⚙️ Logic & physics
Which way does the red gear turn?
The green gear turns clockwise. Follow the chain to the red one – and watch out: sometimes nothing turns at all!
The rules of gears
- Two meshing gears always turn in opposite directions.
- In a chain the direction flips at every gear. Odd position = same direction as the first, even position = the opposite.
- A straight belt keeps the direction, a crossed belt reverses it.
The trap: gears in a loop
If three (or five, seven …) gears form a closed loop, the whole system jams: the last gear would have to turn clockwise and anticlockwise at the same time. With four gears in a square it works perfectly – an even number always adds up. Engineers check exactly this before they build a gearbox.