[Federal Register Volume 64, Number 22 (Wednesday, February 3, 1999)]
[Proposed Rules]
[Pages 5259-5264]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-2486]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA 99-5045]
RIN 2127-AH11


Federal Motor Vehicle Safety Standards: Air Brake Systems

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

ACTION: Notice of proposed rulemaking; partial grant/partial denial of 
petition for rulemaking.

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SUMMARY: Pursuant to the agency's partial grant of a petition for 
rulemaking from the Truck Manufacturers Association, NHTSA proposes to 
amend the air brake standard to correct an inconsistency between two 
provisions concerning emergency brake stops, provide that single-unit 
truck axles should not be overloaded, clarify the wheel-lock provisions 
by adding a definition of ``tandem axle,'' and permit the use of roll 
bars on vehicles undergoing brake testing.
    NHTSA denies requests by the petitioner to amend the standard by 
revising the braking test sequence, changing the provisions regarding 
manual brake adjustments, changing the burnish procedure, specifying 
application of the service brake prior to applying the parking brake, 
and clarifying that emergency brake requirements for trucks and buses 
do not become effective until March 1, 1998.

DATES: Comment closing date: Comments on this notice must be received 
by NHTSA not later than April 5, 1999.
    Proposed effective date: If adopted, the amendments proposed in 
this notice would become effective 30 days after publication of the 
final rule. Optional early compliance would be permitted on and after 
the date of publication of a final rule in the Federal Register.

ADDRESSES: Comments should refer to the docket number for this rule 
noted above and be submitted to: Docket Management Room, PL-401, 400 
Seventh Street, SW, Washington, DC 20590. Docket Room hours are from 10 
a.m. to 5 p.m., Monday through Friday.

FOR FURTHER INFORMATION CONTACT:

    For technical issues: Mr. Joseph Scott, Safety Standards Engineer, 
Office of Crash Avoidance Standards, Vehicle Dynamics Division, 
National Highway Traffic Safety Administration, 400 Seventh Street, SW, 
Washington, DC 20590; telephone (202) 366-2720, fax (202) 493-2739.
    For legal issues: Mr. Walter Myers, Attorney-Advisor, Office of the 
Chief Counsel, National Highway Traffic Safety Administration, 400 
Seventh Street, SW, Washington, DC 20590; telephone (202) 366-2992, fax 
(202) 366-3820.

SUPPLEMENTARY INFORMATION:

1. Background

    Federal Motor Vehicle Safety Standard (Standard) No. 121, Air brake 
systems, specifies performance and equipment requirements for trucks, 
buses, and trailers equipped with air brake systems to ensure safe 
braking performance under normal and emergency conditions.
    Pursuant to the March 4, 1995 directive entitled ``Regulatory 
Reinvention Initiative'' from the President to the heads of departments 
and agencies of the Federal government, NHTSA reviewed its standards 
and regulations to identify superseded or unneeded regulations as well 
as to amend and update regulations as appropriate. One such regulation 
identified by NHTSA for revising and upgrading was Standard No. 121. 
Consequently, on May 31, 1996, NHTSA published a revision of Standard 
No. 121 in the Federal Register to remove obsolete provisions and 
update and reorganize the standard (61 FR 27288). The revision 
substantially clarified and simplified the standard without changing 
any of its substantive requirements. The effective date of this 
revision was March 1, 1997. Optional early compliance with the revised 
standard was permitted for vehicles manufactured prior to that date.

2. The Petition

    The Truck Manufacturers Association (TMA) submitted a petition for 
rulemaking to NHTSA dated January 6, 1997. The TMA is a trade 
association

[[Page 5260]]

