Hello there HEF team!!! I need your expertise to help solve some issues I am having with installing a hydraulic thumb on my mini. I have scoured the forum board, and I think I know what to do, but I wanted to reach out to the experts. Here is my scenario: I am working on a mid 90s Kobelco SK35-2. The machine came from the factory with three ports at the front of the machine. One is a return to take port, and the other two ports are for hooking up a breaker (1 way) or a thumb (2 way). I have helped run the plumbing, friend built the thumb, etc. etc. but of course I am an idiot and didn't know about pressure relief valves and therefore bent the thumb cylinder rod... :-( Now here is my question. Does my machine come with pressure reliefs built in to the "aux circuit valve stack"? Where the **** is my aux. circuit in this diagram? Can someone please educate me? ---ADDED PHOTOS FROM LAST NIGHT--- So it seems to me that my machine has the proper 2 way valving built in to therefore use a thumb, but I don't believe that I have the proper port relief cartridge(s) in the "aux. section" aka my service spool to be able to safely run a thumb? Looking at my machine, it seems I could only install one port relief cartridge in my "aux. section" vs. two? One top and bottom? I am thinking of just putting in a in-line pressure relief valve on the butt end of the thumb cylinder, and just teeing off that and running another section of hose to the tank return? What do you all think?
Any input or suggestions? I would rather not run a third line back to the tank, etc.
I will have to look at my manual tonight if I get home in time but I believe #6 should be the valve for the aux which is what you are using they call it service.
Thank you so much for the response. #6 is def. the aux section "service section". I have confirmed that by taking the bottom cover panels off, and can see the pipes are routing from section #6 to the two front ports on my machine. The two pipes are shown in the third picture from the bottom. The two all black pipes. The foot pedal in the cab is definitely a 2 way valve becasue before I bent the thumb cylinder rod, the thumb would close when I push the pedal forward, and open when I push the pedal back towards me. I just don't see any factory relief valves in section #6? So therefore, I don't know how to reduce the pressure of the thumb cylinder so my curl can overcome the thumb. Any help/guidance is very very much appreciated. I will take as many photos as you all need, either of the machine, or of my manuals.
Hi, there are no factory port relief valves for aux section in your machine. You would probably be best to fit in line relief valves on both open and close functions.
Thank you very much for the reply. I was thinking of only running one relief valve, so that the curl could overcome the thumb without bending the cylinder rod, etc. Can you please explain to me why I would need two relief valves? Also, is it possible to install a port relief cartridge into my aux. control block? It seems if I could, it would only be on "one side" of the spool? Does that make any sense at all?
Single acting aux needs one port refief, double acting needs two port reliefs or things start to bust and break. Being a while since I worked on that size/model but as far as I can remember that aux section can't have genuine port reliefs screwed into them. Even if you could last time I ordered a port relief valve for a kobelco of that size it was over 600 euros each.