Lubrication; Cooling - BENDIX BA-921 COMPRESSOR-STD-CLOSED ROOM Service Data Sheet

Head
Discharge
Bolt (4)
Safety Valve
Discharge
Port
Governor
Connection
Unloader
Cover
Coolant In or Out
CYLINDER HEAD PORT IDENTIFICATION
The cylinder head connection ports are identifi ed with cast
in numerals as follows:
AIR IN
Compressed AIR OUT
Coolant IN or OUT
Governor Control
FIGURE 10 - STANDARD BENDIX
CYLINDER HEAD
Discharge
Safety Valve
Head
Bolt (6)
Inlet
Port
Coolant In or Out
CYLINDER HEAD PORT IDENTIFICATION
The cylinder head connection ports are identifi ed with cast
in numerals as follows:
AIR IN
Compressed AIR OUT
Coolant IN or OUT
Governor Control
FIGURE 11 - CLOSED ROOM BENDIX
COMPRESSOR CYLINDER HEAD
Coolant In or Out
(One or other not used)
Inlet
Port
0
2
9
4
® BA-921 ® COMPRESSOR
Coolant In
or Out
(One or other not
used)
Governor
Connection
Unloader
Cover
Discharge
Port
0
2
9
4
® ®
BA-921

LUBRICATION

The vehicle's engine provides a continuous supply of oil
to the compressor. Oil is routed from the engine to the
compressor's oil inlet. An oil passage in the crankshaft
routes pressurized oil to the precision sleeve main bearings
and to the connecting rod bearings. Spray lubrication of
the cylinder bores, connecting rod wrist pin bushings, and
ball type main bearings is obtained as oil is forced out
around the crankshaft journals by engine oil pressure.
Oil then falls to the bottom of the compressor crankcase
and is returned to the engine through drain holes in the
compressor mounting fl ange.
Standard Compressor Lubrication for Caterpillar C11
and C13 engine applications
Bendix ® BA-921 ® compressor - for Caterpillar C11 and
C13 engine installations only - use an "oil jet" that sprays
oil under the piston for purposes of cooling. This oil jet
is part of a special crankcase cover that is used only on
®
the BA-921 compressor for CAT C11 and C13 engine
installations (see Figure 17).
This design slightly alters the fl ow of oil for lubrication. The
oil supply line from the engine is directly connected to the
back side of the special crankcase over. The oil fl ows in
parallel through a passageway in the crankcase cover and
through the oil jet to spray oil under pressure up onto the
underneath of the piston for cooling. At the same time,
oil fl ows out of the opposite end of the special crankcase
cover, through a fi tting and a metal tube and second fi tting
into the oil supply port of the compressor. At this point oil
fl ows in a similar manner as in the fi rst paragraph of this
section.

COOLING

® ®
Bendix BA-921 compressors are cooled by air fl owing
through the engine compartment as it passes the compres-
sor's cast-in cooling fi ns and by the fl ow of engine coolant
through the cylinder head. Coolant supplied by the engine
cooling system passes through connecting lines into the
cylinder head and passes through internal passages in
the cylinder head, cooling plate and valve plate assembly
and returns to the engine. Figures 10 and 11 illustrate the
various approved coolant fl ow connections. Proper cooling
is important in minimizing discharge air temperatures - see
the tabulated technical data on page 18 of this manual for
specifi c requirements.
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