121. There is even further significance in this change to the large volume requirement in that many vehicles were built and are being built in 1973 with reservoir capacities less than the requirements specified in J813.

Perhaps it was not recognized at the time that FMVSS-121 issued that the efficiency of brake chambers has the characteristic shown in Figure 2. The performance requirements of FMVSS-121 for (1) actual stopping distance measurements and (2) timing requirements are based on brakes being adjusted to the vehicle manufacturers' recommendation. Figure 2 demonstrates that the mid stroke of most brake chambers is the point of approximate 100% efficiency. Shorter strokes are associated with higher output than would be nominally expected. In S5.1.2.1 and S5.2.1.2 the volume of all service reservoirs and supply reservoirs is based on ". . . the combined volume of all service brake chambers at maximum travel of pistons or diaphragms." As vehicle manufacturers begin to finalize the design of the variety of systems essential to the different vehicle chassis, space for air reservoirs is precious. It is advantageous for the vehicle manufacturers and the component suppliers to select a limited number of reservoir sizes for the purposes of simplicity in design, ease of procurement, and economy of using a few standard reservoir sizes.

If the most adverse characteristics are to be determined for compliance, not only must the chambers be subjected to extremely close measurement of displacement but the net displacement of air reservoirs must be measured very precisely. We believe it is advantageous for the NHTSA to recognize that the twelve (12) and eight (8) times minimum volume requirement for trucks and trailers respectively does not require the same degree of accuracy needed to measure application and release times or to measure stopping distance compliance. We are therefore proposing that chamber strokes used in these calculations be based on the nominal values established as the maximum allowable stroke for the components installed on the vehicle. It will be noted in Figure 1 that the probable variation between a nominal stroke of 2.50" and a stroke which allows for all production tolerances is only 97.1-90.0 = 7.1 cubic inches per chamber. On a tandem axle trailer or a tandem drive axle tractor this 28 cubic inch variation has been noted to warrant an increase in the number of reservoirs essential for very precise compliance to the general requirement in Sections 5.1.2.1 and 5.2.1.2. This seems to be an unnecessary expense for the manufacturers to incur since standard reservoir volumes could be used at the lower value without any real sacrifice in vehicle performance. The slight variation in stored volume will not have any adverse effect on application time. If it did, then correction in the volume would have to be necessary in order to comply with the application time requirements for a given vehicle. We do not see that this slight volumetric difference is essential for skid control systems. It is characteristic of skid control systems to exhaust air from the service line and deplete the service reservoir(s). When skid control is functioning the performance of any system becomes self-limiting at a point at which the air pressure no longer produces sufficient brake torque to generate impending skids. Once this pressure level is achieved there is no further demand for reserve capacity in the air brake system. Therefore the stopping requirements for vehicles from 60 and 20 mph can be satisfied in the road test phase of FMVSS-121 without having to be too precise in establishing the actual net chamber/reservoir measurements.

Typical of some of the problems which can be generated by the preciseness of FMVSS-121 is the Figure 1 test rig for trailers. While 2000 cubic inch reservoirs could be obtained or could be made by modification of standard reservoir sizes, the typical unit produced in the industry is 2020 cubic inches. By using inert ballast material, a reduction of 20 cubic inches in the stored capacity of the reservoir is relatively easy. This is a case where we do not feel that a 20 cubic inch variation is really a significant part of the over-all performance requirement of either the vehicle or the test rig but the strict implementation of Figure 1 requires special equipment and added expense.

We have presented this appraisal of the situation which confronts the vendor and vehicle industry in order to provide some relief that will be of mutual benefit to the public, the vehicle manufacturers, and the NHTSA by concentrating on the critical aspects of FMVSS-121. If each phase of the Standard is put into its proper perspective it will enable the NHTSA and the industry to begin implementation of good cost/benefit practices. For this reason (Illegible Word) then ask the following:

Will the NHTSA accept the vehicle or chamber manufacturers' nominal value for maximum allowable stroke on each actuator when determining the minimum vehicle reservoir capacity required by S5.1.2.1 and S5.2.1.2?

For minor clarification, this question is directed at using (1) the middle of the three curves shown on Figure 1; (volume versus stroke at 100 psi) and (2) a volumetric requirement of 90 cubic inches at a nominal stroke of 2.50". We have encircled that point for emphasis.

Very truly yours,

John W. Kourik -- Chief Engineer, Automotive Products

Attach. Figures 1 & 2 (Graphics omitted)

ID: 2797o

Mr. Kent B. Robinson
18230 Kingsdale Ave., Apt. D
Redondo Beach, CA 90278

Dear Mr. Robinson:

This is in reply to your letters of December 3, l987, January 19, 1988, and April 4, l988 (to Taylor Vinson of this Office), asking whether a device of your invention complies with all applicable Federal regulations. You have also requested information on how to petition for adoption of this device as mandated equipment on new motor vehicles. We regret the delay in responding to your letter.

