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[Federal Register Volume 60, Number 8 (Thursday, January 12, 1995)]
[Rules and Regulations]
[Pages 2892-2896]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-752]

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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. 93-54, Notice 2]
RIN 2127-AE54

Federal Motor Vehicle Safety Standards; Air Brake Systems; Long-
Stroke Brake Chambers

AGENCY: National Highway Traffic Safety Administration (NHTSA), 
Department of Transportation.

ACTION: Final rule.

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SUMMARY: Consistent with a recommendation by the National 
Transportation Safety Board and in response to a petition for 
rulemaking from the American Trucking Associations (ATA), this final 
rule amends the reservoir requirements in Standard No. 121, Air Brake 
Systems, for trucks, buses, and trailers equipped with air brakes. The 
agency believes that the amendments will improve the braking efficiency 
of such vehicles and reduce the number of brakes found to be out of 
adjustment during inspections. It will do this by removing a design 
restriction that tends to discourage the use of long-stroke brake 
chambers, a technology with potentially significant safety benefits.

DATES: Effective Date: The amendments become effective on February 13, 
1995.
    Petitions for Reconsideration: Any petitions for reconsideration of 
this rule must be received by NHTSA no later than February 13, 1995.

ADDRESSES: Petitions for reconsideration of this rule should refer to 
Docket 93-54; Notice 2 and should be submitted to: Administrator, 
National Highway Traffic Safety Administration, 400 Seventh Street SW., 
Washington, D.C. 20590.

FOR FURTHER INFORMATION CONTACT: Mr. Richard Carter, Office of Vehicle 
Safety Standards, National Highway Traffic Safety Administration, 400 
Seventh Street SW., Washington, D.C. 20590 (202-366-5274).

SUPPLEMENTARY INFORMATION:

I. Background

    Standard No. 121, Air Brake Systems, specifies performance 
requirements applicable to vehicles equipped with air brakes. The 
Standard also requires air-braked vehicles to be equipped with various 
types of equipment, including an air compressor, reservoirs, and a 
pressure gauge. (See section S5.1) Standard No. 121 does not specify 
the length of stroke of brake chambers, but it establishes a ratio 
between the volume of the service reservoirs and the volume of the 
brake chambers. The reservoirs store energy, in the form of air at high 
pressure that is used to apply the vehicle's brakes. Without such 
reservoirs, the vehicle's air compressor could not maintain adequate 
brake system pressure during successive rapid brake applications. The 
effect of this ratio is that if the brake chamber stroke is lengthened, 
thereby increasing its volume, it may be necessary to enlarge the 
service reservoirs.
    With respect to trucks and buses, Section S5.1.2.1 currently 
specifies that

    The combined volume of all service reservoirs and supply 
reservoirs shall be at least 12 times the combined volume of all 
service brake chambers at maximum travel of pistons or diaphragms. 
However, the reservoirs on the truck portion of an auto transporter 
need not meet this requirement.

    Similarly, with respect to trailers, section S5.2.1.1 specifies

    The total volume of each service reservoir shall be at least 
eight times the combined volume of all service brake chambers 
serviced by that reservoir at the maximum travel of the pistons or 
diaphragms of those service brake chambers. However, the reservoirs 
on a heavy hauler trailer and on the trailer portion of an auto 
transporter need not meet the requirements specified in S5.2.1.1.

    These provisions were intended to ensure that a vehicle's braking 
system has sufficient compressed air to provide adequate brake pressure 
after a number of brake applications.
    Brake chambers with longer strokes are commonly known as ``long-
stroke'' chambers, in reference to the longer piston or pushrod travel 
that they require. Reports\1\ by NHTSA and the National Transportation 
Safety Board (NTSB) have indicated that long stroke chambers can help 
improve brake adjustment on heavy vehicles. However, the reports also 
note that the reservoir requirements in Standard No. 121 would 
necessitate much larger reservoirs when long-stroke chambers are used. 
Thus, while the current requirements do not prohibit long-stroke 
chambers, the requirements for reservoir size significantly discourage 
their use.

