[Federal Register Volume 66, Number 239 (Wednesday, December 12, 2001)]
[Rules and Regulations]
[Pages 64154-64159]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-30636]
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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: Final rule.
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SUMMARY: NHTSA is amending its 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 Atandem axle,'' and
to permit the use of roll bars on vehicles undergoing brake testing.
This rulemaking was initiated in response to a petition for rulemaking
from the Truck Manufacturers Association.
DATES: Effective Date: The amendments made in this rule are effective
January 11, 2002.
Petition Date: Any petitions for reconsideration must be received
by NHTSA no later than January 28, 2002.
ADDRESSES: Any petitions for reconsideration should refer to the docket
and notice number of this notice and be submitted to: Administrator,
National Highway Traffic Safety Administration, 400 Seventh Street,
SW., Washington, DC 20590.
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) 366-8525, fax (202) 493-2739.
For legal issues: Mr. Otto Matheke, 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.
On January 6, 1997, the Truck Manufacturers Association (TMA)
submitted a petition for rulemaking to NHTSA requesting that Standard
No. 121 be amended. The TMA petition stated that the organization,
through a Society of Automotive Engineers (SAE) task force, had
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 Standard No.
121 and SAE J1626 should be aligned to improve test efficiency and
decrease testing costs to the industry. Contending that aligning
Standard No. 121 with SAE J1626 would have no detrimental impact on
motor vehicle safety, TMA suggested 10 changes to the standard:
a. Test sequence--The first change suggested by TMA involved
amending Standard No. 121 to change the braking test sequence. TMA
noted that Standard No. 121 currently allows truck tractor braking-in-
a-curve tests to be performed in the loaded and unloaded (bobtail)
condition on the same surface by permitting the test vehicle to be
unloaded between tests. This eliminates the step of moving vehicles
from one test site to another and limits the need to water the test
track to only a single time. TMA requested that Standard No. 121 be
modified to allow unloaded straight line stops and loaded straight line
stops immediately following the braking-in-a-curve test. Allowing this,
in
[[Page 64155]]
TMA's view, would simplify testing and have little impact on the test
results as long as the burnish procedure is performed first and final
inspection follows all other required tests.
b. Brake adjustments--TMA requested that Standard No. 121 be
modified to allow brakes to be adjusted using the procedure specified
by the vehicle manufacturer at any time during testing other than the
burnish procedure. TMA stated that some automatic brake adjusters
overadjust during Standard No. 121 testing, but not in normal service.
According to TMA, SAE J1626 recognizes this and allows brakes to be
adjusted in accordance with the manufacturer's procedure at any time to
reduce brake performance variability.
c. Driveline engagement--TMA requested 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
currently provides that tests, but not the burnish procedure, 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. The organization contended 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. Parking brake test--TMA requested that Standard No. 121 be
modified to allow a service brake application prior to applying and
testing the parking brake application and that S5.6.3.1 be amended to
provide explicitly that this section's requirements apply to the case
in which a single leakage failure occurs in the service brake system
after the parking brakes are applied.
e. Emergency brake effective date--TMA asked NHTSA to clarify the
effective date of emergency brake requirements for trucks and buses.
Section S5.7, in TMA's view, 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. Loaded tractor emergency brake--TMA requested that the loaded
tractor emergency brake test, which contained a requirement that such
tests be performed with loaded tractors with unbraked control trailers,
be deleted.
g. Roll bar--TMA requested that the agency modify Standard No. 121
to 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.
h. Axle loading--TMA requested that S5.3.1.1. of Standard No. 121
be modified to establish the specifications for the loading of the
axles of single unit trucks. TMA submitted that the lack of a load
limit in the requirements for single trucks could result in testing of
these vehicles at a greater weight that the vehicle, or individual
axles of the vehicle, were designed to carry.
i. Wheel lock--TMA sought clarification of the wheel lock
provisions found in S5.1.6.1(b) of Standard No. 121. TMA pointed out
that the section 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 contended that
these requirements conflicted with each other and gave 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 2 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 argued 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 therefore requested that the wheel
lockup provisions of S5.3.1(a) through (d) be rescinded, and that
S5.3.1 be redrafted.
j. Typographical errors--Finally, TMA requested that several
typographical errors be corrected.
