tbone1471
Well-Known Member
We have a pc490-10 and occasionally the boom will raise slow. Some other function like stick out and slew seem to also be slow. It is very random.
What we are seeing is the rear pump not increase displacement. It sits at 24cc while the front pump will go to 206cc. When the boom functions normally both stroke to 206.
Both pumps will deliver the same pressure. Pcc boom up pressure is 380psi when both fast and slow.
I have attached screenshots of what the computer is seeing when it is acting slow. Is there a valve that could be randomly hanging that would cause the rear pump to not increase displacement but would still allow it to build pressure?
Machine has 7000 hours and has been trouble free up until now. We did a hydraulic service recently and there were no contaminants. Issue had come up prior to the service. The main reason for the service was a leaky return to tank line.
Looking for some insight as komatsu doesn’t seem to have any techs readily available.
What we are seeing is the rear pump not increase displacement. It sits at 24cc while the front pump will go to 206cc. When the boom functions normally both stroke to 206.
Both pumps will deliver the same pressure. Pcc boom up pressure is 380psi when both fast and slow.
I have attached screenshots of what the computer is seeing when it is acting slow. Is there a valve that could be randomly hanging that would cause the rear pump to not increase displacement but would still allow it to build pressure?
Machine has 7000 hours and has been trouble free up until now. We did a hydraulic service recently and there were no contaminants. Issue had come up prior to the service. The main reason for the service was a leaky return to tank line.
Looking for some insight as komatsu doesn’t seem to have any techs readily available.