A small excavator with working pivoting, a tracked driving base, and a fully functional arm.
About this creation
Pivoting is done with a turntable. When the knob is turned, two knob wheels move, one of which is connected to the 24t gear that turns the turntable.
The arm is lifted by the use of an 8t gear and a worm gear.
Dumping the bucket is controlled by a small lever. The lever moves a series of beams that move the elbow and bucket joints. This system is almost identical to that used by the backhoe arm in the Backhoe Loader set.