2. Notice of Proposed Rulemaking
On February 3, 1999, the agency published a Notice of Proposed
Rulemaking (NPRM) in the Federal Register. The NPRM announced that the
agency was partially denying and partially granting the TMA petition.
The petition was denied as to items a through e above. It was granted
as to the remaining five items, referenced as f through j. For those
items that it granted, the agency proposed several changes to Standard
No. 121.
The request to change the braking test sequence to conduct the
unloaded straight line stops before the loaded straight lines stops was
denied because the current GVWR/LLVW (lightly-loaded vehicle weight) is
consistent with the other tests in the overall test sequence. In
addition, 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. We also observed that 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.
TMA's request that the agency initiate rulemaking to allow brake
adjustments at any time during testing was also denied. As we explained
in the NPRM, the potential of automatic brake adjusters to over-adjust
brakes during the test sequence does not overcome the agency's other
concerns. Manual adjustment of the brakes after each test sequence is
inappropriate because it would be less representative of real-world
braking conditions. Further, Standard No. 121 already 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. Accordingly, the agency concluded that the
existing provisions for manual brake adjustments during the test
sequence sufficiently addressed the potential for brake over-adjustment
while preserving a well-defined test procedure.
As indicated in the NPRM, NHTSA also declined to start rulemaking
proceedings to change the brake test and burnishing procedure to
specify that all burnishing and testing be conducted with the
transmission in neutral or the clutch disengaged. As we explained in
the NPRM, TMA's request to allow the vehicle's brakes to be burnished
with the clutch disengaged or the transmission in neutral would result
in a higher temperature burnish similar to
[[Page 64156]]
a previously revised burnish procedure. In contrast, 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 design will be conditioned fairly under
this approach. We also noted that while TMA was concerned about the
burden of testing every engine and driveline package offered on a given
chassis, vehicle manufacturers are not required to and currently do not
test every combination of engine and drivetrain that is offered on each
vehicle. At the time the NPRM was published, as well as today, 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.
We also denied TMA's request to modify the parking brake
requirements to allow full application of the service brake prior to
application of the parking brake. TMA did not submit any data comparing
the grade holding ability of heavy truck air brakes using a full
service application before engaging the parking brake, making it
difficult to evaluate their proposal. NHTSA noted that full service
brake applications prior to engaging the parking brake could damage
brake components. The agency decided to conduct vehicle research to
evaluate this issue, but could not clarify the test procedure or revise
Standard No. 121 until testing had been completed and data had become
available.
Finally, TMA's request that NHTSA clarify the emergency brake
requirements for trucks and buses do not become effective until March
1, 1998 was denied on the basis that the request had become moot by the
time the NPRM had been issued.
The February 3, 1999 NPRM also outlined those portions of the TMA
petition that NHTSA considered to be appropriate for further rulemaking
action.
The agency proposed to amend Standard No. 121 to eliminate the
fully loaded truck-tractor emergency brake testing requirements of
S5.7.3(b), to permit the use of roll bars in brake testing. As noted in
the NPRM, permitting the use of roll bars in testing would protect
drivers in the event of a rollover during a test. To prevent the
overloading of single-unit axles in fully loaded brake tests, the
agency proposed to amend S5.3.1.1. To clarify the wheel lock
requirements, the agency proposed altering Standard No. 121's
definition of ``tandem axle'' that would not include a requirement that
all axles in a tandem would be driven. In the agency's view, this
definition would resolve potential confusion over the application of
ABS requirements for heavy vehicles with three or more axles.
Finally, the agency proposed to correct typographical errors in
S6.1.8 and S6.2.5 of Standard No. 121.
3. Comments Received in Response to the NPRM
NHTSA received four comments in response to the NPRM. Comments were
submitted by three trade groups, the American Truck Dealers Division of
the National Automobile Dealers Association (ATD), the Heavy Duty Brake
Manufacturers Council of the Motor Equipment Manufacturer's Association
(HDBMC), the Truck Manufacturers Association (TMA), and by one
manufacturer, AlliedSignal Truck Brake Systems Company (AlliedSignal).
All of the commenters supported, in whole or in part, the series of
amendments proposed in the NPRM. HDBMC and AlliedSignal took issue with
the agency's decision to deny portions of the original TMA petition for
rulemaking.
