gears.mechanics.im
Count the teeth. Trade speed for turning force.
Gears work in pairs. Count the teeth and you can say how the pair will share speed and turning force — then see where those gears hide in a mill, a clock and a bicycle hub.
What is a gear?
A gear is a machine component consisting of a toothed wheel attached to a rotating shaft. Britannica Scholars: gear Gears operate in pairs to transmit and modify rotary motion and torque (turning force) without slip. Britannica Scholars: gear
The smaller of a gear pair is called the pinion. Britannica Scholars: gear If the driven gear has twice as many teeth as the pinion, the torque of the driven gear is twice the pinion torque, and the pinion speed is twice the speed of the driven gear. Britannica Scholars: gear
A short tour of the idea, then of the gears hiding in mills, clocks and bikes:
- What gears are, and how they work in pairs
- Counting teeth to work out the ratio
- Spur, helical, bevel and worm gears
- Gear trains, for a large ratio
- Mechanical advantage, and why a machine cannot do more work than you put in
- A waterwheel, a shaft and a millstone
- The great wheel and the motion work
- A Sturmey-Archer three-speed hub
- Watt’s sun-and-planet gear
- Gears that are not circular
Printables
Fact-checked PDFs in A4 and US Letter, sold as instant downloads from the ReallyByte store: our own drawings, a guide, and worksheets with answers. Prices in US dollars. Visit the shop.
Sister sites
- Steam engines — How steam engines work, from Newcomen and Watt to Rocket, with no-heat experiments and games.
- Simple machines — The six simple machines, mechanical advantage, kitchen-table experiments and a lever calculator.
- Clocks and clockwork — How a clock turns a weight or a spring into a steady tick: gear trains, escapements, pendulums and Harrison’s sea clocks.
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