39
A-20
Bulletin No.: TCH-008-021
Effective Date: 3/5/2010
Page: 2 of
2
System Leakage
Check the air brake system for excessive air leakage using the Bendix “Dual System Air Brake Test and Check
List” (BW1396). Excessive system leakage causes the compressor to “pump” more air and also reduce the life
of the air dryer desiccant cartridge.
Reservoir Draining (System without an Air Dryer)
Routine reservoir draining is the most basic step in reducing the possibility of freeze-up. All reservoirs in a
brake system can accumulate water and other contamination and must be drained! The best practice is to
drain all reservoirs daily if the air brake system does not include an air dryer. When draining reservoirs; turn
the ENGINE OFF and drain ALL AIR from the reservoir, better still, open the drain cocks on all reservoirs and
leave them open over night to ensure all contamination is drained (reference Service Data Sheet SD-04-400 for
Bendix Reservoirs). If automatic drain valves are installed, check their operation before the weather turns cold
(reference Service Data Sheet SD-03-2501 for Bendix
®
DV-2
™
Automatic Drain Valves). It should be noted that,
while the need for daily reservoir draining is eliminated through the use of an automatic drain valve, periodic
manual draining is still required.
Reservoir Draining (System with an Air Dryer)
Daily reservoir draining should not be performed on systems with an air dryer. This practice will cause the dryer
to do excessive work (e.g. build pressure from 0-130 psi instead of the normal 110-130 psi).
Alcohol Evaporator or Injector Systems
Bendix Commercial Vehicle Systems LLC discourages the use of alcohol in the air brake system as a means
of preventing system freeze-up in cold temperatures. Studies indicate that using alcohol and alcohol based
products sold for this purpose removes the lubrication from the components of the air braking system. In
addition, the materials used for the internal seals of the air system components may be adversely impacted
by the residue that some anti-freeze additives leave behind. Both are detrimental to air system component life
expectancy, causing premature wear. Because of this, Bendix
®
air system components warranty will be void if
analysis shows that alcohol was added to the air brake system.
Alcohol is not an acceptable substitute for having adequate air drying capacity. If the air dryer is maintained in
accordance with the manufacturer’s recommended practices and moisture is found to be present in the system
reservoirs, more drying capacity is required. Bendix has several viable options including extended purge air
dryers, extended purge tandem dryers in parallel with common control, and air dryers arranged to provide
continuous flow as with the Bendix
®
EverFlow
®
continuous flow air dryer module. To address concerns with
contaminants in trailer air brake systems, the Bendix
®
Cyclone DuraDrain
®
water separator and the Bendix
®
System-Guard
®
trailer air dryer are available. Refer to Bendix Technical Bulletin TCH-008-042 “Alcohol in the
Air Brake System” for additional information.
Air Dryers
Make certain air brake system leakage is within the limits stated in BW1396. Check the operation and function
of the air dryer using the appropriate Service Data Sheet for the air dryer.
Air Dryer
Service Data Sheet
AD-2
®
air dryer
SD-08-2403
AD-4
™
air dryer
SD-08-2407
AD-9
®
air dryer
SD-08-2412
AD-IP
®
air dryer
SD-08-2414
AD-IS
®
air dryer
SD-08-2418
AD-IS
®
EverFlow
®
air dryer
SD-08-2417
AD-SP
®
air dryer
SD-08-2415
Cyclone DuraDrain
®
water separator
SD-08-2402
PuraGuard
®
QC system filter
SD-08-187B
Trailer System-Guard
®
air dryer
SD-08-2416
Bendix literature is available
to order or download on
www.Bendix.com
