Sold down the Sprinkler

The Impact Sprinkler
The Impact Sprinkler



  • How does an Impact Sprinkler work?
  • Who invented the Impact Sprinkler?
  • The simple design which works without any electricity.
  • How the flow of water helps in the function of the impact sprinkler?
  • This week in Invisible History: "Sue and Stan". Domain: Palaeontology.
  • Discuss the article here.

I am from Pune. And one benefit of being from this city is the rich history it carries. I live close to Aga Khan Palace. For those who don't know, Aga Khan Palace is a majestic building which was used as a prison during the Indian freedom movement to keep Mahatma Gandhi. I have been there many times to see how he lived and appreciated life. But the engineer in me fell prey to totally something else during a visit back in 2007.

I was sitting in the gardens of this palace and got in a conversation with the gardener. He was very keen on a gift he got from the trust— the sprinkler for feeding all the grass and plants in the garden. At that time, I felt good for him and thought how exactly did this thing work. It wasn't until I saw one up close and opened it up, I understood the mechanisms of it. In this article, I would like to share what I learnt. Let's get into it.

The genius grower

The Impact sprinkler is one of the inventions which led to a broad international privately-held manufacturer and provider. This company is called "Rain Bird." Orton Englehart, a Glendora, California, citrus grower, was unhappy with the other sprinklers he used to irrigate his citrus groves. So instead of waiting for a better design, he began building a better sprinkler for his use in 1933.

Orton Englehart
The Genius behind the Impact Sprinkler

His invention consisted of short pipes, cross-joint, solder, scrapped irons, tin cans, and the winding off of an old broom handle. Englehart's prototype led to the development of the first full-circle impact sprinkler. It offered a slow and reliable rotation. It was leading to more uniform watering than other sprinklers of the day. He further perfected the design and started "Rain Bird" with his friend Clem LaFetra.

The Devine design

For me, in the beginning, the impact sprinkler made zero sense. How does it work without electricity? Why does it make that sound? And how does it sprinkle water over such a large area? The function of the sprinkler starts when the water comes in. It has the word "impact" in its name because of the impact that water creates on entering the system. As water enters, the top half lifts and it becomes harder to rotate. The water can go out of the nozzle provided at the angle.

The Impact Sprinkler mechanism
The basic working mechanism

On its way out, the water hits the arm which spreads the water out. In this process, the arm is slammed (impacted) against the body of the sprinkler. This impact turns the whole assembly clockwise. Now if seen carefully, this arm is attached to the frame using a spring which operates based on torsion. The spring brings the arm back in the way of water and away from the frame. (In some designs it can be the opposite.) And then the whole cycle repeats itself.

Tick tick tick vs Tststststststs

But how does it rotate in one direction (tick tick tick tick tick tick tick tick) and then rotate faster in the other (tstststststststststststststs)? To answer this, we need to have a closer look at this collar. These are called the limiting collars. They are used to limit the circular range of the sprinkler.

These collars are deployed when it reaches a certain angle (which can be set manually.) It merely restricts the motion of the arm. It prevents the arm from hitting the frame of the sprinkler. This lack of impact lets the spring to unwind to the original position to 0°. Once reached, it moves away, and the cycle repeats.

Your turn now

Impact sprinkler is one of the most innovative designs I've ever encountered. It taught me a lot of things like the energy efficiency of it, the mechanisms, the clever tricks to spread the range and limit it, and many other things. Right now, I am designing a part which could learn a lot of things from the humble impact sprinkler. So the next time you hear the irrigating sound of an impact sprinkler, remember that it's quite ingenious.

This week in Invisible History

The answer to last week's history puzzle (Little Boy) is the bombing of Hiroshima. Little Boy" was the codename for the atomic bomb dropped on the Japanese city of Hiroshima on 6 August 1945 during World War II. It was the first nuclear weapon used in warfare. It used uranium-235, a rare isotope of uranium separated at the Clinton Engineer Works at Oak Ridge, Tennessee. It was a result of the development due to the Manhatten Project. The project included several huge names including Richard Feynman, Robert Oppenheimer, Enrico Fermi, and various others. The winners of last week's quiz are Arati Dube (Instagram), Shubham Jain (WhatsApp), SmaugTheMagnificent (Reddit) and Sidharth Singh (Reddit).

Little Boy
Little boy internal components

The clue for next week is something related to palaeontology. The clue is "Sue and Stan." You can write the answers to me in the comment section or on social media. I have left the links down below.

If you want to read more about such inventions, why not subscribe to the blog? And if you are really into it, follow us on social media. Feel free to share this article with your friends and family to show them how awesome you are!

See you next Saturday! Cheers!

  1. Reddit:r/theinvisiblegenius
  2. Instagram: @theinvisiblegenius
  3. Twitter: @notnitinchopra

Reference links

  1. Landers, John David (2001). Glendora California. Charleston, SC: Arcadia Publishing. pp. 62–64. ISBN 978-0-7385-0826-9.
  2. "Glendora Family Shares Wealth With Community - Los Angeles Times
  3. International Directory of Company Histories.
  4. Publication: Operating Characteristics of Center Pivot Sprinklers
  5. Section 8.0 The First Nuclear Weapons


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