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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

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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
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