whose members include all the major U.S. manufacturers of medium and 
heavy trucks, i.e., those trucks with a gross vehicle weight rating 
(GVWR) greater than 8,845 kilograms (19,500 pounds). The petition was a 
followup to TMA's comments submitted in connection with the rulemaking 
action culminating with the final rule of May 31, 1996, discussed 
above.
    In its petition, the TMA stated that it, through a Society of 
Automotive Engineers (SAE) task force, reviewed Standard No. 121 in 
detail. As a result of that evaluation, SAE developed a recommended 
practice, J1626, Braking, Stability, and Control Performance Test 
Procedures for Air-Brake Equipped Trucks (REV APR96), to provide a 
process for verifying vehicle compliance while minimizing test 
variability. TMA commended NHTSA for its efforts to update and 
reorganize Standard No. 121, but stated that some inconsistencies 
remain. TMA stated that Standard No. 121 and SAE J1626 should be 
aligned to improve test efficiency and decrease testing costs to the 
industry with no detrimental impact on motor vehicle safety. 
Accordingly, TMA suggested amending Standard No. 121 as follows:
    a. Test sequence. Change the braking test sequence to perform the 
unloaded straight line stops and then the loaded straight line stops 
immediately following the braking-in-a-curve test. TMA asserted that 
the standard currently allows the truck tractor braking-in-a-curve 
control and stability tests to be performed loaded and unloaded 
(bobtail) on a surface with 0.5 coefficient of friction. This 
simplifies the logistics of moving vehicles from one test site to 
another and limits the need to water the test track to only a single 
time. TMA asserted, however, that the test sequence has little impact 
on the test results as long as the burnish procedure is performed first 
and final inspection follows all other required tests. The number of 
times that a vehicle must be loaded and unloaded has a significant 
impact on the time and effort to complete the sequence of tests. Thus, 
the suggestion to conduct the unloaded straight line stops before the 
loaded straight line stops would eliminate one loading/unloading 
sequence, thereby simplifying the test sequence to that extent.
    b. Brake adjustments. Adopt the following language of SAE J1626: 
``(O)ther than during the burnish, brakes can be adjusted per the 
vehicle manufacturer's procedure at any time.'' Although automatic 
brake adjusters are required by the standard, TMA stated that some 
automatic brake adjusters overadjust during Standard No. 121 testing, 
but not in normal service. SAE J1626 recognizes this and would allow 
brakes to be adjusted in accordance with the manufacturer's procedure 
at any time to reduce brake performance variability.
    c. Brake test and burnish procedure. Require that the entire brake 
test procedure, including the burnish procedure, be conducted with the 
transmission in neutral or with the clutch disengaged. Standard No. 121 
specifies that tests are conducted with the vehicle's transmission in 
neutral or with the clutch disengaged. This minimizes the effect of 
engine and driveline drag on stopping distance test results and also 
relieves the manufacturer of the burden of having to test every engine 
and driveline package offered on a given chassis. TMA asserts that 
engine and driveline drag can also affect burnish temperatures and the 
conditioning that brake linings receive. Thus, TMA argues that 
conducting the entire test sequence as well as the burnish procedure 
with the transmission in neutral or the clutch disengaged would 
eliminate variability in the burnish and the need to test with numerous 
combinations of engines and drivelines that are offered with each 
chassis.
    d. Service brake application prior to parking brake application. 
Permit a full service brake application prior to applying the parking 
brakes, and clarify S5.6.3.1 to provide that it applies to the case in 
which a single leakage failure occurs in the service brake system after 
the parking brakes are applied. As a practical matter, when parking on 
a hill, the vehicle operator first applies the service brakes to hold 
the vehicle in place, then applies the parking brake before releasing 
the service brakes. TMA stated that it is not clear whether S5.6 
permits this procedure. It argues that Standard 105, Hydraulic and 
electric brake systems, clearly permits a procedure in which the 
service brake is applied prior to application of the parking brake. 
Further, that standard permits reapplication of the service brake and 
parking brake up to two additional times if the vehicle does not hold 
on the grade. Thus, TMA requests that NHTSA clarify the parking brake 
requirements of Standard No. 121 to make them more consistent with 
those of Standard No. 105 in permitting a full application of the 
service brakes prior to application of the parking brake, with 
reservoirs at compressor cut-out pressure.
    e. Clarify that emergency brake requirements for trucks and buses 
do not become effective until March 1, 1998. Section S5.3 of the 
standard specifies a schedule of effective dates for service brake 
stopping distance requirements, which indicates that trucks and buses 
have until March 1, 1998 to comply. Section S5.7 does not contain such 
a schedule for emergency brake requirements. TMA considers that an 
oversight on the agency's part that should be clarified.
    f. Correction of inconsistency. TMA stated that the rulemaking 
process confirmed that emergency brake stops for loaded tractors with 
unbraked control trailers (item 4(b), Table I) are ``inappropriate.'' 
Subsection S5.7.3(b), however, retained the loaded tractor emergency 
test that was in effect earlier. Therefore, TMA requested that NHTSA 
delete S5.7.3(b) to correct the inconsistency.
    g. Roll bar provision. Permit the use of a roll bar for any vehicle 
conducting the brake test sequence, including the 60-mile-per-hour 
(mph) straight-line stops and the 30-mph stops in a curve. TMA asserted 
that the safety of drivers and technicians is a primary concern during 
vehicle testing, and that use of a roll bar would protect them in the 
event of a vehicle rollover. TMA pointed out that truck tractors are 
permitted to be so equipped during the braking-in-a-curve stability and 
control tests. It said that this protection is just as important for 
short-wheelbase, high center of gravity trucks. A roll bar would ensure 
the safety of the driver in all tests and would eliminate the need to 
remove the roll bar after completing the braking-in-a-curve test 
sequence.
    h. Single-unit truck axles should not be overloaded. Paragraph 
6.1.10.4 of the standard provides for loading the tractor control 
trailer in such a manner as to avoid overloading the tractor's axles. 
The axles of a single-unit truck should likewise not be overloaded to 
achieve GVWR. Thus, the same provision should be incorporated into 
paragraph S5.3.1.1.
    i. Need for additional clarification of the wheel lock provisions. 
TMA stated that the wheel lock provisions are not consistent with the 
ABS provisions. Specifically, TMA pointed out that paragraph 
S5.1.6.1(b) provides that ``the wheels of at least one rear axle'' of a 
truck tractor must be equipped with an antilock brake system (ABS) that 
directly controls the wheels on that axle. On the other hand, TMA 
stated that subparagraph S5.3.1(a) places wheel lock restrictions on 2 
rear axles, and that S5.3.1(b) allows one of those 2 axles to lock up 
both of its wheels, but only if it is a tandem axle. TMA believes that 
the wheel lock provisions were originally written for the stopping

