Parts and Accessories Necessary For Safe Operation; Automatic Brake Adjusters and Brake Adjustment Indicators |
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Topics: Federal Highway Administration
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Rodney E. Slater
Federal Register
3 August 1994
[Federal Register: August 3, 1994]
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DEPARTMENT OF TRANSPORTATION
Federal Highway Administration
49 CFR Part 393
[FHWA Docket No. MC-94-9]
RIN 2125-AD37
Parts and Accessories Necessary For Safe Operation; Automatic
Brake Adjusters and Brake Adjustment Indicators
AGENCY: Federal Highway Administration (FHWA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
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SUMMARY: The FHWA is proposing to require the use of automatic brake
adjusters (ABAs) on hydraulically-braked commercial motor vehicles
(CMVs) and air-braked CMVs manufactured on or after October 20, 1993,
and October 20, 1994, respectively. The FHWA is also proposing a
requirement for brake adjustment indicators on air-braked CMVs with
external adjustment mechanisms manufactured on or after October 20,
1994. This rulemaking is intended to: Insure that the operational
standards for brakes in the Federal Motor Carrier Safety Regulations
(FMCSRs) are consistent with the manufacturing standards in the Federal
Motor Vehicle Safety Standards (FMVSSs) numbers 105 and 121, which now
require the installation of automatic brake adjusters and adjustment
indicators on certain CMVs manufactured on or after these dates; and
improve the safety of operation of CMVs by reducing the incidence of
brakes that are out of adjustment.
In addition, the FHWA requests information concerning the
possibility of requiring these devices to be retrofitted to CMVs placed
in operation prior to the effective dates of the recent amendments to
FMVSS Nos. 105 and 121.
DATES: Comments must be received on or before October 3, 1994.
ADDRESSES: Submit written, signed comments to FHWA Docket No. MC-94-9,
room 4232, HCC-10, Office of the Chief Counsel, Federal Highway
Administration, 400 Seventh Street, SW., Washington, D.C. 20590. All
answers to questions should refer to the appropriate question number
and all comments on specific provisions should refer to the appropriate
section and paragraph number. All comments received will be available
for examination at the above address from 8:30 a.m. to 3:30 p.m., e.t.,
Monday through Friday, except Federal holidays. Those desiring
notification of receipt of comments must include a self-addressed,
stamped postcard.
FOR FURTHER INFORMATION CONTACT: Ms. Deborah M. Freund, Office of Motor
Carrier Standards, (202) 366-2981, or Mr. Charles Medalen, Office of
the Chief Counsel, (202) 366-1354, Federal Highway Administration,
Department of Transportation, 400 Seventh Street, SW., Washington, D.C.
20590. Office hours are from 7:45 a.m. to 4:15 p.m., e.t., Monday
through Friday, except Federal holidays.
SUPPLEMENTARY INFORMATION:
Background
A. General Information
Proper brake adjustment is critical to the safe operation of
commercial motor vehicles. When brakes are correctly adjusted, vehicles
can generally be brought to a stop within a satisfactory distance and
in a controlled manner. However, brakes that are not properly adjusted
cannot develop the retardation force designed into the vehicle's brake
system, resulting in increased stopping distances. Under emergency
conditions, this can result in a collision that might otherwise have
been avoided, or in a more severe collision than would have occurred
with properly-adjusted brakes.
Out-of-adjustment brakes are the primary equipment-related cause
for commercial motor vehicles to be placed out of service during
roadside inspections. According to the FHWA's Office of Motor Carrier
Field Operations Annual Report for Fiscal Year 1992, 36.2 percent of
vehicles placed out-of-service are cited for this deficiency. A copy of
this report has been placed in the docket.
