16 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
CHAPTER
1
Review and Assessment
Summary
• Agriculture includes producing food, fi ber, and fuel, in a sustainable manner, for the
global population.
• Agriscience applies scientifi c principles to improving agriculture through technology and
agricultural mechanics.
• Agricultural mechanics includes the design, construction, maintenance, repair,
management, and use of agricultural technology and mechanical systems.
• Over the years, agricultural mechanics and technology have changed agricultural
processes, making them more effi cient and better able to meet global needs.
• Math is an essential tool in the fi eld of agriculture and agricultural mechanics because it is
critical for solving problems related to equipment and technology.
• Work is the result of a force that pushes or pulls an object through a specifi c distance and
is equal to the force applied multiplied by the distance the object moved.
• Power is the rate at which work is done and is calculated by dividing the work performed
by the time required to do the work.
• A machine’s theoretical mechanical advantage is the ratio of the resistance or load to the
effort applied.
• The six simple machines on which all agricultural machinery is based are the lever, wheel
and axle, pulley, inclined plane, screw, and wedge.
Words to Know
Match the key terms from the lesson to the correct defi nition.
A. agricultural mechanics
B. agriculture
C. agriscience
D. effort
E. force
F. fulcrum
G. horsepower
H. inclined plane
I. internal combustion
engine
J. law of conservation
of energy
K. lever
L. machine
M. mechanical advantage
N. power
O. production agriculture
P. pulley
Q. resistance
R. screw
S. subsistence farming
T. wedge
U. wheel and axle
V. work
1. A fl at, sloping surface used as a ramp.
2. The ratio of the resistance force to the effort force of a machine.
252 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
Know and Understand
Answer the following questions using the information provided in this chapter.
1. What are some important considerations when choosing lumber pieces for use in an
agricultural project?
2. How do quarter-sawn lumber and plain-sawn lumber differ in the way they are cut?
Which type of lumber is most often used for agricultural projects?
3. True or False? It is important to store pressure-treated lumber indoors prior to use if it is
going to be used indoors.
4. Plywood and oriented strand board are both examples of _____ lumber.
5. What are some characteristics that infl uence the type of metal you would use for a
particular project?
6. In what ways do types of steel vary?
7. Each of the following is an example of a nonferrous metal, except _____.
A. aluminum
B. copper
C. iron
D. bronze
8. What are some of the most common nonferrous metals encountered in the agricultural
mechanics shop?
9. Why is copper widely used in plumbing?
10. What are some characteristics of concrete that make it useful for agricultural projects?
11. Why are thermoplastics commonly used in agricultural projects?
12. What are some qualities of thermoset plastics that make them important to the agricultural
industry?
13. What are fi ve common types of fasteners used for agricultural projects?
14. A _____ nail is very thin and has almost no head.
A. common
B. twisted shank
C. brad
D. cut
15. What are some reasons that drywall screws are used in various construction projects in
addition to drywall applications?
16. What is a washer and how is it used with a bolt to join materials?
17. Explain why a corrugated fastener would be used instead of a nail.
18. Briefl y explain why fl ush hinges may be used on many materials, including metal.
19. What is a piano hinge and in what type of application is a piano hinge used?
20. What is the function of a lockset and what are the main parts of a lockset?
Chapter 9 Materials, Fasteners, and Hardware 253
Copyright Goodheart-Willcox Co., Inc.
STEM Connections and Academic Activities
1. Science. Power tools often combine the principles of two or more of the six simple
machines (lever, screw, wheel and axle, pulley, wedge, and inclined plane). Observe the
operation of different types of power tools and try to identify which simple machines
are involved. For example, a circular saw combines the wheel and axle (rotating blade)
with the wedge (cutting teeth). Try to list as many tools as possible along with the simple
machines used.
2. Technology. Using special software, produce a podcast of an interview about composite
materials used in agricultural mechanics projects.
3. Engineering. Build a model (such as a gate, bridge, or box) using three distinct materials,
such as plastic, wood, metal, or composite. Destructively test each model, and record the
strengths and weaknesses of each material. Determine which material is best for building
a full-scale project of the model.
