Bendix Commercial Vehicle Systems BA-921 COMPRESSOR_STD/CLOSED ROOM - Manual (Page 8)

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buildup indicates inadequate cooling. Closely inspect the
compressor cooling system. Check all compressor coolant
lines for kinks and restrictions to fl ow. Minimum coolant line
size is 3/8" I.D. Check coolant lines for internal clogging
from rust scale. If coolant lines appear suspicious, check
the coolant fl ow and compare to the tabulated technical
data present in the back of this manual. Carefully inspect
the air induction system for restrictions.
LUBRICATION
Caterpillar Engine Installations.
Check the external oil supply line for kinks, bends, or
restrictions to fl ow. Supply lines must be a minimum of
3/16” I.D. Refer to the tabulated technical data in the back
of this manual for oil pressure minimum values.
Check the exterior of the compressor for the presence of
oil seepage and refer to the TROUBLESHOOTING section
for appropriate tests and corrective action.
Detroit Diesel S60 Installations
On Detroit Diesel Series 60 engine installations, the
compressor utilizes an internal oil feed design. Check
the exterior of the compressor for the presence of oil
seepage and refer to the TROUBLESHOOTING section
for appropriate tests and corrective action. Refer to the
tabulated technical data in the back of this manual for oil
pressure minimum values.
OIL PASSING
All reciprocating compressors pass a minimal amount of
oil. Air dyers will remove the majority of oil before it can
enter the air brake system. For particularly oil sensitive
systems, the Bendix
® PuraGuard ® system can be use in
conjunction with a Bendix ® air dryer.
If compressor oil passing is suspected, refer to the
TROUBLESHOOTING section (starting on page A-1)
for the symptoms and corrective action to be taken. In
addition, Bendix has developed the “Bendix Air System
Inspection Cup” or BASIC
™ kit to help substantiate
suspected excessive oil passing. The steps to be followed
when using the BASIC
™ kit are presented in APPENDIX
B, on page A-16.
COMPRESSOR DRIVE
Check for noisy compressor operation, which could indicate
excessive drive component wear. Adjust and/or replace
as necessary. Check all compressor mounting bolts and
retighten evenly if necessary. Check for leakage and
proper unloader mechanism operation. Repair or replace
parts as necessary.
COMPRESSOR UNLOADER & GOVERNOR
Test and inspect the compressor and governor unloader
system for proper operation and pressure setting.
1. Check for leakage at the unloader port. Replace leaking
or worn o-rings.
2. Make certain the unloader system lines are connected
as illustrated in Figure 6.
3. Cycle the compressor through the loaded and unloaded
cycle several times. Make certain that the governor
cuts-in (compressor resumes compressing air) at a
minimum of 105 psi (cut-out should be approximately
15 - 20 psi greater than cut-in pressure). Adjust or
replace the governor as required.
4. Note that the compressor cycles to the loaded and
unloaded conditions promptly. If prompt action is not
noted, repair or replace the governor and/or repair the
compressor unloader.
IMPORTANT NOTE
Replacement air governors must have a minimum cut-in
pressure of 100 psi. The cut-in pressure is the lowest
system pressure registered in the gauges before the
compressor resumes compressing air.
Compressors with no signal line to the unloader port should
have a vent cap (e.g. Bendix part number 222797) installed
in the port. Under no circumstances should the port be
plugged or left open.
SERVICE TESTS
GENERAL
The following compressor operating and leakage tests need
not be performed on a regular basis. These tests should be
performed when it is suspected that leakage is substantially
affecting compressor buildup performance, or when it is
suspected that the compressor is “cycling” between the
loaded (pumping) and unloaded (non-pumping) modes
due to unloader leakage.