Gday, I was digging and clearing with my HitachiEX150LC excavator when suddenly I heard a clonk, not that loud and I lost control of the swing. The excavator still drives and the arm still functions but the top half just goes where it wants. There wasn't any hydraulic oil hose breaks. I drove it out of where it was onto a flat spot asap and shut it down. When I restarted it it was still the same, no swing response. Any advice would be greatly appreciated, cheers Otis.
When you aren't swinging and all of your controls are in neutral, there should be a swing brake that holds the upper house stationary. There might be a slight chance this has broke, but then the swing motor would also be junk too if it will free swing. Park it some place flat. Pick the boom up just enough to clear the ground. BE CAREFUL!!! Get out and push on the boom/stick/bucket. If you can push the upper, I'd be safe to say you have stripped/busted gears in the swing gearbox.