Nepedia
Back to Discover
Fluent Reader
💻

Ratchet (device)

technology Maturity 9-11 Next article →

A ratchet is a clever mechanical device. It allows motion to go in only one direction. It stops things from moving in the opposite way. This tool is used in many machines and tools. You might even hear people call a socket wrench a ratchet. It is a very useful part of engineering.

Ratchet Drawing
Ratchet Drawing

A ratchet has two main parts. One part is a gear with teeth. This gear can be round or a straight line called a rack.

Ratchet Rack and Pawl
Ratchet Rack and Pawl

The second part is a finger called a pawl. The pawl is often held by a spring. The teeth are usually asymmetrical. This means one side of each tooth has a gentle slope. The other side has a much steeper slope.

Ratchet Gear and Pawl
Ratchet Gear and Pawl

Here is how the thing works. When the gear moves forward, the pawl slides over the gentle slope. A spring forces the pawl into the space between teeth. This often makes an audible click sound.

Ratchet example
Ratchet example

If the gear tries to move backward, the pawl hits the steep slope. This locks the gear against the tooth. It prevents any further motion in that backward direction. This is how the device stays in control.

Sometimes a small amount of backward motion still happens. This is called backlash. It is limited to the distance between the teeth. To fix this, some people use a toothless ratchet. These use a high friction surface like rubber. The pawl bears against the rubber at an angle. Any backward motion causes the pawl to jam. This can significantly reduce the backlash.

Ratchet Gear and Pawl
Ratchet Gear and Pawl

You can find ratchets in many everyday items. They are used in cable ties and clocks. You might find them in computer keyboards or seatbelts. They are also in grease guns and jacks. Even roller coasters use them as anti-rollback devices. They are even inside handcuffs. It is amazing how many things use this simple idea to work correctly.

313 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (4)
File:Ratchet Gear and Pawl.gif
Ratchet Gear and Pawl.gif
File:Ratchet Drawing.svg
Ratchet Drawing.svg
File:Ratchet Rack and Pawl.gif
Ratchet Rack and Pawl.gif
File:Ratchet example.gif
Ratchet example.gif
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.