Home Page About Us Contribute

K&N Automotive Air Intakes

LuckyBug LifeStyle



Tweets by @CrittendenAuto










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

American Government Special Collections Reference Desk

American Government Trucking Topics:  National Highway Traffic Safety Administration, Federal Motor Vehicle Safety Standards

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

Christopher A. Hart
Federal Register
April 18, 1994

[Federal Register: April 18, 1994]


=======================================================================
-----------------------------------------------------------------------

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.

-----------------------------------------------------------------------

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.
---------------------------------------------------------------------------

    \1\Appendix G to subchapter B of Chapter III--``Minimum Periodic 
Inspection Standards,'' 49 CFR parts 200 to 399.
---------------------------------------------------------------------------

    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



Connect with The Crittenden Automotive Library

The Crittenden Automotive Library at Google+ The Crittenden Automotive Library on Facebook The Crittenden Automotive Library on Instagram The Crittenden Automotive Library at The Internet Archive The Crittenden Automotive Library on Pinterest The Crittenden Automotive Library on Twitter The Crittenden Automotive Library on Tumblr  
 
 


The Crittenden Automotive Library

Home Page    About Us    Contribute




By accessing the The Crittenden Automotive Library/CarsAndRacingStuff.com, you signify your agreement with the terms and conditions on our Legal Information:  Disclaimers & Privacy Policy page.

To notify The Crittenden Automotive Library of errors, suggest topics, contribute information, make a comment on a page or to ask a question e-mail us.