[Federal Register Volume 64, Number 100 (Tuesday, May 25, 1999)]
[Notices]
[Pages 28242-28243]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-13160]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
[Docket No. NHTSA-99-5681]
American Transportation Corp., Receipt of Application for
Decision of Inconsequential Noncompliance
American Transportation Corporation (AmTran) has determined certain
air brake systems on AmTran buses were built with air tank volumes that
are not in full compliance with Federal Motor Vehicle Safety Standard
(FMVSS) No. 121, ``Air brake systems,'' and has filed an appropriate
report pursuant to 49 CFR part 573, ``Defect and Noncompliance
Reports.'' AmTran has also applied to be exempted from the notification
and remedy requirements of 49 U.S.C. Chapter 301--``Motor Vehicle
Safety'' on the basis that the noncompliance is inconsequential to
motor vehicle safety.
This notice of receipt of an application is published under 49
U.S.C. 30118 and 30120 and does not represent any agency decision or
other exercise of judgment concerning the merits of the application.
FMVSS No. 121 establishes the performance and equipment
requirements for the braking systems on vehicles equipped with air
brake systems. Paragraph S5.1.2.1. of FMVSS No. 121 states that the
combined volume of all service reservoirs and supply reservoirs shall
be at least 12 times the combined volume of all service brake chambers.
From October 27, 1995 through November 5, 1998, AmTran produced 122
units with an air reservoir combined volume of 3,630 cubic inches or
11.6 times the combined volume of all service brake chambers. AmTran
supports its application for inconsequential noncompliance by stating
the following:
``The combined air reservoir capacity of 3,630 cubic inches is
only 114 cubic inches under the required volume of the system to
meet FMVSS [No.] 121 S5.1.2.1. The 12 times formula was established
at a time when automatic slack adjusters were not common in the
industry. Today, they are standard [and provide] improved brake
adjustment. Properly adjusted brakes require less air volume for
application. A driver of a unit with a volume shortage of 114 cubic
inches more than likely would never experience any difference in
braking capability. [A] previous test conducted by NHTSA indicated
that the 12 times volume provided sufficient reserve volume to stop
an air-braked vehicle equipped with antilock brakes even under the
worst-case conditions. The table below adds further credibility when
theoretical calculations supporting our statement that [a] driver
would not experience any significant effect on stopping distance due
to air pressure differentials. The calculations were based on SAE
J1911, a test procedure for air reservoir capacity. SAE J1609 gives
the criteria that after the eighth brake application, the pressure
in the air reservoir shall not be less than 45 psi. The calculations
also assume no split between the wet, secondary and primary for
simplicity. [Note: For the Hard Stop--full application in traction
limited condition] Pressure in the system assumes worst case of full
on, full off eight times. Somewhat simulates a crude antilock
system.''
[[Page 28243]]
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Pressure in system (psi)
-------------------------------
Initial Compliant Non-compliant
Type of stop reservoir reservoir reservoir
pressure (psi) volume (3,744 volume (3,630
in \3\) in \3\)
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Normal Application (30 psi or less)............................. 120 117.5 117.4
110 107.5 107.4
Hard Stop (Full application in non-traction limited condition).. 120 110.8 110.5
110 101.5 101.3
Hard Stop (Full application in traction limited condition)...... 120 63.3 62.0
110 58.0 56.9
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Interested persons are invited to submit written data, views, and
arguments on the application described above. Comments should refer to
the docket number and be submitted to: U.S. Department of
Transportation, Docket Management, Room PL-401, 400 Seventh Street,
SW., Washington, DC, 20590. It is requested that two copies be
submitted.
All comments received before the close of business on the closing
date indicated below will be considered. The application and supporting
materials, and all comments received after the closing date, will also
be filed and will be considered to the extent possible. When the
application is granted or denied, the notice will be published in the
Federal Register pursuant to the authority indicated below.
Comment closing date: June 24, 1999.
(49 U.S.C. 30118, 30120; delegations of authority at 49 CFR 1.50 and
501.8)
Issued on: May 19, 1999.
L. Robert Shelton,
Associate Administrator for Safety Performance Standards.
[FR Doc. 99-13160 Filed 5-24-99; 8:45 am]
BILLING CODE 4910-59-P
