Chapter 3 Engine Classifi cation, Parts Identifi cation 61
Rotary Engine Construction
Rotary engines are classified according to
the number of rotors used in the engine. The
remainder of the engine consists of one or more
rotor housings, end housings, fi xed gears, and
a center housing all held rigidly together with a
series of bolts.
There are just two or three moving parts in
the rotary engine depending upon the number
of rotors the engine has—the eccentric shaft
(also called the mainshaft) and the cast iron
rotor assemblies. The rotors have spring-loaded
cast iron seals to close the very small running
clearance between them and the housing sur-
face while providing a barrier against compres-
sion loss and oil consumption.
Rotary Engine Operation
The rotary engine performs the four dis-
tinct strokes––intake, compression, power, and
exhaust, Figure 3-30. Each face of the triangular
rotor acts like a conventional piston. Instead of a
reciprocating action, however, the rotor continu-
ally revolves in the same direction as the eccen-
tric shaft.
By meshing the rotor internal gear with a
fi xed gear attached to the end housing, it forces
Air
Air
Air
Air
Air
Fuel
Exhaust
Air enters combustion chamber
through intake ports
Exhaust valve closes,
air compresses
Fuel charge injects into
combustion chamber
Exhaust gas exits, clean
scavenging air sweeps cylinder
Supercharger
Figure 3-27.
Two-stroke cycle diesel engine operation. The supercharger forces the air-fuel mixture into the combustion chamber.
Detroit Diesel Corp.