Internal Memorandum
To: ENGR 100 Students
From: ENGR 100 Instruction Team
Date: Today's Date
Subject: Group Engine Questions
Purpose
The purpose of this assignment is to help students learn the basics of how an engine works in preparation for writing the individual reports.
Group Assignment
Each team should answer the following questions together and turn in one copy for the entire team. Note: the questions also appear as part of the Engine Handout. Please ask the instructor or TA if you have any questions:
Engine
Questions
(1)
What is
the purpose of the starter clutch? Explain from your examination how it does its
job.
(2)
Why is
there a cylinder shroud? What specific function does it serve?
(3)
From
reading the appropriate sections of the repair manual, describe in general how
the carburetor works.
(4)
What is
the function of the choke and how does it work?
(5)
Describe
in general how fuel manages to get ignited in your engine (i.e. the ignition
system).
(6)
At what
point(s) in the four-stroke cycle does a spark occur? How often does the spark
plug spark? Does every spark result in combustion?
(7)
Locate
the intake and exhaust valves. Which one is larger? Why?
(8)
Where are
the timing marks on the camshaft and crankshaft gears? How can you tell if the
timing is correct? Why is this important?
(9)
Why is
the cam shaft made of nylon? Refer to US
Patent# 5,497,679 to find out.
(10)
When was
the nylon camshaft in your engine manufactured? How can you tell?
(11)
What are
tappets, and what is their function?
(12)
On the
camshaft there is a small metal piece, including a spring, that is connected
where the gear meets the shaft. Looking at the relation between the tappets and
cams, can you guess what purpose it might serve? Try putting the tappets and the
camshaft back into the engine, rotate the cam through its motions, and see if
you can figure it out. You can also refer to the
patent.
(13)
What
types of materials are used on the flywheel? Why does the flywheel have one
section made from a different material?
(14)
What is
the purpose of the flywheel? How much does it weigh? What would be the
advantages and disadvantages of making it heavier? Why does it have fan-like
vanes on it?
(15)
What type
of bearings does the crankshaft use? How do these bearings avoid becoming worn
out?
(16)
What is
the purpose of the rings on the piston and why is there more than one ring? (if
you did not remove the piston, look at one of the disassembled pistons in the
lab)
(17) Print out and turn in horse power spreadsheet. Explain in a couple sentences how horsepower is calculated.