Federal Motor Vehicle Safety Standards; Air Over Hydraulic Brake Systems

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. 94-56; Notice 1]

RIN 2127-AF01

Federal Motor Vehicle Safety Standards; Air Over Hydraulic Brake

Systems

AGENCY: National Highway Traffic Safety Administration (NHTSA),

Department of Transportation.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This notice responds to a petition submitted by John Kourik.

The notice proposes to amend the requirements in Standard No. 121, Air

Brake Systems, to include a definition of air-over-hydraulic brake

subsystems. The agency believes that this proposed definition would

clarify the classification of vehicles equipped with these subsystems

and thus eliminate the need for manufacturers to request, and the

agency to respond to, interpretations about them.

DATES: Comments. Comments must be received on or before September 9,

1994.

Proposed Effective Date. The proposed amendments in this notice

would become effective 30 days after publication of a final rule in the

Federal Register.

ADDRESSES: Comments should refer to the docket and notice numbers above

and be submitted to: Docket Section, National Highway Traffic Safety

Administration, 400 Seventh Street, SW., Washington, DC 20590. Docket

hours are 9:30 a.m. to 4 p.m., Monday through Friday.

FOR FURTHER INFORMATION CONTACT:

Mr. Chris Tinto, Office of Vehicle Safety Standards, National Highway

Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC

20590 (202-366-5229).

SUPPLEMENTARY INFORMATION:

Background

Air-over-hydraulic brake systems typically consist of an air brake

system from the treadle valve to an air brake chamber that provides the

mechanical force to actuate a hydraulic-operated master cylinder. In

turn, the hydraulic master cylinder actuates the brake shoes or pads.

The air brake chamber unit combined with the hydraulic-operated master

cylinder is called the ``power cluster'' and generally serves as the

separating point between the air- and hydraulic-actuated portions of

the air-over-hydraulic brake system.

Air-over-hydraulic brake systems are installed on about one percent

of medium and heavy trucks sold in the United States. This percentage

represents about 2,000 vehicles, most of which are Class 6 vehicles

with gross vehicle weight ratings (GVWRs) between 19,501 and 26,000

pounds.

Federal motor vehicle safety standard No. 121, Air brake systems,

currently defines ``air brake system'' to mean

a system that uses air as a medium for transmitting pressure or

force from the driver control to the service brake, but does not

include a system that uses compressed air or vacuum only to assist

the driver in applying muscular force to hydraulic or mechanical

components. (49 CFR Sec. 571.121)

Part 570, Vehicle In Use Inspection Standards, defines ``Air-over-

hydraulic brake system'' to mean

a subsystem of the air brake that uses compressed air to transmit a

force from the driver control to a hydraulic brake system to actuate

the service brakes. (49 CFR Part 570, emphasis added)

The italic portion of the definition of air-over-hydraulic subsystem

explicitly states that an air-over-hydraulic brake subsystem means a

subsystem of the air brake system.

In initially issuing Standard No. 121, NHTSA stated that ``it

should be noted that the term `air brake system' as defined in the

standard applies to the brake configuration commonly referred to as

`air-over-hydraulic,' in which failure of either medium can result in

complete loss of braking ability.'' (36 FR 3817, February 27, 1971).

The agency reiterated its position that an air-over-hydraulic brake

system is subject to Standard No. 121, stating that ``Standard No. 105a

[Hydraulic Brake Systems] does not apply to vehicles equipped with

`air-over-hydraulic' systems, which remain within the purview of

Standard No. 121* * *.'' (37 FR 17970, September 2, 1972.) Moreover,

NHTSA has issued several interpretations stating that a vehicle

equipped with an air-over-hydraulic brake system must comply with the

requirements in Standard No. 121.

NHTSA received a petition from Mr. John Kourik, requesting that the

agency amend Standard No. 121 to specify that an air-over-hydraulic

brake subsystem is subject to that Standard. The petitioner stated that

such an amendment would avoid the need for manufacturers to request

interpretations about air-over-hydraulic brake systems.

After reviewing the petition, NHTSA has decided to propose amending

Standard No. 121 by expanding the current definition of air brake

system to incorporate the definition of air-over-hydraulic brake

subsystem. The agency notes that even though the definition of an air

brake system currently includes a description of an air-over-hydraulic

subsystem, it is not explicitly clear on the face of the standard that

such a subsystem is classified as an air-braked system and that a

vehicle equipped with such a subsystem would thus have to comply with

the requirements in Standard No. 121. NHTSA believes that it would be

appropriate to clarify the classification of air-over-hydraulic brake

systems. By amending the definition of an air brake system to state

explicitly that an air-over-hydraulic brake subsystem is classified as

an air brake system, the agency would eliminate the need felt by some

manufacturers to request interpretations regarding the standard's

applicability to vehicles equipped with air-over-hydraulic brake

subsystems.

