Source: http://fmcsa.dot.gov/rules-regulations/administration/rulemakings/Proposed/Brake-Readjustment-Limits%20-NPRM.aspx
Timestamp: 2014-03-08 13:10:21
Document Index: 95868918

Matched Legal Cases: ['art 393', 'art\n393', 'art 571', 'art 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 31502', 'art 393', '§ 31136', '§ 31136', '§ 31136', '§ 31136', '§ 31136', '§ 31136', '§ 31136', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393', '§ 393']

Parts and Accessories Necessary for Safe Operation: Brakes;
Home > Rules & Regulations > Parts and Accessories Necessary for Safe Operation: Brakes;
Print [Federal Register Volume 76, Number 171 (Friday, September 2, 2011)]
[Pages 54721-54727]
[FR Doc No: 2011-22478]
DEPARTMENT OF TRANSPORTATIONFederal Motor Carrier Safety Administration 49 CFR Chapter III
[Docket No. FMCSA-2010-0257]
proposes to revise the requirements
regarding clamp and rotochamber brake
actuator readjustment limits in the
Regulations (FMCSRs). The purpose of
(NPRM) is to amend the readjustment
limits, clarify their application, and
correct an error in cross-referencing a
(FMVSS). This proposal responds to a
petition for rulemaking from the
(CVSA).
DATES: Send your comments on or
before November 1, 2011.
identified by Docket ID Number
FMCSA-2010-0257 by any of the
Federal eRulemaking Portal: http://www.regulations.gov. Follow the online
Mail: Docket Management Facility:
New Jersey Avenue, SE., West Building,
Ground Floor, Room W12-140,
Hand Delivery or Courier: West
Building, Ground Floor, Room W12-
140, 1200 New Jersey Avenue, SE.,
between 9 a.m. and 5 p.m. ET, Monday
Deborah M. Freund, Vehicle and
Roadside Operations Division, Office of
Operations (MC-PSV), Federal Motor
Carrier Safety Administration, 1200
deborah.freund@dot.gov; telephone
(202) 366-5370.
Submitting CommentsViewing Comments and DocumentsPrivacy ActAbbreviationsLegal Basis for the RulemakingBackgroundCVSA's PetitionAgency AnalysisDiscussion of the Proposed RuleRegulatory Analyses
rulemaking (FMCSA-2010-0257),
so that FMCSA can contact you if there
are questions regarding your
the "Submit a Comment" box, which
will then become highlighted in blue. In
the "Document Type" drop-down
menu, select "Proposed Rules," insert
"FMCSA-2010-0257" in the
"Keyword" box, and click "Search." When the new screen appears, click on
"Submit a Comment" in the "Actions"
column. If you submit your comments
by mail or hand delivery, submit them
in an unbound format, no larger than
81⁄2 by 11 inches, suitable for copying
and electronic filing. If you submit
comments by mail and would like to
documents mentioned in this preamble,
available in the docket, go to http://www.regulations.gov and click on the
"Read Comments" box in the upper
right-hand side of the screen. Then, in
the "Keyword" box insert "FMCSA-
2010-0257" and click "Search." Next,
click the "Open Docket Folder" in the
W12-140 on the ground floor of the
Department of Transportation West
and 5 p.m. ET, Monday through Friday,
FMVSSs Federal Motor Vehicle Safety
OOS out of service.
