Youli MB3 valve question.

[K5lwq]

Merry Christmas!

I installed a Youli MB3 valve with third spool on my loader in anticipation of a new grapple from EA. I posted a picture and thats when I noticed it was missing a screw on the joystick. I am not sure when or where it came up missing but I don't see it in the box or around where I installed the valve.

When I tested the valve, I noticed that when you are lifting the boom and dumping the bucket at the same time the boom starts to fall. It will raise and curl up at the same time no issue. It will perform all other functions independently perfectly. So, my question is could this screw be the issue or is that just the design of this valve? If it is the design, I have never seen that before and think that is something I will not like about this valve. Any help would be greatly appreciated.

 

[K5lwq]

Update.

I tried to put one of the other screws in this hole and it just slides in and out. No threads. I am guessing I did not loose anything but it is designed to use only three screws on the joystick. I am still curious as to why the boom falls while raising and curling down at the same time. Maybe a faulty check valve?

 

[oldnslo]

Possibly the load check valve on the raise lower is not sealing properly. Under certain load and spool positions this could allow the loader to drop even while trying to raise.

Using only the raise function While try to raise the loader very slowly does the loader want to drop or will it stay up?

 

[K5lwq]

It seams to be holding fine if I only raise. I haven't picked anything up with yet so all test was just the weight of the bucket. I did test slow as well as normal speed. Thanks.

 

[Xfaxman]

Does the joystick have float?

 

[rScotty]

Update.

I tried to put one of the other screws in this hole and it just slides in and out. No threads. I am guessing I did not loose anything but it is designed to use only three screws on the joystick. I am still curious as to why the boom falls while raising and curling down at the same time. Maybe a faulty check valve?

What's needed here is some more information. BTW, that's a nice looking installation you did.
Since both the bucket curl and boom raising functions draw from the same supply source - in this case the pump output - seeing the boom falling slightly when the bucket curls may be unavoidable at low flow.
My guess at this point is that it may be due to the internal geometry of the loader valve or it could depend on the way that the hydraulic cylinders are configured end-for-end. Try running the same test with the fluid warmed up at medium RPM and see if the same thing happens then.
rScotty

 

[K5lwq]

Does the joystick have float?

It does have float on first spool.

 

[K5lwq]

What's needed here is some more information. BTW, that's a nice looking installation you did.
Since both the bucket curl and boom raising functions draw from the same supply source - in this case the pump output - seeing the boom falling slightly when the bucket curls may be unavoidable at low flow.
My guess at this point is that it may be due to the internal geometry of the loader valve or it could depend on the way that the hydraulic cylinders are configured end-for-end. Try running the same test with the fluid warmed up at medium RPM and see if the same thing happens then.
rScotty

Thanks Scotty! I will try that test and report back. I can learn to live with it as I only see the issue raising and dumping at same time. The old valve would only do one function at a time anyway. I just find it strange that it will raise and curl back with no issue.

 

[K5lwq]

Bad news job is interfering with tractoring. Good news new Grapple will be here Tuesday!! I will be able to run the test on Saturday and report back. Then I will run the new stainless lines to power the grapple and will post pictures of the complete set up. Thanks for everyone's help!

 

[K5lwq]

What's needed here is some more information. BTW, that's a nice looking installation you did.
Since both the bucket curl and boom raising functions draw from the same supply source - in this case the pump output - seeing the boom falling slightly when the bucket curls may be unavoidable at low flow.
My guess at this point is that it may be due to the internal geometry of the loader valve or it could depend on the way that the hydraulic cylinders are configured end-for-end. Try running the same test with the fluid warmed up at medium RPM and see if the same thing happens then.
rScotty

I was able to run some more test. Warmed up tractor and fluid for each test.

Operated at several different RPM settings and found if I curl down while raising boom the boom still falls. If I feather very carefully I can get it to raise or hold while using both functions.

If I curl up and raise at same time everything seems normal. If RPM is to low, it will stop raising the boom and curl up then resume raising the boom.

If I raise boom up then try to feather it back down the system loads as if trying to lift tractor or lifting a heavy load. If I idle down then lower by pushing fully on joystick, it does not strain at all. Not sure why it labors if I just barley push on the joystick to lower boom.?

I am starting to think the new valve has regen and that is why it is performing this way. I will have to get with the folks I got the valve from to find out. They do not open again till next week.

If anyone has any idea of what is happening I would appreciate the info.

 

[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.