The vane motor is something I will be making for some of the attachments. This is to provide rotation to the grab and shears.
Planning is key, I'm an ex digger driver and I haven't lost the love of diggers.
There are companies that build rc diggers but I believe only one does hydraulic tracks and slew control.
The motor is a scaled down version of the real thing. This is the best video that discribes the workings
http://www.youtube.com/watch?v=8l5Ft...e_gdata_player
Great thing is that it works for both pump and motor.