SAE Society of Automotive Engineers.III. Legal Basis for the Rulemaking
Appendix G, Minimum Periodic
Inspection Standards, was added to the
FMCSRs in 1988 (53 FR 49411, Dec. 7,
1988). Under the inspection standards
of Appendix G, all items required to be
inspected must be in proper adjustment,
must not be defective, and must
function properly before a commercial
motor vehicle (CMV) is placed in
service. Appendix G includes, among
many other things, brake adjustment
(readjustment) limits. Paragraph 1.a.(5)
of this appendix currently reads:
Readjustment limits. The maximum stroke
at which brakes should be readjusted is given
below. Any brake 1/4" or more past the
readjustment limit or any two brakes less
than 1/4" beyond the readjustment limit shall
be cause for rejection. Stroke shall be
measured with engine off and reservoir
pressure of 80 to 90 psi with brakes fully
The figures in the rightmost column
of each of the three tables following
paragraph 1.a.(5) indicate the maximum
stroke at which brakes should be
Subsequently, in June 1991, the
developed International Recommended
Practice J1817 (SAE J1817) to provide a
marking system that distinguishes longstroke
from standard-stroke air brake
actuators, rotochambers, and their
components. It defines "rated stroke" as
the minimum design stroke of a brake
The 2001 revision of SAE J1817
includes tables listing recommended
values for minimum rated stroke and
maximum readjustment stroke for clamp
band/sealed design standard-stroke
brake actuators (Table 1A), clamp band/
sealed design long-stroke brake
actuators (Table 1B), and rotochamber
designs (Table 1C). Table 1B is further
broken down to include three classes of
long-stroke actuators. The classes are
defined according to the range of
difference between the maximum
readjustment stroke and the standard
rated stroke. In most but not all cases,
the maximum readjustment stroke is 80
percent of the minimum rated stroke.
The differences are greatest for the
smaller sizes of brake chambers.
In 1997, the Federal Highway
Administration (FHWA), FMCSA's
predecessor agency within the U.S.
published in the Federal Register an
NPRM titled "Parts and Accessories
Necessary for Safe Operation; General
Amendments" (62 FR 18169, Apr. 14,
1997). This NPRM proposed to amend
49 CFR part 393 by removing obsolete and redundant regulations; responding
to several petitions for rulemaking;
providing improved definitions of
vehicle types, systems, and components;
resolving inconsistencies between part
393 and 49 CFR part 571 (FMVSSs); and
codifying certain regulatory guidance
regarding the requirements of part 393.
Generally, the amendments did not
establish new or more stringent
requirements but clarified existing
As part of that NPRM, FHWA
proposed to add a new § 393.47(e) to the
FMCSRs to specify the maximum
permissible stroke for different types
(sizes) of brake chambers and
incorporate by reference SAE J1817,
(June 1991). The NPRM proposed to
require that the maximum values for
pushrod travel for clamp- and
rotochamber-type actuators must be less
than 80 percent of the rated strokes
listed in SAE J1817, or 80 percent of the
rated stroke marked on the brake
chamber by the chamber manufacturer,
or the readjustment limit marked on the
brake chamber by the chamber
manufacturer. For types 16 and 20 longstroke
clamp-type brake actuators, the
NPRM proposed that the pushrod travel
must be less than 51 mm (2 in.), or 80
percent of the rated stroke marked on
the brake chamber by the chamber
manufacturer, or the readjustment limit
marked on the brake chamber by the
chamber manufacturer. The NPRM did
not propose to revise the Appendix G
brake readjustment-limits tables.
FMCSA published the final rule on
August 15, 2005 (70 FR 48007). The
Agency revised § 393.47(e) as proposed,
except that it incorporated by reference
the July 2001 revision of SAE J1817
rather than the June 1991 edition. The
preamble to the final rule did not
indicate whether the Agency received
comments on the decision to
incorporate the July 2001 revision.
On April 16, 2007, CVSA petitioned
the Agency to revise § 393.47(e). CVSA
stated that, although the readjustment
(or brake actuator stroke) limits of SAE
J1817 are consistent with those listed in
Appendix G and CVSA's North
American Standard Out-of-Service
(OOS) Criteria, § 393.47(e) "specifies
readjustment (stroke) limits based on 80
percent of the rated (full) strokes listed
in SAE J1817." Relying on this criterion
introduces discrepancies between
§ 393.47(e) and SAE J1817. Although the
readjustment limits listed in SAE J1817
agree with those in Appendix G and the
OOS Criteria, they differ, for some brake
chambers, from the "80 percent of rated stroke" specified in § 393.47(e).
