Tractor Crane

Two cables are attached to the bucket - one to the center and the other to the sides; the cable attached to the sides is used to open the bucket. The cable attached to the center is used to lift the bucket. The crane operator must coordinate the action of the two cables, preventing a tangle by keeping the slack out of the cable that is not in use. The boom can be raised or lowered without affecting the open or closed position of the bucket.

In real life, tractor cranes are used to carry loads from place to place. Track pads, instead of wheels, allow the crane to travel over rough or muddy ground. This model crane can pick up and carry pencils, coins, and other small objects. If you can make two you can compete against a friend to see who can operate the crane to pick up objects more quickly. 

Difficulty level: 
Hard
What you will need: 
  • Scissors
  • White glue
  • Super glue
  • Metal-edged ruler
  • Hobby knife
  • Wire
  • Needle-nosed pliers with cutting edge
  • Dowelling
  • Sewing needle
  • Sewing thread
  • Straight pins (3)
  • Paper clips (2)
  • Salt or craft sand