Lesson 1/Learning Event 1
FIGURE 9. HORIZONTAL-OPPOSED ENGINE.
Horizontal-Opposed. The horizontal-opposed engine has its cylinders laid on their sides in two straight rows
directly opposite each other. The crankshaft is in the center of the engine between the rows or banks of the
cylinders. By being made this way, the engine is not very high and can be mounted under the body of the
vehicle it is used in. The horizontal-opposed engine is often called a pancake engine because of its flat shape.
These engines are generally air-cooled.
BASIC ONE-CYLINDER ENGINE
The internal combustion engines we will study in this lesson are built to produce rotary-mechanical motion
from heat energy. They can be built light enough for a man to carry; for example, the engine on a small
lawnmower. The engine may also be large and heavy. Examples of such power plants include the engines used
to drive large tanks and trucks. Fortunately, you do not have to study each of these engine types to understand
how they operate, because they all operate on the same basic principles. With this in mind, let's read about the
different parts of the engine.