I recently built the basic construction for a crane out of lightweight material. Basically the head of the crane contains an electric servo motor which spins the head of the crane by pushing itself away from the tower (the rotor is fixed to the axis which is fixed to the tower. The axis isn't fixed to the head in any way).
All electronics required to operate the motor and more are inside the head. The only thing I should extend to the rest is a 240 V cable.
Since the head is allowed to make multiple rotations (preferably limitless), how do I avoid snapping my cable by rotating it too often? I'm aware such solutions exist, but I have no experience in this area so I have no idea what to ask for specifically.
/---------------------\ | | | motor | \----------|----------/ | ___________|___________ \ | / \ | /