Pilot pressure varies?

[ROAMER_AUS]

Hi all,

Is it normal in any model of excavator that pilot pressure vaires up to 20 bar. So say, normal is 40, once you apply full joystick movement, it drops to 20, and then slowly (maybe 2 seconds) it rises up back to 40. So in normal working mode with excavator, as multiple jostick movements are constantly applied. Pilot pressure basicaly constantly varies between 20 and 40 BAR. I had 2 cases of this recently. One on Kobelco, one on Hyundai. Excavator operators, did not report any problems in performace, I was just doing some other checks, and I noticed this. On Liebherrs that I so most of my work on, pressure varies 2 BAR max.

What could cause this sort of a problem? I did temporarely remove pilot line filters just to check if they are blocked, but no change in both cases. Is it maybe that pressure regulator is sticking in pilot system? Or did anybody have other experiences?

Thanx!!!

 

[funwithfuel]

Sounds like the pilot safety accumulators are flat. The accumulators should fill the drop of multifunction demands. Simple test, start the machine, let the pilot accumulator charge up. Raise the boom in the air and leave it. Shut the machine off, lower the safety flag. Turn the key on 15-30 seconds later. Raise the safety with the engine off, see if you can slowly lower the boom or open the bucket under control. Don't just dump to ground. If you can't lower the implement, the accumulator is flat or the check valve has failed.

 

[Vetech63]

From what I know any pilot pressure should be maintainable working both joysticks and travel levers. Even though the pressure may dip for a second when you first apply it, it still should recover and maintain. It almost sounds like your pilot pressure is weak from a flow standpoint.

 

[uffex]

Good day
Attached may be of help.
Kind regards
Uffex

 

[ROAMER_AUS]

Thanks all for the info. I will check once I'm one these machines!!!