Bruder Cat Excavator Conversion

[mojo]

nice stuff....really nice stuff... being new and poor to this hobby and lurking for a few weeks on this forum i was trying to find another way of moving the arms of an excavator and what you seem to have seems to be the ticket... hydraulics seem out of the question.... way out of my range of know how and cost.... my question is where did you pick up those screw type cylinders, if thats what they even are, and how do they work radio wise, do you need a speed control or just reciever.... and while i'm asking questions, how do you make a servo go around and around acting like a drill, i thought they had limits to how far they could turn...

thanks Joe ...i'm really green to all this stuff