HDBMC supported the agency's proposed amendments regarding roll
bars, wheel lock requirements, and corrections. The organization
disagreed with the agency's denial of the remainder of the portions of
the TMA petition that would have aligned Standard No. 121 with SAE J-
1626. HDBMC stated that the SAE J-1626 is in the final ballot process
with completion expected in the second quarter of 1999. They strongly
urged the agency to refrain from denying any portion of the TMA
petition until the Recommended Practice is finalized by the Society of
Automotive Engineers.
AlliedSignal stated that it joined in the comments provided by
HDBMC and provided additional comments to supplement that response.
AlliedSignal supported the agency's proposed amendments that grant
portions of the TMA petition. The company disagreed with the agency's
denial of the remaining TMA requests. AlliedSignal urged NHTSA to
optimize testing efficiency by giving manufacturers the option of
sequencing the unloaded braking-in-a-curve test with the other unloaded
tests and, since there are a number of possible test sequences, NHTSA
should consider rulemaking to provide manufacturers the opportunity to
arrange the testing sequence as they see fit. NHTSA would, however,
test in the sequence outlined in the agency's test procedure for FMVSS
121. This, in AlliedSignal's view, ``would allow alternate test
sequences to be considered in the test procedure when further data is
available, without impacting the safety standard.''
AlliedSignal supported a common industry standard procedure for
brake testing and urges NHTSA and SAE to agree upon a common approach
to brake adjustment during compliance testing. AlliedSignal stated that
the current limited periods of adjustment seem to be generally
adequate; however, in the future, as additional information on
automatic adjustment and air disc brakes become available, some
modifications may be needed. AlliedSignal said that NHTSA must
recognize that automatic adjustment devices are designed to operate
under normal use conditions on the road, unlike the testing conditions
during the compliance testing process. AlliedSignal also stated that
the burnish should be conducted either with the transmission in neutral
or with the clutch engaged. The company argued that this procedure is
more repeatable and yields more consistent data. AlliedSignal contended
that during a parking brake 20 percent gradient hold test, the service
brake would be used to initially hold the vehicle on the grade, before
the parking brake control is applied. The use of anti-compounding
devices, as applicable, in the system to protect the brakes from over-
stressing, should not be a concern for compliance, but should be at the
manufacturer's discretion based upon good design practice. AlliedSignal
suggested that since NHTSA is researching the grade holding procedure,
it should also evaluate the equivalence of grade holding as an option
to the static draw bar pull procedure. AlliedSignal also stated that
although it understood that only issues addressed in this NPRM are to
be subjects for rulemaking at this time, the company also recommended
that NHTSA consider deleting the Trailer Test Rig Figure 1(a) and
section S6.1.13(b) from the standard as these pertained to the old test
rig.
ATD supported the agency's proposed amendments relating to wheel
lock and the definition of tandem axles. TMA indicated that as NHTSA
had proposed to delete S5.7.3(b) to properly reflect the earlier
deletion of the loaded truck-tractor emergency brake testing
requirements, all references to S5.7.3(b) elsewhere in the standard
need to be modified or removed. TMA also indicated that as the agency
had proposed to allow the use of roll bars in brake testing, the
specifications for vehicle weights contained in Table 1, S5.6.2(b) and
S5.7.1 should be modified
[[Page 64157]]
to allow for the additional weight of the roll bars.
4. Final Rule
NHTSA is adopting the changes proposed in the NPRM, with two minor
modifications. The agency notes that these modifications to Standard
No. 121 were either supported by the commenters or were not addressed
by any of the commenters. As noted in the NPRM, the agency believes
that these modifications will eliminate certain inconsistencies in
Standard No. 121, simplify the test burdens of manufacturers, and allow
for increased safety during brake testing.
Two of the four commenters, AlliedSignal and HDBMC, indicated their
opposition to the agency's decision to deny portions of the TMA
petition for rulemaking. NHTSA notes that its rationale for denying
portions of the TMA petition are contained in the February 3, 1999
NPRM. Neither AlliedSignal or HDBMC submitted any data or test results
with their comments that would support any change from the agency's
earlier decision to deny portions of the TMA petition. The agency also
notes that HDBMC urged NHTSA not to deny any portion of the TMA
petition until the SAE finally approved and adopted the most recent
revisions to the SAE J-1626 standard. The most recent revisions of the
J-1626 standard were approved and adopted by the SAE in June 1999. The
final revisions to J-1626 did not, in NHTSA's view, change that
voluntary standard to address the concerns voiced by the agency in the
NPRM.
