Loader bucket "swings free".

[TheOldMan]

Yanmar Ex450 w/CL400 FEL. Been trying to locate this problem with the dlr and with Yanmar America, so far nobody knows whats wrong. Loader has a Prince valve, with float and regeneration. Dlr added solenoid operated valve for front remote for grapple at purchase. Raise a load and dump, leave the bucket pointed downward and try to back blade, and the bucket will float up over the top, and if the tip of the budket doesn't hit the ground, it will actually swing free, like a pendulem a couple of times. Once you put hyd pressure on the bucket, it is solid as a rock til the next time you dump it. There is just enough play when it's solid that it is impossible to load the bucket, it will either dive or float on top. As far as i can tell, when the dlr installed the remote, he used the power beyond port on the valve to feed it, and returned into the xmission. I seem to recall reading somewhere that there was a blind plug that had to be installed in the valve to utilize power beyond. If this was missing, would it cause this problem. Any hydraulics experts out there that could give us any ideas? Yanmar America sent two men, regional sales mgr and cust svc rep here to the farm last week to look at the problem, and they were stumped.

 

[oldseabee]

Sounds like problem in regeneration circuit. Try dumping with engine at high idle and just crack the dump valve so the bucket dumps slowly. The Regen valve works when you dump the bucket with a load and engine at low idle. The cylinder moves faster then the pump can fill the dump side creating a negative pressure which would shift the regen spool to divert oil from the return back to the dump side of the cylinder to prevent a void. If the centering spring is broken or weak or the spool is sticking the regen valve may not be coming back to block the return oil from the Cylinder letting the bucket swing when dangling.

 

[TheOldMan]

As I mentioned above, the factory guys were here last week because the dealer couldn't fix it, and I guess he couldn't explain what it was doing. They made a video while I operated it, and took it back to the engineers to study. It doesn't seem to matter how fast you dump the bucket. The best example of failure is if you dump a load and try to backblade, the bucket will curl right up over. It will continue to do this until you apply pressure to the dump side of the cylinders. In order to apply that pressure, you must hold the control over at the detent before regen. At idle it takes about 7 seconds to pick up pressure, at higher rpm 4 - 5. I've tried to convince them to just change the valve, but they don't seem to want to do that. I'm about at my wits end on this thing. Can't tear into it myself, that would let them out of the warranty. I think he problem probably can be attributed to a tractor that is more powerful than the loader, and has broken something inside that valve.

 

[oldseabee]

It may sound silly but have the cylinders been bled out so there is no air trapped in them, not always easy. You have to get the cylinder pointed up and bottomed out, remove or loosen the fitting at the rod end, then extend the cylinder slowly to clear all the oil and air out of the rod end then the same for the base. The other possibility is a loose piston on one cylinder. Can you un pin one cylinder and operate the dump with just one cylinder, then do the same with the other cylinder, at least that will tell you that it is in the valve for sure.

 

[TheOldMan]

I'll give the one cylinder at a time thing a try, hadn't thought of that, bu I have extended cylinders all the way then removed the fitting and added pressure to see if a cylinder was by passing. Also swapped the disconnects from the loader to the bucket, and the problem moved with it, so think it has to be in the valve. I'm a little confused as to why Yanmar would send two people, one from Pensacola and one from Atlanta, looks to me like it would have been cheaper to just swap the valve while the tractor sat at the dealers for 2 weeks and he never touched it.

 

[maytag]

I'm far from an expert especially with mobile applications but I haven't found a Prince valve with both float and regen-found several with either but not both but I may have missed it on their website-if you could supply the model code we might give you a little more help.

 

[oldseabee]

It seems to me that normally the valve would have float in the boom circuit for back dragging and regen in the bucket circuit for anti void.

 

[TheOldMan]

The Prince valve is LVS, and it does have float on boom and regen on bucket.

 

[maytag]

Tuesday

The Prince valve is LVS, and it does have float on boom and regen on bucket.

