[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