You have requested confidentiality of this matter to the extent permissible. As Mr. Donaldson of this Office explained to you by phone on January 14, our practice is to make available for public perusal copies of all agency interpretations, but not necessarily the correspondence that occasioned the interpretation, and, upon request, to delete from the interpretation the name and address and other data that might identify the person requesting the interpretation. You have assented to the withholding of your name and address in your letter of January 19. In that letter you requested withholding the drawings you enclosed on December 3. We shall not attach them to the copy of this letter made publicly available (although they will be subject to review by agency personnel who review this letter before I have signed it, and may be subject to eventual disclosure under a Freedom of Information Act request). However, the device must be described to the extent necessary to allow a reader to understand just what the opinion covers.

Your device is a horizontal bar of lamps mounted inside the rear window of a passenger car consisting of the center highmounted stop lamp in the center, flanked by back up lamps, which are themselves flanked by left and right turn signal lamps. Each of the five lamps would have a lens area approximately 6" wide and 1 1/2 inches high.

The applicable Federal law and regulation is the National Traffic and Motor Vehicle Safety Act and Federal Motor Vehicle Safety Standard No. l08 Lamps, Reflective Devices, and Associated Equipment. With respect to acceptability of your device as an item of original equipment, for purposes of this interpretation we assume that the device is intended to replace the standard center highmounted stoplamp, but only to supplement the backup and turn signal lamps. Your device appears permissible as an item of original equipment under Standard No. l08 provided that all requirements for the center highmounted stoplamp continue to be met. We call your specific attention to the fact that means must be provided to minimize reflections from the center lamp upon the rear window glazing that might be visible to the driver, either directly or indirectly in the rearview mirror. Supplementary original lighting equipment is permissible under Standard No. l08 as long as it does not impair the effectiveness of lighting equipment required by the standard. The certification by a manufacturer that its vehicle complies with Standard No. l08 would encompass a certification that there is no impairment by any supplemental lighting equipment. The vehicle manufacturer must also consider whether any device installed in a rear window affects compliance with the interior rearview mirror field of view requirements specified by Standard No. lll Rearview Mirrors, and if affirmative to provide a passenger side exterior mirror.

The Vehicle Safety Act covers safety related defects as well as motor vehicle safety standards, requiring notification of purchasers and remedy of safety related defects when they occur. Spillage of light upon the rear glazing could be considered as a safety related defect, and, for this reason, means should be provided to minimize reflections upon the rear glazing from all lamps in the array, and not just the center lamp.

The applicable Federal law for aftermarket equipment is also the Vehicle Safety Act. It prohibits modifications by manufacturers, distributors, dealers, and motor vehicle repair businesses to vehicles if those modifications render inoperative in whole or in part equipment installed in accordance with a safety standard. Center highmounted lamps have been required as original equipment on new cars manufactured on or after September l, l985. Because of the potential for interfering with the effectiveness of the center lamp, we would regard removal of an original equipment center lamp and substitution of your device including its center lamp as rendering the center lamp partially inoperative within the meaning of the prohibition. However, if the modification is such that it can be done by the vehicle owner, the Act does not prohibit an owner from it. Further, the Act would not prohibit in any way the installation of your device on passenger cars manufactured before September l, 1985. However, supplementary lighting devices sold in the aftermarket are regulated by each State in which the device would be sold and used. Although we are not conversant with those laws, you may consult the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, Va. 22203 for an opinion.

You have also asked how this device could be mandated as original equipment on new passenger cars. Any interested person may petition the Administrator for an amendment of Standard No. l08. However, the Vehicle Safety Act requires the safety standards to be standards for motor vehicle performance, and, to the extent possible, the agency attempts to minimize standards expressed in terms of design. For the same reason, the agency does not normally propose adoption of proprietary designs. As one of the requirements of a petition for rulemaking is that it contain the name and address of the petitioner, it might not be possible to afford the same degree of confidentiality to a petition that it is to a request for an interpretation.

Your letter of April 4 asks a slightly different question on the subject of what is allowed to be viewed by other motorists in or around the rear window, with specific reference to turn signals, backup lamps, and hazard warning signals. The relevant portions of Standard No. l08 are those relating to mounting height. The maximum mounting height of 83 inches allowed for turn signals (which commonly also serve as hazard warning signals) is unlikely to be exceeded by turn signals mounted in the rear window area. There is no maximum restriction on the mounting height of backup lamps but we do have performance criteria which must be met in order to ensure that they can satisfy their intended function of providing illumination behind the vehicle. Finally, you should realize that it is incorrect to refer to your device as a "third tail light assembly." A taillamp is a specific rear lamp required by Standard No. l08, and one which you have not incorporated into your assembly.

I hope that this answers your questions. As you requested in a phone call to Taylor Vinson the other day, we are returning the originals of your correspondence.

Sincerely,

Erika Z. Jones Chief Counsel

Enclosures

ref:552#108 d:8/l2/88

ID: nht76-2.46

DATE: 01/14/76

FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA

TO: Department of California Highway Patrol

TITLE: FMVSS INTERPRETATION

TEXT: This is in response to your letter of December 8, 1975, asking four questions, the answers to which would provide an interpretation of Standard No. 108 with respect to separation distance of a turn signal lamp from the nearest edge of a Type 2 headlamp.