In addition, brake-related accidents, some stemming from gross
brake maladjustment, are also a factor in some ``equipment
malfunction'' CMV accident citations. The National Highway Traffic
Safety Administration's (NHTSA) regulatory evaluation, prepared in
conjunction with their rulemaking on automatic brake adjusters (ABAs),
noted that 6.8 percent of all medium and heavy truck accidents were
reported as being caused by defective equipment. Of that figure, 31
percent were due to defective brakes, with 60 percent of those brakes
judged to be out of adjustment; this amounts to 1.3 percent of
accidents reported--or nearly 4,000 accidents per year. The regulatory
evaluation also cited a review of National Transportation Safety Board
(NTSB) reports on 97 serious heavy truck accidents investigated from
1969 to 1981. Out-of-adjustment brakes were cited as a causal or
contributing factor in 27 of those 97 accidents, or 28 percent. A copy
of the NHTSA's regulatory evaluation has been placed in the docket.
B. Safety and Operational Role of Automatic Brake Adjusters and Brake
Adjustment Indicators
Automatic brake adjusters significantly reduce the effort required
for inspection and manual adjustment of the brakes. Clearance-sensing
ABAs limit the clearance between brake linings and drums, or pads and
rotors, to a level that ensures effective brake actuator strokes. They
adjust on every complete brake application. Stroke-sensing ABAs adjust
on brake applications severe enough to cause the brake actuator stroke
to exceed that which the ABA is designed to maintain. ABAs include, but
are not necessarily limited to, automatic slack adjusters (ASAs). The
term ``automatic brake adjusters'' is used to provide a performance-
based description of this class of devices.
Brake adjustment indicators (BAIs), especially when used in concert
with ABAs, can do a great deal to address the brake adjustment problem.
A BAI conforming to the NHTSA requirements can significantly reduce the
time necessary to assess brake adjustment levels. Use of these
indicators will make it easier for drivers and maintenance personnel to
make brake-adjustment checks at more frequent intervals, and detect
brake adjustment problems before they become severe enough to cause, or
worsen the outcome of, an accident.
C. NHTSA and NTSB Research on CMV Brake Performance and ABAs.
Two extensive research studies of CMV brake performance, and
operational and maintenance experiences of motor carrier fleets
utilizing CMVs equipped with ABAs, have been performed by the NHTSA and
the NTSB. We summarize both here. Copies of the NHTSA and the NTSB
studies are available from the National Technical Information Service
(NTIS, Springfield, Virginia, telephone (800) 553-6847). Copies have
also been placed in the public docket.
1. NHTSA Research. The NHTSA research was reported in ``Automatic
Brake Adjusters for Heavy Vehicle Air Brake Systems,'' February 1991,
report DOT-HS-807-724 (PB 91-215814). Seven fleets participated during
a 2.5-year initial study period and an additional 3 years of follow-up;
245 tractors and 289 trailers accumulated nearly 50 million miles of
travel during this time.
Researchers and fleet maintenance staffs made nearly 20,000
measurements of brake stroke length on approximately 1,800 brake
adjusters (four different manufacturers' ABAs, plus manual brake
adjusters (MBAs)). For 36 types of ABA installations, the median out-
of-adjustment rate was 4.0 percent, and the median number of out-of-
adjustment observations per brake per 10,000 miles was 0.016. The NHTSA
noted that ``[t]he ASAs tested were principally models designed and
marketed in the early to mid 1980's. There have been extensive design
improvements in both ASAs and other brake system components since that
time. Thus, the performance data presented here for these earlier ASA
designs likely understate the performance levels that can be expected
from ASAs purchased today.''
The NHTSA collected a limited amount of control data on MBAs. There
were 96 MBAs used in portions of 3 of the fleets. The use of MBAs
generally resulted in higher percentages and rates of out-of-adjustment
brakes than did the use of ABAs, and the differences were considered to
be statistically significant.
2. NTSB Research. The NTSB, an independent Federal agency
responsible for investigating and determining the probable cause or
causes of certain transportation-related accidents, has studied
numerous accidents in which brake deficiencies have been cited as
causal factors.