One commenter, TMA, suggested several changes to Standard No. 121
that were not part of the agency's proposal. As TMA indicated, these
amendments are, however, related to the agency's proposal. Both are
conforming amendments.
The first of these is TMA's suggestion that S6.1.14, which
specifies requirements for venting brake lines to the atmosphere for
the emergency braking test, be amended to delete a reference to
S5.7.3(b). As the agency's proposal and the final rule call for the
deletion of S5.7.3(b), TMA's suggestion appears to be well founded. The
deletion of this reference does not alter the substance of Standard No.
121, the agency's proposal or this final rule but merely reflects the
deletion S5.7.3(b). Therefore, NHTSA is adopting TMA's suggested
change.
The second modification suggested by TMA is to modify the
specifications for allowable vehicle weights contained in steps 2b, 7
and 8 of Table I and Sections 5.6.2(b) and S5.7.1. We note that these
sections all set forth the allowable vehicle weights for the different
tests to be performed in the test sequence. If these specifications
were to remain unmodified, they would conflict with the final rule's
adoption of provisions allowing the use of roll bars during testing as
no allowance would be available for the added weight of the roll bar.
As the final rule states that up to 1000 pounds may be added to
allowable vehicle weights to facilitate the use of roll bars, NHTSA
considers TMA's comments on this issue to be appropriate. The agency is
therefore revising its earlier proposal and amending Table I, S5.6.2
and S5.7.1. to allow an additional 1,000 pounds of weight.
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 clarifies and amends 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 do 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 this final
rule will not result in any increased costs to manufacturers,
distributors, or consumers. The agency also notes that the amendments
contained in this final rule will, to a limited degree, eliminate and
simplify certain requirements of Standard No. 121. These amendments may
result in very small cost savings for manufacturers. 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 final rule will 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)). This final rule will 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.
This final rule amends 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 amendments were requested by the trade
organization that represents the major manufacturers of medium and
heavy trucks in the U.S. The amendments do 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 does this final rule result in any increased costs for small
businesses or consumers. Accordingly, there is no significant impact on
small businesses, small organizations, or small governmental units by
these amendments. As noted above, the agency also notes that the
amendments contained in this final rule will, to a limited degree,
eliminate and simplify certain requirements of Standard No. 121. These
amendments may result in very small cost savings for manufacturers. For
these reasons, the agency has not prepared a regulatory flexibility
analysis.
c. Paperwork Reduction Act
NHTSA has analyzed this rule in accordance with the Paperwork
Reduction Act of 1980 (Pub. L. 96-511). There are no requirements for
information collection associated with this rule.
d. Executive Order 13132 (Federalism)
NHTSA has analyzed this rule in accordance with the principles and
[[Page 64158]]
criteria contained in E.O. 13132, and has determined that this rule
will not establish policies with federalism implications.
e. Civil Justice Reform
This rule will 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.
f. Executive Order 13045
Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any
rule that: (1) Is determined to be ``economically significant'' as
defined under E.O. 12866, and (2) concerns an environmental, health or
safety risk that NHTSA has reason to believe may have a
disproportionate effect on children. If the regulatory action meets
both criteria, we must evaluate the environmental health or safety
effects of the planned rule on children, and explain why the planned
regulation is preferable to other potentially effective and reasonably
feasible alternatives considered by us.
This rule is not subject to the Executive Order because it is not
economically significant as defined in E.O. 12866, and does not have a
disproportionate effect on children, who are unlikely to be conducting
brake tests on heavy trucks.
g. Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) requires
agencies to prepare a written assessment of the cost, benefits and
other effects of proposed or final rules that include a Federal mandate
likely to result in the expenditure by state, local, or tribal
governments, in the aggregate, or by the private sector, of more than
$100 million annually. This final rule does not meet the definition of
Federal mandate because this rule simply adds a compliance alternative
for one year. In no case will annual expenditures exceed the $100
million threshold.
h. 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 will not have any significant
impact on the quality of the human environment.