SAE Standard J588d, Turn Signal Lamps, June 1966, incorporated by reference in Standard No. 108, requires in pertinent part that "The optical axis (filament center) of the front turn signal lamp shall be at least 4 inches from the inside diameter of the retaining ring of the headlamp unit providing the lower beam . . . ." We agree with your opinion that the reference to filament center may have been added because of the difficulty of determining the location of the optical axis in certain instances. In the vast majority of cases, however the filament center is on the optical axis, and the addition of the provision assists in determining compliance with the requirement.

You have asked:

"1. Is the filament center always to be taken as the center of the optical axis?"

The answer to this question is no. In some instances the filament center will not be on the optical axis. When this is the case the standard is ambiguous as to whether distance is measured from the optical axis or the filament center. While we prefer the optical axis, under the present wording either must be viewed as legally supportable.

"2. Is the center of the emitted light always to be taken as the center of the optical axis?"

The answer is yes.

"3. If the answers to the above two questions are no, does the vehicle manufacturer have the choice as to which method is most favorable to him?"

Yes, because of the ambiguity the manufacturer may choose either the optical axis or filament center as the point of measurement.

"4. What is the optical axis of a two- or three- compartment lamp?"

The optical axis of a multi-compartment lamp is the center of the light emitted by the array, treated as a single complex light source. The "half-value" method you described in your letter is a valid method of finding the optical axis of a complex light source as well as that of a simple one.

Finally you have asked whether, if we agree with the need for clarification, the letter can be considered a petition for rulemaking or whether a formal petition should be submitted.

We agree that clarification is needed and accordingly plan to issue a notice of proposed rulemaking in the near future.

Yours truly,

ATTACH.

December 8, 1975

Frank Berndt -- Chief Counsel, National Highway Traffic Safety Administration

Dear Mr. Berndt:

When inspecting 1976 passenger cars, we discovered a problem in measuring the distance of a front turn signal lamp from the nearest edge of the Type 2 headlamp. Federal Standard No. 108 requires that turn signal lamps meet the 4-inch minimum spacing in SAE J588d. Standard No. 108 also permits lamps to be mounted closer than the 4-inch interval if they emit 2-1/2 times the minimum candlepower otherwise specified.

SAE J588d clearly states that the distance shall be measured from the optical axis of the turn signal lamp to the inside diameter of the retaining ring from the headlamp providing the low beam. It then, unfortunately, makes the requirement ambiguous by a parenthetical reference to the filament center.

The SAE wording was satisfactory when it was adopted a number of years ago, because lamp designs then had the optical axis coincident with the filament. More recent designs have kept the filament 4 inches from the headlamp but have used the ambiguity as a loophole to allow the optical axis to be unreasonably close to the headlamp.

The 4-inch separation was adopted by SAE after a number of complaints about the lack of effectiveness of some turn signals that were snuggled up against the headlamps. The brightness of the adjacent low beam headlamps washed out the turn signals so they would not attract an oncoming driver's attention unless he was looking almost directly at them. The SAE Lighting Committee made nighttime demonstrations of turn signals at various distances from the headlamps in view of a proposal that the edges of the lamps be separated by a minimum distance such as 2 or 2 inches. A jury-type judgment indicated that the present requirement was barely acceptable usually and would allow vehicle manufacturers sufficient design freedom in placing the lamps on vehicles.

The attached drawing illustrates the absurdity of the "filament center" interpretation for modern-day turn signals (and incidentally the skill and ingenuity of lamp designers). Figure I shows a current lamp with a filament center meeting the 4-inch requirement but with an optical center much closer to the headlamp. Figure II illustrates a left-hand version of the same lamp with a filament center that does not meet the 4-inch requirement but with an optical center farther removed from the headlamp. The second lamp provides a more effective signal from an opposing driver's viewpoint, but it would be illegal if measured from the filament center.

The filament center reference apparently was added to the SAE standard because of an assumed difficulty in determining the location of the optical axis. An axis of any object usually passes through a point of symmetry. In the case of a symmetrical light beam meeting turn signal photometric requirements, the optical axis falls in a plane on either side of which is one-half of the total light output. The optical axis is easily located by measuring the intensity of the lamp at HV and then sliding an opaque card with a straight edge across the face of the lens until the photometer reading is one-half the HV value.

In view of the foregoing discussion, we would appreciate your interpretation of Standard No. 108 with respect to the following questions:

1. Is the filament center always to be taken as the center of the optical axis?

2. Is the center of the emitted light always to be taken as the center of the optical axis?

3. If the answers to the above two questions are no, does the vehicle manufacturer have the choice of which method is most favorable to him?

4. What is the optical axis of a two- or three-compartment lamp?

If you agree with the need for clarification, can this letter be considered a basis for your initiating a proposed change in Standard No. 108 or must this Department submit a formal petition for a rulemaking?

