My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

[EE_Bota]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Looking at the pictorial of the lowering speed control valve on my 2200 makes it look like there is a spring and check ball that keeps it from also being a raising speed valve.

I'm not sure this helps at all...but it could be possible to remove the ball and spring that does the check portion, and instead plug the port the ball blocks only one way so it is blocked both ways. This might deny it it's full speed up path, and force all oil through only the part controlled by the twist knob.

 

[Navigator7]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

I'm just having fun with this theory.

Hello Harvest Moon!

I'm not familiar with your piece of equipment....I didn't read all the posts....but am I to understand you are trying to smooth out your boom so it's perfect and not jerky?

Your post somewhere else drug me over here.
I know a bit about hydraulics and if your machine wasn't doing what you wanted in the first place...that's where you need to get back to.

Cun you speel out your problem for us publicall edukated yoots?
;-)

 

[Rockyridge]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Hydraulic basics for dummies: My understand is that with power beyond valves the high pressure fluid passes through each valve in series until one of the valves redirects it, or a portion of it, to a cylinder to operate the cylinder. The rest of the fluid continues to downstream valves for use as necessary and finally back to the reservoir. The FEL valve can redirect a small portion of the fluid to move the cylinder very slow or all of the fluid to move the cylinder fast. Is the problem that the 3ph valve on these specific tractors does not allow for redirecting only a portion of the fluid as the FEL valve does? Is it all or nothing with that valve, but only on some tractors? Additionally, in the parts manual, the valve control look very similar to valve control for tractors that work smooth.

Another question comes to mind, is the valve is all or nothing, or is the feed back mechanism over reacting. Would it be a reasonable test to disconnect one end of the feedback rod (under the seat), , and slowly move the valve end until the 3ph went up to see if still jerked while controlling it that way. This would remove the hand lever linkage and verify that the feedback is not over reacting.

I would to do the test myself (and will if nobody has done it by the time it warms up a little) but I don稚 have a heated place to work on a tractor and we have minus 35 degree wind chill right now.

 

[slowzuki]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

The videos look exactly like on a large ag tractor when you adjust the 3 point hitch to have a fast raise response with a light implement.

It can be pretty violent on the implement and tractor.

I think it just adjusts the flow to the 3 pt hitch but I could be wrong.

 

[Navigator7]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Another question comes to mind, is the valve is all or nothing, or is the feed back mechanism over reacting.

If the pump providing the flow of oil is a gear pump type, when you put a load on the flow of oil via a power beyond valve, that which is downstream can suffer a little or shut off all the oil.

If the pump is pressure compensated, like an excavator, all the valves will see the pressure and flow up to the limits of the pump.

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Hi Navigator7, if you didn't have a chance to read all 101 posts the first post #1, canoetrprs great ideas in post #65 & #72 and my experiment results in #81 will get you the gist of it. There are lots of ideas, suggestions and other input throughout. As for the pump, I'm just about positive it's not a pressure compensated pump.

Rockyridge, I've pretty much been convinced that there are two problems. A) the valve I have is lousy. The valve from the L3010 is much better and B) The flow to the hitch is too fast.

I haven't put much though into the feedback lever or the power beyond aspect. If or anyone wants to see if adjustments to the feedback linkage make a difference that would be great but I think the feedback linkage is overpowered by the bad valve and high flow.

I'm still holding on to hope changing the LSV out for the better one will help smooth out the performance with the L3010 PCV valve and the only problem left will be that the hitch is a bit on the fast side. I've pretty much asccpeted that we won't get L3010 performance because the L3010 probably has a larger cylinder but it would be nice to hear from someone with the specs. on that.

I have an order in for the L3010 PCV. $372.63. Should be in my hands next week. Oh how I love spending money.

 

[Reg]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Reg, I'm thinking if we rule out the $5 parts with the 15 minute task then we can move on to more advanced solutions.

As far as factory set up, well, I think all L3400's with the lousy PCVs demonstrate similar malfunctions. Many thousands of them but I've only seen a few. The only solution I'm aware of to date is to replace the PCV with the one from the L3010.

There is definitely over shoot and quick stop. The quick stop first then the overshoot as the momentum throws the implement up past the stopping point. This is allowed by the one way/float nature of the 3 point.

I wonder if that can have a resonating effect on the linkage system or not.

