Bendix Commercial Vehicle Systems BA-921 COMPRESSOR_STD/CLOSED ROOM - Manual (Page 2)

2
The compressor's discharge valves are part of the valve
plate assembly. The inlet reed valve/gasket is installed
between the valve plate assembly and the top of the
crankcase.
The cast iron crankcase houses the piston assembly,
connecting rod, crankshaft and related bearings.
All Bendix ® BA-921 ® compressors are equipped with a
safety valve to protect the compressor head in the event
of, for example, a discharge line blockage downstream
of the compressor. Excessive air pressure will cause the
safety valve to unseat, release air pressure and give an
audible alert to the operator. The safety valve is installed
in the cylinder head safety valve port, directly connected
to the cylinder head discharge port.
The crankcase cover located at the bottom of the crankcase
is stamped with information identifying the compressor
model, customer piece number, Bendix piece number and
serial number. See Figures 1 and 4.
OPERATION
The compressor is driven by the vehicle's engine and
functions continuously while the engine is in operation.
Actual compression of air is controlled by the compressor
unloading mechanism operating in conjunction with a
governor.
Compressor Model,
Customer Piece Number,
Bendix Piece Number and
Serial Number shown here
FIGURE 4 - CRANKCASE BASE COVER
FIGURE 3 - BENDIX ® BA-921 ® COMPRESSOR (CUT-AWAY) (STANDARD AND CLOSED ROOM)
Unloader
Piston
Piston
Rod
Coolant Ports
(3 total)
Piston
Air
Intake
Unloader
Cover
Discharge
Reed
Valves (2)
Crankshaft
Cooling
Plate
Crankcase
Cover
Splash
Shield
Unloader
Piston
Piston
Rod
Coolant Ports
(3 total)
Piston
Unloader
Cover
Discharge
Reed
Valves (2)
Crankshaft
Cooling
Plate
Crankcase
Cover
Closed Room Standard
FIGURE 5 - TYPICAL COMPRESSOR DRIVE FLANGES
Detroit
Diesel S60
Caterpillar
HD Acert
Engines
Caterpillar
C7, C9
Engines