Air Brake Systems

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.

-----------------------------------------------------------------------

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)

---------------------------------------------------------------------------

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]

BILLING CODE 4910-59-P