Directions of input and output and relative positions of fixed and floating pivots


  1. Ask students with mechanisms whose output goes in the same direction as the input:
  • Is the floating pivot (the input) between the fixed pivot and the output? Or
  • Is the fixed pivot between the floating pivot (the input) and the output

Identify as 3rd class levers those mechanisms whose output and input go in the same direction, and whose input is between the fixed pivot and output.

  1. Ask students with mechanisms where the output goes in the opposite direction as the input:
  • Is the floating pivot (the input) between the fixed pivot and the output? Or
  • Is the fixed pivot between the floating pivot (the input) and the output?
  1. Identify as 1st class levers those mechanisms whose output and input go in opposite directions.  The fixed pivot of 1st class levers lies between the input and the output.  See the illustrations below.

Unit Lessons