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Air Brake Systems Publication: Federal Register Agency: National Highway Traffic Safety Administration Byline: Barry Felrice Date: 24 July 1995 Subject: American Government  • Safety
Topic: Federal Motor Vehicle Safety Standards |
[Federal Register Volume 60, Number 141 (Monday, July 24, 1995)]
[Proposed Rules]
[Pages 37864-37866]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-18107]
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DEPARTMENT OF TRANSPORTATION
49 CFR Part 571
[Docket No. 95-57; Notice 01]
RIN 2127-AF72
Air Brake Systems
AGENCY: National Highway Traffic Safety Administration (NHTSA), DOT.
ACTION: Request for comments.
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SUMMARY: This notice requests comments about devices that remove water
and other contaminants from air brake systems. These devices include
automatic drain valves and air dryers. If it appears from the agency's
analysis of the comments that such devices are a cost-effective method
of improving heavy vehicle safety, the agency would issue a notice
proposing to amend Standard No. 121, Air brake systems, to require such
equipment.
DATES: Comments must be received by September 7, 1995.
[[Page 37865]]
ADDRESSES: Comments should refer to the docket and notice numbers set
forth above and be submitted to the Docket Section, NHTSA, Room 5109,
400 Seventh Street, SW, Washington, DC 20590 (Docket hours are from
9:30 a.m. to 4 p.m., Monday through Friday).
FOR FURTHER INFORMATION CONTACT: Mr. Richard Carter, Office of Vehicle
Safety Standards, National Highway Traffic Safety Administration, 400
Seventh Street, SW, Washington, DC 20590, (202) 366-5274.
SUPPLEMENTARY INFORMATION: Federal Motor Vehicle Safety Standard No.
121, Air Brake Systems, establishes braking performance requirements
for vehicles equipped with air brake systems. The standard also
requires these vehicles to be equipped with certain braking equipment,
including a ``condensate drain valve that can be manually operated.''
(see S5.1.2.4 for trucks and buses and S5.2.1.3 for trailers). The
condensate drain valve allows contaminants, such as water, oil, and
dirt to be drained from the brake system's reservoirs. The requirement
for air reservoirs to be equipped with a drain valve that can be
manually operated became effective in 1971 and has remained unchanged.
(36 FR 3817; February 27, 1971)
On July 28, 1994, Domenic F. Coletta, M.D., the Deputy Medical
Examiner of Salem County, New Jersey, submitted a petition for
rulemaking requesting that Standard No. 121 be amended to require
condensate drain valves that automatically purge the contaminants from
the air supply reservoir. He stated that currently available automatic
drain valves would better ensure safety since reservoirs equipped with
manual drain valves are not usually drained on a regular basis. As a
result, he contends that contaminants are present in reservoirs, a
situation which leads to the unsafe operation of trucks and buses. The
petitioner referenced conversations with truck drivers and New Jersey
State police to support his contention that manual drain valves are
typically not being used to remove contaminants from the reservoirs.
However, he supplied no data about the extent to which requiring
automatic drain valves would enhance motor vehicle safety.
On February 21, 1995, NHTSA granted Dr. Colleta's petition to
consider amending Standard No. 121 to require automatic drain valves.
The agency has determined that it is desirable to issue today's notice
requesting comments about automatic drain valves and the effects of
contaminants in air brake systems before proceeding further with a
rulemaking to amend the standard.
Manufacturers of heavy vehicles and heavy vehicle users believe
that it is important to ensure that an air brake system is clean and
dry. If water is present, valves in the air brake systems may freeze,
which may cause the brakes to fail. More generally, contaminants may
enter relay valves, causing their intake and exhaust seals not to seal
properly. This will result in air leakage and in turn degrade brake
performance. This is particularly likely to be a problem for valves
used with antilock systems since they have smaller orifice sizes and
therefore are more sensitive to contaminants. Notwithstanding these
potential safety problems, the predominant effect of contaminants in an
air brake system appears to be shortened component life rather than a
significant causal factor in heavy vehicle accidents. The Truck
Maintenance Council of the American Trucking Associations has been
working with the vehicle manufacturers to achieve longer component life
for the fleet owners.
