Q3-1. What happens to the temperature of a gas
being in line with each other (fig. 3-7). The cylinders
when it is compressed?
fire or deliver the power strokes in the following order:
1-5-3-6-2-4. Thus, the power strokes follow each other
so closely that there is a fairly continuous and even
delivery of power to the crankshaft.
It remains the same
It depends on the original pressure before
Even so, additional leveling off of the power
it is compressed
impulses is desirable, so that the engine will run more
smoothly. The flywheel shown in figure 3-7 is used to
Q3-2. Which of the following items is NOT required
achieve this result.
To understand how a flywheel functions, let us
consider a single-cylinder, 4-stroke cycle engine. It is
delivering power only one-fourth of the time during the
power stroke. During the other three strokes, it is
absorbing power to push out the exhaust gas, to pull in a
Q3-3. When a piston is at the top of the stroke, it is in
fresh charge, and to compress the charge. The flywheel
makes the engine run without varying much in speed
during each revolution. It is a heavy steel wheel
attached to the end of the crankshaft. When it is
Top right angle
rotating, considerable effort is required to slow it down
or stop it. Although the wheel does slow down
Top dead center
somewhat as it delivers power to the engine during the
Q3-4. The intake valves open when the piston is in
exhaust, intake, and compression strokes, the wheel
which of the following positions?
speed increases during the engine power stroke. In
effect, the flywheel absorbs some of the engine power
Traveling in the upward direction
during the power stroke, and then gives it back to the
Nearing the top of the cylinder
engine during the other three engine strokes.
Traveling in the downward direction
At the top of the stroke
In the multicylinder engine, the flywheel functions
in a similar manner, absorbing power when the engine
Q3-5. What is the primary purpose of the flywheel
tends to speed up during the power strokes and giving
up power to the engine when the engine slows down
1. It provides a place to attach the trans-
during intervals when little power is being delivered by
2. It allows for the attachment of the ring
In addition to the engine itself, which is the power
producer, there must be accessory systems to provide
the engine with other requirements necessary to operate
4. It allows the engine to run without varying
it. These systems are the fuel system, the lubrication or
in engine speed
oiling system, the electric system, the cooling system,
and an exhaust system.
Figure 3-7.--Crankshaft for a 6-cylinder engine.