Shirley Wenger is a professional journalist and editor who has been working in the publishing industry for more than 15 years. She is an award-winning...Read more

People have been building for centuries. The evidence is clear. Look at the castles in Europe, the pyramids in Egypt, the Great Wall of China, and even the tall, stone, monolithic buildings in cities like New York and Chicago. If you think about it you would realize all of this was done without modern machinery. They didn’t have large trucks that hauled the materials from the quarry to the building site. And they didn’t have any type of powered machinery we use now to build skyscrapers and high-rises. So how did they do it?

 Sure, in ancient times they had slaves, indentured servants, debtors, or prisoners do the heavy work for them, all by hand. That certainly provided the muscle and the multitudes of people they needed to get the job done, but it still raises the question of how they managed to get stones to the top of the castles. The answer is really quite simple and if you look at today’s building machinery, you will see that it is still in use. The only difference between then and now is that this system is automated now and needs fewer people for work. 

So What Is This Ancient System We Use Today?

As in the days of old, what we use today is called a pulley. A pulley is essentially a wheel that has a rope, a chain, or a belt on a groove made on the wheel. Usually, sets of pulleys are used because they help spread the force needed to get the job done. So in ancient times, what did they use?

To get an idea of how a pulley works, start with this idea, which is how the pulley began. Ancient peoples, and even today you may do this, would throw a vine or rope over the limb of a tree and attach what they wanted to lift to one end. At the other end, of course, was human labor. The human pulled the rope and the tree limb took the brunt of the force necessary to move the object. Of course, this was not a perfect system because friction came into play and could burn through the rope and cause it to beak and drop the load. 

This is where the pulley invention came into play. With a pulley, a block of wood had a groove cut into it that went around the block. The rope was then put into the groove. One end of the rope was attached to the object you wanted to move and the human held the other end of the rope. You then attached the block of wood to, for example, a tree limb. You pulled on the rope, it ran along the groves in the wheel, and the object lifted. The result was that instead of using 10 people to pull on a rope to lift a large stone block and have others swing it into place, you could have two people do the lifting. This left the other eight to do other things thereby increasing efficiency. 

Is There Only One Kind of Pulley?

There are actually six different types of pulleys: fixed, movable, and compound. Block and tackle is a specific type of compound pulley. Each is used for the same purpose which is to move an object with a reduced amount of force required. Some people also use the word sheave as a type of pulley. Sheaves and pulleys are used in Lancaster, PA but technically, a sheave is not a different machine. The sheave is actually part of the pulley system. It is the rotating, grooved wheel in the pulley that the rope is attached to. 

A fixed pulley has no sheave. In a fixed pulley you attach the wheel to an immovable structure, like a floor or a wall. In this type of pulley, the rope is free and the pulley is stationary. With this type of pulley, you push down on the rope to pull the object up.

Pulleys with Sheaves

If you use a movable pulley, the pulley’s rope is attached to a stationary structure and the wheel is free to move. With this type of system, the object is attached to the wheel instead of the rope and the wheel moves up the rope as you pull it and brings the load along. This decreases the amount of work needed to move the object.  

A compound pulley is a fixed pulley and moveable pulley used in tandem. In this type of pulley, the object to be moved is attached to the wheel of the movable pulley. A rope that’s attached to the fixed pulley is also attached to the moveable pulley. This lets you change the direction of the object you are moving and the force required to do that. It also reduces the total workload you need to complete the task.

A block and tackle system have several fixed and movable pulleys that are parallel to one another. This aligns fixed pulleys with other fixed pulleys and moveable pulleys with other moveable pulleys. The pairs are each attached to the next pair which considerably reduces the total amount of work required to handle the job at hand. 

Finally, there are cone pulleys. A cone pulley uses multiple pulleys that have different circumferences. They are stacked on one another in a cone shape. The person operating the pulley can shift the pulley’s speed in this way, though the smaller circumference does less work. A perfect example of this system is the gears on a bicycle. When the bike rider shifts to the smaller circumference gear, it requires less effort to move the bike. But if distance is what you are looking for, the larger gears make the bike move further with each revolution, but there is more labor involved to get that done.

Why Are Sheaves Important?

A sheave reduces the amount of force you need to move an object. You may wonder why used pulleys without sheaves at all then? The reason is that as you increase the number of sheaves you increase the friction and eventually this makes your work harder. For a sheave to work well it has to have a small amount of surface area that the rope is attached to. If you use several sheaves in a pulley system, it is best to arrange them so there is a fixed axle between each one.

Shirley Wenger is a professional journalist and editor who has been working in the publishing industry for more than 15 years. She is an award-winning writer and her work has been featured in various publications, including The New York Times, The Wall Street Journal, and Time Magazine.

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