A recent NTSB study, ``Heavy Vehicle Airbrake Performance,''
adopted April 29, 1992, report NTSB/SS-92/01 (PB 92-917003), analyzed
information gathered over a 17-month period from selected brake-related
accidents involving heavy trucks and buses, as well as data collected
by NTSB staff during roadside inspections in 5 States. The report's
findings highlighted the role of brake system components in certain
vehicle instability accidents, and pointed out that many brake out-of-
adjustment problems were due both to the small tolerance range and to a
lack of proper brake maintenance. The NTSB recommended that the DOT,
among other things: (1) Require air-braked vehicles to be equipped with
visible adjustment indicators that will allow one person to check the
level of adjustment (Recommendation H-92-50); (2) require automatic
adjusters on vehicles equipped with airbrake systems (Recommendation H-
92-51); and (3) encourage the installation of visible brake adjustment
indicators on all vehicles equipped with air brake systems for easy
detection of adjustment levels (Recommendation H-92-57).
D. NHTSA Requirement for ABAs and Automatic Adjustment Indicators
The FHWA strives to maintain consistency between the manufacturing
standards for commercial motor vehicles contained in the NHTSA's
Federal Motor Vehicle Safety Standards (FMVSSs), and the operations and
maintenance regulations contained in the FMCSRs. On October 20, 1992
(57 FR 47793), the NHTSA issued a final rule amending FMVSS No. 105,
Hydraulic Brake Systems, to require ABAs on motor vehicles equipped
with hydraulic brake systems. The NHTSA also amended FMVSS No. 121, Air
Brake Systems, to require ABAs on all air-braked motor vehicles and
adjustment indicators on air-braked vehicles with external adjustment
mechanisms. The effective dates are October 20, 1993, for the
amendments to FMVSS No. 105 and October 20, 1994, for the amendments to
FMVSS No. 121.
While the NHTSA rulemaking requires manufacturers to equip new
vehicles with ABAs in order to ensure brakes are in proper adjustment,
it does not affect the readjustment limits used by the States in
roadside inspections nor those required by the FHWA for periodic
inspections (contained in Appendix G to the FMCSRs, ``Minimum Periodic
Inspection Standards''). The reach of the NHTSA's regulatory authority
extends only to vehicle manufacturers. The FMCSRs apply to employers,
employees, and commercial motor vehicles which transport property or
passengers in interstate commerce.
E. Brake Adjustment Criteria
The North American Uniform Driver-Vehicle Inspection Procedure
(NAUDVIP) provides a standardized procedure used by States and local
governments to inspect in-service CMVs. The NAUDVIP was developed by
the Commercial Vehicle Safety Alliance (CVSA). The Commercial Vehicle
Safety Alliance is an association of Federal, State, and Provincial
officials responsible for the administration and enforcement of motor
carrier safety laws in the United States, Canada, and Mexico, who work
together to enhance commercial motor vehicle safety.
As a part of the NAUDVIP, the CVSA specifies certain limits for
pushrod travel. These limits, which are identical to the limits
contained in Appendix G to the FMCSRs, ``Minimum Periodic Inspection
Standards,'' have been set in consultation with motor carrier safety
enforcement officials and brake manufacturers. Brakes at or beyond
these limits are considered to be out of adjustment.
The origin of the CVSA out-of-adjustment criteria can be traced
back to the California Highway Patrol (CHP) inspection criteria
established in the 1960's. The CHP readjustment limits were based on
brake adjustment limits developed by the former Motor Vehicle
Manufacturers Association (now the American Automobile Manufacturers
Association, which no longer deals with heavy truck issues). These
limits are approximately 80 percent of full brake chamber stroke. This
is generally the point on the force versus stroke curve for a typical
brake chamber where the brake force starts decreasing rapidly with
increasing stroke.
CVSA criteria regarding brake adjustment limits specify that a
vehicle is to be placed out of service if 20 percent or more of its
brakes are defective. A brake is considered defective if its adjustment
is 1/4 inch (6.5 mm) or more beyond the readjustment limit. Two brakes
at the readjustment limit or less than 1/4 inch beyond the readjustment
limit are also considered one defective brake. For example, on a 5-axle
combination vehicle with 10 brakes, 4 brakes at the readjustment limit
would be considered as 2 defective brakes, and would also result in an
out-of-service condition.
Since the readjustment limits are based upon the characteristics of
the brake chamber, the use of ABAs would not affect the brake chamber
output force. Therefore, the FHWA believes that the current
readjustment limits are appropriate for CMVs equipped with ABAs, as
well as those currently equipped with MBAs. When properly installed and
maintained, ABAs can thus help prevent sudden and unexpected loss of
braking ability due to a loss of brake force resulting from excessive
pushrod stroke.