Very truly yours,

WARREN M. HEATH -- Commander, Enforcement Services Division

Enclosure

cc: Lou Owen, NHTSA; Francis Armstrong, NHTSA

(Graphics omitted)

ID: nht88-3.4

TYPE: INTERPRETATION-NHTSA

DATE: 08/12/88

FROM: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA

TO: Anonymous (Confidential)

TITLE: NONE

TEXT: This is in reply to your letters of December 3, 1987, January 19, 1988, and April 4, 1988 (to Taylor Vinson of this Office), asking whether a device of your invention complies with all applicable Federal regulations. You have also requested information on how to petition for adoption of this device as mandated equipment on new motor vehicles. We regret the delay in responding to your letter.

You have requested confidentiality of this matter to the extent permissible. As Mr. Donaldson of this Office explained to you by phone on January 14, our practice is to make available for public perusal copies of all agency interpretations, but not nece ssarily the correspondence that occasioned the interpretation, and, upon request, to delete from the interpretation the name and address and other data that might identify the person requesting the interpretation. You have assented to the withholding of your name and address in your letter of January 19. In that letter you requested withholding the drawings you enclosed on December 3. We shall not attach them to the copy of this letter made publicly available (although they will be subject to review by agency personnel who review this letter before I have signed it, and may be subject to eventual disclosure under a Freedom of Information Act request). However, the device must be described to the extent necessary to allow a reader to understand just what the opinion covers.

Your device is a horizontal bar of lamps mounted inside the rear window of a passenger car consisting of the center highmounted stop lamp in the center, flanked by back up lamps, which are themselves flanked by left and right turn lamps. Each of the fiv e lamps would have a lens area approximately 6" wide and 1 1/2 inches high.

The applicable Federal law and regulation is the National Traffic and Motor Vehicle Safety Act and Federal Motor Vehicle Safety Standard No. 108 Lamps, Reflective Devices, and Associated Equipment. With respect to acceptability of your device as an ite m of original equipment, for purposes of this interpretation we assume that the device is intended to replace the standard center highmounted stoplamp, but only to supplement

2 the backup and turn signal lamps. Your device appears permissible as an item of original equipment under Standard No. 108 provided that all requirements for the center highmounted stoplamp continue to be met. We call your specific attention to the fa ct that means must be provided to minimize reflections from the center lamp upon the rear window glazing that might be visible to the driver, either directly or indirectly in the rearview mirror. Supplementary original lighting equipment is permissible under Standard No. 108 as long as it does not impair the effectiveness of lighting equipment required by the standard. The certification by a manufacturer that its vehicle complies with Standard No. 108 would encompass a certification that there is no i mpairment by any supplemental lighting equipment. The vehicle manufacturer must also consider whether any device installed in a rear window affects compliance with the interior rearview mirror field of view requirements specified by Standard No. 111 Rea rview Mirrors, and if affirmative to provide a passenger side exterior mirror.

The Vehicle Safety Act covers safety related defects as well as motor vehicle safety standards, requiring notification of purchasers and remedy of safety related defects when they occur. Spillage of light upon the rear glazing could be considered as a s afety related defect, and, for this reason, means should be provided to minimize reflections upon the rear glazing from all lamps in the array, and not just the center lamp.

The applicable Federal law for aftermarket equipment is also the Vehicle Safety Act. It prohibits modifications by manufacturers, distributors, dealers, and motor vehicle repair businesses to vehicle if those modifications render inoperative in whole or in part equipment installed in accordance with a safety standard. Center highmounted lamps have been required as original equipment on new cars manufactured on or after September 1, 1985. Because of the potential for interfering with the effectiveness of the center lamp, we would regard removal of an original equipment center lamp and substitution of your device including its center lamp as rendering the center lamp partially inoperative within the meaning of the prohibition. However, if the modific ation is such that it can be done by the vehicle owner, the Act does not prohibit an owner from it. Further, the Act would not prohibit in any way the installation of your device on passenger cars manufactured before September 1, 1985. However, supplem entary lighting devices sold in the aftermarket are regulated by each State in which the device would be sold and used. Although we are not conversant with those laws, you may consult the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, Va. 22203 for an opinion.

You have also asked how this device could be mandated as original equipment on new passenger cars. Any interested person may petition the Administrator for an amendment of Standard No. 108. However, the Vehicle Safety Act requires the safety standards to be standards for motor vehicle performance, and, to the extent possible, the agency attempts to minimize standards expressed in terms of design. For the same reason, the agency does not normally propose adoption of proprietary designs. As one of the requirements of a petition for rulemaking is that it contain the name and address of the petitioner, it might not be possible

3 to afford the same degree of confidentiality to a petition that it is to a request for an interpretation.

Your letter of April 4 asks a slightly different question on the subject of what is allowed to be viewed by other motorists in or around the rear window, with specific reference to turn signals, backup lamps, and hazard warning signals. The relevant port ions of Standard No. 108 are those relating to mounting height. The maximum mounting height of 83 inches allowed for turn signals (which commonly also serve as hazard warning signals) is unlikely to be exceeded by turn signals mounted in the rear window area. There is no maximum restriction on the mounting height of backup lamps but we do have performance criteria which must be met in order to ensure that they can satisfy their intended function of providing illumination behind the vehicle. Finally, y ou should realize that it is incorrect to refer to your device as a "third tail light assembly." A taillamp is a specific rear lamp required by Standard No. 108, and one which you have not incorporated into your assembly.

