L3400 3-point hitch adjustment

[timberland]

Anyone tried the " Jeff's Homebrew repair " ? I think its on youtube.

Maybe his repair would also be an option...

 

[timberland]

Anyone tried the " Jeff's Homebrew repair " ? I think its on youtube.

Maybe his repair would also be an option...

His handle is J252 on here, maybe he will chime in on this

 

[LD1]

I think right now we are looking for a solution without having to purchase any parts.

 

[kubotacres]

I got a chance to give it a good try today clearing snow with a rear blade.

The good news is it's still silky smooth on the raise stroke.

The bad news is I discovered that if you use hydraulics other than the 3-point, the load settles as it does when you shut the engine off, then when you release the lever for the loader or rear remote, the hitch snaps back to the original position.

What's happening is that with the valve in neutral position, it's using hydraulic power to maintain that position, when you take power away from it by using other hydraulics upstream of the 3-point valve, it drops as if the engine was shut off. This is what I suspected, that there was still flow to and through the valve in a steady state position.

It only drops about an inch, but it's noticeable. The heavier the implement, the worse the shock load is going to be.

I can't say as I'm happy with this "side effect", in fact it means I'll be digging into it again and trying some more adjustments to try and get rid of or at least reduce this problem. If I can't, I'll be going back to the factory settings, to me it's worse than the rough hitch movement.

If I reduce the gap from 0.045" to maybe 0.040" or 0.035" I should be able to reduce the amount the hitch jerks without getting into the "hunting" up and down I was seeing at 0.030". I doubt it'll be as smooth as it is at the WSM settings, but I can live with some compromise.

I'll post the results as I get a chance to make changes.

Sean

so I'm assuming "other hydraulics" is the FEL?

 

[Caseyb1]

I wonder if these specs are the ones for an older model?

http://www.tractorbynet.com/forums/2622676-post229.html

 

[Chilly807]

Hey Sean.....or anyone???

Do you know if those specs you got are the same for the older model valves??

I decided to heck with it and tore mine appart just now. If it is supposed to be the specs you listed I am awe-struck....

For starters, that 47.5mm spec you listed on mine came out to 1.970" (50mm)

And then I set the gap to .630 (16mm) and I have a good 1/4" gap where you say should be .004-.008:confused2:

Just wondering if the old valves are the same before I tighten that much and re-assemble I notice mine appears to have an additional plate where you are measuring your .630". I wonder if mine is supposed to have a different spec as a result???????

pic attached

I'm thinking the specs caseyb1 posted above are applicable to yours, assuming your valve has the same shape as the one shown, with one corner rounded off. The newer style valves, like mine for example, are more square shaped.

It sounds like yours is even more confused than mine, all mine does is settle slightly then jump back into position when you release the FEL or remote valve lever.

Sean

 

[Chilly807]

Before tearing back into it, it seems to me that "Feedback Rod" *may* have something to do with it??? If the 3ph drops, that movement will be transferred back to the valve? Right? Just guessing on things to try...

I wish "someone with knowledge" would send you a note explaining what you need to do next!!!

I tried tweaking the feedback rod a bit, it didn't seem to have much effect on the settling issue.

I think the problem I'm having is that both the raise and lower circuit are active at the same time, with the raise overcoming the lower possibly due to a larger flow area past the spool valve.

As soon as the hydraulic pressure is reduced on the inlet side due to a demand upstream of the PCV, the lower circuit is now able to let the hitch drop, until the feedback lever moves the linkage enough to close the circuit and stop downward motion.

As soon as the demand is removed, the raise circuit has a pressure supply available again and lifts the hitch until the feedback once more shuts it off.

I'm thinking I need to back the setscrew out to eliminate the two circuits being active at the same time to get rid of the settling and the problem described above. I know that the original setting of 0.045" gap will be jerky raising, but has zero settle.

The trouble is the no-man's land in the middle of the two adjustments. If I go too far in, from about 0.006"-0.016" both circuits are active and I have settling, from 0.020"-0.030" the hitch hunts up and down, and 0.045" is jerky.

I'm going to try 0.040" and 0.035" and see what happens. I think the jerkiness should be reduced, but if I go too far I'll get hunting again.

Sean

 

[Chilly807]

so I'm assuming "other hydraulics" is the FEL?

Yes, either the FEL or my rear remote (which I use to angle my rear blade) will cause the settle and snap back. The hydraulics will reduce or eliminate the flow to valves further downstream depending on how much you open the FEL or rear remote valve, for example.

Sean

 

[LD1]

I'm thinking the specs caseyb1 posted above are applicable to yours, assuming your valve has the same shape as the one shown, with one corner rounded off. The newer style valves, like mine for example, are more square shaped.

It sounds like yours is even more confused than mine, all mine does is settle slightly then jump back into position when you release the FEL or remote valve lever.

Sean

Yes, I think those are the specs for mine.

With the plate at 12.5mm, a .020 gap for the set-screw is about where I started. with the jerky hitch. It is currently @ .010 and I have the issue with the loader I described above. So I guess I am just going to have to back it off a few thousandths at a time and see if there is a happy medium. I hope it doesnt go straight from smooth with side-effects to jerky.

Considering the thread pitch on that screw is probabally 1mm, That puts 1/4 turn @ .010. That means the setting I need is somewhere between where it is now, and only another 1/4 turn out. Man these things are really finniky.

 

[LD1]

Sean, I think I may have some things figured out. I will know more when I get a change to try them out today.

But I have been studying the flow diagrams courtesy of a mutual friend just to try to understand how this thing works.

The first time around, I didnt care how it worked. I thought I'd set it according to spec and see. After a few more adjustments without luck....I began studying.

I am confident that I have the old Type 2 valve. The issue I am having with tle loader influencing the 3PH is pretty easy to explain.

When the 3PH is in neutral, poppet #2 (the one the setscrew actuates) is supposed to be completely closed. This allows poppet #1 to close due to the pressure generated by the weight of the implement, thus isolating the cylinder and forcing the new fluid coming into the valve to exit via the unload poppet.

With the set-screw too tight creating a little overlap between when the spool opens the cylinder port, and when poppet 2 closes to isolate the cylinder, the poppet 2 never actually closes all the way. This overlap makes for a really smooth hitch. The problem is when in N, There is a constant flow of fluid into the cylinder through the spool and poppet 1, and then back out via poppet 2.

This "open circuit" isnt allowing the cylinder to be isolated. And anything that changes the hydraulic flow (loader or RPM change) is seen as movement of the cylinder and 3PH.

So I think idealy, poppet 2 needs to close off at the EXACT moment the spool cuts off fluid to the cylinder. If there is ANY overlap at all, we have an "open" circuit. And I suspect that any delay in the timing of the valve and poppet is what results in the jerkyness.

So I think today, I am going to do some testing with som compressed air to see exactally when the spool closes off fluid. And then set the poppet 2 (set screw) so it has JUST closed as well and see what my results are:confused2: