gresen 25p hydraulic valve parts, tree farmer c4d

[Marcg007]

Hello.  trying to locate a valve repair kit for my gresen 25p hydraulic 5 spool valve. i found the manual, Some old part numbers are K-7001 or the service kit is K-7018.

treefarmer c4d pp  s#4932-008

In particular, the last spool valve in the housing is for the grapple, the one i wish to rebuild. this spool (far right) the relief is labeled "P". as the others have a "800" "500" stamped for the psi. also another housing (#2 main boom) has no spot for a relief, i believe. Setup for a Barko 4000, s#11435

I am wondering if the P could be a plug?and the relief was removed. as it is a completely different then the other relief valve inserts. Basically looks just like a cap or plug.  

the grapple is leaking down, opening up. a pain when trying to divert energy to keep the grapple closed while using other functions.

i will try to relocate the hoses to another spool function, see if i get the leak down there



 

[Autocar]

All the valve banks I have rebuilt just have O rings to seal and your local Ace Hardware have O rings and that's about all it takes 

[Marcg007]

All the valve banks I have rebuilt just have O rings to seal and your local Ace Hardware have O rings and that's about all it takes

autocar thanks for the reply. Any specific areas to check or must do's when reassembling? Known problem areas etc. ( i do have the manual an will review again)

thinking forward(bad pun), I am wondering if no pressure relief in that spool could have caused any damage to the grapple hydraulics. the grapple and rotator was replaced in 2019/20 before my purchase. a krpan grapple , and rotator from some company called Formiko Hydraulics model fhr 45sf. claims max load is 45kn or 10,100lbs. 20/lmin flow.   the krpan grapple portion i havent found much info on.

thanks again

[bushmechanic]

The first thing I would do is check the piston seals of the grapple if it is leaking off. More common for that to be worn out. Spool seals can leak but not really affect the cylinder function. If your going to change spool seals you should replace any o-rings with quad seals as they seal better.

[Grandpa]

It sounds like someone may have switched the functions on that loader. Some guys do that to suit their preference but you end up with the wrong port relief for the function. I believe the correct way is, from left to right, swing, bucket open and close, main boom, stick boom, and bucket rotor. Bucket open and close and bucket rotor do not have port reliefs. 

I'm with bushmechanic on the bucket cylinder.

[C5C Tree Farmer]

Port reliefs are used to control the maximum pressure on a particular valve function if the desired pressure is lower than what the main relief valve is set at.  Valves without port reliefs are meant to operate at the maximum line pressure which is controlled by the main relief valve. I doubt that the grapple function would have a port relief.

On a double cylinder function with a single feed it only only takes one defective piston seal to screw things up. To find the offending cylinder open the grapple and remove the cylinder hoses. Cap the cylinder ports and the suspend the grapple. The jaw with the defective cylinder packing will move toward the closed position all by itself.