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Gears & V E X

Gears & V E X. J.M. Gabrielse. Agenda. Essential Terminology Gear Types Direction Gearing Up / Gearing Down Gear Ratios Examples. gear testing apparatus. Essential Terminology. Driver – gear attached to a motor Follower – gear doing useful work

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Gears & V E X

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  1. Gears & VEX J.M. Gabrielse

  2. Agenda • Essential Terminology • Gear Types • Direction • Gearing Up/Gearing Down • Gear Ratios • Examples gear testing apparatus

  3. Essential Terminology • Driver – gear attached to a motor • Follower – gear doing useful work • Idler – gear between the driver and follower • Geared Up – the follower moves faster than the driver • Geared Down – the follower moves slower than the driver

  4. Do you get it? • Which gear is the driver (A or B)? • Which gear is the follower (A or B)? B A motor

  5. Do you get it? driver follower • Which gear is the driver (A or B)? →A • Which gear is the follower (A or B)? →B B A motor

  6. Do you get it? • Which gear is the follower (A, B, or C)? • Which gear is the driver (A, B, or C)? • Which gear is the idler (A, B, or C)? wheel motor A B C

  7. Do you get it? • Which gear is the follower (A, B, or C)? → C • Which gear is the driver (A, B, or C)? → A • Which gear is the idler (A, B, or C)? → B wheel motor A B C

  8. Gear Types spur gears differential bevel gears rack & pinion worm gear X - not used by the Summer STEM Academy

  9. Spur Gears 12 tooth 24 tooth 84 tooth 36 tooth 60 tooth The number of teeth on each spur gear is a multiple of 12. 12 = 1 x 12, 36 = 3 x 12, 60 = 5 x 12, 80 = 7 x 12 X - only works with the worm gear

  10. Rack & Pinion pinion rack Racks and pinions are used to translate rotational motion into linear motion.

  11. Direction follower • every time you add a gear the direction reverses • even number of gears: driver & follower turn in opposite directions • odd number of gears: driver & follower turn in same direction driver driver follower follower driver

  12. Would the follower gear move clockwise or counterclockwise? Did you get it? driver

  13. Would the follower gear move clockwise or counterclockwise? Did you get it? driver

  14. Would the follower gear move clockwise or counterclockwise? Did you get it? driver

  15. Would the follower gear move clockwise or counterclockwise? Did you get it? driver

  16. Geared Up • large driver turns small follower • less torque (turning force) • more speed follower driver driven gear follower gear

  17. Geared Down • small driver turns large follower • more torque (turning force) • less speed driver follower driven gear follower gear

  18. Gear Analysis To analyze any gear train you need to: • Find the number of driver teeth • Find the number of follower teeth

  19. Example Gear Analysis • follower teeth: 36 • driver teeth: 12 • 3/1 or 3:1 • read as 3 to 1 • 3 turns of the driver will turn the follower 1 time 36 tooth follower 12 tooth driver

  20. What is the gear ratio? 84 tooth driver 84 tooth driver 60 tooth follower 60 tooth follower

  21. What is the gear ratio? 84 tooth driver 60 tooth follower

  22. Your Turn What is the gear ratio of the Protobot? 60 tooth gear 60 tooth gear

  23. Your Turn What is the gear ratio of the Protobot? 60 tooth gear 60 tooth gear Gear Analysis • follower teeth: 60 • driver teeth: 60

  24. Thanks/Resources • Inventor’s Guide: 3·19 - 3·13 • Teaching Gear Theory to Students • CMU's Vex Curriculum: Gearbox Lesson

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