Hello i have a komatsu pw98 mr-6 wheeled excavator The issue starts when the hydraulics get warm, the hydraulic pump stays under load even though the joysticks are at neutral position, and it tends to get worse and worse as im working to the point where, if i leave the engine at low idle, it stalls. i checked the pressure of the pump and it gets as high as 150 bar, the load sensing line pressure is always 30-40 bar lower than pump pressure. i adjusted (unscrewed) the load sensing valve and the pump pressure gets as high as 100 bar. also the excavator is slower than before, but in two separate occasions the excavator returned to normal speed, meaning the functions and travel speed were significantly faster, but then they get slow and soon as i turn the engine off and on again. things i have checked: hydraulic filter replaced unloading valve replaced ls bypass valve checked if anyone has experience with this issue help is greatly appreciated. Thanks
Good day The LS pressure should match pump minus delta P. Kind regards Uffex
The delta p is around 30 bar The issue is that the pump pressure is increasing when the hydraulics get warm, to the point where the engine is unable to low idle and it wont event start.
It's a disease characteristic of Komatsu from the Dash 6 series and up! We call it the "STICKY LOAD" disease. The machine cannot return to the "UNLOAD" state when the control arm is in the neutral position. I suggest you check the " PRESSURE COMPENSATION VALVE " which are the valves marked in the picture below. To make it easier, you start the machine and then try each operation to check which of the operations causes the disease.
Ok should i check the travel valves first, because the travel pedal relieves the pressure when pressed slightly? Hopefully this fixes the slow speed issue aswell.