Sawhead Hydraulic Creep

[T4R11]

I have a Timber Harvester mill and when any of the hydraulic levers (taper, turner, log lift etc) are moved the head creeps toward the front/operators station. It moves maybe 6" or so.The hydraulic fluid level is where it should be and I have changed the filter. Any ideas as to why this is happening?

[YellowHammer]

I don't have a timber harvester but assume the head motor is hydraulic?

Many times this could indicate a loose hydraulic fitting (look for drips) in the return side of the head pump plumbing allowing flow, or a worn oring or seal on the valve body itself allowing flow, or a sticky valve allowing flow.

[rusticretreater]

We need a hydraulic diagram to diagnose remotely.  Trace the line where the fluid needs to go to make the carriage move the direction it takes.  Follow that line back to the lever manifold.  That will take you right to the problem area.  Somehow, pressurized fluid gets in this line when other levers are moved.  Likely the carriage control manifold needs to be replaced.

Does the carriage move only when you extend a cylinder, when you retract or both?  

[fluidpowerpro]

I would make sure the spool controlling the head is centering properly. There is likely a spring on the end of the spool. Make sure its not loose.