Gears

• Gear trains


  • Cog wheels are meshed together to create gear trains
  • A simple gear train has a drive cog or 'gear' which rotates the 'driven gear'
  • Gear ratios can be worked out by comparing the number of teeth on each gear
  • Drive gear is moved and it spins the driven gear
  • Drive gear - pedals on bike, driven gear - the gear on the back wheel
• Gear ratio = Driven gear teeth/Drive gear teeth
• Idler gear

  • An idler gear ensures that the direction of the drive gear and the driven gear are the same
  • The idler gear sits between the two gears and directly transfers the drive
• Rotary systems (CAMs)


  • Rotary systems drive mechanisms in machinery and equipment
  • A rotating axle called a camshaft is used to drive, or is driven by, other mechanical components
  • Cams are shaped pieces of material that are attached to the camshaft
  • Cams change rotary motion into reciprocating motion
• Compound gear train


  Speeds up the final gear as the sizes go big to small, needs to be in contact with a smaller gear