ID: nht74-1.42

DATE: 06/20/74

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: Blue Bird Body Company

TITLE: FMVSS INTERPRETATION

TEXT: In your letter of May 30, 1974, you ask whether a rear lighting configuration intended for your 1975 vehicles, based upon a proposal in Docket No. 69-19, would meet the current requirement that stop lamps be "as far apart as possible."

The photographs you enclose show that the intent of the proposed S8.10 has been met by providing a separation distance between turn signal and stop lamps that is 5 inches or more, and by placing the stop lamp so that its optical axis is inboard of a vertical longitudinal plane passing through the optical axis of the taillamps. Although it is obviously "practicable" for you to retain the stop lamps in their present location, we consider that the reasons you wish to introduce the change support a determination of practicability under the current requirements, even though the proposal remains under consideration and may not be adopted.

Yours truly,

ATTACH.

BLUE BIRD BODY COMPANY

May 30, 1974

Richard B. Dyson -- Assistant Chief Counsel, U. S. Dept. of Transportation, NHTSA

Dear Mr. Dyson:

In the Federal Register Vol. 37, No 206, dated October 25, 1972, appeared a proposed change for FMVSS 108. This was identified as Docket 69-19, Notice 3. In paragraph S8.10 of this notice NHTSA proposed to physically separate the stop lamp, tail lamp and the turn signal functions. Blue Bird Body Company concurs with this proposed change and in fact, we would like to incorporate it into our 1975 model buses. The attached photographs show our current stop lamp location and our proposed stop lamp location. As you can see from the photographs, our proposed lighting configuration would physically separate the stop lamp and turn signal lamps by placing the back-up lamps between them.

Although we believe this lighting scheme will provide safer vehicles because of greater discrimination between the stop lamp and turn signal functions, we are concerned with the current requirement of FMVSS 108, table 2, which says that the stop lamps must be ". . . as far apart as practical."

Certainly NHTSA must be of the opinion that such a lighting configuration will provide safer vehicles or they would not have made this proposal. Therefore, it is our opinion that our proposed 1975 lighting configuration meets the intent of the current regulations as well as the proposed future regulation and request your approval of this change. Thank you for your consideration of this request and your early reply.

Yours very truly,

W. G. Milby -- Project Engineer

c Dave Phelps; Jim Moorman

ID: nht74-1.43

DATE: 04/28/74

FROM: AUTHOR UNAVAILABLE; E. T. Driver; NHTSA

TO: Mark Bedrossyan

COPYEE: L. OWEN

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of March 21 to the National Highway Traffic Safety Administration concerning your "Straight Ahead" directional signal for motor vehicles.

Federal Motor Vehicle Safety Standard No. 108. "Lamps, Reflective Devices and Associated Equipment," permits lamps, reflective devices or other motor vehicle equipment in addition to those that are required (headlights, parking lamps, turn signal lamps, etc.) providing that the effectiveness of the required devices is not impaired. It does not appear that your device would impair the effectiveness of the required lamps; therefore, it would be permitted, either as original equipment, or as an aftermarket item.

Since the performance aspects of your device are not covered by Standard No. 108, the individual States are free to regulate the sale and use of your device. If your "Straight Ahead" signal flashes, its use would probably be prohibited in most of the States, because of their restrictions on flashing lights for motor vehicles.

Thank you for your interest in highway safety.

Not controlled

ATTACH.

ATLANTIC ELECTRONICS LABORATORIES

March 21, 1979

The National Highway Traffic Safety Administration Washington, D.C.

Gentlemen:

Subject: "Straight Ahead"

Directional Signal for Motor Vehicles

Over two decades ago, the use of electrical (Illegible Word) signals on motor vehicles became mandatory nation-wide, this decision has proved both useful and effective in preventing accidents.

It is believed there is room for an additional device, and to fill this need, we have designed the "Straight-Ahead" electrical directional signal for cars and trucks, which is controlled from the dashboard by a switch. This is intended to be used at intersections and certain other road conditions. (Please see the inclosed pictorial representations).