I hope that this answers your questions. As you requested in a phone call to Taylor Vinson the other day, we are returning the originals of your correspondence.

Enclosures

Sincerely,

ID: 10-001391 217

ID: nht94-8.28

DATE: February 7, 1994

FROM: John Womack -- Acting Chief Counsel, NHTSA

TO: Donald W. Vierimaa -- Vice President - Engineering, Truck Trailer Manufacturing Association

TITLE: None

ATTACHMT: Attached to letter dated 9/2/93 from Donald W. Vierimaa to John Womack (OCC-9050)

TEXT:

We have reviewed your letter of September 2, 1993, asking for three interpretations of S5.7 of Federal Motor Vehicle Safety Standard No. 108, the provisions that relate to heavy trailer conspicuity.

You have set forth the metric dimensions specified in S5.7, together with corresponding values under the headings "English (actual)," and "English (nominal)." The latter is a rounding off of the values of "English (actual)." Your first question is whether you may consider the English (nominal) dimensions equivalent for the purpose of compliance with Standard No. 108.

We assume that you would like to provide measurements in the conventional manner to your members who may not be familiar with the metric system, as a means of assisting them to comply with the conspicuity requirements that become effective December 1, 1993. However, the Federal motor vehicle safety standards are not expressed in equivalents, but in precise values, whether metric or conventional, and there can be no rounded "equivalences" for purposes of compliance with Standard No. 108. SAE J1322 JUN85 "Preferred Conversion Values for Dimensions in Lighting" which you reference has not been incorporated into Standard No. 108. In implementation of Departmental and national policy, NHTSA has begun to specify the requirements of the Federal motor vehicle safety standards using metric system values, and manufacturers are expected to learn and to comply with them.

We would also like to correct a misimpression indicated in your letter. You have placed a single asterisk by certain metric values reflecting your assumption that these are minimum values. This is incorrect; the standard expresses these values as fixed values rather than minimum ones. However, you are correct in your identification as minimum of those values that are not designated by an asterisk.

Your second question concerns the location of rear and side sheeting. You point out that cargo tank trailers may have a "vertical surface" only at their "belt line" which may be as high as 2.3 m above the ground. You ask whether retroreflective sheeting may be located higher that 1.25 m if there is no vertical surface lower than this height "without installing structure just for the sheeting." As adopted, Standard No. 108 specified a mounting height as close as practicable to 1.25 m. However, in a notice published on October 6, 1993, NHTSA amended the requirement to "as close as practicable to not less than 375 mm and not more than 1525 mm above the road surface." The practicability qualification allows manufacturers to choose a location for conspicuity treatment that is outside the specified

range to avoid body modifications that might otherwise be required to mount the material within the specified range.

The manufacturers of conspicuity material certify its performance as mounted on a vehicle in a vertical plane. Trailer manufacturers are expected to mount the material in a vertical plane or as close to a vertical plane as the trailer shape offers. In the case of your hypothetical tank trailer without a suitable vertical surface below the belt line of the tank, reflective material at the belt line, whether 2.3 m or higher, would be considered to have been mounted as close as practicable to the upper specification of the height range (1.525 m). As NHTSA observed when it adopted the original mounting height specification with its practicability provision, flexibility in the vertical location of conspicuity material is necessary for compliance of some tank trailers. However, it should not be overlooked that other types of tank trailers may have vertical surfaces on the frames, fenders, or other equipment well suited for conspicuity material.

Your third question presents five Figures and asks with respect to each whether the vertical and horizontal sheeting for the upper right and left contours, as specified by S5.7.1.4.1(b), may be of the dimensions and locations shown. This section requires application of two pairs of white strips of sheeting, each pair consisting of strips 300 mm long, applied "vertically" and "horizontally" to the contours "as close to the top of the trailer and as far apart as practicable." With respect to Figures 1 and 2 (van trailers), we shall assume that the horizontal strips are mounted as close to the top of the trailer as practicable. Figure 1 depicts two separate strips at right angles to each other, each 300 mm in length. This design is not in accordance with Standard No. 108. The side strip does not appear mounted as close to the top of the trailer as practicable, and the top strips do not appear to be mounted as far apart as practicable. While the presence of door hinges may necessitate designs similar to Figure 1, this design, as drawn on an unobstructed surface, does not comply. To effect compliance, either the side strips should be moved upwards, or the top strips should be moved closer to the outside corners.

Figure 2 depicts two strips joined at the corners to make an inverted "L." Each leg of the "L" is 300 mm in length when measured from the outside, top to bottom, or side to side. This configuration is in accordance with S5.7.1.4.1(b).

Figures 3 and 4 present alternative conspicuity treatments for liquid tank trailers where the body is curved rather than rectangular. In Figure 3, two strips 30 mm in length intersect at an angle greater than 90 degrees. In Figure 4, a curved strip 600 mm in length follows the contour of the body. Paragraph S5.7.1.4.1(b) of Standard No. 108 requires marking the upper outer contours of the body with strips "applied horizontally and vertically to the right and left upper contours of the body ...." However, the rear contours of a tank body are rounded rather than vertical and horizontal. In view of this fact, the agency accepts the treatment shown in your Figure 3 as meeting the requirement for horizontal and vertical application. The design of Figure 4 does not differ in any significant way, and we consider that it is equivalent.

