Mechanical Devices

• Mechanical advantage=load/effort
• Types of cams

  • Eccentric
  • Pear
  • Snail/Drop
  • Hart-shaper
• Follower


  Follows the shape of the cam
• Base of follower

  • Flat
  • Can withstand load but lots of friction
  • Point- low friction but wears away
  • Roller-more expensive
• Gear ratio


  Number of teeth on driven gear divided by number of teeth on drive gear
• Velocity ratio

  Diameter of driven pulley divided by diameter of drive pulley
• Pulleys in series

  • Block and tackle
• Mechanical advantage is equal to number of sections of rope pulling the load
• Linkages

  A) Reverse Motion

  B) Treadle

  C) Push-pull / Parallel motion

  D) Bell crank

  E) Crank and Slider

  
• Types of motion

  A) Reciprocating

  B) Linear

  C) Oscillating

  D) Rotary