To keep air brake systems, particularly the air reservoirs, dry and
free from contaminants, manufacturers have installed certain equipment
in the air brake systems. These include drain valves and air dryer
systems. Maintenance personnel and truck drivers are encouraged to keep
air brake systems dry and clean, by opening the reservoir drain valve
and inspecting the brake hoses.
There are two types of drain valves: Manual and automatic. Both
types of valves serve to purge the reservoir of water and other
contaminants. With a manual drain valve, it is necessary for the truck
driver or maintenance person to open the valve and drain the reservoir.
While ideally this should be done each morning before the vehicle is
started, some drivers do not do so. With an automatic drain valve, the
reservoir is drained without the need for human intervention.
Air dryers also serve to reduce the amount of water and other
contaminants in an air brake system by cleaning and drying the air.
There are two types of air dryers, desiccant style systems and ``after-
cooler'' systems. In a typical desiccant style system, the incoming air
is routed into the air dryer at the bottom end of the unit, which
contains an area called a sump. The rapid swirling of the incoming air
into the sump causes a large portion of the oil and water mist to fall
to the bottom of the sump. This partially cleaned air then goes through
an oil separator which is placed directly above the sump area. Next the
air, which is still moist with both oil and water vapor, is passed
through a ``drying bed'' of desiccant material that removes the
remaining moisture. These dryers are equipped with an automatic drain
valve that periodically purges water and contaminants from the air
system and are mounted directly after the compressor. In contrast, in a
typical ``after-cooler'' system, which uses an air cleaner only, not
all the moisture is removed, since the air is not passed through a
drying bed of desiccant material. Each type of dryer may be equipped
with built-in heaters to prevent the purge valves from freezing in cold
weather. The heaters are standard equipment on some models and optional
on others.
In its October 1993 fleet study on antilock brake systems, NHTSA
concluded that while fleets equipped with after-cooler style air dryers
experienced leaky valves, other fleets equipped with desiccant style
air dryers ``have not experienced leaking relay valves.'' \1\ Over 80
percent of new air braked heavy trucks are being built with air dryers,
according to AlliedSignal. That brake manufacturer estimates that more
than 90 percent of the dryers are the desiccant type. Moreover, that
company predicted that in five years almost all air braked vehicles
will be equipped with an air cleaning and drying system.
\1\ An ``In-Service Evaluation of the Performance, Reliability,
Maintainability, and Durability of Antilock Braking Systems (ABSs)
for Semitrailers'' (DOT HS 808 059, Final Report, October 1993)
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To assist NHTSA in determining whether to initiate a rulemaking to
require equipping air braked vehicles with automatic drain valves or
desiccant type air dryers, the agency seeks responses to the following
questions:
1. Do contaminants in air brake systems cause a significant safety
problem? Are any data available to support the existence of such a
problem? How many vehicle crashes per year can be attributed to being
caused by air contaminants of the type that would be eliminated by the
mandatory installation of automatic drain valves? How many deaths and
injuries, and how much property damage, result from these crashes?
2. What is the experience of manufacturers, vehicle operators, and
maintenance personnel with automatic drain valves and desiccant type
air dryers? How effective is each device in removing water and other
contaminants from an air brake system? Are both automatic drain valves
and desiccant type air dryers being installed on the same air braked
vehicle?
3. Is it necessary or appropriate to require air braked vehicles to
be
[[Page 37866]]
equipped with both desiccant style air dryers and automatic drain
valves as well?
4. Based on its preliminary analysis, NHTSA estimates that the cost
to the customer at retail for automatic drain valves ranges from $75 to
$400 per reservoir depending upon the type of system . AlliedSignal
manufactures an automatic drain valve costing approximately $75 per
unit, installed at retail, while the $400 unit would include a
desiccant type system with a heater. Stop Enterprises, the company
referenced by the petitioner, manufactures an automatic drain valve
costing approximately $100 per unit. This compares to approximately $15
for a manual drain valve installed at retail. The agency requests
comments about whether these estimated costs for automatic and manual
drain valves are accurate.