Finally, Figure 5 depicts a dry bulk trailer with a 300 mm strip centered horizontally at the top of a round body, and two strips of the same length placed lower, at an angle slightly off of vertical, but far from the edges of the body contour. We understand that the body of the trailer tapers to a blunt end represented by the circle upon which the horizontal conspicuity treatment is laced. As the approximately vertical strips cannot be placed on the tapering trailer body, they should be located as far apart as practicable, and the depicted location appears to represent that placement. Similarly, if two horizontal strips cannot be placed on the trailer body, NHTSA will not question the compliance of the vehicle based on the provision of a single, center strip of retroreflective material.

ID: 77-3.22

TYPE: INTERPRETATION-NHTSA

DATE: 07/11/77

FROM: AUTHOR UNAVAILABLE; Joseph J. Levin Jr.; NHTSA

TO: Timpte Inc.

TITLE: FMVSR INTERPRETATION

TEXT: This responds to your May 6, 1977, letter asking whether your tire information label complies with the requirements of Standard No. 120, Tire Selection and Rims for Motor Vehicles Other Than Passenger Cars, and Part 567, Certification. Further, you request that the National Highway Traffic Safety Administration (NHTSA) expedite treatment of Docket No. 73-31; Notice 1, which, if implemented would simplify the certification and information labels.

Concerning Docket 73-31, the NHTSA published on June 20, 1977, a notice (42 FR 31161) implementing Notice 1 which proposed the use of the designation "all axles" rather than listing each axle individually on the certification label. The implementation of this regulation should resolve many of your problems.

Regarding the sample information label you submitted with your letter, the NHTSA does not give advance approvals of compliance with Federal safety regulations or standards. We will, however, give an informal opinion of whether your label appears to comply with the requirements. The label you submitted does not appear to comply with the requirements of Part 567 or Standard No. 120. I have enclosed copies of both of these regulations for your information.

Your certification label should use the designation "all axles" not "each axle." The tire and rim information should follow that designation stated in the form presented in the examples in Standard No. 120 and Part 567.

SINCERELY,

TIMPTE, INC.

MAY 6, 1977

NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION

ATTENTION: JOAN CLAYBROOK, ADMINISTRATOR

WE ARE A MANUFACTURER OF SEMI-TRAILERS, BASICALLY REFRIGERATED VAN TYPE TRAILERS AS WELL AS GRAIN HAULING TRAILERS OF SEVERAL TYPES. THESE ARE HIGHWAY OPERATED UNITS AND ARE NON-EXEMPT FROM ANY FEDERAL STANDARDS INCLUDING 121. THE 60 M.P.H. RATING IS STANDARD ON ALL OF THEM AND IN THIS CONTEXT, WE WOULD LIKE TO PRESENT OUR PROBLEM AND ASK FOR YOUR ASSISTANCE IN EXPEDITING ACTION AS WELL AS ADVISING OF YOUR CONCURRENCE OR NOT WITH OUR INTERPRETATION OF PART 567, AS WELL AS STANDARD 120. AS YOU KNOW, IT IS NECESSARY THAT WE AS MANUFACTURERS, CHANGE OUR CERTIFICATION PLATES AND TIME IS NOW OF THE ESSENCE OF OBTAINING DELIVERY SO THAT IN ORDER TO BE IN COMPLIANCE, IT BECOMES NECESSARY FOR US TO ACT RATHER QUICKLY.

PERTINENT TO THIS IS THE FACT THAT DOCKET #73-31; NOTICE #1 CLOSED COMMENT ON JANUARY 7, 1974 AND NO RESPONSE FROM NHTSA HAS BEEN FORTHCOMING, IN SPITE OF WHAT WAS APPARENTLY FAVORABLE POSITIVE COMMENT ON THE PROPOSED RULE-MAKING. THE AMENDMENTS PROPOSED TO PART 567.4 AND 567.5 WOULD GREATLY SIMPLIFY THE LABEL ITSELF AND YET NOT DETRACT FROM THE INFORMATION THEREON. SINCE NEARLY ALL OF THE HIGHWAY TYPE SEMI-TRAILERS MANUFACTURED HAVE IDENTICAL AXLES AND TIRES AND HENCE, GAWR RATINGS, IT SEEMS ONLY APPROPRIATE THAT A SINGLE GAWR RATING BE ALLOWED INDICATING THAT THAT IS FOR EACH AXLE OR ALL AXLES ON THE TRAILER. COMPARE THIS TO THE NECESSITY OF HAVING TO LIST FRONT, INTERMEDIATE, AND REAR AXLE GAWRS INDIVIDUALLY WHEN, IN FACT, NEARLY 100% OF THE TIME THEY ARE THE SAME. ON THOSE OCCASIONS WHEN THERE MIGHT BE A DIFFERENCE, THEN GAWR FOR THE DIFFERENT RATED AXLES WOULD BE REQUIRED. FURTHER, THIS NEED NOT MODIFY THE CONTEXT OF STANDARD 120 SINCE IN S5.3 (A) THE REFERENCE IS TO CERTIFICATION LABEL AS REQUIRED BY PART 567.4 OR 567.5.

