Our PC220 LC-8 excavator changes track speeds constaintly, or shifts down then back up, every second or so, when it is in 2nd or 3rd speed range. When it in 1st range it will stay there. We're not sure what to check.
Possibly a loss of pilot pressure which changes the displacement on the motors. Pilot pressure comes from the reducing valve on the end of the bank
Hi Mike, Thanks for the info, we'll check pilot pressure. I imagine that it would be around 300 PSI?
Hi there, 450 or so, I would check it at the motor.
These are designed to "shift" down if pressure raises too high. Possible just trying to climb too high a hill? Bad pressure sensor could do this too as well as a bad travel speed solenoid.
It will shift up and down even on level hard road traveling
How many hours are on this machine? I think pilot pressure and terrain would be the first considerations as stated above. What is the condition of the undercarriage? In addition to the pilot pressure I would suggest watching the main circuits and observe the points at where the travel shifts. I believe on that model you can read each pump pressure from the monitor panel in the cab. Maybe one sensor is reading and the other isn't. I've had earlier machines shift all the time when just trying to turn. You could also have a swivel seal leaking off internally. As I recall the two speed land is next to the case drain land in the barrel.
Hi John C, The monitor shows 3150 hrs, We are not really sure if that's correct as we,re the second owner. The UC is about 50%. The track speed constantly changes when traveling even on a hard road going downhill.