I've built this excavator in 2007/2008. In 2012 i've made some reconstructions in electric parts, winches and tracks.
the grey track is the old, the brown the new
completing the cab with sliding doors and a new construction for calming the clamshell bucket.
the principle of function in motion. The end of the rope is fixed at the clamshell bucket and tries to pull at the weight. Therefore the clamshell bucket can't turning and twisting. A typical Menck construction, built from the beginning in 1900 till the end in 1978
https://www.youtube.com/watch?v=vNIVlKAHGIQ
Best Regards
Wolfgang