I've got a CX130D with a Strickland hydraulic thumb. Since the thumb was installed new it has bled off while using the bucket unless pinned. When fully retracted it will drop about a foot within 5-6 buckets. I'm constantly having to bump it back up. Since I'm mostly in timber this becomes quite annoying an is obviously damaging the cylinder. Twice now the piston bolt has come lose an damaged the cylinder. They'e fixing to put the 3rd cylinder on. Since this is the only track hoe I've ever operated I'm not sure if the thumb weight causes this on its own or if theres another problem. Any advice would be appreciated.
It sounds like a circuit relief valve problem. May have gotten some trash in it from the first cylinder problem. Have your dealer tech check pressures on that circuit.
Was trash in the valve? The piston nut shouldn't come loose if its tight enough but, a loose piston can cause the cylinder to bleed off too.
I'm not sure about the trash in the valve. Its done the same thing since it was brand new. They have replaced the cylinder again since I posted and I have built a rubber bump stop to keep it from banging so hard when it is fully retracted. It still bleeds off but only to a certain point now...so I don' have to continually pull it back up....we'll see.!!
Are there circuit relief valves in the thumb hydraulics. The thumb cylinders are not designed to run at system pressure. I usually on set them at 2,100 PSI.
I'm not sure on how to tell. I do know that the thumb pressure is adjustable thru the control panel tho.
I don't recall if that is possible? Would like to see how that is done.
I have seen oring chunks from a cylinder failure get in those electronic circuit relief valves and cause the thumb to do what yours is doing. Have you tried temporarily setting your relief pressure to the high side just to see if it stops drifting? You can't leave it too high or you can actually blow your thumb cylinder seals by curling your bucket against it. I've seen that happen too.
With the push of a few buttons I can change the thumb pressure from 2030psi to 2175 psi.
Ive try'd it at both pressures available...no difference. There' got to be some sort of trash hung up somewhere in the system is my thoughts too. The blocks on the dipper can be close off an the thumb will stay in whatever position it's in at the time.
Ok. If those shut off valves can lock it in place then your cylinder is fine. Sounds like its time to take valves apart. If you are the guy for that job. Make sure you follow the procedure for bleeding all the pressure out of the hydraulic system. Each machine seems to have a different procedure. Hydraulic injection into your skin can be deadly.
Fortunately for me , I bought the three year extended warranty. Im' afraid their gonna try an baulk next time on the thumb tho since its over a year old. I don' know what kind of test they can do but to my knowledge Case hasn't done anything but replace the cylinder several times.
Lol. Parts changers masquerading as mechanics. I personally think you have cylinder guts from the first failure stuck in the circuit relief valve. The chance of all of that trash making it back to the tank filter without getting hung up is nearly impossible.
Gawd!! don't you just love the new generation of parts changers. It seems to me the problem is in the main control valve. There is an issue with the circuit reliefs not the cylinder, time to find out who to talk to. There is a Case rep that comes around about once a month. You can ask for him to contact you through Case customer service, you should have number in paper work for machine. If not get on line and get it from there.