I have already installed such a device on my own car on an experimental basis.

It is respectfully requested that you evaluate this idea, and permit its use, if deemed appropriate, since we plan to market it in kit form.

New car manufacturers are being contacted to bring this new idea to their attention.

An (Illegible Word) reply would be greatly appreciated.

Very truly yours,

Mark B. Bedrossyan

(Graphics omitted)

ID: nht74-1.44

DATE: 09/23/74

FROM: AUTHOR UNAVAILABLE; Richard B. Dyson; NHTSA

TO: Pan Commercial

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of August 27, 1974 asking for a clarification of the National Traffic and Motor Vehicle Safety Act.

You are correct in your impression that under section 103(d) of the Act "no state legislation can be more stringent than the Federal ruling." Under paragraph S4.1.1.26 of Standard No. 108, effective October 14, 1974, "a motor-driven cycle whose speed attainable in 1 mile is 30 mph or less need not be equipped with turn signal lamps." This means that as of that date, only motor-driven cycles whose maximum speed exceeds 30 mph are required to be manufactured with turn signal lamps. Lower-speed cycles may continue to be provided with them if the manufacturer chooses, but a State cannot require him to do so. This is the result of the preemptive effect of section 103(d).

Yours truly,

ATTACH.

August 27, 1974

R. Dyson -- Acting Chief Counsel, National Highway Traffic Adminstration

Dear Mr. Dyson:

I am referring to the proposed legislation docket #74-16 pertaining to modifications of requirements for motor driven cycles. Under this proposed ruling, article 571.108 S4.1.1, a motor driven cycle with a speed of less than 30 MPH would not need to be equipped with turn signal lamps.

I have contacted the Registry of Motor Vehicles in Massachusetts and in their opinion Massachusetts will always require turn signal lamps. I was under the impression that under section 103D of the National Traffic and Motor Vehicle Safety Act, no state legislation can be more stringent than the Federal ruling.

In the light of the proposed Federal ruling and the apparent contradiction of State and Federal Traffic Laws, may I ask you for your advice in this matter,

Thank you for your cooperation.

Very truly yours,

PAN COMMERCIAL; Bernard E. Wuthrich

ID: nht74-1.45

DATE: 01/01/74 EST.

FROM: E. T. Driver; NHTSA

TO: M. L. Higgins

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of March 8 to Dr. James B. Gregory, Administrator, concerning an interpretation relative to the [Illegible Words].

[Illegible Paragraph].

ID: nht74-1.46

DATE: 11/05/74

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

TO: Midland-Ross Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This responds to Midland-Ross' October 8, 1974, clarification of its February 8, 1974, petition for an amendment of S5.1.2.1 and S5.2.1.2 of Standard No. 121, Air brake systems, that would establish separate air reservoir volume requirements for several brake chamber types generally available in the air brake component market. You point out that Midland-Ross was referring to chamber stroke and not chamber diameter as the chamber dimension which could affect the safety of a brake system. You also requested that we adopt SAE Standard J10b instead of J10a as our specification of a reservoir that "withstands" certain internal hydrostatic pressure.

In our denial of your petition, we did understand your point that additional stroke could be discouraged by a reservoir capacity requirement based on chamber size at maximum travel of the piston or diaphragm. We found that the stopping distance requirements in effect mandate the installation of high performance components, and we do not anticipate a safety problem. If a safety problem does arise in the future, we would consider a modification of S5.1.2.1 and S5.2.1.2.

SAE Standard No. J10b is identical to J10a in its requirement that no rupture or permanent circumferential deformation of the reservoir exceed one percent. Therefore, for purposes of S5.1.2.2 and S5.2.1.3, we are adopting SAE J10b as our specification of "withstand" until we undertake further rulemaking.

Yours truly,

ATTACH.

POWER CONTROLS DIVISION Midland-Ross Corporation

October 8, 1974

James B. Gregory -- Administrator, U.S. Department of Transportation, National Highway Traffic Safety Adm.

