Bendix Commercial Vehicle Systems LP-3 LOW PRESSURE INDICATORS - Manual

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Bendix ® LP-2 ™ & LP-3 ™ Low Pressure Indicators
SD-06-1600
DESCRIPTION
The low pressure indicator is a safety device designed to
give an automatic warning to the driver whenever air pressure
in the air brake system is below the safe minimum for normal
vehicle operation. It is usually used to operate an electrical
buzzer or warning light, or both, which are audible or visible
to the driver.
Two styles of low pressure indicators are currently
manufactured.
The LP-2 ™ low pressure indicator, which is the older style
and consists of a die cast body with a spring loaded
diaphragm clamped between the body and the Bakelite
cover.
The LP-3 ™ low pressure indicator is the newer style,
consisting of a die cast body, nylon cover and employs a
spring loaded o-ring diaphragm and piston. The LP-3
™
indicator is available with either one terminal or two. The
single terminal unit utilizes a metallic gasket between body
and case to ground the lower contract strip. The two terminal
unit utilizes a phenolic insulating gasket to isolate both
terminals from the vehicle frame.
The electrical contacts provided in both the LP-2 ™ and LP-3 ™
indicators remain closed by spring force until the air brake
system pressure below the diaphragm is above the setting
(force) of the low pressure indicator spring. The setting of
the indicator and piece number is marked on a label on the
valve body. If a label is not present, then the vehicle manual
should be consulted for the proper setting. The nominal
setting of the indicator is 60 psi; however, pressure settings
may vary depending upon the vehicle.
FIGURE 1 - LP-2 ™ LOW PRESSURE INDICATOR FIGURE 2 - LP-3 ™ LOW PRESSURE INDICATOR
COVER
DIAPHRAGM
BODY
SPRING
CONTACT
POINTS
COVER
SPRING
CONTACT
POINTS
PISTON
BODY
O-RING
DIAPHRAGM