Consequently, "[t]he enforcement and/
or noting of § 393.47(e) violations by
cross-referencing the regulation to 80%
of SAE J1817—Long Stroke Air-Brake
Actuator Marking, July, 2001 is proving
problematic for inspectors and
CVSA also pointed out that
§ 393.47(e) considers a brake with the
stroke at the readjustment limit to be
out of adjustment. In contrast, both
Appendix G and the OOS Criteria state
that the brake travel must exceed the
readjustment limit for the brake to be
considered out of adjustment. The
petitioners added that the values in both
Appendix G and the OOS Criteria were
established consistent with brake
Although the CVSA subsequently
updated the OOS Criteria to include
several types of long-stroke clamp-type
brake chambers, FMCSA has not
similarly revised the Appendix G
In addition, CVSA requested that
FMCSA revise § 393.53, Automatic
brake adjusters and brake adjustment
indicators, to include references to the
FMVSSs applicable to trailers. Sections
393.53(b) and (c) would be revised so
that the FMVSS citations read, "49 CFR
571.121, S5.1.8 or S5.2.2."
On June 10, 2008, CVSA amended its
April 2007 petition to correct the text of
the table subheadings for clamp-type
and rotochamber-type chamber data in
the original petition and to add tables
for Bendix DD-3 and bolt-type brake
chamber data. The amended petition
changed the table subheadings "Brake
Chamber Pushrod Stroke Limit" and
"RC Actuate Pushrod Stroke Limit" to
read "Brake Adjustment Limit" and
"Rotochamber Type Brake Chamber
Data," respectively.
FMCSA has placed copies of CVSA's
2007 petition and 2008 correction in the
V. CVSA's Petition
This NPRM is based on the authority
of the Motor Carrier Act of 1935 (1935
Act) and the Motor Carrier Safety Act of
1984 (the 1984 Act), both of which
provide broad discretion to the
in implementing their provisions.
The 1935 Act provides that the
Secretary may prescribe requirements
for (1) Qualifications and maximum
hours of service of employees of, and
safety of operation and equipment of, a
motor carrier [49 U.S.C. 31502(b)(1)],
and (2) qualifications and maximum
standards of equipment of, a motor
private carrier, when needed to promote safety of operation [§ 31502(b)(2)]. The
2005 final rule amending part 393 of the
FMCSRs (Parts and Accessories
Necessary for Safe Operation, 70 FR
48007, Aug. 15, 2005) and these
proposed amendments are based on the
Secretary's authority to regulate the
safety and standards of equipment of
for-hire and private carriers.
The 1984 Act gives the Secretary
concurrent authority to regulate drivers,
motor carriers, and vehicle equipment.
Codified in 49 U.S.C. 31136(a), section
206(a) of the Act requires the Secretary
to publish regulations on commercial
motor vehicle (CMV) safety.
Specifically, the Act sets forth minimum
safety standards to ensure that (1) CMVs
operated safely [§ 31136(a)(1)]; (2) the
responsibilities imposed on operators of
CMVs do not impair their ability to
operate the vehicles safely
[§ 31136(a)(2)]; (3) the physical
safely * * * [§ 31136(a)(3)]; and (4) the
operation of CMVs does not have a
condition of the operators
[§ 31136(a)(4)].
improved guidance concerning CMV
brake adjustment limits. The proposed
maximum pushrod travel for brake
actuators would enhance the braking
performance of the vehicle, consistent
with § 31136(a)(1). The rule does not
address the responsibilities or physical
condition of drivers addressed by
§ 31136(a)(2) and (3), respectively, and
deals with § 31136(a)(4) only to the
extent that a safer vehicle is less likely
to have a deleterious effect on the
physical condition of a driver. Before
prescribing any such regulations,
however, FMCSA must consider the
"costs and benefits" of any proposal (49
U.S.C. 31136(c)(2)(A) and 31502(d)).