4. Math. Visit a local building supply center and obtain information and literature
concerning the various grades and species of lumber they normally carry. Prepare written
descriptions of the defects permitted in several of the grades commonly selected by
builders in the area. Obtain prices of these grades to gain some understanding of the
savings that can be gained by using a lower grade of lumber. Work out the difference in
cost between two grades of 2″ × 4″ boards if you were purchasing 50 boards that are each
8′ long. Make a report to your class on your fi ndings and conclusions.
5. Language Arts. List fi ve products other than lumber commonly used on construction sites.
Obtain a safety data sheet (SDS) for each product. An SDS can often be downloaded from
the Internet or obtained from a retailer that sells the product. An SDS might be available
in your school. Write a report on one of those products, explaining the information you
found on the SDS. Give recommendations for working with that product.
Thinking Critically
1. When choosing materials for a project, it is important to choose the best possible material
for the desired outcome. If you were building a box to hold tack, what would be the most
important criteria of the building material? Explain.
2. Explain which fastener would best be used in each of the following situations and give
supporting reasons for your choice.
A. Attaching two pieces of wood together
B. Attaching thin metal to wood
C. Attaching two pieces of plastic together
Chapter 1 Introduction to Agriculture and Agricultural Mechanics
15
Copyright Goodheart-Willcox Co., Inc.
advantage of an inclined plane is the ratio of the length of the
plane surface to the height change. For example, if the sloped
surface of the ramp in
Figure 1-10B
is 12′
long, and the high
end of the ramp is 3′
above ground level, the mechanical
advantage is 12:3, which equals 12 ÷
3 = 4.
Screw
The
screw
is an inclined plane wrapped around a
cylinder. This forms threads on a screw or bolt,
Figure 1-11 .
The pitch is the distance between the successive threads. The
smaller the pitch, the greater the holding force. The larger
the pitch, the more distance the screw moves with each
revolution around the cylinder. Technically, the mechanical
advantage of a screw is the ratio of the circumference of
the screw to the pitch. However, screws require a lever
(screwdriver) to turn them, so the mechanical advantage of
a screw takes the l
ever into consideration. The mechanical
advantage
is therefore calculated as the ratio of the
circumference of the handle of the screwdriver (rather than
the screw cylinder) to the pitch distance.
Wedge
The wedge
consists of two inclined planes placed back to
back to form two inclined surfaces that meet at a thin edge at
one end,
Figure 1-12
. The effort force is applied to the vertical
edge or height of the wedge rather than parallel to the slope.
The mechanical advantage of the wedge is the ratio of its
length to its thickness at the thick end. Wedges are often used
to separate or pry apart objects.
Thickness
Length
Inclined plane
Inclined plane
A
Goodheart-Willcox
Publisher
B
Designua/Shutterstock.com
Figure 1-12.
A—Dimensions used to
calculate mechanical advantage in a wedge.
B—Example of a wedge used to separate
wood fibers for splitting logs.
Force
B
Bryan
Eastham/Shutterstock.com
Figure 1-11.
A—Parts of a screw. B—Grain augers use a
screw-type mechanism to move
grain from one location to another.
Ridges
(narrow inclined
plane wrapped
around a cylinder)
Pitch
Cylindrical shaft
A
Designua/Shutterstock.com
xi
Illustrations have been designed to
clearly and simply communicate the
specific topic.
Words to
Know matching
activities reinforce
vocabulary
development
and retention.
All key terms are
included in the
text glossary and
are connected to
numerous online
review activities.
Know and
Understand
questions
allow you to
demonstrate
knowledge,
identification, and
comprehension
of chapter
material.
Summary feature
provides an
additional review
tool for you
and reinforces
key learning
objectives.
STEM and Academic Activities
extend your learning and help you
analyze and apply knowledge.
Thinking Critically questions develop
higher-order thinking, problem solving,
personal, and workplace skills.