    \1\Automatic Slack Adjusters for Heavy Vehicle Brake Systems, 
February 1991, DOT HS 724, and the National Transportation Safety 
Board Heavy Vehicle Airbrake Performance, 1992, PB92-917003/NTSB/SS-
92/01
---------------------------------------------------------------------------

II. Petition

    On March 17, 1992, the American Trucking Associations (ATA) 
petitioned the agency to amend the reservoir requirements in Standard 
No. 121 to facilitate the installation of long-stroke chambers. With 
respect to trucks, buses, and trailers equipped with long-stroke 
chambers, ATA recommended that the combined volume of all the 
reservoirs be based on the ``rated volume'' of the service brake 
chambers, rather than on the volume of the chambers at the maximum 
travel of the piston. The ``rated volume'' of each brake chamber would 
be determined pursuant to a table of specified values according to the 
area of the brake diaphragm and the length of the stroke. In other 
words, under ATA's recommended amendment, if a ``type 30'' brake 
chamber (with a diaphragm of approximately 30 square inches) had a full 
stroke of at least 2.50 inches, then the rated volume of the brake 
chamber would have to be at least 84 cubic inches. As a practical 
matter, the use of long stroke chambers should have a minimal effect on 
reservoir capacity. For other types of brake chambers not presented on 
the table, the rated volume would be the volume of the brake chamber at 
maximum travel of the brake pistons or pushrods.
    In support of its petition, ATA argued that manufacturers would 
have to incur unnecessary costs associated with increasing the size of 
the reservoirs if standard brake chambers were replaced with long-
stroke chambers. Along with these additional costs, some vehicle 
configurations would have to be redesigned due to lack of adequate 
locations with sufficient space to accommodate large reservoirs. The 
lack of space is especially significant with short wheel base single 
unit trucks equipped with extensive accessories (e.g., power-take-off 
units (PTOs), tail gate lifts, refrigeration units, larger brakes) 
which compete for undercarriage space.

III. Notice of Proposed Rulemaking

    On August 2, 1993, NHTSA proposed amending Standard No. 121's 
reservoir requirements for trucks, buses, and trailers to facilitate 
the introduction of long-stroke brake chambers. (58 FR 41078). 
Specifically, the agency proposed that the method for calculating air 
reservoir requirements would be based on the ``rated volume'' 
[[Page 2893]] of the brake chambers rather than on the volume of the 
brake chambers at the maximum travel of the brake pistons or push rods. 
The agency tentatively agreed with the petitioner that the proposed 
amendments would make it easier for vehicle manufacturers to install 
long-stroke brake chambers on air-braked vehicles, because extremely 
large reservoirs would no longer be required. The agency stated that it 
believed that long-stroke chambers would help improve the braking 
efficiency of vehicles, significantly increase the reserve stroke, 
reduce the number of brakes found to be out of adjustment during 
inspections, and reduce the incidence of dragging brakes. NHTSA 
referenced the Safety Board report, which concluded that ``* * * 
combining a properly installed and maintained automatic slack adjuster 
with a long-stroke chamber could reduce the percentage of brakes at or 
past the limit of adjustment from the 26 percent figure for the manual 
slack adjusters on a regular stroke chamber to the 4 percent figure for 
the automatic adjusters installed on a long-stroke chamber.''
    In the NPRM, NHTSA explained its tentative determination that there 
would be no safety problem with the amended reservoir requirements. The 
agency cited tests conducted at NHTSA's Vehicle Research and Test 
Center (VRTC) that indicated that there is sufficient reserve volume to 
stop an air-braked vehicle even under worst-case conditions (i.e., the 
engine was stalled so the compressor was not adding replacement air to 
the system, the vehicle was equipped with long-stroke brake chambers 
and antilock brake systems (ABS), and the vehicle was stopped on a very 
low friction surface). The VRTC tests further indicated that while 
multiple combination vehicles would experience an additional 10 psi 
drop in air pressure because of the compressor's need to fill a greater 
volume when the vehicle is equipped with long-stroke chambers, there 
would still be adequate air pressure to safely stop a triple trailer 
combination vehicle with ABS on a wet Jennite surface. The rapid 
cycling produced by the ABS under this condition places severe demands 
on reservoir capacity and is therefore a good measure of the reserve 
pressure available from reservoirs meeting the revised volumes proposed 
in the NPRM. Notwithstanding its tentative findings, NHTSA requested 
comment about any potential safety problems that might result from 
amending the reservoir requirements to facilitate the introduction of 
long-stroke brake chambers.