Dear Mr. Gregory:

Subject: N40-30 (TWH)

Thank you for your response to our petition dated February 8, 1974 in regard to Section S5.1.2.1 and S5.2.1.2 of Standard 121 Air Brake Systems. We feel that our petition may not have been clear in regard to use of small volume chambers which apparently led to your misinterpreting our concern. We also believe you may have referred to the incorrect SAE Standard regarding air reservoirs.

In regard to our petition for clarification of air reservoir required volumes, we made mention of the fact that "current reservoir volume requirement based on maximum displacement encourages the use of small volume chambers". By this statement we did not imply smaller diameter chambers but shorter stroke chambers. It is quite easily determined that little chamber stroke is required if the foundation brakes are carefully adjusted with minimum liner to drum clearance. A chamber with 1.5" stroke could be adequate and will meet all of the standard's requirements. If a vehicle manufacturer would elect to go with this short stroke, he could reduce reservoir capacity by 25%. However, there would be very little safety factor to allow for drum expansion and liner wear. It is this condition of which we are concerned and feel it is wrong to penalize the vehicle manufacturer by requiring them to have larger reservoirs when they attempt to provide this additional safety advantage. We ask that you again review this matter and adopt one of the recommended changes to S5.1.2.1 and S5.2.1.2 as stated in our petition.

In the last paragraph of your response you mention the NHTSA has adopted the SAE Standard No. J10a in regard to the definition of "withstand". We assume you intended to refer to SAE Standard J10b and would appreciate your concurrence with this assumption.

Sincerely,

M. J. Denholm -- Director of Engineering

ID: nht74-1.47

DATE: 11/12/74

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

TO: Oshkosh

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your October 8, 1974, question whether a front axle automatic pressure limiting valve may be removed during the burnish procedure to permit effective burnish of the front brakes.

The answer to your question appears in Notice 6 to Docket 74-10 in response to a similar inquiry from International Harvester. A copy of that notice is enclosed for your information. It amends S6.1.8.1 to require that any automatic pressure limiting valve be in use except in the case where the temperature of the hottest brake on a rear axle exceeds the temperature of the hottest brake on a front axle by more than 125 degrees F. A bypassed valve is reconnected if the temperature of the hottest brake on a front axle exceeds the temperature of the hottest brake on a rear axle by 100 degrees F.

Yours truly,

Enclosure

ATTACH.

OSHKOSH TRUCK CORPORATION

October 9, 1974

Richard Dyson -- U.S. Dept. of Transportation, National Highway Traffic Safety Administration

Subject: 49 CFR Part 571, FMVSS 121 - Air Brake Systems

Dear Mr. Dyson:

Per Federal Bureau of Motor Carrier Safety Regulations, Part 393, Section 393.48, use of automatic devices for reducing front wheel brake effort is permitted on vehicles complying to FMVSS 121.

With the automatic pressure reduction valve in the front axle, Oshkosh Truck Corporation has found that during burnishing of some vehicles per Section 6.1.8.1 of FMVSS 121, the rear brakes reach 500 degrees F, much earlier than the front axle brakes because of the automatic reduction of brake force to the front axle and, therefore, effective burnishing of the front brakes is not achieved.

Please advise if the automatic device to reduce the front wheel brake force can be removed during the burnishing procedure.

Very truly yours,

P. K. Kamath -- Sr. Safety Engineer

ID: nht74-1.48

DATE: 05/23/74

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

TO: The Flxible Company

TITLE: FMVSS INTERPRETATION

ID: nht74-1.49

DATE: 05/10/74

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

TO: Superior Trailer Works

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your April 22, 1974, question concerning the certification responsibility of a small manufacturer of trailers that must conform to Standard No. 121, Air brake systems. You ask if road testing of any or all vehicles produced would be necessary to satisfy the requirements.