ACCORDING TO OUR INTERPRETATION OF 120 AND WITH THE AMENDMENT AS PROPOSED IN DOCKET #73-31; NOTICE #1, OUR CERTIFICATION PLATE WOULD COMPLY AS SHOWN IN THE ATTACHED DRAWING 044-027A. S5.3.1 AND S5.3.2 CLEARLY ALLOW TIRE AND RIM DESIGNATIONS NOT NECESSARILY THOSE ON THE VEHICLE, BUT SUBSTANTIVE OF THE GAWR SHOWN. S5.1.2 IS COMPLIED WITH IN THAT 10:00X20F, RIMS 7.5 AT 75 P.S.I. COLD DUAL, IS THE MINIMUM TIRE THAT WILL GIVE THE GAWR OF 19,000 LBS. WHICH AGAIN IS THE MOST COMMON ONE IN USE TODAY DUE TO OTHER LIMITING FACTORS OF THE SUSPENSION, AXLE, WHEEL AND BRAKE SYSTEMS. OF COURSE, THE NEXT TO THE LAST SENTENCE WOULD BE COMPLIED WITH AND DOES ALLOW FOR TIRES FITTED TO THE AXLE NOT APPEARING ON THE CERTIFICATION LABEL. IN ALL CASES, THESE TIRES WOULD BE IN EXCESSIVE RATINGS OF THOSE WE WOULD HAVE PRINTED ON THE LABEL. FROM A PRACTICAL STANDPOINT, MANY OF OUR TRAILERS BEING SOLD THROUGH DISTRIBUTORS AND/OR DEALERS ARE EQUIPPED WITH TIRES OF A CERTAIN SIZE LEAVING OUR PLANT; HOWEVER AT VARIOUS LOCATIONS THROUGHOUT THE COUNTRY, WHEN HE DISTRIBUTOR OR DEALER IS SELLING THESE TRAILERS FROM STOCK, THEY MAY BE EQUIPPED WITH A DIFFERENT SIZE TIRE, YET ADEQUATE TO SUSTAIN THE GAWR.

THERE ARE TWO MORE POINTS IN REGARD TO THAT CERTIFICATION TAG AND ONE OF THEM IS POSSIBLE ELIMINATION OF THE ABBREVIATION OF THE WORD MINIMUM PRECEEDING TIRES. WHILE IT IS FACTUAL, IT IS NOT INDICATED IN THE STANDARD. THAT CAN EASILY BE ELIMINATED IF IT WAS NOT IN ACCORDANCE WITH YOUR INTERPRETATION OF THE STANDARD. THE OTHER ITEM THAT WE FEEL MIGHT BE DESIRABLE TO DO IS HAVE IN PLACE OF THE BLANK IN WHICH WE MUST STAMP NUMBERS OPPOSITE GAWR EACH AXLE, TO HAVE THAT PRINTED IN AT THE TIME OF THE MANUFACTURE OF THE LABEL IN THE SAME MANNER THAT WE WOULD THE TIRES AS SHOWN PRINTED IN. THE NUMBER WOULD BE 19,000 LBS. AS MENTIONED, THIS IS THE NEAR UNIVERSAL STANDARD RATING ON AXLES IN REGARDS TO VARIOUS OTHER LIMITING STANDARDS. THIS OF COURSE, LEAVES A MINIMUM OF ITEMS TO BE STAMPED IN ON THE PLATE AND STILL GIVES THE TOTAL INFORMATION REQUIRED. BUT FOR ANY POSSIBLE EXCEPTIONS THAT MIGHT OCCUR, WE WOULD PROPOSE USING A PLATE SIMILAR TO 044-027, THEREIN WE WOULD BE STAMPING ALL OF THE INFORMATION AND WE WOULD SUSPECT THAT THIS WOULD ONLY BE USED POSSIBLY 5% OF THE TIME.

I WOULD LIKE TO EMPHASIZE ONCE AGAIN THE URGENCY FROM A STANDPOINT OF TIME AND REQUIREMENTS FOR ORDERING, MANUFACTURING AND DELIVERY OF THE CERTIFICATION PLATES TO US. EXPEDITED FAVORABLE ACTION ON DOCKET #73-31; NOTICE #1 WILL GREATLY CLARIFY THINGS FOR OUR ENTIRE INDUSTRY AND WHILE IN THE INTERPRETATION AREA, WE ARE SPEAKING OF OUR OWN PLATE, THIS TOO, WOULD BE CLARIFIED BY AN OPINION FROM YOUR OFFICE. THANK YOU.

