ABSTRACT
Wheelbarrow is a simple machine, which belong to the second-class lever.
This is because the load or resistance is placed between the effort and the
fulcrum. It is used in many areas of work to convey loads that are too heavy or
bulky to be carried by hand. Wheelbarrow can be used as farm equipment,
industrial equipment among others.
However, the efficiency of the wheelbarrow depends on the materials used
for the construction. A wrong choice of these materials can reduce the
efficiency and the life span of the machine.
Although no machine can operated with 100 percent efficiency because the
friction of its parts always use up some of the energy that is being supplied
to the machine. But friction can be decreased by oiling any sliding or rotating
parts.
Moreover, depending on the type/size of machine to be constructed, the
materials are reduced to smaller and more convenient sizes. The shapes and
forms are changed by the following constructional operations, marking out,
cutting, drilling, filling, recurring, taping broaching, folding/bending,
welding, surface coating etc.
Most of these operations may be carried out by use of manual or
mechanized processes depending on the size of the workshop.
In conclusion, a fixed amount of load was placed on the wheelbarrow to
determine the efficiency and the effort required to lift the load. And
according to the result gotten, the machine is highly efficient and required a
very small effort to move objects many times their own size.
TABLE
OF CONTENT
Title page
Dedication
Acknowledgement
Letter of
transmittal
Abstract
Table of
contents
CHAPTER
ONE
INTRODUCTION
1.1 History/origin
1.2 Machine
1.3 Principles of machines
1.4 Efficiency
1.5 Mechanical advantage
1.6 Simple machine
1.7 Lever
CHAPTER
TWO
LITERATURE REVIEW
2.1 Science of material
2.2 Properties of material
2.2 Alloy designation
CHAPTER
THREE
3.1 Material selection
3.2 Basic machine tool operation
3.3 Metal removal
3.4 Metal forming
3.5 Construction method
3.6 Autographic drawing
CHAPTER
FOUR
4.1 Calculation
4.2 Cost evaluation
CHAPTER
FIVE
5.1 Discussion
5.2 Recommendations
5.3 Conclusion
5.4 Reference
Appendix
CHAPTER ONE
INTRODUCTION
HISTORY/ORIGIN
Archimedes, a Greek, was also a physicist and a
mechanical engineer who proved the law of the lever and invented the compound
pulley. With these machines, it is possible to move a great weight with a small
force. Archimedes reportedly once boasted, “give me a place to stand on, and I
will move the entire earthâ€.
He was
referring to the way levers and pulleys can help people move objects many times
their own size. He proved this law of pulley by using a system of pulleys to
move a ship fully loaded with goods and passengers.
In his
investigations of force and motion, Archimedes also discovered that every
object has a center of gravity and the force acting on this point must be
conquered before the body will be moved or lifted. This is because it is a
single point at which the force of gravity appears to act on the object.
MACHINE
A machine is a device that does
work. They are designed to make life easier for us. Some machines perform tasks
that would be impossible to do without them. We use machines all the time,
industries use them in lifting and moving very heavy loads. Without machines,
the residents of our cities would find it more difficult to live, and farmers
could not raise enough food to feed us.
Engineers have constructed a wide
variety of machines to satify their needs. Early people made stone axes that
served as weapons and tools. The machines that were gradually developed gave
people great control over their environment.
PRINCIPLES OF MACHINE
A machine produces force and
controls the direction and the motion of the force. But it cannot create
energy. A machine can never do more work than the energy put into it. It only
transforms one kind of energy, such as electrical energy, and passes it along
as mechanical energy. Some machines, such as chisel engines or steam turbines,
change energy directly into mechanical motion other machines, such as simple
machines, simply transmit mechanical work from one part of a device to another
part.
A machine’s ability to do work is
measured by two factors. They include Efficiency and Mechanical Advantage.
EFFICIENCY
The efficiency of a machine is
the ratio between the energy it supplies and the energy put into it. No
machines can operate with 100 percent efficiency because the friction of its
parts always uses up some of the energy that is being supplied to the machine.
Although friction can be
decreased by oiling any sliding or rotating parts, all machines produce some
friction. For this reason, a perpetual motion machine is impossible.
A simple lever is a good example
of a machine that has a high efficiency. The work it puts out is almost equal
to the energy it receives, because the energy used up by friction is quite
small. On the other, an automobile engine has an efficiency of only about 25 percent, because much of the
energy supplied by the fuel is lost in the form of heat that escapes into the
surrounding air.
MECHANICAL ADVANTAGE
In machines that transmit only
mechanical energy, the ratio of the force exerted by the machine to the force
applied to the machine is known as Mechanical Advantage. Mechanical
advantage can be demonstrated with a crowbar, which is a type of lever. When
one end of the crowbar is directly under the weight, a part of the crowbar must
rest on a FULCRUM (support). The closer the fulcrum is to the load, the less
the effort required to raise the load by pushing down on the handle of the
crowbar, and the grater the mechanical advantage of the crowbar.
For example, if the load is kilograms, and the
distance from the load to the fulcrum is one fourth of the distance from the
handle to the fulcrum, it will take 50 kilograms of effort to raise the load.
Therefore, the mechanical advantage will be four to one. But the distance to
the load moved will be only one fourth of the distance through which the effort
is applied.
SIX SIMPLE MACHINES
Most machines consist of a number of elements, such as
gears and ball bearing, that work together in a complex way. But no matte how
complex they are, all machines are based in some way on six types of simple
machines. These six types of machines are the lever, the wheel and axle, the
pulley, the inclined plane, the wedge, and the screw.
LEVER
Lever is one of the six simple
machines for performing work. It consist of a rod or bar that rests and turns
on a support called a FULCRUM. A force of effort is applied at one end of the
rod to lift a load placed at the other end. The distance between the fulcrum
and the load is the LOAD ARM. The distance from the fulcrum to applied force is
the EFFORT ARM.
A lever can help lift a weight
with less effort. Prying something loose with a crowbar is using a lever. Some
machines, such as a catapult use a lever to hurl objects.
CLASSES OF LEVERS
FIRST CLASS LEVERS
This class of levers have the fulcrum placed between the
load and the effort, as in the seesaw, crowbar, and balance scale. If the two
arms of the lever are of equal length, the effort must be equal to the load. To
lift 10 pounds, an effort of 10 pounds must be used. If the effort arm is
longer than the load arm, as in the crowbar, the effort travels further and in
less than the load. A pain of scissors is a double lever of the first class.
SECOND CLASS LEVERS
These have the load between the effort and the fulcrum. A
wheel barrow is a second-class lever. The axle of the wheel is the fulcrum, the
handles take the effort, and the toad in placed between them. The effort
travels a greater distance and is less than the load. A nutcracker is a double
lever of this class.
THIRD CLASS LEVERS
These are simple machines that have the effort placed
between the load and the fulcrum. The effort always travels a shorter distance
and must be greater than the load. The FOREARM is a third-class lever. The hand
holding the weight is lifted by the bicepd muscle of the upper arm which is
attached to the forearm near the elbow. The elbow joint is the fulcrum.
COMPUND LEVERS
In a compound lever simple machine, two or more levers are
combined, usually to decrease the effort. By applying the principle of the
compound lever, a person could used the weight of one hand to balance a load
weighing a ton.
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