# Help Zone

### Student Question

Secondary III • 2yr.

How do you know which way a gear or wheel turns?

Science

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## Explanations (1)

• Explanation from Alloprof

Explanation from Alloprof

This Explanation was submitted by a member of the Alloprof team.

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Team Alloprof • 2yr.

Thank you for your question!

The direction of a wheel or gear’s rotation depends on the direction of rotation of the motor wheel (the input wheel), which affects the direction of rotation of the driven wheel (the output wheel).

When the number of wheels is even, the rotational direction of the first wheel (the input wheel) is opposite to that of the last wheel (the output wheel). When the number of wheels is odd, the rotational direction remains the same between the first wheel and last wheels.

Even number of wheels or gears:

Odd number of wheels or gearsr:

The rotational direction of the wheels or gears inside a chain (or a belt or rope) is identical to that of the chain. Inversely, the rotational direction of a wheel outside a chain is the opposite of the chain’s rotational direction.

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