<< Chapter < Page Chapter >> Page >
The simple mechanical elements that comprise complex machines, like robots, are described.

Complex machines are made up of moving parts such as levers, gears, cams, cranks, springs, belts, andwheels. Machines deliver a certain type of movement to a desired location from an input force applied somewhere else. Somemachines simply convert one type of motion to another type, such as rotary to linear. While there is a seemingly endless varietyof machines, they are all based upon simple machine elements. The elements discussed here include inclined planes, levers, wheels and axles,pulleys, and screws.

It is important to remember that all machines are limited in their efficiency by friction. No machine is 100 percent efficientin its efforts, so the mechanical advantage gained will require additional energy to accomplish the task. For more information on friction, see this module

The inclined plane

An inclined plane decreases the force required to raise an object a given height byincreasing the distance over which that force must be applied, see . Imagine lifting something twice your weight to a 4 foot high shelf. Now imagine rolling the same mass up a gentlysloping surface. The latter would be much easier. Inclined planes are commonly put to use in cutting devices and oftentwo inclined planes are put back to back to form a wedge. In a wedge, forward movement is converted into a parting movementacting perpendicular to the face of the blade. A zipper is simply a combination of two lower wedges for closing and an upper wedge for opening, as shown in .

Inclined Plane
The Inclined Plane at Work

The screw

The Screw

The screw is basically an inclined plane (see ) wrapped around a cylinder. In an inclined plane, a linear force in thehorizontal plane is converted to a vertical "lifting" force. With a screw, a rotary force in the horizontal plane isconverted to a vertical "lifting" force.

When a wood screw is turned, the threads of the screw push up on the wood. A reaction force from the woodpushes back down on the screw threads and in this way the screw moves down even though the force of turning the screw isin the horizontal plane. Screws are known for high friction, which is why they are used to hold things together. A worm gear is sometimes used in machines, but they also have high friction that can waste considerable power.


A lever has three points of interest: the fulcrum, the load, and the effort applied to the lever. The fulcrum is the point around which the lever pivots rotationally. The load is what we wish to manipulate with the lever, and the load is described by its position relative to the fulcrum, and the force (magnitude and direction) it exerts at that point.The effort is also a force that has a magnitude and a direction, and a position with respect to the fulcrum. A leveris used to change the direction of movement, and to trade the magnitude of the effort for the distance over whichthe effort is applied.

Classes of Levers

Questions & Answers

What is the law of demand
Yaw Reply
price increase demand decrease...price decrease demand increase
ıf the price increase the demand decrease and if the demand increase the price decrease
all other things being equal, an increase in demand causes a decrease in supply and vice versa
how is the economy of usa now
What is demand
jude Reply
Demand is the quantity of goods and services a consumer is willing and able to purchase at various prices over a given period of time.
Okay congratulations I'll join you guys later .
calculate elasticity of income exercises
If potatoes cost Jane $1 per kilogram and she has $5 that could possibly spend on potatoes or other items. If she feels that the first kilogram of potatoes is worth $1.50, the second kilogram is worth$1.14, the third is worth $1.05 and subsequent kilograms are worth $0.30, how many kilograms of potatoes will she purchase? What if she only had $2 to spend?
Susan Reply
cause of poverty in urban
DAVY Reply
QI: (A) Asume the following cost data are for a purely competitive producer: At a product price Of $56. will this firm produce in the short run? Why Why not? If it is preferable to produce, what will be the profit-maximizing Or loss-minimizing Output? Explain. What economic profit or loss will the
Falak Reply
what is money
DAVY Reply
money is any asset that is generally acceptable for the exchange of goods and for the settlement of debts
what is economic
Stephen Reply
economics is the study of ways in which people use resources to satisfy their wants
what is Price mechanism
Dhany Reply
what is Economics
The study of resource allocation,distribution and consumption.
introduction to economics
Uday Reply
welfare definition of economics
examine the wealth and welfare definitions of economics
read book by ml jhingan
What do we mean by Asian tigers
Aeesha Reply
Dm me I will tell u
What is Average revenue
How are u doing
it is so fantastic
it is a group of 4 countries named Singapore, South Korea, Taiwan and Hong Kong because their economies are growing very faster
Please, average revenue is an amount of money you gained after deducted your total expenditure from your total income.
what's a demand
Edward Reply
it is the quantity of commodities that consumers are willing and able to purchase at particular prices and at a given time
quantity of commodities dgat consumers are willing to pat at particular price
demand depends upon 2 things 1wish to buy 2 have purchasing power of that deserving commodity except any from both can't be said demand.
Demand is a various quantity of a commodities that a consumer is willing and able to buy at a particular price within a given period of time. All other things been equal.
State the law of demand
The desire to get something is called demand.
what is the use of something should pay for its opportunity foregone to indicate?
Random Reply
Why in monopoly does the firm maximize profits when its marginal revenue equals marginal cost
astrid Reply
different between economic n history
Falma Reply
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play

Source:  OpenStax, An introduction to mechanical engineering for high school students. OpenStax CNX. Feb 08, 2009 Download for free at http://cnx.org/content/col10640/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'An introduction to mechanical engineering for high school students' conversation and receive update notifications?