5. The cost to the vehicle manufacturer of desiccant style air
dryers is estimated to be $160 per unit (exclusive of installation).
The agency requests comments about the costs associated with this
device.
Rulemaking Analyses
This notice was not reviewed under E.O. 12866. NHTSA has analyzed
this notice and determined that it is not ``significant'' within the
meaning of the Department of Transportation's regulatory policies and
procedures. While a full regulatory evaluation is not required because
the notice merely requests comments on a potential rule, the agency
estimates that such a requirement would have the following effect.
Approximately 397,500 vehicles are manufactured each year that are
subject to Standard No. 121. Of these, approximately, 189,000 are
trailers. According to estimates by the agency and the Truck Trailer
Manufacturers Association (TTMA), manual drain valves are installed on
approximately 99 percent of the units. The other one percent have
automatic drain valves. Of the annual production of air braked
vehicles, approximately 60,900 vehicles are comprised of single unit
trucks (including school bus chassis), and transit and intercity buses.
The agency estimates that 75 percent are equipped with automatic drain
valves. The remaining 25 percent have manual drain valves. The balance
of the production in air braked vehicles are truck tractors averaging
approximately 147,600 vehicles annually. These vehicles have the
highest installation rates of automatic drain valves and are presently
estimated to be installed on approximately 85 percent of the vehicles
built new. Industry sources estimate the remaining 15 percent of the
truck tractors not built with automatic purge valves will be so
equipped in the next five years. It is expected that the installation
rate will be in conjunction with the phasing in of antilock brake
systems on heavy vehicles.
NHTSA estimates that the installed cost at retail of adding
automatic drain valves to trailers would range from $75 to $150
depending upon the number of air reservoirs. Considering that
approximately 99 percent of the trailers built new would require the
addition of these units, the estimated cost would range from $15.5
million on single reservoir trailers with no heater to $31 million for
single reservoir trailers with heated valves. On double reservoir
trailers, the costs would be double, if automatic drain valves are
installed on both air tanks. On straight trucks, bus chassis, and other
buses, the additional 25 percent (approximately 15,225 units) which
would require automatic drain valves would represent an additional cost
ranging from $1.2 to $6.1 million depending upon the choice of system
(i.e., ranging from a very basic automatic system with no heater or
dryer to a full desiccant style system with heater). Approximately 85
percent of truck tractors are equipped with automatic drain valves
including air dryers and thus would require an expenditure ranging from
$1.7 million to $8.8 million, depending on the type of system selected.
Based on the above analysis, NHTSA estimates that the total
incremental cost at retail level, resulting from requiring automatic
drain valves ranges from $18.4 to $76.9 million, depending upon the
system being selected.
Public Comments
Interested persons are invited to submit comments on the notice. It
is requested but not required that 10 copies be submitted.
All comments must not exceed 15 pages in length. (49 CFR 553.21).
Necessary attachments may be appended to these submissions without
regard to the 15-page limit. This limitation is intended to encourage
commenters to detail their primary arguments in a concise fashion.
If a commenter wishes to submit certain information under a claim
of confidentiality, three copies of the complete submission, including
purportedly confidential business information, should be submitted to
the Chief Counsel, NHTSA, at the street address given above, and seven
copies from which the purportedly confidential information has been
deleted should be submitted to the Docket Section. A request for
confidentiality should be accompanied by a cover letter setting forth
the information specified in the agency's confidential business
information regulation. 49 CFR Part 512.
All comments received before the close of business on the comment
closing date indicated above for the notice will be considered, and
will be available for examination in the docket at the above address
both before and after that date. To the extent possible, comments filed
after the closing date will also be considered. The NHTSA will continue
to file relevant information as it becomes available in the docket
after the closing date, and it is recommended that interested persons
continue to examine the docket for new material.
Those persons desiring to be notified upon receipt of their
comments in the rules docket should enclose a self-addressed, stamped
postcard in the envelope with their comments. Upon receiving the
comments, the docket supervisor will return the postcard by mail.
Issued on: July 18, 1995.
Barry Felrice,
Associate Administrator for Safety Performance Standards.
[FR Doc. 95-18107 Filed 7-21-95; 8:45 am]
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