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Simple Machines


What are simple machines?

Simple machines are mechanical devices that do not rely on electricity, or battery. They are basic devices used to reduce the effort that is used to move something. So, simple machines are used to make work easier. To be clearer, simple machines use the basic components of physics to make an activity that uses a lot of force easier by changing the size or direction of the force.

Simple Machines

Simple machines are also not automated, and must be manually controlled by a human. A simple machine’s purpose is to act against a force, support a weaker force or apply a force.

The use and creation of simple machines date back to the Stone Age. In the modern-day world simple machines are a moderate part of life, even if you do not notice. In this lesson we will learn about simple machines, their uses, their origins, and the fundamentals of how it works.

 

What are the types of simple machines?

Almost every machine is created using the concepts of simple machines. They have all different uses. However, there are basically six main types of simple machines.

 

Types of simple machines

  • Lever
  • Wheel and axle
  • Pulley
  • Inclined Plane
  • Wedge
  • Screw

 

Lever

A lever is a rigid beam consists of three parts: fulcrum, effort and load. Levers are simple machines that are used to transfer force. So, the lever is one of the most important simple machines in the mechanical world. The great mathematician Archimedes once said: ’give me a place to stand and I shall move the earth’. Though this sounds absurd it is possible. The lever’s purpose is to lift heavy loads without too much effort.

 

Simple Machines - Lever

 

Have you noticed that you use levers every day without your knowledge?

Following is a list of different Types of Levers that we use in our day-to-day life.

 

The pulley’s job is to minimize the amount of human effort to carry a significant load. The more pulleys used you increase your mechanical advantage and decrease the amount of effort you use on the same load.

 

Examples of levers

  • A pair of scissors
  • A crowbar
  • A claw hammer
  • A see-saw (teeter-totter)
  • A weighing balance
  • The break paddle of a vehicle
  • A wheelbarrow
  • A bottle opener
  • A nutcracker
  • A nail cutter
  • An oar
  • A pair of tweezers
  • A pair of barbeque tongs
  • A broom
  • A fishing rod
  • A staple-remover
  • A stapler

 

All the above mentioned examples of levers are grouped into three main types of levers.

 

Types of levers

  • First class levers (Type 1 levers)
  • Second class levers (Type 2 levers)
  • Third class levers (Type 3 levers)

 

Want to know more about levers?

For more information about different type of levers, read the lesson ‘Types of levers’.

 

Wheel and axle

The wheel and axle is an axle with the wheel fixed onto it that rotates simultaneously.

 

Wheel and Axle

 

When we are required to move a heavy load, sometimes human strength is not sufficient. In this case the simple machine, wheel and axle, has a very important role to play. Sometimes human strength cannot oppose a force called friction. Friction is a force that resists the movement of an object on the ground (Read the lesson ‘Friction’). Another problem is gravity. Gravity is the force that pulls an object down to the ground (Read the lesson ‘Gravity’). Those two forces together make it a hard challenge to move a heavy load. The wheel and axle reduces the friction applied on the object and decreases the amount of effort.

 

One of the most significant inventions in history is the wheel as it has been indispensable to life since it was found first. However, the wheel needs the axel to work. The wheel and axle, according to historians, dates back more than 5,500 years and was most likely invented in the Middle East or Eastern Europe. Little by little people use the advantage of wheel and axel to make it easier to transport heavy loads on carts drawn by people or animals. Since then, cogs have been added to the wheel to create gear wheels and then more complex machines have been created.

 

The wheel and axle is probably utilised the most as you can see them everywhere.

 

Examples of wheel and axle

  • Wheels on cars
  • Wheels on Bikes
  • Wheels on toys vehicles
  • Wheels on skateboards
  • Wheels on rollerblades
  • Wheels on shopping carts/trolleys
  • Screwdriver
  • Doorknob
  • Ferris wheels
  • Merry-go-round
  • Table fan
  • Potter’s wheel
  • Pipes
  • A steering wheel
  • Gears
  • In-line skates

 

A wheel and axle can help move things basically in two different ways: the force is applied to the wheel and the force is applied to the axel. Look at the following examples.

 

Screwdriver

In a screwdriver, the handle acts as the wheel where the force is applied. It rotates or turns, increasing the force on the shaft or axle, which aids in the rotation of the screw. This is an example for where the force is applied to the wheel.

 

Doorknob

When a doorknob is turned, force is applied to the wheel in another way. When the wheel (doorknob) is turned, the locking mechanism attached to the shaft turns, allowing the door to be opened. This is also an example for where the force is applied to the wheel.