Having not seen this...
I would take overshoot and the sudden stop as symptoms that it is not acting proportionally on the difference signal.
It is most likely going on at full speed until the sign of the difference signal changes.
Whether this is by (lack of) design or improper set-up - as I said, I havn't even seen one, not even just standing there switched off.

SOMEONE must have a shop manual for this and at some level of detail there has to be a set-up procedure for the rods, bell-cranks, whatever dingus thangs send the position signals back.
I'd want to do whatever set-up, calibration, alignment on all that FIRST.
My guess is that mis-adjustment there would/could/might cause some/most of the symptoms described, so I would want to get the set-up done to eliminate it, resolve the problem, or at least reduce the problem.

A reasonable theory might be that the set-up isn't being done at the factory and isn't part of pre-delivery check either.

 

[GMtb42]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Progress report ?
Work , not work ?

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Progress report ?
Work , not work ?

I think what you are looking for is back in post #81. Still hopeful that the LSV change will affect a positive outcome. Still waiting on the L3010 PCV valve.

 

[Rockyridge]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

This weekend I was able to test the 3ph feed back and it was not any better raising the 3ph using feed back than the normal lever to move the 3ph, still jerked when moving up.

I did learn that the 3ph is not going all the way to the top though. I should be able to get an additional inch or so higher at the top arm by adjusting the feed back rod. This should be two or three inches at the end of the bottom 3ph links. Might be just what I need to keep the PHD from dragging.

There has been some discussion about the capacity of the pump in relation size of the 3ph cylinder. I know that there are many variable to calculate this but we may be able to learn something about their relative capacity by the observing the speed that the 3ph goes up.
For example with two systems with the same size pump capacity, the one with the smaller 3ph cylinder will go up faster and react quicker while the one with a larger cylinder will move slower but will have more power lift capacity.

After warm up plowing snow for about an hour, my L3400 (jerky 3ph) went from all of the way down to the top limit in just a little over 2 seconds running at 1000 RPM.

How about someone with a smooth 3ph timing how long it takes for their 3ph to move from all the way down to the top at 1000 rpm?

Thanks

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Rockyridge, Adjust your feed back to get the extra inch with CAUTION! That extra inch is free play and it's factory spec. I think it is there to protect your tractor from damage and keep the hitch from supporting the full weight of the tractor incase of a misjudgment.

Like the time I hit a hill with my subsoiler fully raised and it didn't bite. I was concerned at fist to see it raise up past the limit, thought I broke something. After I realized the amount, thankfully, that I needed was designed into the hitch I was relieved it was there.

Thanks for being the one to test the feedback! And that's a great question and observation about the raise speed, let's hope some one with the smoother valve gives us a number. And although it has a different pump it may help to get the same number from an L2900 or L3010 owner.

 

[GMtb42]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

I think what you are looking for is back in post #81. Still hopeful that the LSV change will affect a positive outcome. Still waiting on the L3010 PCV valve.

I have one of the L3010 valves it does not go up at the speed of the one in the video , way to fast , if I can get the parts will try and see if valve helps or hurts performance on lift .
Will try suggestion in post #94 :The third and fourth component are the spring and the washer:
04012-50080 Washer $0.06 at tractorsmart.com $0.11 at Messicks.com
30812-37360 Spring $4.74 at tractorsmart.com $5.68 at Messicks.com

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Awesome GMtb42!

My new PCV arrived today and I had a chance to run it and my machine down the road to a local farmer/tractor mechanic. I was going to attempt the repair myself but decided not to for lack of a proper shop and winter weather.

I don't have a clue as to when it will be done, I told the guy I'm not in a hurry. I'm just glad he took on the job, I decided a long time ago that I'm not letting "my" Kubota dealer touch my machine unless I can find no other option.

If GMtb42 goes for it we'll have some long awaited answers. Maybe sooner from GMtb42 than me. The benefit (if the results are good) from GMtb42's effort is that we'll be able to compare the $5 LSV modification with the $90 LSV swap out that includes the alternative shaft. Honestly, I can't imagine how adding the spring and washer could have any negative impact when used with the L3010 valve as it is in several other models.

One problem with the new LSV is that the shaft is too short and the handle is extended on a "pipe" that is too long. If I don't swap it back out I will forgo the L3010 knob and rig up the original. The L3010 handle "pipe" can be shortened but I'd rather have the original anyway.

The beauty of the $5 change is that you'll still have the shaft and original knob, so it's simple, cheap and easy. Replacing the shaft, or entire valve is probably not necessary but we won't know until someone tries. It will be really cool if this helps!

