When I saw a video of the Ponsse Scorpion King, I decided to build this forest harvesting machine in Lego Technic.

With the crane and chopper head, the machine can grab trees, cut it with the build-in chain saw, remove all side branches and chop the now cleen wood in certain lenghts. Also special is that the cabin stays levelled while driving through uneven countryside.

The challenge was to insert all real functions and that was only possible if I used a large scale. So I started with the largest available tires and worked from there on.

The remote controlled functions are:

8 wheel drive, using 4 motors and traction with worm gearing to make it strong.

Steering, using 1 motor and 2 lineair actuators.

Horizontal cabin levelling in driving direction, using 1 motor and two lineair actuators.

Horizontal cabin levelling in the sideways direction, also using 1 motor and 2 actuators.

Rotating the cabin with crane, using 1 motor.

Tilting the complete crane, using 1 motor and two large lineair actuators.

Tilting the second boom, using 1 motor and a gear rack with worm traction.

Extending the second boom, using 1 motor and the same type of gear rack.

All together 11 motors, 5 receivers and 3 batteries.

The manual functions are:

Opening the cabin door.

Opening the hood

The front and rear frame can rotate compared to each other.

Clamping a tree

Transporting the tree in the chopper head.

Everything works fine, but in the position with the crane sideways and all the way out, the construction is not stable enough. This can be solved by replacing the levelling actuators and the rear frame suspension by fixed beams. It this would become a set, then most functions will and can be manual operated, to save motors and receivers!

Well, I hope you like the Scorpion King and the pictures!