[Federal Register Volume 61, Number 231 (Friday, November 29, 1996)]
[Rules and Regulations]
[Pages 60635-60636]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-30055]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 571
[Docket No. 90-3; Notice 7]
RIN 2127-AF63
Federal Motor Vehicle Safety Standards; Air Brake Systems; Air
Compressor Cut-In
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Final rule, petitions for reconsideration.
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SUMMARY: In response to a petition for reconsideration submitted by
Flxible Corporation, this document amends Standard No. 121, Air Brake
Systems, with respect to the air pressure at which a bus's air
compressor must automatically activate. A bus manufacturer will be
allowed to set the air compressor governor cut-in pressure at 85 psi or
greater. The agency believes that allowing the air pressure to fall to
85 psi or greater, instead of 100 psi or greater, before the air
compressor is required to cut in, provides a more appropriate
activation pressure that accounts for the severe duty cycle experienced
by some buses. By reducing the frequency of compressor operation, this
modification will reduce potential safety problems caused by the air
compressor introducing engine oil into the vehicle's air system.
DATES: Effective date. The amendment becomes effective January 28,
1997.
Compliance date. Compliance with the amendment will be required on
and after March 1, 1997.
Petitions for reconsideration. Any petitions for reconsideration of
this rule must be received by NHTSA no later than January 13, 1997.
ADDRESSES: Petitions for reconsideration of this rule should refer to
the above referenced docket numbers and should be submitted to:
Administrator, National Highway Traffic Safety Administration, 400
Seventh Street, S.W., Washington, D.C. 20590.
FOR FURTHER INFORMATION CONTACT:
For non-legal issues: Mr. Richard Carter, Office of Crash
Avoidance, National Highway Traffic Safety Administration, 400 Seventh
Street, SW., Washington, D.C. 20590 (202) 366-5274.
For legal issues: Mr. Marvin L. Shaw, NCC-20, Rulemaking Division,
Office of Chief Counsel, National Highway Traffic Safety
Administration, 400 Seventh Street, SW., Washington, D.C. 20590 (202-
366-2992).
SUPPLEMENTARY INFORMATION:
I. Background
Standard No. 121, Air Brake Systems, specifies performance and
equipment requirements for braking systems on vehicles equipped with
air brakes, including a requirement specifying the minimum air pressure
at which a vehicle's air compressor governor must automatically
activate the compressor, thereby increasing air pressure in the air
brake system. (See S5.1.1.1) The governor maintains reservoir air
pressure between predetermined minimum and maximum pressures.
II. February 1996 Final Rule
In response to a petition for rulemaking submitted by the Truck
Trailer Manufacturers Association (TTMA), NHTSA amended S5.1.1.1 to
require the automatic activation of the air compressor on a powered
vehicle whenever the pressure in the air brake system falls below 100
pounds per square inch (psi) (61 FR 6173, February 16, 1996). Prior to
the February 1996 final rule, the air compressor was required to
automatically activate whenever the air pressure in the reservoir fell
below 85 psi. Manufacturers of air braked vehicles are required to
comply with this amendment on and after March 1, 1997.
Enhanced truck tractor performance is the primary goal of the
February 1996 amendment, which ensures that new air braked truck
tractors are capable both of providing trailers with sufficient
pressure for release of the trailer parking brakes and of providing
adequate service braking. By raising the cut-in pressure, an additional
quantity of stored compressed air will be available for an air brake
system. In addition, requiring an overall higher system air pressure
will allow a better balance between protection valve settings between
the tractors and trailers.
Because NHTSA determined that the change in compressor cut-in
pressure will benefit single-unit trucks and buses as well as truck
tractors, the agency applied the change to all powered vehicles. A
higher cut-in pressure provides a margin of safety for vehicles
equipped with long-stroke chambers and antilock brake systems which
consume more air than conventional brake systems. NHTSA anticipated no
safety problems as the result of the February 1996 amendment. The
agency further anticipated that the amendment would not result in an
undue burden for manufacturers, since most vehicles already complied
with the cut-in requirement.
III. Petition for Reconsideration
On March 4, 1996, Flxible Corporation (Flxible), a manufacturer of
air-braked transit buses, petitioned NHTSA to amend the air compressor
cut-in requirements in Standard No. 121 with respect to buses. It
stated that while the amended requirements were appropriate for truck
tractors, the automatic cut-in pressure requirements should not have
been raised from 85 psi to 100 psi for city transit buses. The
petitioner stated that the air brakes on buses do not experience the
same conditions as those on tractors. Therefore, it stated that the
rule should not be applied to vehicles other than truck tractors,
without a full understanding of the potential problems and consequences
associated with that decision.
Flxible stated that transit buses have a unique duty cycle that
requires more frequent brake applications than other vehicles. It
further stated that the air brake systems on transit buses are
connected to unique air consuming devices and systems that almost
continuously consume air. These devices and systems include air
operated door systems, air operated kneeling systems, air consuming
brake interlocks, and air throttles on mechanical engines.