F. ABA Installation and Reliability
As noted in the NHTSA's final rule, ABAs are currently being
installed on a large percentage of newly-manufactured medium- and
heavy-duty air-braked vehicles. Some fleets have been specifying ABAs
for their vehicles for a number of years. However, NHTSA also noted
that one major manufacturer and several smaller ones did not provide
ABAs as standard equipment, and many purchasers did not order them as
optional equipment. In addition, the majority of CMVs currently in
operation are not equipped with ABAs.
Brake adjuster lifespan generally depends upon the number of brake
applications and the number of brake service cycles of the CMV. The
NHTSA fleet study noted that most ABAs observed performed for the
duration of the study without mechanical failure. The researchers did
observe some mechanical failures, and some apparent failures that were
actually due to other problems in the brake system, such as wear in the
foundation brakes. A number of the failures were caused by wear to
specific parts. The manufacturers reported that they have implemented
design changes to remedy those problems. The NHTSA's supplemental fleet
data collected in 1988-1990 on newer ABAs indicated high levels of
reliability. The reported average replacement rates for ABAs were 0.06
replacements per million tractor miles and 0.3 per million trailer
miles.
The NHTSA research report emphasized that ABAs must be installed in
accordance with manufacturer specifications to maintain efficient
adjustments. In most cases, no special adjustments in brake component
geometry are required. Manufacturers of these devices provide drawings,
templates, and similar aids to facilitate installation.
The figures for CMVs placed out of service appear to indicate that
there are considerable difficulties in monitoring brake adjustment
status. The findings of the NHTSA research demonstrate that BAIs,
especially when used in concert with ABAs, can make a significant
contribution to resolving the brake adjustment problem. Aside from the
clear safety benefits of maintaining proper brake adjustment, ABAs can
have a positive benefit on motor carrier productivity by preventing
CMVs from being placed out of service, reducing roadside service calls
and the resulting delays to transportation operations.
A BAI conforming to the NHTSA requirements (49 CFR 571.121) can
significantly reduce the time needed to assess brake adjustment status.
As their name implies, BAIs provide a visible indication of pushrod
stroke. There are several varieties: some BAIs consist of color-coded
or scribed marks on the pushrod, others raise a plastic or metal
``flag'' when the pushrod stroke reaches the prescribed adjustment
limit.
ABAs do not eliminate the need for periodic inspection and
maintenance of the brake system, but they do reduce the need for brake
adjustment. Recommended Practice RP-609 of The Maintenance Council of
the American Trucking Associations states that ``[a]n automatic slack
adjuster should not have to be manually adjusted except for initial
installation and at brake reline * * *.'' If adjustment is needed, it
could be a sign that the ABA is not working or that there is a problem
with the [foundation] brake system. Brake actuator strokes must still
be monitored, of course.
Like their manual counterparts, ABAs and BAIs require regular
maintenance. They operate in the same hostile and exposed environment
as manual systems. The NHTSA notes that their performance is affected
by failures and wear in other parts of the foundation brake system,
and, like other components, their life expectancy can be less than that
of the tractor or trailer on which they are installed.
Discussion of Proposal
The FHWA believes that the information presented in the reports
cited above indicates that both motor carriers and the travelling
public may derive substantial operational and safety benefits from the
use of automatic brake adjusters and brake adjustment indicators.
The FHWA proposes to amend the FMCSRs by adding a new Sec. 393.53,
Automatic Brake Adjusters and Brake Adjustment Indicators. This section
would be added to Subpart C, Brakes.
The provisions of paragraphs (a), (b), and (c) would require that
automatic brake adjusters and brake adjustment indicators installed on
newly manufactured CMVs to comply with the requirements of FMVSS 105
and 121 be maintained by the motor carriers operating those CMVs.
