Air Brake Systems; Denial of Petition for Rulemaking |
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Topics: Federal Motor Vehicle Safety Standards
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Stanley R. Scheiner
National Highway Traffic Safety Administration
20 July 1994
[Federal Register Volume 59, Number 138 (Wednesday, July 20, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17589]
[[Page Unknown]]
[Federal Register: July 20, 1994]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 552
Air Brake Systems; Denial of Petition for Rulemaking
AGENCY: National Highway Traffic Safety Administration, Transportation.
ACTION: Denial of petition for rulemaking.
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SUMMARY: This notice denies a petition for rulemaking, submitted by the
California Highway Patrol, that requests the agency to amend the air
pressure warning signal requirements in Federal Motor Vehicle Safety
Standard No. 121, Air Brake Systems. After conducting its review, the
agency has determined that the petition should not be granted because
the situation described by the petition does not raise a significant
safety problem. The agency further notes that establishing an upper
limit to the operating range of the low pressure warning signal would
not correct the problem of the signal's failure to warn a driver of low
pressure in the trailer brake system. Since there is no reasonable
possibility that the requested amendment would be issued at the
conclusion of a rulemaking proceeding, the agency is denying the
petition.
FOR FURTHER INFORMATION CONTACT: Mr. Chris Tinto, Office of Vehicle
Safety Standards, National Highway Traffic Safety Administration, 400
Seventh Street SW., Washington, DC 20590, (202) 366-5229.
SUPPLEMENTARY INFORMATION: Federal Motor Vehicle Safety Standard No.
121, Air Brake Systems, establishes performance requirements for
braking systems on vehicles equipped with air brakes. The purpose of
the standard is to ensure safe braking performance under normal and
emergency braking conditions.
The standard requires vehicles equipped with air brakes to have
certain equipment. Section S5.1.5 requires that each vehicle equipped
with an air brake system be equipped with a ``signal, other than a
pressure gage, that gives a continuous warning to a person in the
normal driving position when the ignition is in the ``on'' or ``run''
position and the air pressure in the service reservoir system is below
60 p.s.i.'' The purpose of this requirement is to inform the driver of
situations in which there may be low, potentially unsafe levels of air
pressure in the service brake system.
On June 7, 1993, the California Highway Patrol (CHP), submitted a
petition for rulemaking that requested the agency to amend the low air
pressure warning signal requirements in S5.1.5 of Standard No. 121. The
petitioner contended that:
this subsection permits a warning signal that is activated at any
pressure above 60 psi as long as it also produces the signal at
pressures below 60 psi. This would permit a device that activates a
warning in the normal operating range of the system, approximately
85-115 psi. This could result in a false signal where the driver
would not be warned of a true low air pressure situation. Though
unlikely, a warning device that was activated whenever the ignition
key was in the ``on'' or ``run'' position would comply with the
existing regulation, while fulfilling neither the intent of the
regulation nor any useful purpose.
Based on its concern, CHP requested that the agency initiate
rulemaking to specify an upper limit to the warning signal operating
range, so that it would give a ``true warning'' of a low air pressure
condition. CHP recommended that the upper cutoff be 75 p.s.i.
After reviewing the petition, NHTSA has decided not to establish an
upper limit to the low pressure warning signal requirement. The agency
disagrees with CHP's claims that establishing such an upper limit would
improve safety. The agency notes that under the current requirement,
some valves may activate at slightly higher air pressures than 60
p.s.i. since the valves are typically designed with a tolerance of
about 6 p.s.i. Nevertheless, activation at 65 p.s.i.
rather than 60 p.s.i. also indicates a relatively low pressure level
about which the driver should be concerned. The agency believes that
the modification requested by the petition is not warranted, since the
agency is aware of no safety problems related to this requirement which
has been in effect since 1971. The agency further notes that setting an
upper limit might unreasonably restrict the potential for designing new
air brake systems, since the valve manufacturers would be faced with
the unnecessary task of redesigning the valves, even though such a
modification would not provide any safety benefits.
Based on the above considerations, NHTSA has determined that CHP's
petition should not be granted. In accordance with 49 CFR Part 552, the
agency has completed its technical review of the petition and
determined that there is no reasonable possibility that the requested
amendment would be issued at the conclusion of a rulemaking proceeding.
Accordingly, the agency is denying the petition.
Notwithstanding NHTSA's decision to deny the petition, the agency
is reviewing the pressure setting requirements for the low pressure
warning switch in light of possible problems with a recent amendment to
Standard No. 121. On October 8, 1991, NHTSA issued a final rule that
eliminated the requirements for a separate protected reservoir capable
of releasing the parking brakes. (56 FR 50666) Among other things, that
amendment added a requirement for 70 p.s.i. supply line pressure
retention and established the air pressure at which automatic
application of the parking brakes would commence during loss of air
pressure.
In comments on a separate rulemaking on the parking brake
requirements applicable to air-applied, mechanically held systems (58
FR 13437, March 11, 1993), the American Trucking Associations (ATA) and
Allied Signal contended that the 70 p.s.i. requirement prevents tractor
low air pressure warning systems from warning drivers of the loss of
service air pressure and thus loss of service brakes on trailers.
Allied requested that the agency raise the governor cut-in pressure to
100 p.s.i., which it believed would enable manufacturers to provide low
pressure warnings. It stated that the pressure switch is currently
limited by the 85 p.s.i. minimum governor cut-in pressure requirement.
In addition, ATA has informed the agency that it is conducting tests to
determine whether it should petition the agency to raise the cut-in
requirements from the present 85 p.s.i. minimum and the low pressure
warning limits from 60 p.s.i. to 75 p.s.i. or 80 p.s.i. Based on these
test results, NHTSA may consider initiating rulemaking to raise the
lower limit for the low pressure warning signal.
Authority: 49 U.S.C. 30103 and 30162; delegations of authority
at 49 CFR 1.50 and 501.8.
Issued on: July 14, 1994.
Stanley R. Scheiner,
Acting Associate Administrator for Rulemaking.
[FR Doc. 94-17589 Filed 7-19-94; 8:45 am]
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