BENDIX AD-4 AIR DRYER Manual page 17

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AD-4 AIR DRYER TROUBLESHOOTING CHART (Continued)
SYMPTOMS
2. Water and/or Oil in
Supply or Service
Reservoir (continued).
CAUSE
C. Air dryer not purging
(see Symptom #5).
D. Purge (air exhaust) time
insufficient due to
excessive system
leakage (see causes for
Symptom #1).
E. Excessive air usage,
duty cycle too high - Air
dryer not compatible
with vehicle air system
requirement (Improper air
dryer/vehicle
application).
NOTE: Duty Cycle is the
ratio of time the compressor
spends building air to total
engine running time. Air
compressors 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 fittings,
connections, lines,
chambers or valves, etc.
REMEDY
C. See Symptom #5.
D. Check causes and remedies for Symptom #1.
E. See Appendix A, Table A, column 1, for
recommended compressor sizes. If the
compressor is "too small" for the vehicle vocation
(for example, where a vehicle's vocation has
changed or service conditions exceed the original
vehicle or engine OE spec's) then upgrade the
compressor. Note: The costs incurred (e.g.
installing a larger capacity compressor, etc.) are
not covered under original compressor warranty.
Charge Cycle Time - The AD-4
designed to provide clean, dry air for the brake
system. When a vehicle's air system is used to
operate non-brake air accessories it is necessary
to determine that; during normal, daily operation
the compressor should recover from governor
"cut-in" to governor "cut-out" (usually 100 psi to
120 psi) in 90 seconds or less at engine RPM's
commensurate with the vehicle vocation. If the
recovery time consistently exceeds this limit, it
may be necessary to "bypass" the air accessory
responsible for the high air usage. An example of
where a by-pass system would be required is
when the compressor is used to pressurize a
tank trailer for purposes of off-loading product.
Consult your local authorized Bendix parts outlet
or sales representative for additional information.
Purge Cycle Time - During normal vehicle
operation, the air compressor must remain
unloaded for a minimum of 30 seconds. This
minimum purge time is required to ensure
complete regeneration of the desiccant material.
If the purge time is consistently less than the
minimum, an accessory by-pass system must be
installed. Consult your local authorized Bendix
parts outlet or sales representative for additional
information.
Air Compressor Size - Although the AD-4
dryer can be used in conjunction with larger
compressors, it was designed primarily for units
rated for up to 30 CFM. It is recommended that
when using the AD-4
compressor which has a rated displacement
exceeding 30 CFM that an authorized Bendix
parts outlet or Bendix marketing representative
be contacted for assistance.
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air dryer is
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air
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air dryer with a
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