Federal Motor Vehicle Safety Standards; Air Brake Systems; Automatic Brake Adjusters

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. 91-21; Notice 3]

RIN 2127-AE76

Federal Motor Vehicle Safety Standards; Air Brake Systems;

Automatic Brake Adjusters

AGENCY: National Highway Traffic Safety Administration (NHTSA),

Department of Transportation (DOT).

ACTION: Final rule, response to petitions for reconsideration.

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SUMMARY: This notice responds to petitions for reconsideration of a

final rule amending Standard No. 121, Air Brake Systems, (49 CFR

571.121). The rule amended the standard by requiring, inter alia,

automatic brake adjusters on all medium and heavy vehicles and

establishing readjustment limits for the performance of the adjusters.

NHTSA received several petitions requesting the agency to reconsider

the limits on the adjusters. This document grants those petitions.

DATES: Effective Date: The amendment to Sec. 571.121 becomes effective

October 20, 1994.

Petitions for reconsideration: Any petitions for reconsideration of

this rule must be received by NHTSA no later than May 18, 1994.

ADDRESSES: Any petition for reconsideration should refer to the docket

and notice number set forth in the heading of this notice and be

submitted to: Administrator, NHTSA, 400 Seventh Street SW., Washington,

DC 20590.

FOR FURTHER INFORMATION CONTACT: Richard C. Carter, Crash Avoidance

Division, National Highway Traffic Safety Administration, 400 Seventh

Street SW., Washington, DC 20590 (202-366-5274).

SUPPLEMENTARY INFORMATION: On October 20, 1992, NHTSA published a final

rule that amended Federal Motor Vehicle Safety Standard No. 121, Air

Brake Systems, to require, inter alia, automatic brake adjusters on all

air-braked vehicles. (57 FR 47793.) That amendment improves the braking

performance of vehicles by ensuring that each vehicle has a device that

automatically maintains proper brake adjustment, thus eliminating the

need for frequent inspection and manual adjustment of the brakes. To

provide for a specific performance requirement for the adjusters, the

rule also specified that the adjuster would have to perform such that

``the readjustment limits shall be in accordance with those specified

in'' a regulation of the Federal Highway Administration (FHWA).\1\

(See, S5.1.8(a) of Standard No. 121.) The readjustment limits relate to

the distance that a part of the brake (the pushrod) must travel, or

stroke, before engaging the brake. The readjustment limits specify

maximum distances for pushrod stroke.

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\1\Appendix G to subchapter B of Chapter III--``Minimum Periodic

Inspection Standards,'' 49 CFR parts 200 to 399.

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NHTSA received timely petitions for reconsideration of the rule

from Rockwell International (Rockwell) and White GM/Volvo. Petitioners

asked for reconsideration of the requirements for the readjustment

limits for the adjuster. Mr. John Kourik submitted a late petition to

reconsider various aspects of the rule, including the readjustment

limits. NHTSA is treating Mr. Kourik's petition as a petition for

rulemaking, pursuant to the agency's regulations (see 49 CFR 553.35).

However, NHTSA is responding in today's document to the issues raised

by Mr. Kourik about the readjustment limits, since they are almost

identical to those of Rockwell and White GM/Volvo.

Each petitioner was concerned about the readjustment limit. Among

the petitioners' criticisms were that the requirement is not objective,

is inappropriate for certain air brake systems, and is likely to

restrict new brake designs. Petitioners also believed that NHTSA did

not provide adequate notice about the specification in the final rule

for the FHWA readjustment limits.

The concern about the adequacy of notice resulted from the

development of the requirement from the original proposal in the NPRM.

In the NPRM, NHTSA proposed that a brake adjuster perform so that it

``maintains brake adjustment within the manufacturer's recommended

adjustment limits.'' 56 FR 20396, 20401, May 3, 1991. Several

commenters, including White GM/Volvo, GM, Ford, and Midland-Grau,

believed that the proposal would not provide any significant safety

benefits and might cause unnecessary complications and confusion. For

example, some commenters argued that, since there is no objective

criteria as to what constitutes ``maintains brake adjustment,'' the

requirement would be vague. Also, White GM/Volvo, GM and Ford believed

that the proposal might be misinterpreted as requiring the manufacturer

to be responsible for brake adjustment throughout the vehicle's life,

even though under the National Traffic and Motor Vehicle Safety Act the

manufacturer is responsible for the compliance of the new vehicle only

until the first consumer purchase. One commenter, Midland-Grau,

recommended that NHTSA incorporate the FHWA's requirements for brake

adjustment, set forth in the Minimum Periodic Inspection Standards.

