Why do excavators use such complicated drive motors ?
Actually, the drive system is relatively simple. You have a single engine running a hydraulic pump, and two hydrostatic drive motors on the track system that propel the machine. Beyond that you have two control handles that are tied into the main hydraulic valves with either electronic controls or pilot hydraulics that open and close valves to move the hoe. There are a lot of hoses, but the system itself is really pretty simple in design once you understand it.
