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Figure 1-50.-Expansion tank. | Up
Equipment Operator Basic - Beginning construction equipment operators manual | Next
Chapter 2 Power Train |
Fan and Shroud
Baffles and Fins
All stationary air-cooled engines must have fans or
blowers of some type to circulate a large volume of
cooling air over and around the cylinder. The fan for the
air-cooled engine shown in figure 1-51 is built into the
flywheel. When the engine is assembled, the shrouding,
or cowling, forms a compartment around the engine so
that the cooling air is properly directed for effective
cooling. Air-cooled engines, such as those used on
motorcycles and outboard engines, do not require the
use of fans or shrouds, because their movement through
the air creates a sufficient air flow over the engine for
adequate cooling.
In addition to the fan and shroud, some engines use
baffles or deflectors to direct the cooling air from the
fan to those parts of the engine not in the direct path of
air flow. Most baffles are made of light metal and are
semicircular with one edge in the stream of air. Most
air-cooled engines use fins. These are thin, raised
projections on the cylinder barrel and head. The fins
provide more cooling area or surface and aid in directing
air flow. Heat, resulting from combustion, passes by
conduction from the cylinder walls and cylinder head to
the fins and is carried away by the passing air.
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1-38
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