VI. Agency Analysis
SAE J1817, "Long-Stroke Air-Brake
Actuator Marking," describes a marking
system to distinguish long-stroke from
standard-stroke air brake actuators,
rotochambers, and components. Longstroke
air brake actuators are designed
to provide longer pushrod stroke
capabilities than standard-stroke
actuators. Because some of these
chambers are nearly identical in exterior
appearance to the standard chambers, a
unique marking system is needed for the
purpose of identification by mechanics,
inspectors, and others in the field. This
marking helps ensure that both types of
actuators are serviced correctly and
brakes are adjusted properly. This is
important because long-stroke actuator components from different actuator
manufacturers are not interchangeable,
nor are they interchangeable with
standard actuator components.
In addition to providing discrete
marking requirements for differentiating
long-stroke from standard-stroke
actuators, SAE J1817 includes tables
that specify the rated stroke and the
maximum readjustment stroke for
various types of air brake actuators.
Tables 1A and 1B provide data for
standard-stroke and long-stroke clamptype
brake chambers, respectively, and
Table 1C provides data for rotochamber
Section 393.47(e) of the FMCSRs, as
amended in the August 2005 final rule,
outlines three options for determining
brake actuator readjustment limits for
clamp- and rotochamber-type actuators.
The pushrod travel for these actuators
Less than 80 percent of the rated
stroke listed in Tables 1A, 1B, or 1C of
SAE J1817; orLess than 80 percent of the rated
stroke marked on the brake chamber by
its manufacturer; orLess than the readjustment limit
marked on the chamber by the chamber
As CVSA's petition notes, while
§ 393.47(e) specifies that readjustment
(stroke) limits may be based on 80
in SAE J1817, relying on this criterion
may introduce discrepancies between
§ 393.47(e) and SAE J1817. Although in
some cases, the readjustment limits
listed in SAE J1817 are 80 percent of the
rated stroke for a given actuator,
deviations exist. Where the
readjustment limit listed in SAE J1817
for a given actuator differs from a value
equal to 80 percent of the rated stroke,
the difference generally is small. In
some cases, however, the deviations can
be considered more significant (i.e.,
close to, or greater than, 1⁄8 inch).1 The
differences vary according to the type
(size) of brake chamber. Using the "80
percent of rated stroke" criterion in
§ 393.47(e) may produce a value that is
either more stringent or less stringent
than the value specified in SAE J1817.
The differences, however, are only a
CVSA recommends incorporation of a
set of tables into § 393.47(e)—similar to
the tables that already exist in (a) SAE
J1817, (b) the CVSA OOS Criteria, and
(c) Appendix G to the FMCSRs—that, if
included, would eliminate the
discrepancies resulting from application
of the "80 percent" criterion currently permitted under § 393.47(e) as
discussed above. Inclusion of these
tables would eliminate confusion in the
enforcement community and the
industry by providing explicit values for
the actuator readjustment limits.
In reviewing the tables in SAE J1817,
FMCSA confirmed that the specified
readjustment limits for certain actuators
are not equal to 80 percent of the
corresponding rated stroke for those
actuators.2 For example, the
readjustment limit for a T-30-L3
chamber (common on new trucks) is
listed at 2.5 inches in SAE J1817 and the
CVSA OOS Criteria (Appendix G has
not been updated to include long-stroke
chambers), yet under the requirements
of § 393.47(e), 80 percent of its rated
stroke of 3.0 inches (as provided in SAE
J1817) is 2.4 inches, a difference of
slightly less than an eighth of an inch.