[[Page 5261]]

distance NPRM, when it was not clear that ABS would be mandatory. When 
the ABS and stopping distance proposals were combined for the final 
rule, however, the conflict developed but went unnoticed until 
recently.
    By way of illustration of the suggested inconsistency between the 
ABS and wheel lock requirements, TMA gives the example of a 3-axle 
truck, bus or tractor. If the vehicle had 2 driven rear axles in 
tandem, known as a 6x4 configuration, the wheels on both sides of one 
rear axle might lock up during an entire stopping distance test. 
Conversely, if one of the two rear axles were a nonliftable tag or 
pusher axle, known as a 6x2 arrangement, then neither of the rear axles 
could lock up on both its wheels. Thus, TMA argues that the 6x4 vehicle 
needs ABS control on only one of its rear axles, while the 6x2 must 
have ABS control on both rear axles.
    TMA stated that drive axles are the most logical location on the 
vehicle's rear for ABS, regardless of the number of axles trailing 
behind. These axles have the greatest rolling inertia, are the heaviest 
loaded, and are the only axles that can be used for traction control. 
The wheel lockup provisions, however, discourage this approach on 
vehicles with nonliftable tag axles. TMA therefore requested that the 
wheel lockup provisions of S5.3.1(a) through (d) be rescinded, and that 
S5.3.1 be redrafted to read:
    S5.3.1 Stopping distance--trucks and buses. When stopped six times 
* * * without any part of the vehicle leaving the roadway.
    j. Typographical errors. TMA pointed out 2 typographical errors:
     Paragraph S6.1.8, line 23, ``* * * in 1 mph* * *'' should 
read ``* * * in 1 mile * * * ;'' and
     Paragraph S6.2.5, line 2, ``* * * dynamometer or 
responding * * *'' should read ``* * * dynamometer corresponding * * 
*.''

3. Denials of Certain Requests by the Petitioner

    a. Test sequence (see 2a above). TMA suggested allowing the tester 
to ``perform the unloaded straight line stops and then the loaded 
straight line stops immediately following the braking-in-a-curve 
tests.'' The following table shows the current test sequence and TMA's 
proposed sequence:

------------------------------------------------------------------------
             Current sequence                  TMA's proposed sequence
------------------------------------------------------------------------
1. Burnish (GVWR).........................  1. Burnish (GVWR)
2. a. Braking-in-Curve (GVWR); b. Braking-  2. a. Braking-in-Curve
 in-Curve (LLVW).                            (GVWR); b. Braking-in-Curve
                                             (LLVW)
3. Service Brake (GVWR); Emergency Brake    3. Service Brake (LLVW);
 (GVWR).                                     Emergency Brake (LLVW)
4. Parking Brake (GVWR)...................  4. Parking Brake (LLVW)
5. Service Brake (LLVW)...................  5. Service Brake (GVWR)
6. Emergency Brake (LLVW).................  6. Emergency Brake (GVWR)
7. Parking Brake (LLVW)...................  7. Parking Brake (GVWR)
8. Final Inspection.......................  8. Final Inspection
------------------------------------------------------------------------

    This request is denied because--
    (1) The current GVWR/LLVW (lightly-loaded vehicle weight) is 
consistent with the other tests in the overall test sequence.
    (2) Flat-spotting of tires is minimized when GVWR tests are 
conducted first. Since not all wheels are required to be ABS-controlled 
and are therefore permitted to lock up, conducting the LLVW tests 
first, particularly for the 60-mph stopping distance tests, could 
result in severe flat-spotting of the tires on the non-ABS-controlled 
axles. Subsequent vehicle test runs would be difficult with the tires 
in that condition.
    (3) The TMA proposal would eliminate one loading/unloading sequence 
for truck tractors, but it would necessitate an additional unloading 
sequence for single unit trucks and buses. The current test sequence 
for single unit trucks and buses does not necessitate any load change 
before the stopping distance tests are conducted since these vehicles 
are not currently required to be tested to the braking-in-a-curve test 
procedure. For these vehicles, TMA's proposed sequence would require 
the next test after the burnish, which is conducted at GVWR, to be the 
60-mph stopping distance test at LLVW. TMA did not address this issue.
    (4) Not all vehicle manufacturers have the necessary test facility 
to conduct the braking-in-a-curve test. Some manufacturers must 
transfer their vehicles to a different site for testing. Therefore, if 
TMA's test sequence were adopted, overall test efficiency would not 
necessarily improve, particularly for these manufacturers.
    b. Brake adjustments (see 2b above). The TMA request that the 
agency permit brake adjustments at any time, other than during burnish, 
is denied. Standard No. 121 requires air-braked vehicles to be equipped 
with automatic brake adjusters. The potential for over-adjustment by 
automatic brake adjusters during the series of full-treadle brake 
applications required for braking-in-a-curve tests does exist. However, 
the agency believes that it is important to specify when manual 
adjustments are allowed since this enhances repeatability for 
compliance testing.
    The agency further believes that manual adjustment of the brakes 
after each test sequence is inappropriate because it would be less 
representative of real-world braking conditions. Standard No. 121 
allows some brake adjustment during testing. For example, two manual 
brake adjustments are allowed, one at the end of the braking-in-a-curve 
test and the other at the end of the GVWR parking brake test. For 
single unit trucks and buses, one manual brake adjustment is allowed at 
the end of the GVWR parking brake test. NHTSA believes that current 
limitations on the number of manual brake adjustments during the test 
sequence sufficiently addresses the potential for brake over-adjustment 
while preserving a well-defined test procedure.
    c. Brake test and burnish procedure (see 2c above). The TMA request 
that the entire brake test procedure, including the burnish procedure, 
be conducted with the transmission in neutral or with the clutch 
disengaged is denied.
    Before a vehicle's brakes are tested for compliance with Standard 
No. 121, the vehicle's brakes are burnished, also known as ``break-
in,'' by a series of brake applications called ``snubs''. The burnish 
procedure is intended to simulate the break-in period that a vehicle's 
brakes will receive when it is initially used on the public roads. The 
current burnish procedures, which became effective in September, 1993 
(53 FR 8190, March 14, 1988) specified that the brakes on heavy 
vehicles be burnished without regard to the brake temperatures 
generated during the burnish. The agency believes that this burnish 
procedure is more realistic and representative of the break-in that the 
vehicle brakes receive in actual service without favoring one brake 
design over another.
    The burnish procedure is required to be conducted with the vehicle 
in gear. The agency believes that TMA's proposal to allow the vehicle's 
brakes to be burnished with the clutch disengaged or the transmission 
in neutral will result in a higher temperature burnish similar to the 
old burnish procedure. The burnish procedure rulemaking rejected this 
temperature-based approach to burnishing brake linings on heavy 
vehicles. The current burnish procedure allows the brakes to reach 
whatever temperatures they are designed to reach when driven in typical 
stop-and-go driving. Therefore, any braking system

[[Page 5262]]

design will be conditioned fairly under this approach.
    In addition, the procedure described in S7 of Standard No. 105, 
when testing a vehicle in neutral, requires a four-part procedure that 
is appropriate for a performance requirement, but would be very time-
consuming if applied to a 500-snub burnish procedure. The agency 
believes that using this method in conducting the burnish procedure 
would not be in the interest of testing efficiency that manufacturers 
are striving to achieve.
    TMA is also concerned about the burden on manufacturers to test 
every engine and driveline package offered on a given chassis. The 
agency notes that vehicle manufacturers are not required to and 
currently do not test every combination of engine and drivetrain that 
is offered on each vehicle. The legal requirement is that a 
manufacturer exercise due care in assuring itself that its vehicle is 
capable of meeting the performance requirements of applicable standards 
when tested as prescribed in the standards.
    d. Service brake application prior to parking brake application 
(see 2d above). TMA's request that a full service brake application be 
permitted prior to applying the parking brake is denied. The agency has 
no test data comparing the grade holding ability of heavy truck air 
brake systems using full service brake application prior to engaging 
the parking brakes, nor did TMA supply such data.
    The agency is concerned that, by allowing a full treadle 
application prior to engaging the parking brake, colloquially referred 
to as ``compounding,'' some vehicles may have reduced grade holding 
ability. For example, in some applications, such as the construction 
industry, trucks are often stopped on a grade in the unloaded condition 
by a partial treadle application, after which the driver applies the 
parking brake. In the lightly-loaded condition, a full treadle 
application may not be needed to stop the vehicle on the grade. If the 
vehicle were then loaded, however, it is possible that the parking 
brake would not hold and the vehicle would roll away.
    NHTSA is also concerned about the effects of full service brake 
applications prior to engaging the parking brake on the durability of 
foundation brake components such as brake chamber support brackets. For 
a brief time when the air-applied service brakes and the mechanical 
spring brakes both exert a braking force on the slack adjusters and 
other foundation brake components, these additive forces can cause 
damage to these brake components. Another concern is the effect on 
foundation brake components when vehicles are parked with their brakes 
at high temperatures. As those brake drums cool, they would impose 
greater loads on the foundation brakes which could lead to permanent 
deformation of some components.
    The agency notes that this issue is an ongoing concern to the 
industry in certifying vehicles to Standard No. 121. However, since 
NHTSA has no test data with which to evaluate the feasibility of this 
proposal and TMA did not provide any data to support its proposal, the 
agency has decided to conduct vehicle research to evaluate the issue of 
brake compounding. Since this research is not expected to be completed 
until mid-1999, the agency denies this portion of the petition. 
However, when our research has been completed and the test results 
analyzed, it is the agency's intent to propose a clarification of the 
test procedure or a revision of the regulatory language in S5.6.2 of 
Standard No. 121.
    e. Clarify that emergency brake requirements for trucks and buses 
do not become effective until March 1, 1998 (see 2e above). This TMA 
request is denied as being moot. Emergency brake requirements are now 
in effect for all air braked vehicles as of March 1, 1998. Thus, 
subsection S5.7 of Standard No. 121 will not now be amended to state 
the effective dates of applicable requirements for the emergency brakes 
of trucks and buses. The following table, however, is shown here for 
information purposes:

   Emergency Brake Requirements for Trucks and Buses: Effective Dates
                  (by vehicle and brake configuration)
 
 
------------------------------------------------------------------------
March 1:
    1997 (Air)..........................  New Truck Tractors.
    1998 (Air)..........................  New air-braked trailers &
                                           single-unit trucks, buses.
    1999 (Hydraulic)....................  New single-unit trucks and
                                           buses with hydraulic brakes.
------------------------------------------------------------------------

4. Grants of Certain Requests by Petitioner; Agency Proposals

    a. Correction of inconsistency (see 2f above). TMA suggested that 
emergency brake stops for loaded tractors with unbraked control 
trailers are inappropriate. TMA is correct. The agency grants the 
request and proposes to delete S5.7.3(b) since there is no longer a 
requirement for emergency brake stops for truck tractors in the loaded 
condition.
    b. Roll bar provision (see 2g above). TMA suggested permitting the 
use of a roll bar for any vehicle in this test sequence, including the 
60-mph straight line stops and the 30-mph stops in a curve. The agency 
grants the request and, in order to provide adequate protection for 
test vehicle drivers in the event of a rollover during testing, 
proposes to permit the use of roll bars in all test vehicles utilized 
in the braking-in-a-curve tests and the straight line stopping distance 
tests. Further, for the 60-mph straight line stops in the unloaded 
condition, NHTSA proposes to include an allowance of up to 1,500 pounds 
for driver, instrumentation, and roll bar. This allowance is not 
applicable to tests in the loaded condition since the weight of these 
items would be included as part of the load.
    c. Single-unit truck axles should not be overloaded (see 2h above). 
TMA suggested that paragraph S5.3.1.1 be amended to provide that 
single-unit trucks should not be overloaded to achieve GVWR. The agency 
grants the request and proposes to amend paragraph S5.3.1.1 to so 
provide.
    d. Need for additional clarification of the wheel lock provisions 
(see 2i above). TMA suggested that the wheel lockup provisions be 
clarified by rescinding the provisions of S5.3.1(a) through (d) (see 
b(9) above). Although NHTSA does not agree with TMA's rationale for 
deleting the wheel lock provision, the agency proposes to clarify any 
misconceptions about the wheel lock provisions with respect to vehicles 
with tandem axles.
    The agency believes that the lack of a definition for ``tandem 
axle'' is a primary cause for the misunderstanding of the wheel lock 
restrictions of S5.3.1. The industry considers a tandem to be two or 
more drive axles that are placed in a close arrangement one behind the 
other, whereas NHTSA considers a tandem to be two or more axles (driven 
or non-driven) placed in a close arrangement one behind the other. 
Accordingly, NHTSA believes that for a 2-axle rear tandem with one 
driven axle and one pusher axle, if ABS is on the driven axle and not 
on the pusher axle, the two wheels on the pusher axle are permitted to 
lock up for the duration of the stop, while the 2 ABS-controlled wheels 
on the driven axle are allowed to lock up for only a duration of 1 
second or less.
    If, as TMA assumes, the two rear axles in the configuration of one 
driven and one tag or pusher axle are not considered a tandem, TMA 
would be correct that the lockup restriction of one wheel per axle 
would apply and prevent both wheels on any one of the axles

[[Page 5263]]

from locking simultaneously. However, NHTSA believes that TMA is 
incorrect in its statement that ``neither of the rear axles can have 
lockup on both its wheels'' because NHTSA considers the 2-axle 
configuration to be a tandem.
    The agency believes that a definition of ``tandem axle'' is needed 
in the standard to clarify the wheel lock provisions. That definition 
would not include a requirement that all axles in a tandem be driven. 
That should resolve the issue of having implied differences in the 
stringency of the ABS requirements for heavy vehicles with 3 or more 
axles based on the drivetrain configuration. Thus, a 6x2 single truck 
(3-axle truck with one drive axle) could comply with the wheel lock 
provisions using a 4-sensor/2-modulator antilock system since the two 
rear axles would be defined as a tandem. That would allow any two 
wheels on the tandem, that is either the tag or the pusher axle, to 
lock for the duration of the test, if the axle is not ABS-controlled. 
This definition has recently been included in Standard No. 105, 
Hydraulic and electric brake systems, and NHTSA proposes adding it to 
Standard No. 121 at this time.
    e. Typographical errors (see 2j above). TMA is correct that 2 
typographical errors appear in S6.1.8 and S6.2.5 respectively. NHTSA 
will correct the 2 typographical errors identified by TMA, namely line 
23 of the first paragraph of S6.1.8 which now reads ``1 mph'' will be 
corrected to read ``1 mile.'' Similarly, line 2 of S6.2.5 that now 
reads ``dynamometer or responding'' will be corrected to read 
``dynamometer corresponding.''

5. Rulemaking Analyses and Notices

 a. Executive Order 12866 and DOT Regulatory Policies and Procedures

    This document has not been reviewed under Executive Order 12866, 
Regulatory Planning and Review.
    NHTSA has analyzed the impact of this rulemaking action and has 
determined that it is not ``significant'' within the meaning of DOT's 
regulatory policies and procedures. This action proposes to clarify and 
amend certain provisions of Federal Motor Vehicle Safety Standard No. 
121, Air brake systems, to permit the addition of a rollbar on test 
vehicles when undergoing brake testing, clarify when wheel lockup is 
permitted when brake testing, provide that single-unit truck axles 
should not be overloaded when brake testing, and delete an obsolete 
requirement. The amendments proposed herein would not impose any 
additional costs on manufacturers of medium and heavy trucks. Although 
the installation of roll bars on test vehicles would involve additional 
costs, that provision is optional to manufacturers who may voluntarily 
want to install them. Further, even if manufacturers chose to install 
the bars on their test vehicles, the number of affected vehicles would 
be very small. Thus, the agency estimates that implementation of the 
proposals herein would not result in any increased costs to 
manufacturers, distributors, or consumers. Accordingly, a full 
regulatory evaluation was not prepared.