IV. Comments to the NPRM

    NHTSA received 15 comments in response to the NPRM. Commenters 
included vehicle manufacturers, brake manufacturers, truck equipment 
suppliers, ATA, the Heavy Duty Brake Manufacturers Council (HDBMC) and 
Advocates for Highway and Auto Safety (Advocates).
    Commenters addressed both the need for the proposal and recommended 
various modifications to the proposed regulations.
    Midland-Grau, Rockwell, Allied Signal, HDBMC, Freightliner, 
International Transquip Industries (ITI), MGM Brakes, Ford, and ATA 
generally believed that the proposal to facilitate the use of long 
stroke brake chambers is in the interest of safety. In contrast, while 
WhiteGMC/Volvo, Haldex, Eaton, and Advocates, agreed that long stroke 
brake chambers could enhance safety, they opposed the agency's specific 
proposal which they believed would reduce the stringency of the 
reservoir requirements and thus result in detriment to safety.

V. Agency Determination

A. Overview

    After reviewing the comments in light of the available information, 
NHTSA has decided to amend Standard No. 121's reservoir requirements 
for trucks, buses, and trailers to facilitate the introduction of long-
stroke brake chambers. Specifically, under today's amendments, the 
method for calculating air reservoir requirements is now based on 
either the ``rated volume'' of the brake chambers or the volume of the 
brake chambers at the maximum travel of the brake pistons or push rods, 
whichever is less. As a result of these amendments, it will be easier 
for vehicle manufacturers to install long-stroke brake chambers on air-
braked vehicles, because extremely large reservoirs will no longer be 
required to meet the reservoir requirements. The agency has determined 
that long-stroke chambers will help improve the braking efficiency of 
vehicles, increase the reserve stroke, reduce the number of brakes 
found to be out of adjustment during inspections, and reduce the 
incidence of dragging brakes.
    NHTSA has decided to modify the proposed Table V ``Brake Chamber 
Rated Volumes'' by specifying upper limits to the stroke lengths for 
which rated volumes may be used. As explained below, the agency has 
determined that specifying an upper limit is necessary to preclude 
manufacturers from extending stroke lengths beyond the point at which 
adequate air pressure reserves are available to bring a vehicle to a 
complete stop. Accordingly, the amendment would not affect extremely 
long stroke chambers, the use of which could adversely affect air 
reservoir capacity. Specifically, Table V has been modified such that a 
vehicle manufacturer can use the ``rated volume'' rather than the 
actual brake chamber volume, when determining minimum reservoir volume, 
only when the maximum strokes for long stroke chambers are no more than 
20 percent longer than the nominal stroke for standard stroke chambers. 
In addition, the rated volumes have been increased to reflect the 
largest volumes of standard stroke air brake chambers that are 
available.

