I spent the past month figuring out the mechanism to extend the 3 boom sections.
It is somehow based on the Liebherr system, one section at the time. I use a spindle, which propels 2 pins, which can hook into the bottom of each section and push it up. The whole assembly can rotate and with 3 positions available I can choose which section to extend. the motor is mounted on the side of the boom where the real one has an oil tank for the same function. Once in place the sections get locked manually.
kerst