In another example, for a standard T-36
chamber (common on transit buses),
SAE J1817, the CVSA OOS Criteria, and
Appendix G all list the readjustment
limit as 2.25 inches—but under the
requirements of § 393.47(e), 80 percent
of the rated stroke of 3.0 inches (as
provided in SAE J1817) is 2.4 inches, a
difference of slightly more than an
eighth of an inch. In the first example,
the § 393.47(e) criterion is more
stringent; in the second it is less
stringent. But in both cases the
differences are only a small fraction of
Even though the discrepancies are
minimal, they are confusing to the
industry. Accordingly, for the reasons
discussed above, FMCSA proposes to
amend § 393.47(e) as recommended by
FMCSA does not, however, agree with
CVSA's recommendation to limit out-ofadjustment
findings to cases where the
brake travel exceeds the readjustment
limit. An s-cam brake that is at the
readjustment limit when it is cold will
be beyond the readjustment limit when
it gets hot. FMCSA believes that
vehicles should not be dispatched with
brakes at the readjustment limit,
because those brakes will be found to be
beyond the adjustment limit—and out of
compliance with the regulations—if
evaluated during a roadside inspection
after the brakes have become hot due to
operational use. Based on these
characteristics of s-cam brakes, the
August 2005 final rule included a
provision in § 393.47(e) that requires brake stroke to be "less than" the
readjustment limit(s), as opposed to the
Appendix G provision under which
brakes "at" the adjustment limit are in
compliance with the FMCSRs. This
difference reflects roadside inspection
tolerances. Roadside inspectors
typically refrain from citing a brake
adjustment violation until the brake is
beyond the adjustment limit. Further,
under the 20 percent rule for brake
violations in the OOS Criteria, roadside
inspectors do not remove a CMV from
service unless 20 percent of the
vehicle's brakes are out of adjustment.
The Agency believes, however, that it is
appropriate to require motor carriers to
take action under the requirements of
§ 393.47 when a brake is at the
adjustment limit. This position is
consistent with findings from a 1995
study concerning the accuracy with
which brake adjustment can be
measured 3 performed by the University
Institute for FHWA's Office of Motor
Carrier Safety. To avoid confusion in the
industry, this NPRM proposes to amend
Appendix G to make its requirements
consistent with those of § 393.47(e)
adopted in the August 2005 rule.
VII. Discussion of the Proposed Rule
This NPRM proposes to revise and
expand the readjustment-limits tables as
recommended by CVSA, and includes
these revised tables in § 393.47(e) and
Appendix G. The revised tables cover
readjustment limits not only for
clamp-, bolt-, and rotochamber-type
brake chambers but also for Bendix DD-
3 chambers. The table for clamp-type
brake chambers also differentiates
between adjustment limits for more
sizes of standard-stroke and long-stroke
The NPRM also proposes to eliminate
the cross-reference to SAE J1817 in
§ 393.47(e). Inclusion of the new tables
in § 393.47(e) would provide explicit
readjustment limits for each type of
actuator, eliminating the need for the
FMCSA notes that the SAE Truck and
Bus Brake Actuator Committee has
initiated work on a new SAE
Recommended Practice, J2899, which
would describe the physical
characteristics of air brake actuators that
allow the correct brake readjustment
limits to be determined. The new
recommended practice would also
define the maximum readjustment limits based on the rated stroke and type
(size) of the chamber. The committee
voted to develop this new Jspecification
to identify maximum
readjustment limits independently of
SAE J1817 and focus the latter on
actuator long-stroke marking
requirements. As the committee noted,
limiting SAE J1817 to the topic defined
within its scope will facilitate
maintenance of the standard. This
project was initiated in May 2009, and
it is not known when the new
recommended practice will be
The proposed rule would adopt
CVSA's suggestion to replace the
heading "Maximum stroke at which
brakes should be readjusted" with the
term "Brake Adjustment Limit." The
proposed wording is more concise and
As discussed in the Agency Analysis
section, FMCSA proposes changes to
paragraph 1.a.(5) of Appendix G, "Brake
System, Service Brakes," to be
consistent with the § 393.47(e)
requirement that pushrod travel be less
than the values specified in the
accompanying tables. For actuator types
not listed in these tables, the pushrod
stroke must be less than 80 percent of
the rated stroke marked on the actuator
by the actuator manufacturer, or less
than the readjustment limit marked on
the actuator by the actuator
Lastly, the Agency would revise
§ 393.53 in response to CVSA's request.