A manufacturer must "exercise due care" in certifying that the vehicles manufactured by him comply with the applicable standards (National Traffic and Motor Vehicle Safety Act of 1966, @ 108(b)(2), 15 U.S.C. @ 1392(b)(2)). What constitutes due care in a particular case depends on all relevant facts, including such things as the time to elapse before a new effective date, the availability of test equipment to small manufacturers, the limitations of current technology, and above all the diligence evidenced by the manufacturer.

A small manufacturer of standard and custom trailers might fulfill his due care responsibility to assure that each of his trailers is capable of meeting the standard in several ways. For example, he could establish categories of models which share a common brake and axle system and certify them all on the basis of tests on the most adverse configuration in the category. Calculations should be written down in such a case to establish that reasonable care was taken in these decisions.

Alternatively, joint testing might be undertaken with a trade association or with a major supplier of brake and axle components. In the case of standard models, you might be able to rely on the supplier's warranty of his products' capacities.

Neither of these methods would require road testing of each vehicle manufactured, nor would every model have to be road tested. A manufacturer must simply satisfy himself that the trailer is capable of meeting the stopping performance requirements if it were tested by the NHTSA.

Yours truly,

ATTACH.

April 22, 1974

National Highway Traffic Safety Administration Attn: James B. Gregory, Administrator

Gentlemen:

We are a small trailer manufacturing firm currently producing approximately 100 trailers per year. These trailers are predominantly standard models (with some variations in body length and height), however, we also manufacture some custom trailers, principally low beds.

We do not manufacture brakes or axles or air system components, instead we purchase a complete axle-brake assembly and the air components, and assemble them into a trailer chassis. Under the Motor Vehicle Safety Standard 121 we will, of course, install components that meet the new requirements.

We are in the process of determining all the changes that we will be required to make under MVSS 121 and would appreciate clarification of the following:

1. Will we be required to road test complete trailers or will the inclusion of all certified components satify the requirements of the law?

2. If road testing of the complete trailer is required, is it required of every trailer produced, or would the test of a single prototype of a standard model be sufficient for all other trailers of the same model?

3. What road testing would be required for custom trailers that vary widely in length, width, height, capacity, etc.?

We have contacted several California trailer manufacturers, and they are in the same position that we find ourselves, i.e., no testing facilities of our own and without knowledge of any independent testing facility offering such a service. The size of the facilities required would make it all but impossible for any but a very large business firm to construct a special facility.

We are including some literature that will show the variations in equipment that we manufacture.

Your earliest possible comments would be greatly appreciated.

Very truly yours,

SUPERIOR TRAILER WORKS Charles R. Richards -- President

ID: nht74-1.5

DATE: 09/19/74

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

TO: U. S. Technical Research Corporation

TITLE: FMVSS INTERPRETATION

TEXT:

NOA-30 (ZTV) Sep 19 1974

Mr. Bernard Belier U.S. Resident Engineer for Citroen, S.A. U.S. Technical Research Corporation 801 Second Avenue New York, New York 10017

Dear Mr. Belier:

This is in further reply to the petition of November 16, 1973, by Citroen, S. A. for rulemaking to amend Motor Vehicle Safety Standard No. 105-75, Hydraulic Brake Systems.

The petition has been thoroughly reviewed by engineering and legal staff personnel of this agency. Before a recommendation is made to the Administrator on the merits of your petition, we request that you furnish further information to us.

First of all, NHTSA is interested in obtaining any available data which will support the contention that the Citroen central power braking system provides a level of safety equivalent to a fully split system with indefinite residual failure mode performance such as is currently required by FMVSS 105-75. Do the highway accident statistics provide such support? Is the incidence of accidents occurring to Citroen vehicles attributable in whole or part to brake failures significantly different from the norm for other European passenger cars? Can it be demonstrated that when failures of the service brakes do occur in emergency situations, drivers are able to adjust their behavior patterns sufficiently quicly to bring the vehicles to a safe stop using the hand operated emergency brakes?

