Troubleshooting guide
12
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: Governors, Etc.
Governors and Components
The Governor monitors the air pressure in the supply
reservoir and operates the compressor unloading
mechanism to control whether or not the compressor
builds air pressure.
The Bendix
®
D-2
®
governor is an adjustable piston-
type valve. It is available preset to a choice of pressure
settings. Note: The pressure range between the cut-in
and cut-out pressure is designed into the governor and
is not adjustable. The D-2 governor may be direct-
mounted to the compressor or remote-mounted as
desired. Specialized governors are available for vehicles
needing a governor adapted to abnormally high or low
temperatures, as well as a “weatherproof” model. For
example:
• The Bendix
®
D-2A
™
governor is a non-adjustable
version of the D-2
®
governor.
• The D-2
®
/SV-1
™
governor module is a special com-
bination device used with the Bendix
®
DuraFlo
596
™
air compressor to provide the fast-rising unloader sig-
nal needed by this compressor.
Safety Valves are used in an air brake system to protect
against excessive air pressure build-up and to sound
an audible alert. Safety valves are available in both
adjustable (e.g. the Bendix
®
ST-1
™
valve) and non-
adjustable (e.g. Bendix
®
ST-3
™
, and ST-4
™
valve) styles,
in a variety of pressure settings, and for a variety of port
sizes. Maximum service system air pressure allowed by
government regulation is typically 150 psi. A variety of
safety valve settings are used at different points in the
charging and treatment system.
Specifi cally designed for use in compressors, ST-4
safety valves are installed — in an extra compressor
head discharge port, if available or in the discharge line
near the compressor — to prevent compressor damage
in the event of discharge line blockage.
An Inlet Regulating Valve (or “IRV”) is typically used
on multi-cylinder compressors which receive their
input air supply from the pressurized side of the engine
turbocharger. The IRV, which is generally mounted to
the compressor inlet, is designed to regulate compressor
inlet pressure to 10 psi or less. The outlet fl ange of the
IRV can be mounted to all Bendix
®
Tu- Flo
®
compressors
except the Tu-Flo 300 compressor. The IRV may not be
used in conjunction with single cylinder compressors.
Bendix
®
D-2A
™
Governor
Inlet Check Valves (or “ICV” valves) are used on naturally
aspirated compressors to prevent oil mist from entering
the inlet line during the unloaded cycle. The inlet check
valve either mounts to the intake side of the compressor
(and must be used in conjunction with an inlet valve stop
or inlet adapter), or may be mounted remotely.
Visit the Bendix website at www.bendix.com for more
information, including the Advanced Compressor
Troubleshooting Guide (BW1971) and compressor
Service Data sheets.
Bendix
®
ST-1
™
, ST-3
™
and ST-4
™
Safety Valves
Bendix
®
D-2
®
/SV-1
™
Governor Module
Bendix
®
D-2
®
Governor
Exhaust Port
Shown With
Breather Valve
Installed
Inlet Regulating
Valve
Inlet Check
Valves