After reviewing the comments, NHTSA agreed that the proposed

requirement for readjustment limits was potentially vague and

misleading. However, NHTSA believed Midland-Grau's recommendation about

the FHWA alternative had merit. NHTSA stated:

As for Midland-Grau's recommendation to use FHWA's regulations

for ``Driver Out-of-Service Criteria'' for brake adjustment, NHTSA

has decided to reference these provisions in Standard No. 121

because they are relevant to in-use heavy truck operation regulated

by FHWA. Because amendments to Standard No. 121 require the use of

brake adjustment indicators which require the display of

underadjustment, a reference to adjustment limits is necessary.

57 FR at 47796.

Petitions for Reconsideration

All the petitioners raised identical concerns about the

incorporation of the FHWA requirements.

1. Design Specific Requirements

Rockwell stated that the FHWA adjustment criteria that NHTSA

incorporated would eliminate most air disc brakes from the market. The

petitioner said that until 1988, FHWA's readjustment limits for the

brake adjuster were in the form of guidelines. These guidelines

provided separate requirements for air disc brakes, recognizing that

air disc brakes need a slightly longer maximum stroke limit for each

chamber size than that specified for drum brakes. For example, Rockwell

said, for a type 30 chamber, the old FHWA ``minimum criteria'' provided

for a maximum stroke of 2 inches for drum brakes and 2\1/4\ inches for

air disc brakes.

Rockwell stated there are fundamental differences between air disc

brakes and drum brakes that account for why the FHWA guidelines

permitted air disc brakes to have a slightly longer pushrod stroke

limit than drum brakes. The petitioner explained:

In both types of systems, the pushrod stroke length is

proportionate to the clearance between the brake lining and the

rubbing surface (the drum or the disc). On drum brakes, the

clearance and therefore the pushrod stroke gets longer as the brakes

become hot and the circular drum wall expands in diameter by as much

as one-eighth inch at 800 degrees F. By contrast, a disc brake

pushrod stroke gets shorter as the brake gets hotter, because the

expansion of the hot rotor brings it closer to the pads which are

also expanding in the direction of the rotors.

Rockwell said that when FHWA adopted its rule for readjustment

limits (53 FR 49402, December 7, 1988), the rule did not continue to

provide separate specifications for air disc brakes, as it had

previously done in its guidelines. Rockwell argued that ``by omitting

the separate table for disc brakes, and requiring drum brakes and air

disc brakes to meet the same adjustment criteria, the FHWA Final Rule

had the effect of imposing a more stringent requirement on the air disc

brakes than it imposed on drum brakes.''

Rockwell said that it has asked FHWA to reconsider the agency's

1988 rule and that FHWA has agreed to reopen Docket MC-90-7 for

additional comment on the issue of the appropriate requirements for air

disc brakes. FHWA anticipates that a notice will be issued in the near

future.

Rockwell stated that the effect of incorporating the FHWA

readjustment limits would be to prohibit future sales of the air disc

brake in certain applications. The petitioner argued that this would be

anomalous in view of what Rockwell believes is an excellent safety

record for the air disc brake system. Rockwell said that the system has

been in use on the road for over 10 years, and,

[S]ince 1985, Rockwell has been the sole North American

manufacturer of air disc brakes. Many using customers have

purposefully selected the air disc brake because of its unique

performance features. High performance requirements of fire service

vehicles, frequent braking requirements of refuse vehicles and

minimal brake fade requirements desired by tractor/trailer operators

hauling hazardous and flammable cargos are typical air disc brake

applications.

The National Transportation Safety Board in their April 1992 Heavy

Vehicle Airbrake Performance Safety Study noted:

Air disc brakes have several advantages over drum brakes. When

subjected to intense braking demands, disc brakes do not suffer the

same performance degradations as do drum brakes. Disc brakes also

reduce down hill runaways as well as brake imbalances caused by

varied brake adjustments on the same vehicle.