B. Safety Consequences

    In the NPRM, NHTSA considered the safety implications of amending 
the reservoir requirements to facilitate the installation of long-
stroke brake chambers. The agency had tentatively determined that 
relaxing the current reservoir volume requirements would not result in 
any safety problems. Notwithstanding its tentative findings, the agency 
requested comment about potential safety problems that might result 
from decreasing the stringency of the reservoir requirements.
    Midland-Grau, Rockwell, Allied Signal, HDBMC, Freightliner, ITI, 
MGM Brakes, Ford, and ATA generally believed that the proposal to 
facilitate the use of long stroke brake chambers would have no 
corresponding safety problems. HDBMC stated that long stroke brake 
chambers will provide a significant improvement in maintaining a more 
reliable level of automatic brake adjustment. Freightliner stated that 
long stroke chambers will improve highway safety by providing 
additional reserve stroke at force levels that will maintain brake 
performances under extreme operating conditions. ATA stated that the 
use of long stroke brake chambers will decrease the number of vehicles 
with defective brakes and provide for more effective brakes, especially 
when they are hot. Rockwell stated that the current regulations 
unnecessarily impede the adoption of long stroke chambers and the 
potential benefits they offer. It further stated that long stroke 
chambers would keep the useful stroke of a vehicle's slack adjuster 
within the acceptable stroke limits, reduce the number of out-of 
adjustment vehicles, and the number of incidents of dragging brakes. 
[[Page 2894]] 
    In contrast, WhiteGMC/Volvo, Haldex, Eaton, and Advocates believed 
that the proposal would be detrimental to safety, primarily because the 
proposed amendments would make the reservoir requirements less 
stringent. WhiteGMC/Volvo stated that the proposal promotes less 
reservoir volume and extended application times. Advocates had 
``misgivings about the regulatory approach'' in the NPRM which it 
believed would significantly reduce the total operating reserve volume 
of the brake reservoirs, thereby allowing manufacturers to install 
undersized brake reservoirs. Haldex stated that the proposal was ill 
advised and premature because it would result in a decrease in the 
reserve air volume. Instead, it favored issuance of a ``performance 
based standard.'' Eaton was concerned that the proposal was a ``quick 
fix'' that would degrade heavy truck brake system performance.
    After reviewing testing conducted at VRTC, the comments, and other 
available information, NHTSA has determined that the amendments to 
Standard No. 121's reservoir requirements will ensure the safe braking 
of air-braked vehicles, since it will not adversely affect their 
reservoir capacity. Specifically, testing conducted at VRTC indicate 
that today's amendments to Standard No. 121 will not cause a 
significant reduction in a brake system's maintaining adequate pressure 
even under adverse conditions, affect its application and release 
times, or contribute to a vehicle's propensity to jackknife.
    With respect to a brake system's air reserves, VRTC and SAE testing 
indicate that long stroke chambers perform safely, even if the volume 
of the reservoirs are not increased to reflect the increased volume of 
the long stroke chambers. In general, long stroke chambers use no more 
air than standard length brake chambers, if they are properly adjusted. 
This testing information has been placed in the public docket under 
``Reservoir Pressure Drop With ABS Cycling'' and ``SAE J1911 Tractor 
and Trailer Tests.'' Similarly, long stroke chambers in SAE J1911 tests 
show the same air consumption as a conventional brake chamber, when 
properly adjusted.
    The only time a long stroke chamber will consume more air is when 
the automatic adjuster is not functioning correctly and the stroke is 
at the outer limit of adjustment. To protect against such situations, 
the agency has decided to specify an upper limit for the maximum stroke 
of brake chambers for which a vehicle manufacturer can use the ``rated 
volume'' in determining the minimum reservoir volumes. The agency has 
specified that the upper limit be 20 percent above the nominal stroke 
for a normal stroke brake chamber. For instance, Type 9 brakes will be 
allowed to have a stroke length of between 1.75 and 2.10 inches. The 
agency has rejected the upper limits recommended by Midland-Grau which 
in some cases would have increased the stroke length up to 40 percent. 
The agency believes that using ``rated volumes'' for such long stroke 
chambers might undermine the reservoir requirements.
    With respect to brake application times, NHTSA has determined that 
long stroke brake chambers typically do not significantly affect brake 
apply and release times. The effect of brake adjustment level on timing 
is discussed in ``NHTSA Heavy-Duty Vehicle Brake Research Program 
Report No. 5: Pneumatic Timing.'' DOT HS 806 897, December 1985. The 
one exception is in the highly unusual situation in which all the 
automatic brake adjusters on a vehicle fail and at the same time all of 
the units operate at the outer limit of adjustment or beyond. Even 
under this highly unlikely condition, the apply time would only 
increase by approximately 0.040 second and the release time by 0.024 
second. Moreover, standard stroke chambers would be ineffectual in this 
situation. This equates to about three additional feet of stopping 
distance on the apply time and two additional feet on the release 
time.2 Any such increases can be minimized, since vehicle 
manufacturers can change the apply and release times by modifying the 
valving to adjust or remove air flow restrictions. Similarly, the 
vehicle manufacturers could remove air flow restrictions to the glad 
hand and pass the signal faster to the trailer.