List of Subjects in 49 CFR Part 571
Imports, Motor vehicle safety, Motor vehicles.
In consideration of the foregoing, 49 CFR Part 571 is amended as
follows:
PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS
1. The authority citation for Part 571 of Title 49 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 S4 to add a definition of
``tandem axle'' in alphabetical order; by revising S5.3.1.1 (a) through
(c), S5.6.2, S5.7.1 and S5.7.3(b); by withdrawing and reserving
S5.7.3(c); and by revising S6.1.8, S6.1.14, S6.2.5 and Table I, 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.
* * * * *
S5.6.2 Grade holding. With all parking brakes applied, the vehicle
shall remain stationary facing uphill and facing downhill on a smooth,
dry portland cement concrete roadway with a 20-percent grade, both
(a) When loaded to its GVWR, and
(b) At its unloaded vehicle weight plus 1500 pounds (including
driver and instrumentation and roll bar).
* * * * *
S5.7.1 Emergency brake system performance. When stopped six times
for each combination of weight and speed specified in S5.3.1.1, except
for a loaded truck tractor with an unbraked control trailer, on a road
surface having a PFC of 0.9, with a single failure in the service brake
system of a part designed to contain compressed air or brake fluid
(except failure of a common valve, manifold, brake fluid housing, or
brake chamber housing), the vehicle shall stop at least once in not
more than the distance specified in Column 5 of Table II, measured from
the point at which movement of the service brake control begins, except
that a truck-tractor tested at its unloaded vehicle weight plus up to
1500 pounds shall stop at least once in not more than the distance
specified in Column 6 of Table II. The stop shall be made without any
part of the vehicle leaving the roadway, and with unlimited wheel
lockup permitted at any speed.
* * * * *
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) [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
[[Page 64159]]
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.
* * * * *
S6.1.14 In testing the emergency braking system of towing vehicles
under S5.7.3(a), the hose(s) is vented to the atmosphere at any time
not less than 1 second and not more than 1 minute before the emergency
stop begins, while the vehicle is moving at the speed from which the
stop is to be made and any manual control for the towing vehicle
protection system is in the position to supply air and brake control
signals to the vehicle being towed. No brake application is made from
the time the line(s) is vented until the emergency stop begins and no
manual operation of the parking brake system or towing vehicle
protection system occurs from the time the line(s) is vented until the
stop is completed.
* * * * *
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.
* * * * *
Table I--Stopping Sequence
1. Burnish.
2. Stops on a peak friction coefficient surface of 0.5:
(a) With the vehicle at gross vehicle weight rating (GVWR), stop
the vehicle from 30 mph using the service brake, for a truck tractor
with a loaded unbraked control trailer.
(b) With the vehicle at unloaded weight plus up to 1500 lbs., stop
the vehicle from 30 mph using the service brake, for a truck tractor.
3. Manual adjustment of the service brakes allowed for truck
tractors, within the limits recommended by the vehicle manufacturer.
4. Other stops with vehicle at GVWR:
(a) 60 mph service brake stops on a peak friction coefficient
surface of 0.9, for a truck tractor with a loaded unbraked control
trailer, or for a single-unit vehicle.
(b) 60 mph emergency brake stops on a peak friction coefficient of
0.9, for a single-unit vehicle. Truck tractors are not required to be
tested in the loaded condition.
5. Parking brake test with the vehicle loaded to GVWR.
6. Manual adjustment of the service brakes allowed for truck
tractors and single-unit vehicles, within the limits recommended by the
vehicle manufacturer.
7. Other stops with the vehicle at unloaded weight plus up to 1500
lbs.:
(a) 60 mph service brake stops on a peak friction coefficient
surface of 0.9, for a truck tractor or for a single-unit vehicle.
(b) 60 mph emergency brake stops on a peak friction coefficient of
0.9, for a truck tractor or for a single-unit vehicle.
8. Parking brake test with the vehicle at unloaded weight plus up
to 1500 lbs.
9. Final inspection of service brake system for condition of
adjustment.
Issued on December 6, 2001.
Jeffrey W. Runge,
Administrator.
[FR Doc. 01-30636 Filed 12-11-01; 8:45 am]
BILLING CODE 4910-59-P