Flxible stated that higher governor cut-in pressures result in
higher compressor pumping pressures. Frequent air depletion by the
various on-vehicle devices causes the compressor to operate on an
almost continuous duty cycle. This severe duty cycle, combined with the
new higher pumping pressures, causes the air compressor to introduce
greater quantities of engine oil into the vehicle's air system, because
the air compressors must run a substantially
[[Page 60636]]
longer period of time. This condition occurs even on newer mileage
vehicles, and worsens with vehicle and component age. According to the
petitioner, oil carry-over can affect elastomeric seals, diaphragms and
other items in the vehicle air system. Such contamination may cause
components to stick or otherwise function in a manner that may
adversely affect brake timing. The result is costly system maintenance
and repair at more frequent than normally recommended service periods.
Flxible requested that the governor cut-in pressure setting be set
at 85 psi. Flxible stated that although it uses governors with higher
cut-in and cut-out pressures to meet specific vehicle in-service
conditions and requirements, it would like the option to use lower cut-
in pressures.
IV. Agency Determination
After reviewing Flxibles petition, NHTSA has decided to amend
Standard No. 121 with respect to the air pressure at which a bus's air
compressor must automatically activate. A bus manufacturer is allowed
to set the air compressor governor cut-in pressure at 85 psi or
greater. The agency believes that reducing the required automatic cut-
in pressure from 100 psi or greater to 85 psi or greater provides buses
with a more appropriate activation pressure that accounts for the
severe duty cycle experienced by some buses. This modification will
avoid potential safety problems caused by the air compressor
introducing engine oil into the vehicle's air system.
NHTSA believes that today's modification in the cut-in pressure
will not adversely affect the use of long-stroke brake chambers. After
reviewing the issue of air pressure depletion starting at 85 psi, 100
psi, and higher levels, the agency concludes that changing the
requirements to 85 psi will not interfere with the safe introduction of
long-stroke chambers.1 Therefore, the rationale for raising the
minimum cut-in pressure for single unit vehicles, i.e., to facilitate
the introduction of long-stroke chambers, is not undermined.
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\1\ Those data have been placed in the public docket.
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NHTSA anticipates that the practical affect of today's amendment
will be limited, because most air compressor governor settings are
preset by the air compressor manufacturers and not by the vehicle
manufacturers. NHTSA estimates that over 95 percent of air compressor
governors are set at 100 psi or greater. Flxible stated that it would
readjust only those units where it was determined to be necessary.
Accordingly, as a practical matter, in only a few special situations
will the air compressor cut-in pressure actually be activated at 85
psi.
V. Rulemaking Analyses and Notices
1. Executive Order 12866 (Federal Regulatory Planning and Review) and
DOT Regulatory Policies and Procedures
This rulemaking was not reviewed under E.O. 12866. NHTSA has
analyzed this rulemaking and determined that it is not ``significant''
within the meaning of the Department of Transportation's regulatory
policies and procedures. A full regulatory evaluation is not required
because the rule will have a minimal effect on the costs or performance
of the existing air brake systems. Today's amendment merely affords
greater flexibility to manufacturers of air-braked buses.
2. Regulatory Flexibility Act
In accordance with the Regulatory Flexibility Act, NHTSA evaluated
the effects of this action on small entities as part of the February
1996 final rule. Based upon that evaluation which remains valid, I
certify that the amendment will not have a significant economic impact
on a substantial number of small entities. Vehicle and brake
manufacturers typically do not qualify as small entities. Vehicle
manufacturers, small businesses, small organizations, and small
governmental units which purchase motor vehicles will not be
significantly affected by the requirements since the cost of new
vehicles will not change. Accordingly, no regulatory flexibility
analysis has been prepared.
3. Executive Order 12612 (Federalism)
This action has been analyzed in accordance with the principles and
criteria contained in Executive Order 12612, and it has been determined
that the rule will not have sufficient Federalism implications to
warrant preparation of a Federalism Assessment. No State laws will be
affected.
4. National Environmental Policy Act
Finally, the agency has considered the environmental implications
of this rule in accordance with the National Environmental Policy Act
of 1969 and determined that the rule will not significantly affect the
human environment.
5. Civil Justice Reform
This rule will not have any retroactive effect. Under section
103(d) of the National Traffic and Motor Vehicle Safety Act (49 U.S.C.
30111), 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. Section 105 of the Act (49 U.S.C. 30161) sets forth a
procedure for judicial review of final rules establishing, amending or
revoking Federal motor vehicle safety standards. That section does not
require submission of a petition for reconsideration or other
administrative proceedings before parties may file suit in court.
List of Subjects in 49 CFR Part 571
Imports, Motor vehicle safety, Motor vehicles, Rubber and rubber
products, Tires.
In consideration of the foregoing, the agency is amending Standard
No. 121, Air Brake Systems, in part 571 of title 49 of the Code of
Federal Regulations as follows:
PART 571--[AMENDED]
1. The authority citation for Part 571 continues to read as
follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166;
delegation of authority at 49 CFR 1.50
2. In Sec. 571.121, S5.1.1.1 is revised to read as follows:
Sec. 571.121 Standard No. 121; Air brake systems.
* * * * *
S5.1.1.1 Air compressor cut-in pressure. The air compressor
governor cut-in pressure for each bus shall be 85 p.s.i. or greater.
The air compressor governor cut-in pressure for each truck shall be 100
p.s.i. or greater.
* * * * *
Issued on: November 19, 1996.
Ricardo Martinez,
Administrator.
[FR Doc. 96-30055 Filed 11-27-96; 8:45 am]
BILLING CODE 4910-59-P