Troubleshooting guide

16
For more information, visit www.bendix.com or www.foundationbrakes.com • 1-800-AIR-BRAKE (1-800-247-2725)
The Charging, Air Treatment and Storage System: Reservoirs, Etc.
Reservoirs, Etc.
Reservoirs (or “air tanks”) serve the air brake system
as a storage tank for compressed air. The reservoir size
is selected by the vehicle manufacturer to provide an
adequate amount of air for use by the braking system
and other control devices.
Bendix reservoirs are built in accordance with Society
of Automotive Engineers (SAE) specifi cations and
are available in a variety of sizes in both single and
double compartment design confi gurations. They are
certifi ed to comply with government regulations (such as
FMVSS 121).
Reservoir draining devices are installed in air brake
reservoirs, and allow liquid contaminants collected to be
drained off. Vehicles with Bendix
®
brand desiccant air
dryers should be drained every 30-90 days — See the
chart on page 10 for more information.
The presence of water may indicate that the air dryer
cartridge may need to be replaced. Other potential
sources of water in the reservoirs are: when shop air has
been used to fi ll the system, an excessive duty cycle (see
page 11), or excessive air leakage.
Vehicles without air dryers are normally drained each
day.
Manual draining devices are drain cocks which require
manual operation at the point at which they are installed.
Drain cocks are available in a variety of styles and pipe
thread sizes. Always drain the contents slowly for the
best results.
Single Check Valves
In-line single check valves allow air fl ow in one direction
only. Several sizes and confi gurations are available to
accommodate a variety of piping arrangements. Single
check valves are used in air brake systems to prevent
loss of remaining system pressure if another reservoir, or
hose etc. — upstream in the system — fails.
For double check valves and pressure protection valves,
see the Miscellaneous Components section.
Low Pressure Indicators
Low pressure indicators are pressure-operated electro-
pneumatic switches. They are designed to complete
an electrical circuit and actuate a warning light and/
or buzzer to inform the driver in the event that the air
pressure in the service brake system is below a minimum
level for normal operation. Low pressure indicators are
not adjustable, but are available in a variety of pressure
settings.
Reservoirs are
available in many
confi gurations.
Drain
Cock
Bendix
®
SC-3
™
Single Check
Valves
Bendix
®
LP-3
™
Low
Pressure
Indicator