BENDIX BW1637 Manual Do Utilizador

The duty cycle is the ratio of time the compressor spends 
building air to the total engine running time. Air compres-
sors are designed to build air (run "loaded") up to 25% of 
the time. Higher duty cycles cause conditions that affect 
air brake charging system performance which may require 
additional maintenance. Factors that add to the duty cycle 
are: air suspension, additional air accessories, use of an 
undersized compressor, frequent stops, excessive leakage 
from fi ttings, connections, lines, chambers or valves, etc. 
Refer to Table A in the Troubleshooting section for a guide 
to various duty cycles and the consideration that must be 
given to maintenance of other components.

While the original compressor installation is usually com-
pleted by the vehicle manufacturer, conditions of operation 
and maintenance may require additional consideration. The 
following presents base guidelines.

The discharge line allows the air, water-vapor and oil-vapor 
mixture to cool between the compressor and air dryer or 
reservoir. The typical size of a vehicle's discharge line, 
(see column 2 of Table A in the Troubleshooting section) 
assumes a compressor with a normal (less than 25%) duty 
cycle, operating in a temperate climate. See Bendix and/or 
other air dryer manufacturer guidelines as needed.

™

® 

™

supplies the 

compressed air for the braking system as well as other air 
accessories for the vehicle. The system usually consists 
of an air compressor, governor, discharge line, air dryer, 
and service reservoir.

The discharge line must maintain a constant slope down 
from the compressor to the air dryer inlet fi tting or reservoir 
to avoid low points where ice may form and block the fl ow. 
If, instead, ice blockages occur at the air dryer or reservoir 
inlet, insulation may be added here, or if the inlet fi tting is 
a typical 90 degree fi tting, it may be changed to a straight 
or 45 degree fi tting. Shorter discharge line lengths or 
insulation may be required in cold climates.

While not all compressors and charging systems are 
equipped with a discharge line safety valve this compo-
nent is recommended. The discharge line safety valve is 
installed in the cylinder head (Tu-Flo

®

 550/750) or close to 

the compressor discharge port and protects against over 
pressurizing the compressor in the event of a discharge 
line freezeup.

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