    \2\NHTSA's Heavy-Duty Vehicle Research Program Report No. 5: 
Pneumatic Timing. DOT HS 806 897, December 1985.
---------------------------------------------------------------------------

    With respect to jackknifes, NHTSA disagrees with Eaton's claim that 
equipping vehicles with long stroke chambers would increase the 
likelihood of jackknifes. Jackknifes are caused by wheel lockup due to 
hard brake applications on wet roads or when vehicles are empty or 
lightly loaded. The presence or absence of long stroke chambers will 
not affect the underlying foundation brakes. Specifically, VRTC 
studies3 show that stroke lengths do not affect brake timing. The 
agency further notes that long stroke chambers improve brake adjustment 
and the resulting brake balance between tractors and trailers, thereby 
improving a combination vehicle's directional stability and control and 
decreasing the likelihood of jackknifing.

    \3\Id.
---------------------------------------------------------------------------

C. Changes to Proposed Regulatory Text

    Several commenters recommended that the proposed wording of Table V 
and S5.1.2.1 and S5.2.1.2 be modified to provide greater flexibility to 
manufacturers. For instance, ATA requested that the words ``on CAM 
Brakes'' be deleted from the title in Table V so that it reads--``Brake 
Chamber Rated Volumes.'' ATA also requested that the words ``brake 
chamber'' be changed to ``brake actuator'' and that ``actuator'' be 
inserted into Table V to clarify that the ``type'' is a brake actuator 
classification and not a brake classification. Similarly, ITI 
recommended that S5.1.2.1 and S5.2.1.2 be revised to permit brake 
chambers that were not of the sizes specifically listed in Table V. 
Allied recommended that the wording ``maximum travel of pistons or push 
rod'' be replaced with ``full stroke of push rods.'' It also 
recommended ``defining chamber type as being the nominal effective area 
of a piston or diaphragm.''
    NHTSA has modified certain provisions in the regulatory text 
pursuant to the comments. For instance, it has modified the title to 
Table V to state ``Brake Chamber Rated Volumes'' instead of ``Brake 
Chamber Rated Volumes on Cam Brakes.'' The agency agrees with the 
commenters that including the reference to cam brakes was unnecessarily 
narrow and might imply exclusion for use of other brake types such as 
air disc, wedge, and air-over-hydraulic. NHTSA has also incorporated 
Allied Signal's request for the regulation to indicate that chamber 
type is the nominal effective area of a piston or diaphragm, by adding 
this information to the top of column one in Table V.
    NHTSA decided not to modify other provisions in the regulatory 
text, notwithstanding recommendations by commenters to the NPRM. For 
instance, the agency decided not to adopt ATA's request to change the 
phrase ``brake chamber'' to ``brake actuator.''
    There are numerous references to brake chamber throughout Standard 
No. 121, which are well understood by the technical personnel who rely 
on the requirements. ``Brake actuator'' may explain what an air-brake 
chamber does (i.e., that it actuates the brakes when it fills with 
air); however, it adds nothing to what is already understood. 
Similarly, the agency decided not to adopt Allied Signal's request to 
eliminate the term ``piston.'' While the [[Page 2895]] commenter 
apparently believed that the use of the additional word ``piston'' 
added nothing because every system has a push rod, the agency 
nevertheless has decided to include this term to clarify that the 
necessary measurements of stroke length can be measured at the piston 
or the push rod. Accordingly, the regulatory text retains this word.

D. Future Rulemaking

    NHTSA notes that it is considering rulemaking consistent with the 
draft SAE Recommended Practice J1609X, Air Reservoir Capacity 
Performance Guide--Commercial Vehicles. The purpose of such a 
rulemaking would be to establish a performance requirement addressing 
the minimum air storage capacity for air-braked vehicles. If the agency 
determined that such a performance requirement were appropriate, it 
would issue a proposal in the Federal Register on which the public 
could comment. A considerable amount of testing needs to be completed 
before a viable set of performance requirements are established.