2. Design Restrictions

The petitioners raised concerns that the incorporation of the FHWA

requirements could hinder technological development, such as that of

long stroke brake chambers. (On August 2, 1993, NHTSA published an NPRM

to facilitate the use of long stroke brake chambers. 58 FR 41078).

Rockwell stated:

By referencing the FHWA readjustment criteria in FMVSS 121,

NHTSA has ``frozen'' the FHWA criteria in their current form as of

October 20, 1992, for purposes of FMVSS 121. Even if FHWA later

amends its criteria in response to Rockwell's petition or to

accommodate new technology, NHTSA will have to take affirmative

action to update its cross-reference. * * * The time consuming

process of adopting future changes to FMVSS 121 will deter air brake

technology or, at least, prevent its rapid introduction into the

marketplace. Rockwell believes that NHTSA did not intend this

result.

Agency's Decision

After reviewing the petitions, NHTSA has decided to delete

reference to the FHWA's regulations at issue. It appears that the FHWA

readjustment limits are suitable for conventional drum brakes, but do

not account for differences between conventional drum brakes and new

types of air brake systems. When the agency adopted the readjustment

limits, NHTSA did not intend to impede the development of brake systems

that could provide comparable performance to conventional drum brakes,

such as piston-type brakes. The FHWA requirements appear to be not

fully appropriate for piston-type brakes because of substantially

longer stroke length air brake chambers, which are fully developed and

are undergoing fleet testing. Additional air brake chamber categories

will have to be added to the FHWA Schedule A inspection tables as

technology moves forward. Moreover, when NHTSA adopted the readjustment

limits, the agency did not intend to prevent or hinder the development

of brake designs that may offer potentially superior performance over

drum brakes in specific applications, such as the air disc brake

system.

The air disc brake system is subject to the same readjustment

limits in the FHWA requirements as conventional drum brakes, which does

not seem appropriate, given differences between the two types of air

brake systems. Rockwell's air disc brake system has a stroking distance

that is about \1/4\ inch longer than that permitted by the current FHWA

requirement. However, Rockwell submitted test data to NHTSA that show

that, with this stroking distance, the air disc brake system performs

well when tested to the specifications and requirements of Standard No.

121. (These data have been placed in docket 91-21, Notice 3.)

Available information indicates that the air disc brake system

appears to perform to Standard 121 specifications and may perform

better than conventional drum brakes in some situations. There does not

appear to be any data to support the need to impose a shorter stroke

limit on air disc brake systems such as Rockwell's, that would impede

the development of those systems. NHTSA believes the development of

alternative, potentially superior brake systems, such as the air disc

brake systems, should be facilitated to the extent possible. NHTSA

believes there is an alternative requirement that would address the

need for readjustment limits, yet avoid the problems the petitioners

addressed.

Alternative Approach

Rockwell recommended that NHTSA require that the automatic

adjuster's readjustment limits ``be in accordance with the

manufacturer's recommended limits.'' It commented that this language

would be sufficiently objective because NHTSA could confirm the

compliance of a brake system by comparing the actual readjustment

limits of a brake system with those recommended by the manufacturer.

These manufacturer recommendations are routinely provided by the

manufacturer with each vehicle. The petitioner stated that NHTSA has

taken this approach in other circumstances, such as with respect to

testing safety belts for permissible levels of slack. (See, Standard

No. 208, section S7.4.2.)

The agency adopted the FHWA readjustment limits to provide a clear

means of determining whether a brake adjuster was performing properly.

However, as explained above, the agency now believes that the FHWA

requirement is inappropriate for use by NHTSA given the differences

among air brake systems. As mentioned above, FHWA's in-use inspection

requirements were developed primarily with drum brake systems in mind,

and thus place disc brake systems, long stroke brake chambers and

piston-type systems at a competitive disadvantage.

