Troubleshooting guide

17
For more information, visit www.bendix.com or www.foundationbrakes.com • 1-800-AIR-BRAKE (1-800-247-2725)
The Charging, Air Treatment & Storage System: Misc. Components
Miscellaneous Components
A double check valve is used in the air system when a
single function or component must receive air from, or
be controlled by, the higher of two pressure sources. An
internal disc, or shuttle, moves in response to the higher
air pressure and allows the air source to fl ow out of the
delivery port. It is recommended that double check
valves are always mounted so that the shuttle (or disc)
operates horizontally.
While not strictly part of the charging system, in some
vehicle brake systems, the Bendix
®
DS-2
™
double
check valve and stop light switch (shown on this page)
is used to detect air pressure from either brake circuit
source. It will operate the stop lamp switch, illuminating
the stop lamps.
Pressure Protection Valves
The Pressure Protection Valve is a normally-closed
pressure sensitive control valve. These valves can be
used in many different applications but are most often
used:
(a) To protect or isolate one reservoir from another, by
closing automatically at a pre-set pressure. Pressure
protection valves can be used to allow air to be “shared”
between two reservoirs above the closing setting of the
valve. The sharing ceases when pressure drops below
the closing pressure of the valve and the reservoirs are
then isolated from each other.
(b) To delay the fi lling of one, or more, auxiliary reservoirs
until a pre-set pressure is achieved in the primary, or
braking, reservoirs.
(c) To delay supplying auxiliary components and systems
(e.g. air actuated wipers, air suspension) until the
braking system reservoirs have reached a pre-defi ned
minimum pressure suffi cient for braking purposes. Once
the braking system has reached the pre-set minimum,
the pressure protection valves open to supply the
auxiliary systems.
The Bendix
®
PR-2
™
pressure protection valve is
externally adjustable, while the Bendix
®
PR-4
™
pressure
protection valve (shown) has a fi xed set tin g. Both va lves
are available in a variety of factory pre-set pressure
settings. The Bendix
®
PR-3
™
pressure protection
valve differs from the two valves previously mentioned
since its design includes a check valve preventing air
return. The Bendix
®
AD-IS
®
Integrated system air
dryers have a set of pressure protection valves internal
to the design.
Pressure Reducing Valves
Pressure reducing valves are used in a variety of
applications where a constant set air pressure (lower
than supply pressure) is required. A typical application is
an air-operated accessory that requires less than system
pressure for operation. The Bendix
®
RV-1
™
pressure
reducing valve (shown) is available in a wide range of
pressure settings and can be manually adjusted. The
Bendix
®
RV-3
™
pressure reducing valve is available
only with factory pre-set pressure settings and cannot be
manually adjusted.
Bendix
®
DC-4
®
Double Check
Valve
Bendix
®
RV-3
™
Pressure
Reducing
Valve
Bendix
®
RV-1
™
Pressure
Reducing
Valve
Pressure
Protection
Valve
Auxiliary
Bendix
®
PR-3
™
Pressure
Protection Valve
Bendix
®
PR-4
™
Pressure
Protection Valve
Bendix
®
DS-2
™
Double Check
Valve and Stop
Light Switch