JACK GROMER VICE PRESIDENT - TECHNICAL OPERATIONS

CC: TTMA

ID: nht87-1.33

TYPE: INTERPRETATION-NHTSA

DATE: 02/20/87

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: Bruce Torrey -- Product Performance Specialist, General Electric Company

TITLE: FMVSS INTERPRETATION

TEXT:

Mr. Bruce Torrey Product Performance Specialist General Electric Company One Plastics Avenue Pittsfield, MA 01201

Thank you for your letters of August 13, and 26, 1986, concerning how the requirements of Standard No. 205, Glazing Materials, apply to glazing materials installed in the side windows of some New York City Transit Authority (NYCTA) buses. As explained be low, the information you provided in your letters and in your phone conversations with Stephen Oesch of my staff and the information provided by NYCTA in a June 19, 1986 letter to the agency indicates the glazing materials installed in the NYCTA buses do not comply with the marking requirements of the standard.

You explained in your letter that the glazing material used in the side and standee windows in the buses is Lexan sheet, which is a plastic material manufactured by General Electric. According to your letter, the Lexan glazing material used in these wind ows can meet all of the performance requirements set in Standard No. 205 for "AS-5" glazing materials. However, the material apparently was not marked as "AS-5" material, but may have instead been marked "AS-4/6." (Information provided to the agency by t he NYCTA in June 1986 indicates that the windows did not contain any "AS" number. At the time of your phone conversation with Mr. Oesch, you had not been able to confirm what markings, if any, had been placed on the glazing material by General Electric).

Standard No. 205 specifies performance and location requirements for glazing used in new vehicles and glazing sold as replacement equipment. (The various types of glazing are designated as "items" in the standard): Plastic glazing materials, such as Lexa n, can be used in a number of different locations in a bus depending on which performance requirements the glazing meets. If the plastic glazing meets the requirements set for AS-5 glazing materials, it can be used in any window in a bus, except for the windshield, windows to the immediate right and left of the driver and the rearmost windows if used for driving visibility.

In addition to setting performance requirements for different items of glazing, the standard requires glazing materials to contain certain markings. The marking requirements of S6 of the standard vary depending on the intended use of the glazing and the person that is marking the glazing. At a minimum, the standard requires the glazing to be marked pith the AS number (which indicates that the material meets the performance requirements set for that "item" of glazing material), a model number and the man ufacturer's logo. The information the agency has received about the markings on the glazing installed in the NYCTA buses indicates that the glazing does not have an AS number marked on it.

Any glazing sold for use in a motor vehicle must conform to the applicable requirements of Standard No. 205. Since there appears to be an apparent noncompliance, General Electric is required by Part 573 of our regulations to file a report with the agency providing additional details about the noncompliance and General Electric's plans to remedy the noncompliance. As you requested of Mr. Oesch, I am also enclosing a copy of the agency's regulation concerning the filing of a petition for a determination t hat a noncompliance is inconsequential.

If you have any further questions, please let me know.

Sincerely,

Erika Z. Jones Chief Counsel Enclosures

August 26, 1986

Office of the Chief Council National Highway Traffic Safety Administration 400 7th Street, S.W. Washington, D.C. 20590

Re: Letter from General Electric Company - August 13, 1986

Gentlemen:

In reference to my letter dated August 13, 1986 concerning the incorrect marking of glazing materials a matter of some urgency has come to my attention. It seems that the New York City Transit Authority is exercising exceptional prudence with regard to t his matter. If this situation continues hundreds of thousands of dollars worth of perfectly good material will be excluded from use.

It would be greatly appreciated if you could respond to the following.

Mr. William Wallace New York City Transit Authority 25 Jamaica Avenue Brooklyn, NY 11207

Mr. R.J. Watters Commercial Plastics & Supply Company Transportation Division 1620 Woodhaven Drive Cornwells Heights, PA 19020

If you have any questions or concerns please feel free to contact me. I can be reached at (413)448-7629. I thank you in advance for you cooperation.

Regards,

Bruce M. Torrey Product Performance Specialist

August 13, 1986

Office of the Chief Council National Highway Traffic Safety Administration 400 7th Street S.W. Washington, D.C. 20590

Re: Incorrect Glazing Marking

Gentlemen:

In order to satisfy the Department of Transportation in New York City I need an official statement concerning the following matter.

Lexan sheet, manufactured by General Electric Company is a plastic (polycarbonate) material typically used for bus side windows and standee glazings. These products are tested per ANSI Z26.1 standards on a regular basis and submitted to AAMVA for verific ation and certification.

During this process our Lexan@ MR-5000 Bronze tinted material was assigned an AS 4/6 designation, as it appears on the Notice of Equipment Compliance from AAMVA. Apparently a misinterpretation of ANSI Z26.1 test NO. 2 which requires minimum light-transmi ssion value of 70%. (1/4" Bronze Lexan@ MR5000 has a value of 53%).

Instead of being appropriately marked, AS-5, they received the AS 4/6 marking.

The following, details pertinent information.

Material Distributor:

Commercial Plastics & Supply Corp. Transportation Division 1620 Woodhaven Drive Cornwells Heights, PA 19020

Bus Manufacturer:

Blitz Bus & Truck 4525 W. 26th Street Chicago, IL 60623

This particular situation involves some 3,000 side windows and another 390 standee windows.

Enclosed you will find supporting test data and a copy of our original Notice of Equipment Compliance.

If you have any questions please feel free to contact me. I can be reached at (413)448-7629.

Regards,

Bruce M. Torrey

Enclosures Omitted.