b. Regulatory Flexibility Act

    NHTSA has considered the effects of this rulemaking action under 
the Regulatory Flexibility Act, 5 U.S.C. 601, et seq. I hereby certify 
that this notice of proposed rulemaking would not have a significant 
impact on a substantial number of small entities.
    The following is the agency's statement providing the factual basis 
for the certification (5 U.S.C. 605(b)). The amendments proposed herein 
would primarily affect manufacturers of medium and heavy trucks. The 
Small Business Administration (SBA) regulation at 13 CFR part 121 
defines a small business as a business entity which operates primarily 
within the United States (13 CFR 121.105(a)).
    SBA's size standards are organized according to Standard Industrial 
Classification (SIC) codes. SIC code No. 3711, Motor Vehicles and 
Passenger Car Bodies, prescribes a small business size standard of 
1,000 or fewer employees. SIC code No. 3714, Motor Vehicle Part and 
Accessories, prescribes a small business size standard of 750 or fewer 
employees.
    The amendments proposed in this rulemaking action would amend 
Standard No. 121 to permit the addition of a rollbar on test vehicles 
when undergoing brake testing, clarify when wheel lockup is permitted 
when brake testing, provide that single-unit truck axles should not be 
overloaded when brake testing, and delete an obsolete requirement. 
These proposed amendments were requested by the trade organization that 
represents the major manufacturers of medium and heavy trucks in the 
U.S. The proposed amendments, if adopted, would not mandate any 
increased costs or other burdens on truck manufacturers, most if not 
all of which would not qualify as small businesses under SBA 
guidelines. Neither would the proposed amendments result in any 
increased costs for small businesses or consumers. Accordingly, there 
would be no significant impact on small businesses, small 
organizations, or small governmental units by these amendments. For 
these reasons, the agency has not prepared a preliminary regulatory 
flexibility analysis.

c. Executive Order No. 12612, Federalism

    NHTSA has analyzed this rulemaking action in accordance with the 
principles and criteria of E.O. 12612 and has determined that this rule 
does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.

d. National Environmental Policy Act

    NHTSA has analyzed this rulemaking action for the purposes of the 
National Environmental Policy Act and has determined that 
implementation of this rulemaking action would not have any significant 
impact on the quality of the human environment.

e. Paperwork Reduction Act

    In accordance with the Paperwork Reduction Act of 1980, Pub. L. 96-
511, NHTSA states that there are no information collection requirements 
associated with this rulemaking action.

f. Civil Justice Reform

    The amendments proposed herein would not have any retroactive 
effect. Under 49 U.S.C. 30103(b), whenever a Federal motor vehicle 
safety standard is in effect, a state or political subdivision thereof 
may prescribe or continue in effect a standard applicable to the same 
aspect of performance of a motor vehicle only if the standard is 
identical to the Federal standard. However, the United States 
government, a state or political subdivision of a state may prescribe a 
standard for a motor vehicle or motor vehicle equipment obtained for 
its own use that imposes a higher performance requirement than that 
required by the Federal standard. Section 30161 of Title 49, U.S. Code 
sets forth a procedure for judicial review of final rules establishing, 
amending or revoking Federal motor vehicle safety standards. A petition 
for reconsideration or other administrative proceedings is not required 
before parties may file suit in court.

6. Comments

    Interested persons are invited to submit comments on the amendments 
proposed herein. It is requested but not required that any such 
comments be submitted in duplicate (original and 1 copy).
    Comments must not exceed 15 pages in length (49 CFR 553.21). This 
limitation is intended to encourage commenters to detail their primary