Rulemaking Analyses and Notices

1. Executive Order 12866 (Federal Regulation Planning and Review) and

DOT Regulatory Policies and Procedures

This proposal was not reviewed under E.O. 12866. NHTSA has analyzed

this proposal and determined that it is not ``significant'' within the

meaning of the Department of Transportation's regulatory policies and

procedures. A full regulatory evaluation is not required because the

rule, if adopted, would have no mandatory effects. Instead, the

proposal would only codify a longstanding agency interpretation.

Therefore, this rulemaking would not have any cost impacts.

2. Regulatory Flexibility Act

In accordance with the Regulatory Flexibility Act, NHTSA has

evaluated the effects of this action on small entities. Based upon this

evaluation, I certify that the proposed amendment would not have a

significant economic impact on a substantial number of small entities.

Vehicle and brake manufacturers typically would not qualify as small

entities. This amendment would affect small businesses, small

organizations, and small governmental units to the extent that these

entities purchase vehicles. However, this amendment would have no

significant cost impact on vehicles. For these reasons, vehicle

manufacturers, small businesses, small organizations, and small

governmental units which purchase motor vehicles would not be

significantly affected by the proposed requirements. Accordingly, no

regulatory flexibility analysis has been prepared.

3. Executive Order 12612 (Federalism)

This action has been analyzed in accordance with the principles and

criteria contained in Executive Order 12612, and it has been determined

that the proposed rule would not have sufficient Federalism

implications to warrant preparation of a Federalism Assessment. No

State laws would be affected.

4. National Environmental Policy Act

Finally, the agency has considered the environmental implications

of this proposed rule in accordance with the National Environmental

Policy Act of 1969 and determined that the proposed rule would not

significantly affect the human environment.

Public Comments

Interested persons are invited to submit comments on the proposal.

It is requested but not required that 10 copies be submitted.

All comments must not exceed 15 pages in length. (49 CFR 553.21).

Necessary attachments may be appended to these submissions without

regard to the 15-page limit. This limitation is intended to encourage

commenters to detail their primary arguments in a concise fashion.

If a commenter wishes to submit certain information under a claim

of confidentiality, three copies of the complete submission, including

purportedly confidential business information, should be submitted to

the Chief Counsel, NHTSA, at the street address given above, and seven

copies from which the purportedly confidential information has been

deleted should be submitted to the Docket Section. A request for

confidentiality should be accompanied by a cover letter setting forth

the information specified in the agency's confidential business

information regulation. 49 CFR part 512.

All comments received before the close of business on the comment

closing date indicated above for the proposal will be considered, and

will be available for examination in the docket at the above address

both before and after that date. To the extent possible, comments filed

after the closing date will also be considered. Comments received too

late for consideration in regard to the final rule will be considered

as suggestions for further rulemaking action. The NHTSA will continue

to file relevant information as it becomes available in the docket

after the closing date, and it is recommended that interested persons

continue to examine the docket for new material.

Those persons desiring to be notified upon receipt of their

comments in the rules docket should enclose a self-addressed, stamped

postcard in the envelope with their comments. Upon receiving the

comments, the docket supervisor will return the postcard by mail.

List of Subjects in 49 CFR Part 571

Imports, Incorporation by reference, Motor vehicle safety, Motor

vehicles, Rubber and rubber products, Tires.

In consideration of the foregoing, the agency proposes to amend

Standard No. 121, Air Brake Systems, in Title 49 of the Code of Federal

Regulations at part 571 as follows:

PART 571--[AMENDED]

1. The authority citation for part 571 would continue to read as

follows:

Authority: 15 U.S.C. 1392, 1401, 1403, 1407; delegation of

authority at 49 CFR 1.50.

2. In Sec. 571.121, S4 would be amended by revising the definition

of ``Air Brake System'' and by adding the definition of ``Air-over-

hydraulic brake subsystem'' to read as follows:

Sec. 571.121 Standard No. 121; Air brake systems.

* * * * *

S4 * * *

Air brake system means a system, including an air-over-hydraulic

brake subsystem, that uses air as a medium for transmitting pressure or

force from the driver control to the service brake, but does not

include a system that uses compressed air or vacuum only to assist the

driver in applying muscular force to hydraulic or mechanical

components.

* * * * *

Air-over-hydraulic brake subsystem means a subsystem of the air

brake that uses compressed air to transmit a force from the driver

control to a hydraulic brake system to actuate the service brakes.

Issued on: July 5, 1994.

Barry Felrice,

Associate Administrator for Rulemaking.

[FR Doc. 94-16613 Filed 7-8-94; 8:45 am]

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