Hi there, My komatsu PC30mr-1 drops revs just a little bit when slewing to the left, the revs don't pick up till i slew to the right for a bit. I wasn't to worried about it, its only a slight drop and doesn't really affect performance, but thought i would ask in case it is a sign of something bad to come. Its an old machine and they don't make a lot of parts for this model, so if a major part is on its way out it would be good to know. I called komatsu they didn't have a clue.
There's a leak somewhere around the valve bock or possibly from the swing motor but wouldn't have thought a leaking hose could drop revs?
Sounds like the valve is over stroking the pump and load sense is sending a signal to pump...might be a little by pass in load sense system. Those older machine needed the std by pressure adjusted from time to time....there are two screws on pump...one for main pressure other for std by pressure.
Might need the reliefs in the counterbalance valve for the swing adjusted, they get weak over time.