Obviously and oddly, I'm still optimistic that this will help!

 

[canoetrpr]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Harvest - glad you are an optimist!

I spent some time studying the shop manual wrt. the valve, feedback linkage and so on. I'm amazed and to an extent happy at how simple and basic the mechanics of this model are.

The PC lever opens the valve, fluid rushes into the cylinder raising the hitch, the feedback lever closes the valve back.

I also continue to be amazed that Kubota did not get this right given the simplicity of the design.

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

I also continue to be amazed that Kubota did not get this right given the simplicity of the design.

Probably should leave this alone but I say product differentiation.

I know, I know... they don't say, hey, come on this Grand L (or B3030) has a smooth hitch and the L3400 has a junky one but they've gotten quite good at saying, hey, you bought our economy model...

 

[EE_Bota]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

I sure wish you fellows luck. I have spent several hours studying parts books online. It's a rough way to go compared to an actual schematic, but it did give me a few more clues than before.

I'm sure you fellows have seen these videos, but forgive me if you have,
but it does add weight to a valve change..
Before
YouTube - Kubota L2800 - Trying to raise the 3point Hitch
After:
YouTube - Kubota L2800 After Valve Replacement 3PH

Canoeptr, you said in an earlier post that the function is simple. Looking at the second video, I can see the control handle progresses upward (does not return to center to stop movement)....are there sliding friction disks in the linkage that the feedback linkage causes to slip? Does item 250 attach to the valve?
I tried to do an attachment of a L2800 parts page.

 

[teg]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Hey!!! that's me!!! I was very glad to have gotten mine replaced (and do feel sorry for those that could not). I saw that my dealer went out of business coming back from Christmas... not sure how I felt. Sorry to think that kuboota might have gone back to those valves... hopefully, they will not follow my dealership... Glad to see people trying to fix the problem.

 

[Harvest Moon]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Hey EE_Bota, thanks for your continued help with this. I'm not up to speed on the nuances of the feed back levers mechanics, just the basics as canoetrpr outlined.

I did a quick compare between the L3010 "feed back lever" and the L2800 "feed back lever" and it looks like all the part numbers match up except for the actual feed back rod. I didn't check every number but the little parts like #250 that I did check (at least half at random) all have the same part numbers.

What does it all mean? What do all those little parts do other than seem to make the PCV lever stick and difficult to move smoothly?

I'm pretty sure #250 is the part that connects to the valve but I don't have my WSM or tractor at the moment so I can't take a closer look.

 

[EE_Bota]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Sure Harvest_Moon..you guys have worked hard on solving the problem and I hoped Teg's videos would provide a little encouragement.

I really appreciate Teg's video showing the before and after.

This thread is so long now, I can't be sure I have read it all. I did notice Canoe_ptr's very nice description of how he would go about installing a flow control valve, and he said he understood the linkage a bit, and because I don't have the tractor (therefore neither do I have the service manual) I am struggling a bit with the linkage. But obviously, it's not really important that I know, so it would be a bit of a waste of someone's time to explain it to me.

I truly believe you will succeed. But, if for some reason it does not work out, don't let it get you down. Canoe_ptr's concept of the flow control valve also has promise..so either way, you WILL get the results you are seeking.

Good to meet Teg.. I spent 10 years in Raleigh. First four years getting an Animal Science degree, also working at the Dairy Research Unit, and a couple of years a D.Dix dairy farm as assistant manager. Returned a few years later to get the Electrical Engineering degree. GO WOLFPACK!

 

[canoetrpr]

Re: My quest for "Grand" 3 point performance from my "economy" tractor. The L3400

Hi EE_bota. I don't know what a sliding friction disk is unfortunately. Not quite sure how to get my printer to scan. I think it has the functionality so I will take shot at it soon and try to scan in the page from the service manual that explains the workings of the position control valve.

I'll try to describe but its bound not to do much good.

- The position control lever turns a shaft which is connected to the a control on the valve which causes the valve to open thus moving the hitch.
- The feedback linkage from the hitch arms is also connected to the same control on the valve and as the hitch moves into position, the feedback linkage arm closes the control on the valve which causes the valve to close.
- The delta between the position of the position control lever and the feedback arm is what causes the valve to open. Once the hitch moves (or drops) because a delta is created by moving the position control, the feedback lever moves into place to close the delta.

It is all a simple mechanical feedback mechanism. No rocket science to it whatsoever.