Questions
The FHWA believes there are also opportunities for improvements to
operational safety of CMVs manufactured prior to the effective dates of
the recent amendments to FMVSS 105 and 121. The FHWA therefore requests
information regarding the potential impacts of requiring CMVs subject
to the FMCSRs to be retrofitted with ABAs, and for requiring air-braked
CMVs with external adjustment mechanisms to be retrofitted with brake
adjustment indicators. The FHWA specifically requests comments on the
following questions:
1. Should air-braked CMVs manufactured before the effective date of
NHTSA's rule be required to be retrofitted with ABAs?
2. Should all air-braked CMVs with external brake adjustment
mechanisms be required to be retrofitted with brake adjustment
indicators?
3. If certain CMVs are to be retrofitted, how much time should be
allowed for installation of the new equipment?
4. Are there certain types or configurations of air-braked vehicles
that cannot be equipped with ABAs because of space limitations around
the axles and wheels?
5. Should different periods be specified for retrofitting single-
unit trucks, tractors, converter dollies, and trailers?
6. The requirements proposed by this NPRM would exclude air-braked
vehicles that were not subject to FMVSS No. 121 on the date of
manufacture. (Vehicles not subject to the requirements are listed under
Paragraph S3 of Sec. 571.121, and include certain types of limited- or
specialized-use vehicles such as wide trailers, vehicles equipped with
an axle with a gross axle weight rating of 29,000 pounds or more, any
truck or bus that has a speed attainable in 2 miles of not more than 33
mph, heavy hauler trailer sets, and load divider dollies.) Should
specific types of CMVs, or CMVs used in unique operations, (i.e., CMVs
that are not subject to the requirements of FMVSS 121, but are subject
to the FMCSRs) be exempt from a requirement to be retrofitted with
ABAs? Should these specific types of air-braked CMVs manufactured on or
after October 20, 1994, be required to be equipped with ABAs prior to
being placed in operation in interstate commerce? Please provide
details.
7. What are the costs associated with retrofitting an ABA compared
to replacement of an MBA? Please include the cost of the device, the
time required to complete the installation, and a representative hourly
salary of the mechanic performing the installation. Please also include
a ``loss of use'' cost figure if a CMV were to be taken out of revenue
service for retrofitting at some time other than a time when a brake
adjuster would normally be due for replacement. How often do tractors
and trailers visit a facility where retrofitting could take place?
8. Should the FHWA consider a retrofitting requirement for
hydraulically-braked CMVs? Please address the cost questions asked in
Question 7.
The FHWA requests that commenters address the specific questions
above. However, the FHWA encourages commenters to include a discussion
of any other issues that the commenters believe are relevant to the use
and/or retrofitting of automatic brake adjusters and brake adjustment
indicators on CMVs.
Rulemaking Analyses and Notices
All comments received before the close of business on the comment
closing date indicated above will be considered and will be available
for examination in the docket at the above address. Comments received
after the comment closing date will be filed in the public docket and
will be considered to the extent practicable. In addition to late
comments, the FHWA will also continue to file, in the public docket,
relevant information that becomes available after the comment closing
date. Interested persons should continue to examine the public docket
for new material.
Executive Order 12866 (Regulatory Planning and Review) and DOT
Regulatory Policies and Procedures
The FHWA has determined that this action is not a significant
regulatory action within the meaning of Executive Order 12866 or
significant within the meaning of Department of Transportation
regulatory policies and procedures. This rule would, if adopted,
provide a companion operational standard for brakes in the FMCSRs to
make them consistent with the manufacturing standards in the FMVSSs 105
and 121. It would require automatic brake adjusters and brake
adjustment indicators installed on newly manufactured CMVs in
accordance with those manufacturing standards to be maintained by the
motor carriers operating those vehicles. Based on the NHTSA studies,
the FHWA believes that operation and maintenance costs of the automatic
brake adjusters and adjustment indicators required under the new FMVSSs
will be lower than costs of the devices previously required. Although
the FHWA requests information concerning the possibility of requiring
these devices to be retrofitted to CMVs placed in operation prior to
the effective dates of FMVSSs 105 and 121, no rule to require such
retrofitting is being proposed at this time. It is anticipated that the
economic impact of this rulemaking will be minimal; therefore, a full
regulatory evaluation is not required. If the FHWA proposes
retrofitting of these devices at some future date, a regulatory
evaluation of the effects of that action will be prepared at that time.
