All About Pulleys
What Is A Pulley?
A Pulley is regarded as a simple machine, which we use to move or lift heavy objects.
Although it is described as a simple machine because of its basic design which simply consists of a wheel and a rope surrounding the wheel, after the invention of pulleys various different upgrades were made to make it more effective.
Depending on the design and the placement of the wheel, a pulley can either provide a huge mechanical benefit that will allow you to lift heavy objects with significantly less effort or it will allow you to apply a same amount of force in various different directions.
There are also other pulley systems which may provide you both of these benefits.
So, it can be said that a pulley is simply a wheel with grooves on it, a belt or rope wraps around the wheel while the groove is used so that the belt or rope stays in one place.
A pulley system is generally used to lift or lower down heavy objects.
When you are using a pulley to lift an object, you need to tie the object with the one side of the rope and apply the necessary force to the other side of the rope by pulling the rope downwards, the downward force on the rope moves the wheel and lifts the object.
But this is just the working principle of a pulley. It is so popular and effective because of the mechanical advantage it provides, cutting your effort in half by lifting double the weight.
What Types Of Pulleys Are There?
There are basically three types of Pulleys…
It is the most common type of pulley and as the name suggests they are fixed in a single position.
This stationary type of pulley is usually attached to a wall or ceiling or any hard surface and the belt usually wraps around the pulley.
The force will only be applied to the side you are pulling from as the pulley is fixed but an equal amount of force will be exerted on the opposite side of the pulley.
A Fixed Pulley is very important, not because it can exert the same amount you are applying but because it can change the direction of the object you are lifting, which can be very helpful in certain scenarios.
This is a completely different kind of pulley. In this case, the pulley itself moves with a supporting load. The work of the Movable Pulley is also very different as it multiplies the force of the user applied to the machine.
Usually, this kind of pulleys is mainly attached to the objects whereas, in case of a Fixed Pulley, it is generally attached to something stationary. The Movable Pulley is not able to change the direction of the object but it is very effective as it can help to multiply the applied force to the opposite side of the user.
This kind of pulley is very useful if you are lifting a heavy object, as the force gets multiplied during the process and you are able to lift the object with less work.
The Compound Pulley system cannot be identified as a completely different system from Movable Pulley or Fixed Pulley but it is a combination of both the Pulley systems.
This is the most advanced pulley system among the three and Compound Pulley is able to lift heaviest of objects with just a little effort. The reason why this kind of pulley system is so effective is its multiplication force, which is far greater than any simple Movable Pulley system.
The Compound Pulley system can not only change the direction of the loaded object but a heavy object can be easily lifted with very little force applied by the user.
The above three categories are the fundamentals of a pulley system.
The Fixed Pulley, Movable Pulley, and the Compound Pulley are the three basic kinds of pulley system. The modern and the most advanced pulley systems to date are based on these three.
Block and Tackle
A Block and Tackle can be defined as a more advanced form of Compound Pulley system. It can reduce the applied force dramatically when you are moving a heavy object.
The Block and Tackle Pulley system consists of various Fixed and Movable Pulleys which are placed parallel to each other.
Fixed Pulleys are always aligned with other Fixed Pulleys while the Movable Pulleys are with aligned with other Movable Pulleys respectively.
So, these Fixed and Movable Pulleys makes a pair and each pair is attached to the next pair. Each of these compound pairs of pulleys reduces the required force to get the work done easily.
This particular pulley system was invented by the famous inventor and mathematician named Archimedes.
The Cone Pulley system is another upgraded pulley system. Here, the basic mechanics of a simple system are applied and there are spaces for various mechanical adjustments.
So, the Cone Pulley system consists of multiple pulley wheels attached to the top of one another, but as the height increases the circumference decreases; essentially forming a cone shape. Surprisingly this cone shape allows the user to control or even change the speed of the pulleys as the smaller the wheel gets, the applied force gets reduced, that also means the amount of work produced also gets reduced.
There are many types of bicycles available in the market which are made with multiple gears.
Their principle of operation is same as the Cone Pulley system. Here the user can change the gear to the smaller shaft to make the bike move slower. The bigger shafts without any doubt require huge effort but it also makes the bike move greater distances in a short amount of time.
The History Of The Pulley
Pulley is one of the most used simple machines, and without them, we cannot imagine our modern lifestyle.
Although the origin of the pulley system is not known, historians have proved that in 1500 BC the people of Mesopotamia were using pulley systems for bringing in water from deep wells.
The very first documented use of a Compound Pulley system or also known as a Block and Tackle system was made by the great inventor and mathematician Archimedes. So, based on this evidence, many historians said that the famous Stonehenge in the UK was built with the help of pulleys.
