Caterpillar 525 Skidder Hydraulic Issues

[williamson210]

We have a 1999 Caterpillar 525 Skidder that is having some crazy hydraulic issues. When you start the rig, the Hydraulics will build pressure to 3000 psi then release to nothing. Then repeats about every 5 seconds. We have changed the hydro pump, and main hydraulic valve block. Everything works it just surges real bad when this happens. There is a small 3/8 pressure line coming off the valve block to the hydro pump, if you block that line off the surging stops, however nothing works then. Has anyone had this issue? Thank you... 

 

[chep]

@kiko 

[newoodguy78]

Chep you read my mind

[chep]

No brainer! Kiko is the man! 8)

[barbender]

Is the small line your load sensing line?

[williamson210]

Yes the small line is the load sensing line

[kiko]

Your brake accumulators are damaged or discharged or there are issues with the accumulator charge valve.  Is this a 1DN machine or  3KZ?

[williamson210]

Thank you!! That would cause it to build and release build and release every few seconds? 

[kiko]

Yes , when the nitrogen is discharge there is no cushion and it will slam when it re charges.  If the accumulator was holding pressure it would not cycle that much.  The function of the brake accumulator I to allow to still have service brake function in the event of an engine stall.