[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]
BILLING CODE 4910-59-P