The basic principle of a pulley is to change the direction of the applied force and reducing the effort applied. Simply said, if you are using two pulleys to lift an object, you will only need to apply half of the force compared to lifting it with only one pulley.
The measurement of the belt is also important; like if you are lifting the object one-meter-high then you will need a two-meter rope.
There is a term used for a pulley system called Mechanical Advantage, which can be increased just by adding more pulleys in a Block and Tackle system.
Today, the Pulley system has come a long way after various specified upgrades but there are three basic kinds of Pulleys; this is where it all began…
1. Fixed Pulley with the mechanical advantage of 1.
2. Movable Pulley with the mechanical advantage of 2.
3. Compound Pulley which is a combination previous two pulleys. Here, the mechanical advantage is equal to the number of pulleys used.
The creation of the pulley system as we can see the Pulley system has been very useful over the years.
It also gave birth to Cranes. The very first time history recorded the use of a crane in ancient Greece was late 6th century BC.
Now, Cranes are a very important piece of machinery used for construction and demolition. There are also a few other applications of this equipment.
What Is A Pulley System?
Very simply, a pulley system helps to lift a heavy object and it also acts as a lever. While only a single pulley has the power to change the direction of the applied force.
When you go for two or more pulleys in a single system, the applied effort gets multiplied, also changing the direction of the force.
If you are using a Fixed Pulley and a Movable Pulley in a single system, which is called a Compound Pulley system, it reduces the effort in half.
• It is a simple machine
First of all, a pulley is known as one of the 6 simple machines present.
A pulley has two arms of equal length and the wheel in the center works more or less like a lever. The wheel has grooves to hold a rope or belt in one place.
When a pulley is hanging from the roof and a strong belt or rope of double the length of the height is wrapped around the wheel, it will help you to lift heavy objects with half the effort compared to, if you had to lift the object with your hands.
• Provides a mechanical advantage
The main working principle of a pulley is the mechanical advantage it provides. Needless to say that when you are operating a pulley it makes you stronger than you actually are in real life!
The increased strength is only dependent on the mechanical advantage provided by the pulley.
Physicists are able to calculate the mechanical advantage of a specific pulley in Newton, the name derived from the great physicist Sir Isaac Newton. He was the one who gave us the Laws of Motion.
As per the laws, you need just 1 Newton of force to move or lift 1 kg of mass. The rate is 1 square meter per second in the direction of the force that is applied.
• Fixed and Movable Pulley
If you are using a pulley system where you are using only one pulley, then you will only have to apply slightly less force compared to if you were lifting that same object by hands. But if you combined a Fixed Pulley with a Movable Pulley in a system, then the applied force would be doubled and it will be even easier and faster to lift the object.
• The Pulley System
Essentially, the job of a pulley is to make your life easier.
As a single pulley will not only make you move a heavy load with half the required force; but also, if you apply a system of pulleys, then the mechanical advantage increases exponentially. This will be equal to the number of pulleys in the system and the length of the belts. The number of belt strands involved in the system is also important as if you are using 2 Fixed and 2 Movable Pulley in the system then you will need 4 lengths of rope just to support the weight of the object and that takes the mechanical advantage to 4.
So, you will need to apply only 25 Newton of force to lift a load of 100 Newton.
What Are Pulleys Used For?
Pulley is a simple system that revolutionized the civilization. Science has given us many things and no longer lifting heavy things is tough; except when we are in the gym.
So, jokes apart, when it comes to the uses or applications of pulleys, it can be safely said that it is everywhere.
From the most simple machines to the most complicated machines we use pulleys everywhere and even in our daily lives.
When talking about the uses of pulleys, the most obvious things that come to our minds are Cranes and Boats. But there are other uses as well, unfortunately, most of the times we do not pay any attention.
The most basic application of pulley is to gather water from the well.
This practice has been going on since the invention of the machine. We use pulley system on our garage doors, curtains on the theatres and if you want to go for the biggest applications; you can look at our modern vehicles and industries.
We also use pulleys in the gym to lift weights safely.
Some of the most common pulley uses are…
• As mentioned previously, Well pulley system has been used for ages.
• The modern elevator can lift more than 5 people against gravity all thanks to the pulley system.
• You can find uses of a pulley in the gym you are visiting.
• The Flagpoles or the sales of a Sailboat use a pulley system to get the work done easily.
• You can also find various different uses of pulley system applications in industrial machines.
Where Do We Use Pulleys And What Fields Of Work Do We Use Them In?
Pulley is a simple machine specifically designed to increase the strength and efficiency of the user with the help of a wheel and rope, belt or a chain. This is a very useful piece of machinery used by many advanced machines till date. If you carefully gaze around you, uses of a Pulley can be found everywhere such as.