Although the introductory text of each
paragraph clearly states that it is
applicable to "each commercial motor
vehicle," § 393.53(b) and (c) omit a
cross-reference to the FMVSSs
applicable to trailers (S.5.2.2). The
proposed rule adds this cross-reference
to eliminate potential confusion.
Planning and Review) and DOT
by Executive Order 13563, and does not
Order. FMCSA expects the economic
impact of this NPRM to be minimal. The
proposal affects the conditions under
which motor carriers are cited for outof-
adjustment brakes during roadside
inspections and CMVs are placed OOS
for such violations. Each brake
adjustment violation cited during a
roadside inspection must be addressed by the carrier, and each OOS order
results in time lost for the carrier and
driver because the vehicle may not be
operated until the OOS defects have
been corrected. Consequently, a
decrease in OOS orders can be
considered a benefit of these proposed
amendments to the readjustment limits,
while any increase in violations and
OOS orders would be a cost. With
respect to the safety impact of OOS
orders for brake adjustment violations,
more such orders on vehicles with
defects may produce a safety benefit by
reducing crashes. Neither the petitioners
nor the Agency, however, are able to
estimate whether the number of brakeadjustment
violations resulting from
this proposal would increase or
decrease by a significant amount. It
should be noted, however, that FMCSA
requires motor carriers to maintain their
vehicles in safe and proper operating
condition at all times and to have a
systematic inspection, repair, and
maintenance program to avoid
dispatching CMVs with safety defects
and deficiencies (see, e.g., 49 CFR
396.3(a)(1) and 398.7). Therefore, the
potential costs of this NPRM relate only
to carrying out the maintenance task
(e.g., readjusting the brakes or replacing
an inoperable slack adjuster) at the
inspection location rather than at one of
the carrier's usual maintenance
From 2000 to 2009, the annual
number of Level I and Level V roadside
inspections of CMVs—the only
inspection levels that include brake
stroke measurement—ranged from about
0.94 to 1.25 million, and the percentage
of inspections resulting in the CMV
being placed OOS for brake violations of
all kinds ranged from a high of 17
percent to a low of 12.2 percent.
Roughly half of these violations
concerned out-of-adjustment brakes, but
the Agency believes that the changes in
this proposal would have relatively
little impact on this ratio. By proposing
to: (1) Remove from § 393.47(e) the
cross-reference to the readjustmentlimits
tables in SAE J1817 and the
than 80 percent of the rated stroke listed
in those tables, (2) incorporate into
§ 393.47(e) a set of tables (duplicating
those in Appendix G) providing explicit
readjustment limits, and (3) require that
pushrod travel be less than the values
specified in those tables, the NPRM
would eliminate certain discrepancies
between the brake adjustment values
derived using the "80 percent of rated
stroke" criterion under § 393.47(e) and
the values specified in the SAE J1817
tables. In addition, these changes would make § 393.47(e) consistent with
Appendix G, eliminating confusion in
the enforcement community and the
Although substituting the
readjustment-limits tables for the crossreference
to SAE J1817 in § 393.47(e)
would resolve discrepancies that the
cross-reference introduced, these
differences are in many cases quite
small. The differences vary according to
the type (size) of brake chamber. Using
the "80 percent of rated stroke"
criterion may produce a value that is
For these reasons, FMCSA anticipates
that certain brake adjustments that
comply with the current rule would be
out of compliance with the proposed
standard—while the reverse could just
as often be true. On the other hand, the
proposed Appendix G amendment
mirroring the proposed § 393.47(e)
readjustment-limits tables would have
no effect on the rate of OOS violations
for brake adjustment—because roadside
inspection procedures do not reference
the readjustment limits in Appendix G.
