Bendix Commercial Vehicle Systems BA-921 SMC COMPRESSOR - Manual

DESCRIPTION
The function of the air compressor is to provide, and
maintain, air under pressure to operate devices in air
brake systems. The Bendix
® BA-921 ® SMC side mount
compressor is a single-cylinder reciprocating compressor
with a rated displacement of 15.8 cubic feet per minute at
1250 RPM.
The compressor consists of a water-cooled cylinder head
assembly and an integral air cooled crankcase assembly.
The cylinder head assembly is made up of the cylinder
head, cooling plate, and valve plate assembly and uses
two sealing gaskets. Both the cylinder head and cooling
plate are aluminum. The cylinder head contains air and
water ports, as well as an unloader assembly. A cooling
plate is located between the cylinder head and valve plate
assemblies and assists in cooling.
The valve plate assembly consists of brazed steel plates
which have valve openings and passages for air and engine
coolant to fl ow into, and out of, the cylinder head. 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 crankcase has an open side with a machined face and
locating pins. This open face is bolted directly to the side
of the engine block, see Figure 3. The compressor gear
engages the engine drive gear. In addition, the crankcase
houses the piston assembly, connecting rod, crankshaft
and related bearings.
The Bendix ® BA-921 ® SMC compressor is 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.
A nameplate is attached to a fl at cast face on the side of
the crankcase. It is stamped with information identifying
the compressor designation, customer piece number,
compressor assembly part number and serial number.
Refer to Figure 2.
®
SD-01-1327
BENDIX ® BA-921 ® SMC SINGLE CYLINDER COMPRESSOR FOR
NAVISTAR MAXXFORCE ™ 11 AND 13 BIG BORE ENGINES
FIGURE 1 - BENDIX ® BA-921 ® SMC COMPRESSOR
Safety
Valve
Valve Plate
Assembly
Cylinder
Head
Cooling
Plate
FIGURE 2 - NAMEPLATE
Bendix Part Number . . . . . . A
Customer Piece Number . . . . B
Compressor Serial Number . . C
A
B
C
Crankcase