We wuld also like Citroen to provide data to substantiate that the "emergency" system can meet the deceleration requirement of 10 fpsps. What are Citroen's views on an appropriate burnish procedure for testing the emergency braking system? In addition to this, can the 10 fpsps deceleration requirement be achieved using the service brakes with a subsystem accumulator depleted?

Finally, we request data on the costs and leadtime required for Citroen to convert the single central power system to a dual, or full split system.

Yours truly,

Richard B. Dyson Acting Chief Counsel

cc: Maurice Clavel Assistant to the President S.A. Automobiles Citroen

ID: nht74-1.50

DATE: 07/11/74

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

TO: Bendix Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your May 10, 1974, request for interpetation of the volume requirements for service brake chambers in S5.2.1.2 and S5.1.2.1 of Standard No. 121, Air Brake System:

S5.1.2.1 The combined volume of all service reservoirs and supply reservoirs shall be at least twelve times the combined volume of all service brake chambers at maximum travel of the pistons or diaphragms.

You also requested that reservoir volume be based on manufacturer "rated volume" based on the designed volume of the reservoir.

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 "prefill 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.

With regard to air reservoir volumes, the NHTSA will determine the volume of reservoirs by actual measurement. As a practical matter air reservoirs are simple structures whose volumes are relatively easy to measure.

Sincerely yours,

ATTACH.

Bendix

Heavy Vehicle Systems Group

Chief Counsel -- National Highway Traffic Safety Administration

May 10, 1974

Subject: Title 49 CFR, Part 571, Motor Vehicle Safety Standard No. 121, Air Brake Systems

Dear Sir:

Concern has arisen in the motor vehicle industry relative to the matter of brake chamber and reservoir volumes as set forth in Section 5.1.2.1, of the subject standard which provides:

"The combined volume of all service reservoirs and supply reservoirs shall be at least twelve times the combined volume of all service brake chambers at maximum travel of the pistons or diaphragms."

The question posed is: How will the sizing be verified for compliance purposes? Hence, an interpretation of Section 5.1.2.1 is requested.

Historically, the Industry has used the "nominal" or rated full stroke of brake actuators, in determining available stroke. In practice, it was understood that the nominal or rated full stroke is all that can be counted on to provide braking. (The recommended readjustment stroke followed by the Industry has been from 3/8 to 3/4 inch less than the "rated full stroke" depending upon actuator size.) Further, SAE recommended Practice J813, "Automotive Air Brake Reservoir Volume" does not go into any detail relating to strokes, tolerances, etc. of the various components involved in the actuation of a foundation brake.

The design of a braking system requires that a component, such as an actuator, which is called upon to give a specified stroke must have its own dimensions and tolerances so designated that its "minimum" travel provisions are those required for the system. To use the actuator's maximum stroke, taking into account tolerance stack up, as the basis for sizing a reservoir, appears to be unreasonable and would not increase the safety of the vehicle. (The maximum possible stroke is, of course, not available in every actuator and thus cannot be counted on for braking.)

It is therefore recommended that NHTSA give favorable consideration to an interpretation of Section 5.1.2.1 to provide that the brake chamber volume be specified at the advertised nominal or rated full stroke of the brake chamber. This volume can be determined by a manufacturer and precludes the necessity of adding additional reservoir volume to compensate for theoretical tolerances that in all likelihood will never become cumulative in the system.

An analogous situation exists with reservoirs. Because of the profusion of sizes and special configurations (different sizes and quantities of ferrules, and a variety of lengths and diameters) the minimum volume determined by physically filling several reservoirs of each configuration to measure the exact volume does not appear to add any reasonable degree of accuracy or safety.

Therefore, it is also recommended that the reservoir volumes be certified based on a "rated volume" produced by calculation using the actual nominal Engineering drawing dimensions. Ferrules would be ignored in the calculations as being insignificant and at any rate generally a "plus" for volume.

We solicit your comments on these matters and would be happy to discuss our recommendations with you if you feel that additional information is necessary.

Very truly yours,

R. W. Hildebrandt -- Group Director of Engineering