J.M. Gabrielse Gears & VEX J.M. Gabrielse

Agenda Essential Terminology Gear Types Direction Gearing Up/Gearing DownGearing UpGearing Down Gear Ratios Examples gear testing apparatus

J.M. Gabrielse 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

J.M. Gabrielse Do you get it? Which gear is the driver (A or B)? Which gear is the follower (A or B)? A B motor

J.M. Gabrielse Do you get it? Which gear is the driver (A or B)? → A Which gear is the follower (A or B)? → B A B motor driverfollower

J.M. Gabrielse 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)? ABC motor wheel

J.M. Gabrielse 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 ABC motor wheel

J.M. Gabrielse Gear Types spur gears differentialbevel gearsrack & pinionworm gear X - not used by the Summer STEM Academy

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

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

J.M. Gabrielse Direction 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 follower

J.M. Gabrielse Did you get it? driver Would the follower gear move clockwise or counterclockwise?

J.M. Gabrielse Did you get it? driver Would the follower gear move clockwise or counterclockwise?

J.M. Gabrielse Did you get it? driver Would the follower gear move clockwise or counterclockwise?

J.M. Gabrielse Did you get it? driver Would the follower gear move clockwise or counterclockwise?

J.M. Gabrielse Geared Up large driver turns small follower less torque (turning force) more speed driven gearfollower gear follower driver

J.M. Gabrielse Geared Down small driver turns large follower more torque (turning force) less speed driven gearfollower gear follower driver

J.M. Gabrielse Gear Analysis To analyze any gear train you need to: 1.Find the number of driver teeth 2.Find the number of follower teeth 3.

J.M. Gabrielse Example Gear Analysis 1.follower teeth: 36 2.driver teeth: –3/1 or 3:1 –read as 3 to 1 –3 turns of the driver will turn the follower 1 time 12 tooth driver 36 tooth follower

J.M. Gabrielse What is the gear ratio? 84 tooth driver 60 tooth follower 84 tooth driver 60 tooth follower

J.M. Gabrielse What is the gear ratio? 84 tooth driver 60 tooth follower

J.M. Gabrielse Your Turn What is the gear ratio of the Protobot? 60 tooth gear

J.M. Gabrielse Your Turn What is the gear ratio of the Protobot? 60 tooth gear Gear Analysis 1.follower teeth: 60 2.driver teeth: 60 3.

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