Bendix Commercial Vehicle Systems TU-FLO 501 AIR COMPRESSOR 9/04 - Manual (Page 4)

4
DISCHARGE
VALVE
PISTON
STROKE
TO GOVERNOR
INTAKE
STRAINER
UNLOADER
PLUNGER
INLET VALVE
TO RESERVOIR
DISCHARGE
VALVE
PISTON
STROKE
TO GOVERNOR
INTAKE
STRAINER
UNLOADER
PLUNGER
INLET VALVE
TO RESERVOIR
FIGURE 4 - INTAKE
FIGURE 5 - COMPRESSION
DISCHARGE LINE TEMPERATURE
When the temperature of the compressed air that enters
the air dryer is within the normal range, the air dryer can
remove most of the charging system oil. If the temperature
of the compressed air is above the normal range, oil as oil-
vapor is able to pass through the air dryer and into the air
system. Larger diameter discharge lines and/or longer
discharge line lengths can help reduce the temperature.
The air dryer contains a filter that collects oil droplets, and a
desiccant bed that removes almost all of the remaining water
vapor. The compressed air is then passed to the air brake
service (supply) reservoir. The oil droplets and the water
collected are automatically purged when the governor
reaches its "cut-out" setting.
For vehicles with accessories that are sensitive to small
amounts of oil, we recommend installation of a Bendix
®
PuraGuard ® QC ™ oil coalescing filter, designed to minimize
the amount of oil present.
Lubrication
Since all Tu-Flo ® 501 compressors are connected to the
engine’s pressurized oil system, a continuous flow of oil is
provided to the compressor, which is eventually returned to
the engine.
Oil is fed into the compressor in various ways, for example:
through the rear end cover, the drive end of the crankshaft or
through the front flange adapter. An oil passage in the
crankshaft conducts pressurized oil to the precision sleeve
main bearings and to the connecting rod bearings. Splash
lubrication of the cylinder bores, connecting rod wrist pin
bushings, and the ball type main bearings, on some models,
is obtained as oil is forced out around the crankshaft journals
by engine oil pressure.
Check the exterior of the compressor for the presence of oil
seepage and refer to the TROUBLESHOOTING section for
appropriate tests and corrective action.
Cooling
Air flowing through the engine compartment from the action
of the engine’s fan and the movement of the vehicle assists
in cooling the crankcase. Coolant flowing from the engine’s
cooling system through connecting lines enters the head
and passes through the head’s water jacket and back to the
engine. Proper cooling is important in maintaining discharge
air temperatures below the maximum 400°F recommended.
FIGURE 3B - DISCHARGE LINE SAFETY VALVE
HOLE
THREAD
DISCHARGE
VALVE
PISTON
STROKE
TO GOVERNOR
INTAKE
STRAINER
UNLOADER
PLUNGER
TO RESERVOIR
INLET VALVE
FIGURE 6 - UNLOADING