How to use this model
  1. Press Lower (or drag the pole's long end down). Watch the bucket sink into the river and fill.
  2. Press Raise. The counterweight lifts the full bucket, and it is tipped into the basin.
  3. Read the panel: the torque (weight × distance) on each side, and the force you must supply.
  4. Slide the counterweight along the pole and observe how the work moves between lowering and lifting.
  5. Tap any part, or use ◀ ▶, to examine it. Take it apart separates the pieces.
Counterweight side60.0 kg·m
Bucket side14.1 kg·m
Lowering the empty bucket Raising the full bucket Water lifted0 L

16 parts
Pole, pillars, counterweight and bucketGround cut away to show the river below the bankA shaduf is a first-class lever: the pivot lies between the counterweight and the bucket. Each side turns the pole with weight × distance from the pivot. The 60 kg counterweight at 1.0 m gives 60 kg·m; the full bucket (18 kg at 2.8 m) and the pole itself give 58.9 kg·m. So the operator pulls the empty bucket down, a pull of about 16 kg, and the counterweight lifts the full one. Tilting the pole shortens every horizontal distance by the same factor, so the balance does not change with angle. (Multiply kg·m by 9.81 for newton-metres.)