After reviewing the petitions, NHTSA has decided to delete

reference to the FHWA requirements and to adopt a requirement that

``the adjustment of the service brakes shall be within the limits

recommended by the vehicle manufacturer.'' This language is similar to

that of the NPRM (which would have required air brake adjusters to

``maintain brake adjustment within the manufacturer's recommended

adjustment limits''), in that the adjuster would be required to perform

as intended by the vehicle manufacturer. However, NHTSA believes that

the language adopted in this document avoids the concerns about

objectivity and vagueness engendered by the NPRM.

Those concerns about the NPRM stemmed from the word ``maintain'' in

the language quoted above. Since there was no objective criteria

specified for determining whether a particular brake adjuster would

``maintain adjustment'' of the brakes, manufacturers were concerned

that questions could arise between a manufacturer and NHTSA as to

whether a particular system complied with the standard, particularly

when it was unclear when exactly the determination of compliance would

be made. Manufacturers were concerned that the proposed language

implied that Standard 121 requires a vehicle to ``maintain''

conformance to the FMVSS's throughout the life of the vehicle, which is

incorrect and confusing.

NHTSA concurred with the commenters that the proposed language was

inappropriate (57 FR at 47796):

The agency notes that there is no objective criteria as to what

constitutes ``maintains adjustment.'' In addition, as a general

rule, the agency does not establish extended durability testing. The

agency believes that to require that the adjustment be maintained

throughout the lifetime of the vehicle is unrealistic, dependent

upon the vehicle's exposure, and beyond the scope of NHTSA's

authority.

The requirement adopted today provides an objective requirement

that allows the vehicle manufacturer to evaluate conformance to the

standard. As Rockwell stated, NHTSA can readily confirm the compliance

of a brake system by comparing the actual readjustment limits of the

system with those recommended by the manufacturer. Further, the

requirement does not use ``maintain'' and therefore avoids the

implication that compliance with Standard 121 must be maintained

through a vehicle's lifetime. However, as explained below, since NHTSA

is specifying a requisite level of performance for the brake adjusters,

the agency must also specify when, during compliance testing, NHTSA

will evaluate the brake adjusters to determine if they are performing

according to the recommendations of the vehicle manufacturer.

Inspection

During NHTSA's review of the petitions for reconsideration, the

agency realized that the standard had no express requirement for when

the adjustment indicators are to be inspected. However, the brake

adjuster amendment implicitly required that the brakes be inspected,

because the amendment states that the readjustment limits must be in

accordance with the FHWA inspection standards. Also implicit in this

amendment is that inspection will occur at the end of the Standard No.

121 test procedures, since the need for readjustment will only occur

after the vehicle has been driven. In addition, inspection of the

vehicle at the end of testing for conformance with the braking standard

is consistent with the specifications for hydraulic brake systems

(Standard No. 105). Accordingly, in this document, NHTSA is including a

``final inspection provision'' at the end of the test procedures to

require that the service brake system be inspected at the end of the

test sequence.

Procedural Concerns

NHTSA notes that the petitioners' concerns about the adequacy of

notice for the FHWA provisions are now moot. Therefore, these concerns

are not further addressed.

The amendment to Sec. 571.121 becomes effective October 20, 1994,

the effective date for the automatic brake adjusters.

Regulatory Impacts

A. Executive Order 12866 and DOT Regulatory Policies and Procedures

This notice has not been reviewed under E.O. 12866, ``Regulatory

Planning and Review.'' This rulemaking has been determined to be not

``significant'' under the Department of Transportation regulatory

policies and procedures. The amendment will not result in any

additional cost impacts beyond those resulting from the initial final

rule. The agency further concludes that, because the cost impacts are

minimal, a full regulatory evaluation is not required.

B. Regulatory Flexibility Act

NHTSA has also considered the impacts of this rulemaking under the

Regulatory Flexibility Act. I hereby certify that it will not have a

significant economic impact on a substantial number of small entities.

Any impact on small entities from this action will be minimal since the

amendments make minimal changes to the Standard that will not impose

additional costs or result in any savings. Accordingly, the agency has

determined that preparation of a regulatory flexibility analysis is

unnecessary.

C. Environmental Impacts

In accordance with the National Environmental Policy Act of 1969,

NHTSA has considered the environmental impacts of this rule. The agency

has determined that this rule will not have a significant impact on the

quality of the human environment.

