im working on a cat 508 grapple skidder. the hydraulics for arch lift and grapple function are very slow. grapple rotate is ok. i pressure tested the pump. im getting 2600 PSI at full relief on all functions. it takes about 12-15 seconds to completely lift the arch. steering and blade functions are normal. im thinking either i have a restriction in the supply line or the valve is bypassing. i dont have a service manual for the machine
sounds like you’re on the right track. Does the machine labor when lifting the arch? Does it sound like it’s going over relief? You may need to get some run tees to try and find out where you are losing pressure. You could also possibly swap a couple reliefs and see if anything changes.the fact that you have this issue on multiple functions would make me look for a common denominator. Hope I have made this as clear as mud.
If you post a Serial Number I ought to be able to find the Hydraulic Schematic at the very least, and probably also the SysOp document for the hydraulics.
Look for issues with a priority valve if it has one.
Update - I just checked and there are only two S/N prefix options for 508, 2HD & 9NC. Fortunately both are the same Hydraulic SysOp document, so attached is a copy. I didn't bother uploading the hydraulic schematic (which is also the same publication # for both machines) because it doesn't reproduce worth a ****.....