Bendix Commercial Vehicle Systems BA-921 SMC COMPRESSOR - Manual (Page 5)

5
If compressor oil passing is suspected, refer to the
Troubleshooting section (starting on page A-1) for the
symptoms and corrective actions to be taken. In addition,
Bendix has developed the “Bendix Air System Inspection
Cup”, or Bendix
® 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. 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 8.
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 P/N 222797) installed in the
port. Under no circumstances should the port be plugged
or left open.
AIR INDUCTION
The Bendix ® BA-921 ® SMC compressor is designed for
connection to the vacuum side of the engine’s air induction
system.
A supply of clean air is one of the single most important
factors in compressor preventive maintenance. Since
the air supply for Bendix
® BA-921 ® SMC compressor and
engine is the engine air cleaner, periodic maintenance of
the engine air fi lter is necessary.
Inspect the compressor air induction system each time
engine air cleaner maintenance is performed.
1. Inspect the intake hose adapters for physical damage.
Make certain to check the adapters at both ends of the
intake hose or tubing.
2. Inspect the intake hose clamps and tighten them if
needed.
3. Inspect the intake hose or line for signs of drying,
cracking, chafi ng and ruptures and replace if necessary.
4. Verify that the compressor inlet fi tting is tight (check
torque).
5. Any metal tubes should also be tight (torqued properly)
to the mating fi tting. Inspect the metal tubes for any
cracks or breaks and replace if necessary.
COMPRESSOR COOLING
Inspect the compressor discharge port, inlet cavity and
discharge line for evidence of restrictions and carbon
build-up. If more than 1/16" of carbon is found, thoroughly
clean or replace the affected parts. In some case, carbon
build-up 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
The compressor utilizes an internal oil feed design. Check
the exterior of the compressor (i.e. around the mounting
face) 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 used in
conjunction with a Bendix ® air dryer.