Activity #4: Gear Ratio

Gear ratio can be defined as [the number of turns of the driver] : [number of turns of the follower]. In this activity, students will determine the gearing ratios for different combinations of the 8t, 16t, 24t, and 40t gears. This can be done using simple mathematics. For example, a 20t gear driver and a 40t gear follower produce a gear ratio of 2:1. In other words, the 20-tooth gear must make 2 complete rotations to turn the 40-tooth gear 1 time.

Materials: 8, 16, 24, 40 tooth LEGO gears, three LEGO axles, one 11 hole LEGO beam, 6 gray fasteners, one red marker or pencil.

Procedure:

1. When I turn the 8t driver_______time(s), the 24t follower turns______time(s).
This produces a gear ratio of _____ : _____.
2. When I turn the 8t driver_______time(s), the 40t follower turns______time(s).
This produces a gear ratio of _____ : _____.
3. When I turn the 16t driver_______time(s), the 8t follower turns______time(s).
This produces a gear ratio of _____ : _____.
4. When I turn the 40t driver_______time(s), the 8t follower turns______time(s).
This produces a gear ratio of _____ : _____.
5. Which gear ratio produces the greatest speed? Explain.
6. Which gear ratio produces the greatest torque? Can you explain this mathematically?