I just got finished installing a hydraulic thumb. This ex used to operate a hammer and pile driver thing. Alot of use using only one side of the aux hydraulics. Thumb works both ways, has excellent power when done and will hold a load. But when retracted up, it leaks down via gravity. I can hold it up to keep it from going down. Please see these vids attached. I don't know where to start.
My guess is it's returning to tank instead of being two way flow and needs to be switched?
Needs to be switched from breaker to thumb. Should be a valve by hyd tank towards front of machine. Picture may read backwards try both positions
I have either breaker or nibbler in my valve. In breaker it didnt work. Put in nibbler and it worked both ways...just leaking down from that one side. Could the valve be put in another unmarked setting?? Thank y'all for helping with this.
In nibbler setting you need to check the pressures in both lines you could have one of the port reliefs set too low
Been wanting to get pressures checked. In that pic of my valve. I wonder what the other two positions do. I am too much of a chicken s@#% to try....worried I may damage something.
Putting it into the other two positions won't make it work. Get the pressures checked and then there will be some solid information to work with
Will do. will report back with what I find. Thank you!
Switch the lines at the thumb and see if it still settles. Does it settle with the machine off? We had alot of new thumb cylinders that came in with rust in the cylinders because manufacturer didnt fill them with oil. Could be the thumb cylinder is leaking by internally. You can also cap the cylinder at both sides if it settles the cylinder needs to be rebuilt. If not relief might be stuck open a little from contamination from the breaker
Ok, I will swap them today. If it doesn't settle, can I just leave it like that? I have it to where the left toggle closes and right toggle opens. Hell, may be backwards anyway. There was oil in the cylinder. I do think it settles less when off.
If it doesnt settle your problem is on that side of the valve. You can leave it that way and swap the wires at the valve for aux if the you want the rocker to be the way it was. If it settles the cylinder or the valve is the problem. If
An inline check valve in the lower cylinder hose may stop the drop. Unless the cylinder has internal leakage.
What kind of check valve? Thumb needs to work in both directions if the check valve stops it from drifting wont it stop it closing when you need it to?
I should have said an electrically controlled one spool, two way valve, they are quite common. It would work ok. For me it wouldn't be an option. I'm tooo fussy and would want a section in the control valve bank that is designed for a thumb. Hopefully gggraham will read this thread and provide the solution for the drift in that cylinder. It is really weird that the thumb works as it should but drops when it is not in use.
Counterbalance valve on cyliner would work but that's a pricey bandaid
I did not have time to swap hoses today. Will try to do it in next couple days.
Was able to go out and at least crank it up and find out that if I bring all the way up to stowed position and let it start leaking down...if I turn engine off the thumb stops leaking down.
That would mean it’s not the cylinder leaking internally. Relief set way too low? You could try gently pushing the thumb with bucket and seeing if it goes back even quicker, that would likely confirm it’s relief pressure.
Will check. And....just a thought on this. It is former life, it spent it's time doing construction on the gulf. Doing seawalls etc...using a pile driver and hammer often. Wonder if they had the pressures on one side turned up some or would that even matter?
Swapped the lines. Good news is it does not leak down. Bad news is that the circuit that would normally retract thumb does not have near the power. Tried lifting a pole and it wouldn't hold it. Maybe pressure too low on that side? I swapped them back.
Same as I said before check auxiliary line pressures. Sounds to me like you either have a relief valve set too low or a faultly relief valve
I doubt it's set low enough to settle if it is you should be able to tell by looking at relief valves one should have the screw turned way out compared to the other. Swap relief valves around if problem moves then your relief valve is dirty or bad. You can try cleaning it. If problem doesnt change your spool is the issue and you will need a complete valve. Breakers are hard on machines if breaker fails it sends metal right into that valve.
I called a guy today about checking pressures. Gonna have to find the relief valves. New to this. Thank all of you for the help. Will post what I find.
Waiting on someone to get back with me on who I can hopefully trust to not overcharge me for a house call. In the meantime, could I turn up the pressure (gradually of course) on that one side that leaks down to see if it may make a difference? And if I can, where do you do it at? I have parts manual and operator manual. Need to order maint manual still.
You could try sending a PM to gggraham. HeEFwill send an email notice to him that he has a PM. Ask him to post any help he can give, in this thread so it may help others with the same problem.
Will do. Thank you
Melben and Coy Lancaster may be able to help also. Both are super knowledgeable retired Case technicians.
Judging by your earlier pictures your machine is a rebranded kobelco. Most case mini diggers of that age are. Follow the pipe marked in orange back to the valve chest and where it attachs is your aux spool. the relief valve on the top side of the valve chest. If you want to swap the port relief valves in that section around it will tell you if the valve is the problem
Does it unscrew where my finger is or up top? You can see the very top is unscrewed some...the others are not like that. Getting myself a crash course in hydraulics.
That is screwed out a lot. Adjust it in first to see but remember you need to get the pressures set correctly or you will end up damaging something
Will do. Where my finger is pointing, is that where the entire valve comes off to swap it with just another one near it?
To swap remove the whole valve only swap it with the one directly under it on the same spool. But adjust it first see what happens
You can slowly turn screw in until the bucket wont push thumb in then back off until bucket will push the thumb. 1/4 turn at a time. Then turn in other side until thumb pushes bucket then back off so thumb cant push bucket and you'll be good
So any issues making adjustments while running? Planning on putting daughter in cab and me making turns at same time. And the other valve...to be sure is the one directly underneath. Adjustment facing down.
No issue adjusting while running and yes other valve is directly underneath facing down
Ya know, this hydraulic flow is very very close to electronics.....transistors, relays, switches, rheostats...
The only issue with it running and someone in operators seat is operator could bump something and you get hurt. Take your time make small adjustments and don't let someone in the seat with controls not locked
I did it with small adjustments, took maybe half turn to get it to where it does not leak down and is much quicker. Gonna let that be good enough till I get a test kit, figure out how to use to and know what I have. You guys have no idea how much I appreciate all the help. More questions later when I decide to replace all the fittings and hoses for the finals. Very Respectfully