E. Miscellaneous Issues

    Commenters raised a number of issues that were not mentioned in the 
NPRM. These include testing trucks on down-hill grades, the consistency 
of the amendment to the agency's statutory mandate, marking 
requirements, and the rule's effective date.
    With respect to testing truck descents on downhill grades, NHTSA 
disagrees with comments by Advocates and Haldex that the air reservoir 
requirements should be based on such testing and that such testing 
represents worst-case situations. Braking on ice, snow, and rain 
covered roads with low coefficient of friction surfaces is more severe 
than mountain grade braking. The air pressure remaining after a 
complete antilock cycling stop on ice or wet Jennite is substantially 
less than that remaining in the air brake system at the bottom of a 
long mountain grade. Moreover, VRTC studies clearly show that there is 
sufficient air remaining in the air brake system, after stopping on low 
coefficient of friction surfaces or mountain grades using either 
snubbing or steady pressure. Similarly, testing performed by the 
University of Michigan Transportation Research Institute (UMTRI) shows 
sufficient air supply reserves on long down hill grades to make a 60 
psi full braking stop at the bottom of the grade.4 Advocates 
appears to misunderstand how downhill braking affects an air brake 
system's reservoirs. Consumption and apply and release times, which are 
important concerns for long stroke chambers, are not important concerns 
with downhill braking. The major consideration in downhill braking is 
overheated brakes and brake fade caused by brakes that are not in 
adjustment, since improperly adjusted brakes must be applied for longer 
periods of time. As a result, the vehicle will have either no brakes or 
very limited braking. The use of long stroke brake chambers together 
with automatic adjusters will reduce the incidence of out-of-
adjustment, and thus not degrade the performance on downhill braking.

    \4\``The Influence of Braking Strategy on Brake Temperatures in 
Mountain Descents,'' March 1992, Federal Highway Administration 
Report DTFH61-89-C-00106. Report available through the National 
Technical Information Service. NTIS accession number PB 93-137032.
---------------------------------------------------------------------------

    Advocates stated that the petitioner's ``rated volume'' approach to 
establish the air reservoir volumes is equivalent to the European type 
approval approach for establishing compliance. Accordingly, it believed 
that the proposal was inconsistent with the National Traffic and Motor 
Vehicle Safety Act (now codified as chapter 301 of Title 49, United 
States Code). NHTSA believes that Advocates has misinterpreted both the 
proposal and the law. Unlike European type approval, the proposal is 
not for a single manufacturer's product. Rather, it regulates all 
manufacturers' brake chambers of a specific type. Accordingly, today's 
requirements are consistent with the law.
    Rockwell and HDBMC recommended that the agency require the 
identification of long stroke chambers through marking requirements. 
Notwithstanding this request, NHTSA notes that the agency cannot 
include a marking requirement in this final rule that it did not 
propose in the NPRM. Nevertheless, the agency will monitor the progress 
made by the Federal Highway Administration which is working with the 
SAE, Commercial Vehicle Safety Alliance, and brake equipment 
manufacturers to establish an acceptable marking system that can easily 
be identified under the difficult visual conditions on the underside of 
air braked vehicles. If NHTSA determines that Federal marking 
requirements are needed, then it would propose marking requirements in 
a future rulemaking.
    The same problem with inadequate notice is relevant to Midland-
Grau's recommendation to raise the minimum governor cut-in pressure to 
100 psi. The agency may consider such a requirement in a separate 
rulemaking, depending on tests to be conducted at VRTC.
    In response to requests by Freightliner and ATA for NHTSA to make 
the final rule effective upon publication, the agency notes that the 
Administrative Procedure Act generally requires a leadtime of at least 
30 days, unless the agency finds ``good cause'' to issue the rule 
sooner. Since, NHTSA typically makes a finding of good cause only in 
emergency situations, the agency cannot accommodate this request. The 
final rule will take effect 30 days after its publication in the 
Federal Register.

Rulemaking Analyses and Notices

Executive Order 12866 (Federal Regulation) and DOT Regulatory Policies 
and Procedures

    NHTSA has considered the impact of this rulemaking action under 
E.O. 12866, ``Regulatory Planning and Review'' and the Department of 
Transportation's regulatory policies and procedures. This rulemaking 
document was not reviewed under E.O. 12866. This action has been 
determined to be not ``significant'' under the Department of 
Transportation's regulatory policies and procedures. A full regulatory 
evaluation is not required because the rule will not impose any special 
requirements on manufacturers. Instead, the rule will facilitate the 
introduction of a new brake design by removing a design restriction. 
Therefore, the agency believes that this rulemaking will not result in 
significant additional costs or cost savings.