 

Ferris wheel

In a Ferris wheel, when the axle rotates, the giant wheel rotates as well. The wheel is larger than the axle and covers a larger area and distance. This is an example for where the force is applied to the axel. A table fan operates in the same manner.

 

Wheelbarrows

Wheelbarrows excellently combine wheels and levers. A wheelbarrow makes transporting a load from one location to another extremely simple. Its long frame acts as a lever, making the load much easier to lift. Pushing the load with a wheelbarrow is easier because the only friction is between the wheel and the axle. The friction would be much higher if you pushed the load across the rough surface of the ground without using a wheelbarrow.

 

Gears

Gears are special wheels with teeth on the outside of the wheel called threads. Axles are also required for gears. The gears come in a variety of sizes and are arranged with their teeth interlocking. Smaller gears are turned by larger gears.

 

Bicycles, which also use a force applied to the axle to help its wheels move, have gears. Bicycles use gears in both directions. You don’t have to work as hard if you use gears to increase your force when you pedal up a hill. However, they also reduce your speed. You can use gears to increase your speed when racing on a straight road, but the catch is that they reduce your force.

 

Wheels can multiply distance, speed, and force. To multiply force, large wheels are used in several ways as follows.

 

Pipes

Stop valves are wheels that are attached to pipes. When the outer rim of a stop valve is turned, the inner axle turns with much more force, making it easier to close the pipe.

 

Steering wheels

Steering wheels work in the same way. Because it takes more force to turn the wheels of a truck or bus, the steering wheel is usually larger than that of a car. The larger wheel provides the driver with more leverage.

 

Bicycles

Bicycles have large wheels that allow them to travel faster. When you pedal, you are supplying power to the inside of the wheel. However, because the outer rim of the wheel rotates faster and covers more ground, your pedaling has a much greater effect. The same is true for car wheels.

 

Pulley

The pulley’s purpose is to reduce the effort used to put something up or to put something down. The basic pulley consists of a wheel fixed on an axle, with a grove on the wheel to guide a rope or a cable.

 

The pulley is another popular simple machine in the mechanical world. The use of pulleys dates to the ancient Egyptian times when they wanted to lift heavy things up or down during construction.

 

The pulley makes the job easier either by reducing the effort required to lift a load or the direction in which the force must be applied to move the load or both—reducing the force required and the direction.

 

The pulley minimizes the amount of human effort to carry a significant load. The more pulleys you use, the more you increase your mechanical advantage and decrease the amount of effort you use on the same load. This means by increasing the number of pulleys in the setup, you can double the effectiveness of a pulley system.

 

Single pulley system

A simple or single pulley system is any lifting set up that only has one pulley. A single pulley system does not reduce the amount of force required to move the load, because the effort required in a single pulley system is equal to the weight of the load to be moved. However, a single pulley system changes the direction in which the load must be moved, and because of this the load can be lifted to a height, lowered from a depth, or transported to a position other than where the effort is applied.

 

Single Pulley System

 

Double pulley system

A double pulley system has two pulleys. The effort required with this pulley system is only half that of the load, but the rope must travel twice as far to complete the same amount of work. Double pulleys are useful for lifting objects that are too heavy for one person to lift on a single pulley.

 

Double Pulley System

 

Multiple pulley system

A multiple pulley system has a number of pulleys. When three pulleys are used in a multiple pulley system, the effort required to move the load is only one-quarter of the load, and the rope or cable hast to move four times the distance.

 

Multiple Pulley System

 

Basically there are three main types of pulleys:

 

Types of pulleys

  • Fixed pulleys
  • Movable pulleys
  • Compound pulleys
  •  

  • Block and tackle pulleys
  • Conveyor pulleys
  • Cone pulleys are some enhanced versions of pulleys

 

Fixed pulleys

The most common and simple type is the fixed pulley. This type of a pulley should be fixed, and it remains in a constant position during its operation. A fixed pulley is usually attached to a wall, ceiling, or other immovable platform. Once you install a fixed pulley, unless you remove it and replace it, the pulley will remain in that place permanently.

 

Fixed pulleys have zero efficiency, because the amount of pressure or force applied on the pulling side and the lifting side is the same. However, most industries and workshops still use fixed pulley systems. Two good examples of fixed pulleys are flagpoles and blinds on windows.

 

Movable pulleys

As its name implies, a movable pulley can move from its position. This standard makes them perfect for a wide range of applications in many heavy lifting industries.

 

Since the movable pulley moves with the load, the force used to pull the pulley multiplies on the lifting side. The pulley is attached to the object that is being lifted and detached it once the lifting is done. The direction of the object cannot be changed.

