How to Produce Higher RPMs With Pulleys

A pulley system is a method of powering a machine. Pulleys are similar to gears, in that they turn, and the turn of one wheel effects the other. In order to achieve a higher speed on your pulley system, there is a method of calculating using pulley diameter measurements.

Old Pully
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How to Produce Higher RPMs With Pulleys

What Are Pulleys?

Pulleys are wheels with grooved notches. Cords can be held within the edge of a pulley. Pulleys generally work to hold a cord in place, keep it moving at a set speed, and can be used to change the direction of a cord without interrupting its speed. They multiply the input force through mechanical advantage. Pulley systems consist of two differently sized pulleys, typically a larger one turning a smaller one. They are called the driver and driven pulley. Pulley systems are most commonly used in hoists and in trains.

They work in a similar way to differently sized gears. If a secondary pulley is smaller than the first, it will have to rotate faster. The difference between pulley ratio is what effects the system's speed. A pulley speed calculator can help designers decide on the ideal pulley diameter and rotation velocity for their project.

What Is RPM?

RPM stands for revolutions per minute. It acts as a measurement for the speed of a pulley (and any other rotating item). To find out the RPM of a pulley, there is a pulley RPM equation. Once you know the equation, you can manipulate the input numbers in order to achieve a higher RPM.

Pulley RPM Calculator

In order to calculate pulley RPM, you'll need a set of numbers. You'll need the diameter measurements of both pulleys. With these two measurements, you can find out the velocity ratio, or the difference in speed between your driver pulley and driven pulley. To do this, divide the diameter of the driven pulley by the driver pulley.

Once you have the velocity ratio, you can work out the output speed. The output speed is the input speed divided by the velocity ratio. The output speed number is your RPM. There are a variety of online calculators where you can input the numbers you have and it will give you the RPM.

How To Produce Higher RPMs With Pulleys

Using the RPM calculation formula, you can input different numbers to find out how to get to your desired RPM. You first need the numbers for your desired RPMs. There will be two different numbers, one for pulley one, and one for pulley two. You will also need the two pulley diameter numbers.

The equation is diameter one / diameter two = RPM one / RPM two. If you input the two desired RPMs and diameter one, this calculation will give you the diameter you need for your second pulley. Always check that these RPMs are safe for your pulleys to avoid any accidents.


Annie Walton Doyle

Annie Walton Doyle

Annie Walton Doyle is a freelance writer based in Manchester, UK. Her work has appeared in The Huffington Post, The Daily Telegraph, Professional Photography Magazine, Bustle, Ravishly and more. When not writing, she enjoys pubs, knitting, nature and mysteries.