[[Page 5264]]

arguments in concise fashion. Necessary attachments, however, may be 
appended to those comments without regard to the 15-page limit.
    If a commenter wishes to submit certain information under a claim 
of confidentiality, 3 copies of the complete submission, including the 
purportedly confidential business information, should be submitted to 
the Chief Counsel, NHTSA, at the street address noted above, and 1 copy 
from which the purportedly confidential information has been deleted 
should be submitted to Docket Management. A request for confidentiality 
should be accompanied by a cover letter setting forth the information 
called for in 49 CFR part 512, Confidential Business Information.
    All comments received on or before the close of business on the 
comment closing date indicated above for the proposal will be 
considered, and will be available to the public for examination in the 
docket at the above address both before and after the closing date. To 
the extent possible, comments received after the closing date will be 
considered. Comments received too late for consideration in regard to 
the final rule will be considered as suggestions for further rulemaking 
action. Comments on today's proposal will be available for public 
inspection in the docket. NHTSA will continue to file relevant 
information in the docket after the comment closing date, and it is 
recommended that interested persons continue to monitor the docket for 
new material.
    Those persons desiring to be notified upon receipt of their 
comments in the rule 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, Motor vehicle safety, Motor vehicles, Rubber and rubber 
products, and Tires.

    In consideration of the foregoing, 49 CFR part 571 would be amended 
as follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

    1. The authority citation for part 571 would continue 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 would be amended in S4 by adding a definition of 
``tandem axle'' in alphabetical order; by revising S5.3.1.1 (a) through 
(c) and S5.7.3(b); by removing and reserving S5.7.3(c); and by revising 
S6.1.8 and S6.2.5, to read as follows:


Sec. 571.121  Air brake systems.

* * * * *
    S4. Definitions.
* * * * *
    Tandem axle means a group or set of two or more axles placed in a 
close arrangement, one behind the other, with the centerlines of 
adjacent axles not more than 72 inches apart.
* * * * *
    S5.3.1.1 * * *
    (a) Loaded to its GVWR so that the load on each axle, measured at 
the tire-ground interface, is most nearly proportional to the axles' 
respective GAWRs, without exceeding the GAWR of any axle.
    (b) In the truck tractor only configuration plus up to 500 lbs. or, 
at the manufacturer's option, at its unloaded weight plus up to 500 
lbs. (including driver and instrumentation) and plus not more than an 
additional 1,000 lbs. for a roll bar structure on the vehicle, and
    (c) At its unloaded vehicle weight (except for truck tractors) plus 
up to 500 lbs. (including driver and instrumentation) or, at the 
manufacturer's option, at its unloaded weight plus up to 500 lbs. 
(including driver and instrumentation) plus not more than an additional 
1,000 lbs. for a roll bar structure on the vehicle. If the speed 
attainable in two miles is less than 60 mph, the vehicle shall stop 
from a speed in Table II that is four to eight mph less than the speed 
attainable in two miles.
* * * * *
    S5.7.3 * * *
    (b) Be capable of modulating the air in the supply or control line 
to the trailer by means of the service brake control with a single 
failure in the towing vehicle service brake system as specified in 
S5.7.1.
    (c) [Removed and reserved]
* * * * *
    S6.1.8 For vehicles with parking brake systems not utilizing the 
service brake friction elements, burnish the friction elements of such 
systems prior to the parking brake test according to the manufacturer's 
recommendations. For vehicles with parking brake systems utilizing the 
service brake friction elements, burnish the brakes as follows: With 
the transmission in the highest gear appropriate for a speed of 40 mph, 
make 500 snubs between 40 mph and 20 mph at a deceleration rate of 10 
f.p.s.p.s., or at the vehicle's maximum deceleration rate if less than 
10 f.p.s.p.s. Except where an adjustment is specified, after each brake 
application accelerate to 40 mph and maintain that speed until making 
the next brake application at a point 1 mile from the initial point of 
the previous brake application. If the vehicle cannot attain a speed of 
40 mph in 1 mile, continue to accelerate until the vehicle reaches 40 
mph or until the vehicle has traveled 1.5 miles from the initial point 
of the previous brake application, whichever occurs first. Any 
automatic pressure limiting valve is in use to limit pressure as 
designed. The brakes may be adjusted up to three times during the 
burnish procedure, at intervals specified by the vehicle manufacturer, 
and may be adjusted at the conclusion of the burnishing, in accordance 
with the vehicle manufacturer's recommendation.
* * * * *
    S6.2.5 The rate of brake drum or disc rotation on a dynamometer 
corresponding to the rate of rotation on a vehicle at a given speed is 
calculated by assuming a tire radius equal to the static loaded radius 
specified by the tire manufacturer.
* * * * *
    Issued on January 26, 1999.
L. Robert Shelton,
Associate Administrator for Safety Performance Standards.
[FR Doc. 99-2486 Filed 2-2-99; 8:45 am]
BILLING CODE 4910-59-P