BENDIX BW2827 User Manual

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.  

®

Safety 

Valve

Valve Plate 

Assembly

Cylinder 

Head

Cooling 

Plate

Bendix Part Number  .  .  .  .  .  .  A
Customer Piece Number .  .  .  .  B
Compressor Serial Number   .  .  C

A

B

C

Crankcase