 

Movable pulleys are ideal for lifting heavy loads due to its efficiency, and used in construction cranes and utility elevators.

 

Compound pulleys

The combination of a fixed pulley and a movable pulley is called a compound pulley. These pulleys combine the benefits of both fixed and mobile pulleys into a single system. As a result, the fixed pulley can change direction while the moveable pulley can multiply the pulling power.

 

The block and tackle pulley

The block and tackle pulley is an example for a compound pulley. These pulleys are ideal for sailboats, car garages, boat lifts, construction and workshops where large objects are frequently lifted.

 

Conveyor pulleys

Conveyor pulleys are used in conveyor belts.

 

The cone pulley

The cone pulley is made up of numerous pulley wheels stacked on top of one another, the smallest at the top. As a result, the pulley system resembles a cone. These pulleys work in the same way that gear-driven bicycles do.

 

Examples of pulleys

  • Cranes
  • Wells
  • Elevators
  • Escalators
  • Flagpoles
  • Blinds on windows
  • Garage doors
  • Cargo lift system
  • Exercise equipment
  • Construction equipment
  • Theatre curtains
  • Sails on sailboats
  • Car timing belts

 

Inclined plane

The inclined plane is a ramp that supports heavy loads moving upwards and downwards easily with less force. A flat, smooth and even surface is positioned at a right-angle triangle to make an inclined plane. The steeper the inclined plane, the harder it is to push the object up, which means more effort is required to move the load upwards.

 

Inclined Plane

 

Evidences have been found that in the ancient Egyptian times, the inclined plane was used to construct great monuments and pyramids.

 

Examples of the inclined plane:

  • Disability ramp
  • Playground slides
  • Escalators

 

Wedge

A wedge is basically two portable inclined planes joined together. It is a triangular shaped tool and another most used simple machines. Wedges are made of metal, stone, wood, or plastic and can be single wedges or double wedges. They come in a variety of sizes and are usually equipped with handles.

 

When you apply force on a wedge it can cut an object or split through it by changing direction. Wedges can also support an object, leave an object up and keep an object stationary.

 

Simple machines - Wedge

 

Examples of wedges:

  • Metal nails
  • Axe
  • Knife
  • Door-stoppers
  • Scissors
  • Chisel

 

Screw

The screw is also one of the most used simple machines in the world of mechanics. Its purpose is to change rotary motion into linear motion.

 

The screw consists of a long metal shaft with threads spiraling along its length. A screw has the same spacing between threads, which is called a ‘pitch’. Different screws have different spacing between threads. When the angle of the spiral rises, the screw’s mechanical advantage increases.

 

Simple Machines - The Screw

 

The screw has a lot of importance in the mechanical age. The screw can hold things together, pull or push an object together, lift heavy loads, drill holes on objects and tighten things.

 

Examples of screws:

  • The screw
  • Drill bit
  • Nut and bolt
  • Car jack
  • Grooves on bottle, jar and can tops
  • Grooves on bottle, jar, can lids
  • End of light bulbs
  • Guitar tuners
  • Coke openers
  • Tap faucet

 

The screw

The shaft of a screw has ridges all the way around it. Because the ridges on the screw create a lot of friction and resistance, driving a screw into a piece of wood is more difficult. A screw-driver must move in a circular motion to drive a screw into the wood.

 

Bolts

A bolt is similar to a screw, however it lacks the pointed tip. A bolt is not drilled into place; instead, a hole is drilled for it to pass through. The bolt is then screwed through with the help of a nut. Bolts have a lot of power when it comes to binding things together.

 

Drill bit

When used with an electric drill, it is a type of screw that can drill holes in wood, plastic, metal, and stones. It has threads and is pointed at one end, just like a conventional drill. The drill bit features deeper grooves that convey wood fragments from the hole to the surface as it rotates.

 

Compound machines

In most cases machines comprise not only one simple machine but multiple. We call these machines compound machines. Almost all machines are compound.

 

For example, one of the most used machines, the car, includes all the simple machines:

 

Lever

Inside the car the driver uses a break called the hand break. The driver must manually lift the lever to make sure the car doesn’t slide down a slanted surface.

 

Wheel and axle

It’s obvious that the car has the wheel and axle as without it the car will not move.

 

Pulley

In the ICE (internal combustion engine) the timing belt uses the concept of the pulley. Without it the car would completely stop.

 

Inclined plane

The camshaft lobe is and inclined plane the works in the mechanism of the ICE (internal combustion engine).

 

Wedge

Modern day cars use a wedge shaped body to be slicker and go faster.

 

Screw

To hold a car together there are screws placed in multiple places.