Youli MB3 valve question.

[K5lwq]

Still having an issue with this valve. I have upgraded the pump to a 10GPM pump from the 7GPM pump that was original to the tractor. This corrected several other issues I was having but the valve is still a problem. I am talking with the place I bought the valve from but still no answer. From what I can see, if I am doing more than one function, raising and dumping or raising and curling, the boom will fall. If I fully dump or curl and allow the cylinder to dead head while raising, the boom raises as it should. If I try to just feather lowering the boom only, it loads the engine and tries to hammer. If I push up past that initial point it lowers normal. My issue seems to be related to the first spool and it has 4th position float on that spool. Any help would be appreciated.

 

[Xfaxman]

If the loader works right after putting the original valve back on would prove the new valve isn't working correctly.

 

[K5lwq]

I am fairly confident it is in the valve, mainly because of how it labors retracting the boom cylinders. With tractor off and boom in the raised position, I can easily feather the valve to lower the boom. It only shows resistance when the pump is providing pressure. I am sure it would labor with hose disconnected. I had the same issue with the 7GPM pump. I did not have the issue with old valve. The falling I could deal with more so than the inability to lower the boom slowly. If using forks and want to gently set the load down it will be almost impossible.

 

[oldnslo]

K5Lwq,
Some valves have terrible metering and from what you are describing the Youli could be one of those. I know that I removed the "factory" valve on my Branson for this very same reason.

When lowering the valve has to meter oil out of the cap ends while allowing oil into the rod ends. Getting this metering to work effectively can be challenge for valve designers. In most cases better metering requires more spool travel and adds cost.

Can you install pressure gauge in the rod end of the lift cylinders and watch this pressure while lowering? Curious to see if it bounces significantly when lowering.

 

[rScotty]

Next time you talk with the Youli valve technical people, you might ask if they sell this same valve but with a different Power Beyond threaded insert for use on closed circuit hydraulic systems. It is real common to manufacture a valve body that way so that the basic valve body can work with open or closed hydraulic systems. Or simply ask them to send you the power beyond adapter for that valve for open circuit hydraulic use. Then compare it with the one in your valve body.

Some John Deeres use closed circuit type hydraulics, but I believe your Kioti is open circuit like the majority of compact tractors.

What has got me thinking this way is that the odd problems that you are having - especially the one where the hydraulics are loading the tractor when lowering is just exactly what I'd expect if that valve has the wrong Power Beyond insert in it.
luck, rScotty
rScotty

 

[K5lwq]

Thanks guys for the help. I stopped by my local hydraulic shop today where I purchased the valve. Good people. Anyway, when I ordered this valve they decided to order two thinking some others might would like a similar set up. He was going to bench test the one he now has in stock and I have removed my valve to take in tomorrow for him to test. He said they will make it right one way or another. I will let y'all know what is found. I wish I had seen this before I removed as I should have put the gauge on that spool to see what it does as Oldnslo suggested. I will ask about the power beyond plug Scotty, although I would think I would see a similar issue on each spool but it is only on the first one and only lowering. I hope we can get this resolved because I really like the set up. The valve was a little over $500 so I would think it is a quality valve.

 

[rScotty]

That sounds like a real quality shop doing all the right things. My guess was not just for the power beyond plug - I don't know this valve body, and it might not change functions by changing the PB plug. What I meant was if there is anything that is normally done to that valve set to make it closed circuit rather than open circuit, and to check that it is correct for your system. Sounds like the guy will know what we mean.

Hmm....Did you ever change the spool connections (swap the curl and boom lift spool connections) to see if the problem followed the spool or the loader cylinder?

Good luck today. If you watch the test I'd be curious what you think about the test setup.
rScotty

 

[K5lwq]

Completed the bench test for my valve. My man ran the test while I was working and called saying he did not see the issue. I was able to free up to go test personally and was able to duplicate the issue on his test equipment. He thinks I am the only person that would notice that. Lol After me pointing out how it blows past the relief valve only on the first spool and only in the 1 position, his curiosity has climbed. In his mind, it should blow past the relief on all spools. In my mind it should not blow over the relief unless a load is placed on the system that takes the pressure beyond the set point. If I never overload the system it should never reach that point. Regardless of which of us is correct, he agrees something is not correct. Tomorrow he is going to test the in stock valve to see if he gets the same result and if so, is going to reach out to Youli. I guess tomorrow I will learn a little more.

 

[bigdeano]

I have a valve on my hydraulic press that does what yours is doing. When I try to feather it to bring the ram down slowly it deadheads the pump pressure before the port to the ram opens. I have to work it in little jerks instead of a smooth movement if just trying to move a little.

It's just not made right inside. I'm sure it's not supposed to work that way. In the other direction it works properly.

 

[K5lwq]

Very interesting bigdeano, I have been around tractors and other equipment with hydraulics my whole life and this is the first time I have ever seen this issue. Just curious, does the press have a float position? The spool I am having an issue with has float position and my hydraulic guy thinks that might be the issue. I tend to think the spool is just not milled correct. I think it can get into a position that stops flow to the power beyond port and has not opened to the cylinder creating a dead head in the valve. I am strictly guessing as I have a very limited knowledge of how the valve works. We always had someone else on the farm rebuild our valves, pumps and cylinders. I would remove and replace but that was about all I ever had to do. I kinda wish now Dad would have taught me more about that stuff.