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Block and Tackle How To's

15 December, 2020

A block and tackle is a useful pulley system that can be used to lift heavy weights or transfer forces in different directions. This handy system can be used in construction, in a theatre or even in a gymnasium, as this little device can do so much. 

It is simple, efficient and easy to use, which is why it is used in so many different contexts all over the world. But, what are block and tackles? How do they work?

What Is a Block and Tackle?

When you take a look at one you will see the anchor at the top that the ropes are fed through, that can be attached to a secure, solid structure. This is essentially what a block and tackle is: a series of ropes fed through sheaves to a single connection point at the top, which is called an ‘anchor’.

Each rope can work independently of one another, but all together, they become a central pulley system that creates a strong force to move heavy objects up and down or suspend them in the air. Although we now use pulleys for so many different things, they came into popular use on sail ships, but date back all the way to the ancient Greeks.

How Does it Work?

Once you have set up your block and tackle and secured the anchor, simply pull on the single rope. Although there will be various ropes fed through the sheaves, the single one at the side is the one to use that will create a huge transference of force, when you want to lift heavy objects.

A Transference of Force

The way a block and tackle works is that it is a transference of force.  Each rope that is used in the pulley creates an extra force that can be used to lift heavier loads. For example, say the pulling rope leading off the pulley system is being pulled on using a force of one pound, this is transformed into a total force of four pounds, if there are four ropes used in the block and tackle.

This means that you can pull on the block and tackle, then your efforts will be transferred into an even stronger force, enabling you to lift more weight. A two rope pulley is called a gun tackle, one with three ropes is called a luff tackle and with four ropes, it is called a double tackle. 

Fold and Transport

This ingenious little contraption is easy to transport and can be used in lots of different situations. Simply folding it neatly and packing it away is an ideal way to transport it, as there is no need to take it apart and put it back together again if you need to use it somewhere else.

Flip it and Reverse It

A block and tackle can be used in different ways and by flipping it you can even adjust how much force the pulley system can exert. If you remove the anchor from the top and make the bottom sheave the anchor, the block and tackle will still work perfectly.

By doing this, you will adjust the direction of where the single rope needs to be pulled to create the force. So, if you hang your top anchor at the bottom, your central pulley system will still function correctly.

This can even make your pulley system stronger, as there is an extra line supporting the load as we know, the more ropes fed through the sheaves, the greater the weight and force the block and tackle can create and withstand.

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