Elevators are a modern piece of machinery, used on almost every high-rise building all over the world.
But what is an elevator? It is basically a Pulley! The modern elevators use a very powerful electronic pulley system. The elevators use a number of pulleys and various counterweights just to lift the whole cube with safety and power. Although various capable building designers use their creativity to build different variations of elevators, the basic principle stays the same.
If you ever visit a building with a see-through elevator shaft, you will see the big and thick cables, which are made of steel and several counterweights supporting the elevator system.
Although the concept of wells is very old-fashioned and you won’t be able to find them anywhere in the modern cities but wells have been a big part of our civilization since the ancient times.
These wells are often equipped with a basic pulley system to draw the water from the deepest parts.
The Well pulleys are made of a wheel with grooves and a big rope, belt or a chain. A big bucket is attached to the end part of the rope and on the opposite; we use our hands to pull the rope. Simple yet effective!
Getting a fit body is the new trend of the 21st century and most of us try to achieve that by getting a membership to a nearby gym. The machines at the gym are not a very complicated piece of machinery but these machines make use of the pulleys to fix the angle at which weights are going to be lifted.
The weights do not move from their original place. So, by the use of pulleys, weight lifting process has become much easier and safer. This also makes the process more effective and friendly to the users.
The pulleys used in construction are very common. It consists of a wheel which can be lifted to certain heights, a strong rope or a chain wrapped around it and it is attached to a hook. These kinds of pulleys are very convenient as they can lift or lower heavy equipment to the workers so that they do not have to make the climb.
This helps to complete the work on time and with ease.
• Theatre System
In the Theatres, you can see the curtains and fly systems, they work using multiple pulley systems. Unfortunately, you cannot see the pulleys as they are located very high behind the stage and they are operated from there during the performances.
What Type Of Machinery Use Pulleys?
Originally, the pulley was invented to lift heavy objects and the primary mechanism was very simple. A wheel and a rope were the only things needed to make it work. But over the years the concept has been modified a few times and now there are multifarious pulley systems available.
The time when the pulley was invented, it was known as one of a kind and a very rare piece of machinery but now the use of pulleys can be seen almost everywhere. And this modern-day modified version of pulleys can perform several tasks other than just lifting weights…
• Pulley are used in Elevators; actually, multiple numbers of pulleys are used in Elevators, in order to function properly and safely.
• A Cargo lift system uses multiple pulleys.
• Pulley is used to retrieve water from the bottom of the wells.
• Construction companies use pulleys to lift or lower down heavy machinery.
• A Bulldozer is a great example of a pulley system.
• Rock climbers use a pulley to climb.
• Escalator uses pulley system to function properly.
• Cranes used in construction is also a part of a pulley system.
• The sails on a boat are lowered and raised using a pulley system.
• The modern garage door uses pulleys.
• Pulleys are also used in cars especially in steering systems, alternator, and water pumps etc.
Large Pulleys Vs Small Pulleys
The basic principle of using a large pulley or a small pulley in a system is to get the job done effectively and easily. In case, you use a single pulley in a system, choosing the size of pulleys depends on the load you want to lift or pull.
So, high or low workload rated pulleys are specifically designed to take up more load or less load respectively. You can choose the one that suits your needs and requirements.
It is common sense, that more weight can be lifted with a large pulley as compared to a smaller one. It is the same concept when it comes to pulling a vehicle with large wheels. It requires less effort to pull a vehicle with larger wheels as compared to a vehicle with smaller wheels. As with large wheels, comes greater mechanical advantage.
But when it comes to a system of different pulleys bundled in one, the size of the pulleys becomes a very important factor here. In case of a two-pulley system, if the two pulleys in action have the same size or diameter and are connected by a belt, both the pulleys will turn at similar speeds and the power available will also be the same.
If one of the pulleys is smaller and it drives a larger pulley with a bigger diameter, the latter will turn slower, when compared to the smaller one. But, there will be more power available. Now, if a bigger pulley drives a smaller pulley, the latter will turn faster when compared. But in this case, there will be less power available.
So, here is the basic principle when it comes to the difference of large versus small pulleys. These systems are generally used in belt drives and similar applications.
There are various Pulley manufacturers in the world and all of them vows to provide us with excellent quality pulleys to make our lives even easier and at a very reasonable price. But when it comes to choosing the right manufacturer for your needs, you should assess what you exactly need and then approach a manufacturer.
The best way here is to get a custom pulley made just for you.
Why, here at Australian Power Transmission also known as Australian Pulley Manufacturer, we build custom pulleys to your needs. In a time manner that you can rely on.