Chapter 6. Summary Flashcards
What component keeps all engine parts in alignment?
The engine block
what materials are usually used to make engine blocks
casted iron or an aluminum alloy.
The engine block consists of two sections:
The cylinder block
and the crankcase.
What is the portion of the engine block that contains the cylinder bore?
The cylinder block
What portion of the enginr block contains the crankshaft?
The crank case
Which part is the major rotating part of the engine?
The Crankshaft
What is the straight line driving member of the engine?
The piston
what is the purpose of the piston?
To provide a seal between the combustion chamber and the crankcase.
How does the piston provide a seal between the combustion chamber and the crankcase
by grooves being cut into the piston near the top and piston rings being i stalled on the piston.
What would happen to the engine without piston rings?
The piston could not compress the fuel charge properly, and burning gases would leak out between the sides of the pisto and the cylunder wall.
How many piston rings do most pistons use?
Three
If a piston uses three rings; what two ring types do they usually consist of?
The upper two = compression rings.
The lower ring = an oil control ring.
What secures the piston to the connecting rod?
The piston pin
what attaches the piston to the crankshaft?
The connecting rod
How does the connecting rod attach the piston to the crankshaft?
The upper end has a hole that the piston pin is passed through.
The lower end has a large bearing that fits around the crankshaft journal.
What has to occur during normal engine operation?
A fresh air-fuel mixture must be admitted to the engine and once its burned , the waste products have to be exhausted.
How is the process of admitting a fresh air-fuel mixture into an engine then exhausting the waste products carried out?
By using ports that are alernately covered and exposed by the piston
( two-stroke cycle design)
or by using poppet valves to open and close the port openings ( four-stroke cycle design).
What is the purpose of a camshaft in four-stroke engines?
To open the valves the right amount at the right time.
What does the valve train consist of?
All of the components that work together to transform the rotation of the crankshaft into the opening and closing of the valves.
During the non power strokes, what keeps the crankshaft spinning and smoothes engine operation?
The inertia of the heavy flywheel
What do all small gasoline engines have
some provision for spinning the crankshaft during engine starting.
What are the two things that can be used as the provision for spinning the crankshaft during engine starting?
A recoil rope starter assembly or an electric starter
what do some small engines have to make hand cranking easier?
an automatic compression release mechanism on the camshaft
What does an automatic compression release mechanism on the camshaft do that makes hand cranking easier?
It lifts the exhaust valve slightly during cranking and releases part ofbthe compression pressure.
The two main sections of an engine block are the
A: Cylinder block and crankcase
Aluminum cylinder blocks sometimes cast around a(n)_______ sleeve
B: Steel
[True or False]
The crankshaft converts the reciprocating motion of the piston into rotary motion
True
All of the following are used as crankshaft main bearings, except_____________
C: Lip bearings
Each of the following is a type of crankshaft main bearing, except
D: groove
[True Or False]
The piston provides a seal between the crankcase and the combustion chamber.
True
Most pistons use ______ piston rings
C: Three
The ridges between the piston grooves are known as the piston__________
B: Lands
The piston______ keeps the piston from tipping from side to side
A: Skirt
[True or False]
Floating piston rings are installed with their end gaps aligned.
False
What are placed in grooves in the piston pin bosses to prevent full floating pins from rubbing on the cylinder surface.
B: Snap rings
A piston pin may turn in _____
A: Piston bosses
B: Bushings
C: needle bearings
______ Friction bearings are used in the big end of the connecting rod
D: All of the above
(True or False)
Antifriction bearings use rollers or balls to reduce friction between moving parts.
True
In two-stroke engines, the intake and exhaust ports are
alternately covered and exposed by the_______ as it moves up and down in the cylinder.
B: Piston
Four-stroke engines use_____
valves to open and close port openings.
Poppet?
Most small four-stroke engines contain a single camshaft with how many cam lobes for each valve?
A: one
(True or False)
The crankshaft turns the same speed as the camshaft
False
(True or False)
Automatic compressionà