D. Federalism Assessment

This action has been analyzed in accordance with the principles and

criteria contained in Executive Order 12612. NHTSA has determined that

the rulemaking does not have sufficient federalism implications to

warrant the preparation of a Federalism Assessment. No state laws will

be affected.

E. Civil Justice Reform

This final rule does not have any retroactive effect. Under section

103(d) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C.

1392(d)), whenever a Federal motor vehicle safety standard is in

effect, a state may not adopt or maintain a safety standard applicable

to the same aspect of performance which is not identical to the Federal

standard. Section 105 of the Act (15 U.S.C. 1394) sets forth a

procedure for judicial review of final rules establishing, amending or

revoking Federal motor vehicle safety standards. That section does not

require submission of a petition for reconsideration or other

administrative proceedings before parties may file suit in court.

List of Subjects in 49 CFR Part 571

Imports, Motor vehicle safety, Motor vehicles.

PART 571--[AMENDED]

In consideration of the foregoing, 49 CFR Part 571 is amended as

follows:

1. The authority citation for Part 571 continues to read as

follows:

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

authority at 49 CFR 1.50.

Sec. 571.121 [Amended]

2. Section 571.121 is amended by revising S5.1.8, S5.2.2, and Table

I to read as follows and by adding S5.9:

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

* * * * *

S5.1.8 Brake distribution and automatic adjustment. Each vehicle

shall be equipped with a service brake system acting on all wheels.

(a) Brake adjuster. Wear of the service brakes shall be compensated

for by means of a system of automatic adjustment. When inspected

pursuant to S5.9, the adjustment of the service brakes shall be within

the limits recommended by the vehicle manufacturer.

(b) Brake indicator. For each brake equipped with an external

automatic adjustment mechanism and having an exposed pushrod, the

condition of service brake under-adjustment shall be displayed by a

brake adjustment indicator that is discernible when viewed with 20/40

vision from a location adjacent to or underneath the vehicle, when

inspected pursuant to S5.9.

* * * * *

S5.2.2 Brake distribution and automatic adjustment. Each vehicle

shall be equipped with a service brake system acting on all wheels.

(a) Brake Adjuster. Wear of the service brakes shall be compensated

for by means of a system of automatic adjustment. When inspected

pursuant to S5.9, the adjustment of the service brakes shall be within

the limits recommended by the vehicle manufacturer.

(b) Brake Indicator. For each brake equipped with an external

automatic adjustment mechanism and having an exposed pushrod, the

condition of service brake under-adjustment shall be displayed by a

brake adjustment indicator in a manner that is discernible when viewed

with 20/40 vision from a location adjacent to or underneath the

vehicle, when inspected pursuant to S5.9.

* * * * *

Table I--Stopping Sequence

1. Burnish.

2. Control trailer service brake stops at 60 mph (for truck-

tractors tested with a control trailer in accordance with S6.1.10.)

3. Control trailer emergency brake stops at 60 mph (for truck-

tractors tested with a control trailer in accordance with S6.1.10.7.)

4. Stops with vehicle at gross vehicle weight rating:

(a) 20 mph service brake stops on skid number of 81.

(b) 60 mph service brake stops on skid number of 81.

(c) 20 mph service brake stops on skid number range 30.

(d) 20 mph emergency brake stops on skid number of 81.

(e) 60 mph emergency brake stops on skid number of 81.

5. Parking brake test with vehicle loaded to GVWR.

6. Stops with vehicle at unloaded weight plus 500 lbs.

(a) 20 mph service brake stops on skid number of 81.

(b) 60 mph service brake stops on skid number of 81.

(c) 20 mph service brake stops on skid number range 30.

(d) 20 mph emergency brake stops on skid number of 81.

(e) 60 mph emergency brake stops on skid number of 81.

7. Parking brake test with vehicle at unloaded weight plus 500 lbs.

8. Final inspection of service brake system for condition of

adjustment.

* * * * *

S5.9 Final Inspection. Inspect the service brake system for the

condition of adjustment and for the brake indicator display in

accordance with S5.1.8 and S5.2.2.

* * * * *

Issued on April 12, 1994.

Christopher A. Hart,

Deputy Administrator.

[FR Doc. 94-9226 Filed 4-15-94; 8:45 am]

BILLING CODE: 4910-59-P