Regulatory Flexibility Act
In compliance with the Regulatory Flexibility Act (5 U.S.C. 601-
612), the FHWA has evaluated the effects of this proposed rule on small
entities. This rule would modify the operational standards for brakes
in the Federal Motor Carrier Safety Regulations (FMCSRs) to make them
consistent with the manufacturing standards in the Federal Motor
Vehicle Safety Standards (FMVSSs) numbers 105 and 121, which now
require the installation of automatic brake adjusters and adjustment
indicators on certain newly-manufactured CMVs. As stated above, the
FHWA believes that operation and maintenance costs of the automatic
brake adjusters and adjustment indicators required under the new FMVSSs
will be lower than costs of the devices previously required. Therefore,
the FHWA hereby certifies that this action would not have a significant
economic impact on a substantial number of small entities.
Executive Order 12612 (Federalism Assessment)
This action has been analyzed in accordance with the principles and
criteria contained in Executive Order 12612, and it has been determined
that this action does not have sufficient federalism implications to
warrant the preparation of a federalism assessment.
Paperwork Reduction Act
This action does not contain a collection of information
requirement for purposes of the Paperwork Reduction Act of 1980, 44
U.S.C. 3501 et seq.
National Environmental Policy Act
The agency has analyzed this action for the purpose of the National
Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.) and has
determined that this action would not have any effect on the quality of
the environment.
Executive Order 12372 (Intergovernmental Review)
Catalog of Federal Domestic Assistance Program Number 20.217, Motor
Carrier Safety. The regulations implementing Executive Order 12372
regarding intergovernmental consultation on Federal programs and
activities apply to this program.
Regulation Identification Number
A regulation identification number (RIN) is assigned to each
regulatory action listed in the Unified Agenda of Federal Regulations.
The Regulatory Information Service Center publishes the Unified Agenda
in April and October of each year. The RIN in the heading of this
document can be used to cross reference this action with the Unified
Agenda.
List of Subjects in 49 CFR Part 393
Freight Transportation, Highway safety, Highways and roads, Motor
carriers, and Motor vehicle safety.
In consideration of the foregoing, the FHWA is proposing to amend
title 49, Code of Federal Regulations, part 393, as follows:
PART 393--[AMENDED]
1. The authority citation for part 393 continues to read as
follows:
Authority: Section 1041(b) of Pub. L. 102-240, 105 Stat. 1914,
1993 (1991); 49 U.S.C. 3102; 49 U.S.C. app. 2505; 49 CFR 1.48.
2. In Subpart C, Sec. 393.53 is added to read as follows:
Sec. 393.53 Automatic brake adjusters and brake adjustment indicators.
(a) Automatic brake adjusters (hydraulic brake systems). Each
commercial motor vehicle manufactured on or after October 20, 1993, and
equipped with a hydraulic brake system, shall be equipped with an
automatic brake adjustment system that meets the requirements of
Federal Motor Vehicle Safety Standard No. 105 (49 CFR 571.105, S5.1) of
this title) applicable to the vehicle at the time it was manufactured.
(b) Automatic brake adjusters (air brake systems). Each commercial
motor vehicle manufactured on or after October 20, 1994, and equipped
with an air brake system, shall be equipped with an automatic brake
adjustment system that meets the requirements of Federal Motor Vehicle
Safety Standard No. 121 (49 CFR 571.121, S.5.1.8) applicable to the
vehicle at the time it was manufactured.
(c) Brake adjustment indicator (air brake systems). On each
commercial motor vehicle manufactured on or after October 20, 1994, and
equipped with an air brake system which contains an external automatic
adjustment mechanism and an exposed pushrod, the condition of service
brake under-adjustment shall be displayed by a brake adjustment
indicator conforming to the requirements of Federal Motor Vehicle
Safety Standard No. 121 (49 CFR 571.121, S5.1.8) applicable to the
vehicle at the time it was manufactured.
Issued on: July 28, 1994.
Rodney E. Slater,
Federal Highway Administrator.
[FR Doc. 94-18901 Filed 8-2-94; 8:45 am]
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