In summary, although FMCSA is
unable to estimate the net economic and
safety impacts of the changes proposed
in this NPRM, these impacts clearly
agencies to determine whether proposed
rules could have a significant economic
entities. FMCSA estimates that the
economic impact of this rule would be
minimal. Consequently, I certify that
this proposed action would not have a
and Tribal governments, in the
aggregate, or by the private sector, of
$141.3 million (which is the value of
This proposed action meets
applicable standards in sections 3(a)
and 3(b)(2) of Executive Order 12988,
Civil Justice Reform, to minimize litigation, eliminate ambiguity, and
Risks and Safety Risks. The Agency
analyzed this proposed action in
accordance with Executive Order 13132.
substantial direct effect on States, nor
would it limit the policymaking
rulemaking would preempt any State
proposed action does not have any
effect on the quality of the environment. Therefore, this NPRM is categorically
6(bb) relates to "regulations concerning
vehicle operation safety standards,"
such as the amended brake inspection
standards proposed in this rulemaking.
A Categorical Exclusion determination
is available for inspection or copying in
FMCSA also analyzed this proposal
under section 176(c) of the Clean Air
Act (CAA), as amended (42 U.S.C. 7401
et seq.), and implementing regulations
conformity requirement since it does not affect direct or indirect emissions of
FMCSA proposes to amend title 49,
Code of Federal Regulations, subchapter
B, chapter III, as follows:
2. In § 393.7, remove paragraph (b)(15)
and redesignate paragraphs (b)(16)
through (b)(22) as paragraphs (b)(15)
through (b)(21), respectively.
3. Amend § 393.47 by revising
§ 393.47 Brake actuators, slack adjusters,
linings/pads, and drums/rotors.
(e) Clamp, Bendix DD-3, bolt-type,
and rotochamber brake actuator
readjustment limits. The pushrod travel
for clamp- and rotochamber-type
actuators must be less than the values
specified in the following tables:
CLAMP-TYPE BRAKE CHAMBERSTypeOutside diameterBrake adjustment limit: Standard
stroke chamberBrake adjustment limit: Long
stroke chamber64 1⁄2 in. (114 mm)1 1⁄4 in. (32 mm).95 1⁄4 in. (133 mm)1 3⁄8 in. (35 mm).125 11⁄16 in. (145 mm)1 3⁄8 in. (35 mm)1 3⁄4 in. (45 mm)166 3⁄8 in. (162 mm)1 3⁄4 in. (45 mm)2 in. (51 mm)206 25⁄32 in. (172 mm)1 3⁄4 in. (45 mm)2 in. (51 mm)
2 1⁄2 in. (64 mm)*247 7⁄32 in. (184 mm)1 3⁄4 in. (45 mm)2 in. (51 mm)
2 1⁄2 in. (64 mm)**308 3⁄32 in. (206 mm)2 in. (51 mm)21⁄2 in. (64 mm)369 in. (229 mm)2 1⁄4 in. (57 mm).* For type 20 chambers with a 3-inch (76 mm) rated stroke.** For type 24 chambers with a 3-inch (76 mm) rated stroke.