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 amendments will not have a significant 
economic impact on a substantial number of small entities. Vehicle and 
brake manufacturers typically do not qualify as small entities. As 
discussed above, the agency's assessment is that this amendment will 
have no cost impact to the industry. For these reasons, vehicle 
manufacturers, small businesses, small organizations, and small 
governmental units which purchase motor vehicles will not be affected 
by the requirements. Accordingly, no regulatory flexibility analysis 
has been prepared.

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 rule will not have sufficient [[Page 2896]] Federalism 
implications to warrant preparation of a Federalism Assessment. No 
State laws will be affected.

National Environmental Policy Act

    Finally, the agency has considered the environmental implications 
of this final rule in accordance with the National Environmental Policy 
Act of 1969 and determined that the rule will not significantly affect 
the human environment.

F. Civil Justice Reform

    This final rule does not have any retroactive effect. Under 49 
U.S.C. 30103, 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, except to the extent that the State requirement imposes a 
higher level of performance and applies only to vehicles procured for 
the State's use. 49 U.S.C. 30161 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, Rubber and rubber 
products, Tires.

    In consideration of the foregoing, 49 CFR part 571 is amended to 
read as follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

    1. The authority citation for part 571 continues to read as 
follows:

    Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166; 
delegation of authority at 49 CFR 1.50.

    2. Section 571.121 is amended by revising S5.1.2.1 and S5.2.1.1 to 
read as follows:

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

* * * * *
    S5.1.2.1   The combined volume of all service reservoirs and supply 
reservoirs shall be at least 12 times the combined volume of all 
service brake chambers. For each brake chamber type having a full 
stroke at least as great as the first number in Column 1 of Table V, 
but no more than the second number in Column 1 of Table V, the volume 
of each brake chamber for purposes of calculating the required combined 
service and supply reservoir volume shall be either that specified in 
Column 2 of Table V or the actual volume of the brake chamber at 
maximum travel of the brake piston or pushrod, whichever is lower. The 
volume of a brake chamber not listed in Table V is the volume of the 
brake chamber at maximum travel of the brake piston or pushrod. The 
reservoirs of the truck portion of an auto transporter need not meet 
this requirement for reservoir volume.
* * * * *
    S5.2.1.1  The total volume of each service reservoir shall be at 
least eight times the combined volume of all service brake chambers 
serviced by that reservoir. For each brake chamber type having a full 
stroke at least as great as the first number in Column 1 of Table V, 
but no more than the second number in column 1, the volume of each 
brake chamber for purposes of calculating the required total service 
reservoir volume shall be either that number specified in Column 2 of 
Table V or the actual volume of the brake chamber at maximum travel of 
the brake piston or pushrod, whichever is lower. The volume of a brake 
chamber not listed in Table V is the volume of the brake chamber at 
maximum travel of the brake piston or pushrod. The reservoirs on a 
heavy hauler trailer and the trailer portion of an auto transporter 
need not meet this requirement for reservoir volume.
* * * * *

Sec. 571.121  [Amended]

    3. Section 571.121 is amended to include the following table to be 
placed after Figure 3.

                  Table V.--Brake Chamber Rated Volumes                 
------------------------------------------------------------------------
                                                                 Column 
                                                    Column 1,   2, rated
  Brake chamber type (nominal area of piston or    full stroke   volume 
           diaphragm in square inches)               (inches)    (cubic 
                                                                 inches)
------------------------------------------------------------------------
Type 9...........................................    1.75/2.10        25
Type 12..........................................    1.75/2.10        30
Type 14..........................................    2.25/2.70        40
Type 16..........................................    2.25/2.70        50
Type 18..........................................    2.25/2.70        55
Type 20..........................................    2.25/2.70        60
Type 24..........................................    2.25/2.70        70
Type 30..........................................    2.50/3.20        95
Type 36..........................................    3.00/3.60       135
------------------------------------------------------------------------

    Issued on January 5, 1995.
Ricardo Martinez,
Administrator.
[FR Doc. 95-752 Filed 1-11-95; 8:45 am]
BILLING CODE 4910-59-P
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