I'll buy that, never saw both on the same circuit. Prince has some pretty good info on their site, makes mention several times that the boom circuit and the bucket circuit need to be connected correctly to the tha A, B C and D ports-also mentioned the spools need to be oriented correctly and there is a "regen sleeve" that needs to be installed correctly-I expect you will find resolution by looking close at your valve.

Good luck with youe endeavor,
Tom

 

[TheOldMan]

Well, here's the problem. This was reported to my Yanmar dealer while the unit was under warranty. It is no longer in warranty, but bcause I reported it in time, they still have to fix it. I'm afraid the if I tear into it, they're gonna get out from under that warranty. I feel that I have to wait on them. this thing goes way back. It all started in May, and here it is September, and they're still dragging their feet. There's a question of authenticity in the way the tractor was sold to me, so I really can't do anything on my own in case this ends up in a lawsuit. It's really involved, but if I can come up with some suggestions from someone who has experienced this problem in the past, I can pass that info onto Yanmar, and maybe get the tractor fixed and go from there.

 

[oldseabee]

You might want to check your state for a Lemon Law. Mostly they cover motor vehicles. The other option is small claims court. The other thing is to work your way up the food chain at Yanmar, start at regional office, then go to corporate Hq. Make enough noise and someone will pay attention.

 

[TheOldMan]

Florida says the lemon law, written estimates etc. don't apply to any vehicle that is operated primarily off the highways. I hope this doesn't progress to the point of legal action. I'd be fighting the deep pockets of Yanmar America. Don't suppose I could win. Today is a week since the factory reps were here. If I don't hear anything by days end, I'll contact them again tomorrow. It's hard to believe that they have the engineering expertise to design all this equipment, and still can't diagnose a simple hydraulics problem. I've talked to Prince about this, and they say that they built the valve, but they didn't design the application, so it's not thier problem. As I noted in my first post, the dlr installed the power beyond romote to the loader for grapple, but there would have been no reason for him to have gotten inside the valve, except to insert the plug that enables power beyond. I purchased the tractor as a demo. Had 59 hrs on it. I had it at home for about a week prior to them installing the extra hydraulics, but being a new tractor and all, I was playing with it, but don't recall if the problem was there prior to them working on it or not. Hindsight tells me that 59 hours may be excessive for a demo. This may have been a repo or lemon bring back. The bill of sale refers to it as a demo, but the financing paper work that went to GE Credit says new. I wonder if this constitutes fraud?

 

[truckdoctor]

I've seen a similar problem with other loaders I haveworked on before. Those machines had an issue with the bolt or nut on the back of the cylinder rod coming loose and allowing the cylinder to bypass internally. It would stop as soon as the piston reseated on the rod.

 

[TheOldMan]

Thanks truckdoctor, that's something I hadn't thought of. Then what you are saying, is the cylinder hasn't come completely off the rod? If it came completely off, would the rod be able to center itself in the hole in the piston and reseal? Is there any way I could check this without physically opening up both cylinders?

 

[alrman]

Is there any way I could check this without physically opening up both cylinders?

If you support the loader frame, say, up on the back of a ute or truck, & remove the pins that go through the rod ends, you find some slight in & out movement in the loose rod.

 

[TheOldMan]

After thinking about this for a while, since the two tilt cylinders are in parallel, why not block off one cylinder and see how it performs, then vice versa. Went to town and got 2 #6 plugs, plugged off one cylinder, and worked the other one, and it seemed to work correctly. swapped the plugs, and that side floated all over the place. Cycled the dump 20 or so times to work all the air out of it, and decided to check the first one again. This time it floated too. Put everything back together, and it works just like it did before I started except - now i don't find the regenerate detent unless I push the joystick all the way forward as in lowering the loadrr frame,then to the side, then it's there. I guess I didn't acomplish anything except waste time. since this is the tilt ckt that's giving the problem, I could tilt the quick attach all the way down, and pull the attach pin and see if I got any movement.