BENDIX DD-3 BRAKE CHAMBERSType
308 1⁄8 in. (206 mm)2 1⁄4 in. (57 mm)BOLT-TYPE BRAKE CHAMBERSType
6 5⁄16 in. (176
1 3⁄8 in. (35 mm)B
9 3⁄16 in. (234
1 3⁄4 in. (45 mm)C
8 1⁄16 in. (205
1 3⁄4 in. (45 mm)D
5 1⁄4 in. (133 mm)
1 1⁄4 in. (32 mm)E
6 3⁄16 in. (157
1 3⁄8 in. (35 mm)F
2 1⁄4 in. (57 mm)G
9 7⁄8 in. (251 mm)
ROTOCHAMBER-TYPE BRAKE
4 9⁄32 in. (109
1 1⁄2 in. (38 mm)12
4 13⁄16 in. (122
1 1⁄2 in. (38 mm)16
5 13⁄32 in. (138
2 in. (51 mm)20
5 15⁄16 in. (151
2 in. (51 mm)24
6 13⁄32 in. (163
2 in. (51 mm)30
7 1⁄16 in. (180
2 1⁄4 in. (57 mm)36
7 5⁄8 in. (194 mm)
2 3⁄4 in. (70 mm)50
8 7⁄8 in. (226 mm)
For actuator types not listed in these
tables, the pushrod stroke must be less
than 80 percent of the rated stroke
marked on the actuator by the actuator
manufacturer, or less than the
readjustment limit marked on the
actuator by the actuator manufacturer.
4. Amend § 393.53 by revising
§ 393.53 Automatic brake adjusters and
brake adjustment indicators.
(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 must meet the
automatic brake adjustment system
Safety Standard No. 121 (49 CFR
571.121, S5.1.8 or S5.2.2) applicable to
the vehicle at the time it was
(c) Brake adjustment indicator (air
brake systems). On each commercial
motor vehicle manufactured on or after
air brake system which contains an
external automatic adjustment
mechanism and an exposed pushrod,
the condition of service brake underadjustment
must 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 or S5.2.2)
applicable to the vehicle at the time it
5. Amend Appendix G to Subchapter
B by revising paragraph (1)(a)(5) to read
Appendix G to Subchapter B of Chapter
III—Minimum Periodic Inspection
(5) Readjustment limits. The maximum
pushrod travel or stroke must be less than the values given in the tables below and at
§ 393.47(e). Any brake 1⁄4" or more past the
readjustment limit, or any two brakes less
than 1⁄4" past the readjustment limit, will be
rejected. Stroke must be measured with
engine off and reservoir pressure of 80 to 90
psi with brakes fully applied.
CLAMP-TYPE BRAKE CHAMBERSType
Brake adjustment limit: Standard
stroke chamber
Brake adjustment limit: Long
4 1/2 in. (114 mm)
1 1⁄4 in. (32 mm).9
1 3⁄8 in. (35 mm).12
5 11⁄16 in. (145 mm)
1 3⁄8 in. (35 mm)1 3⁄4 in. (45 mm)16
6 3⁄8 in. (162 mm)
1 3⁄4 in. (45 mm) 2 in. (51 mm)20
6 25⁄32 in. (172 mm)
1 3⁄4 in. (45 mm)2 in. (51 mm); 21⁄2 in. (64 mm) *24
7 7⁄32 in. (184 mm)
1 3⁄4 in. (45 mm)2 in. (51 mm); 21⁄2 in. (64 mm) **30
8 3⁄32 in. (206 mm)
2 in. (51 mm) 21⁄2 in. (64 mm)36
2 1⁄4 in. (57 mm).* For type 20 chambers with a 3-inch (76 mm) rated stroke.
** For type 24 chambers with a 3-inch (76 mm) rated stroke.
For actuator types not listed in these tables,
the pushrod stroke must be less than 80
percent of the rated stroke marked on the actuator by the actuator manufacturer, or less
than the readjustment limit marked on the
1 Brake stroke is measured in increments of 1⁄8
2 Whereas SAE J1817 provides values for (1) rated
stroke and (2) corresponding readjustment limits,
the CVSA OOS Criteria and Appendix G provide
only readjustment limits.
3 "Evaluation of Brake Adjustment Criteria for
Heavy Trucks," FHWA–MC–94–016, March 1995. A
copy of the report is in the docket referenced at the
[FR Doc. 2011-22478 Filed 9-1-11; 8:45 am]