JD 850 lift position problem

[jrappl-HT]

I have an '83 JD 850 1500 hours, 2WD non-power steering (no external hydraulic filter) tractor. The tractor starts and runs great but I'm having problems positioning the 3pt lift.

The lift does go up and down but there is only one spot in the lever travel that lifts (at the top of the range), one spot that stops the lift arms (just off the top of the range) and all other positions of the lever release pressure and drop the arms.

I have changed the fluid and cleaned the internal screen (it was dirty). I have also cleaned and lubed all the control levers and bars. Everything on the control side moves freely without any binding and nothing looks bent.

The push valve on the top of the rock arm moves freely. Pushed in the lift goes up, placed in the center the lift stops moving and out it drops the lift.
Is the push valve only suppose to have 3 positions or is it suppose to place the lift according to how far it is pressed? How is this suppose to work? I do have the shop manual but this is not covered!

If there is anyone on the Raleigh NC area with a working 3pt on a JD 850 or a Yanmar 2610? who would be willing to let me look at it in operation that would be great.

 

[Aaron-HT]

It sounds like your linkage is either not adjusted correctly or something is missing/binding/broken/loose.

The system below should compare the current 3pt arm height (using the feedback rod #42,44,45) to the control lever position and adjust the valve accordingly (using the #5/#34 mechanism).


<ATTACHMENT filename="1.JPG" index="0"><s>[attachment=0]</s>1.JPG<e>[/attachment]</e></ATTACHMENT>

 

[jrappl-HT]

Thanks for the reply. I've looked at that diagram in my manual and again here and still cannot figure out how it is suppose to work.

On my tractor, the feedback rod (42,44,45) moves #34 and contacts #5 but only at the top of the lift range. I was thinking it was just a top of range stop. When that engages it pushes the top of #5 and that places the valve in the center position and stops the arm lift. Correct me if I'm wrong but if I adjust (shorten) the feedback rod that would just move the spot where the stop happens down (arms not fully up). I don't know how it translates to moving the arms where the handle is positioned.

I will adjust the feed back rod and see what happens this afternoon.

FYI - my tractor has all the components shown in the diagram. None are bent/loose or missing that I can tell.

Is the push valve in the top of the rock shaft only a 3 position (up, center/stop, down) valve or is the position of the push valve suppose to position the arms depending on how far it is pushed in?

 

[winston-HT]

I think some of the 850's might have had draft control. If yours doesn't it should be just like this. <LINK_TEXT text="https://app.box.co...zravu7q7wsducjk/file/750806912788</LINK_TEXT>

Not sure I'm on the same page with you but if you are talking about the little lever seen here with the blue handle then that is the drop speed adjustment. https://www.hoyetractor.com/PROD/CH19700.htm

 

[Aaron-HT]

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The valve is only 3 positions. Up/Off/Down. The magic all happens with that linkage. I would have to be there and really study it to figure out exactly what is not working correctly but, the basic idea is, If your lift arms are at 45º (for example) but your control lever is at 35º then the pressure should be off the valve's button until the arms get to the 35º then it should push in slightly to the 'off' position. Raise the lever to 45º and the linkage should depress the button until the arms match that 45º and then it goes to 'off'. It is sort of a complicated (genius) mechanism. It sounds to me like maybe there is too much play in your linkage somehow.

Has it ever worked correctly or did you buy it this way?

 

[Aaron-HT]

<QUOTE><s>

</e></QUOTE>

Nice! I keep forgetting that supplement manual exists.

 

[jrappl-HT]

I've got everything except the magic!

I owned this tractor about 20 years ago. At that time everything worked as it should.
I sold it. The new owner (family member, long time farmer) had a set of rear remote hydraulic valves put on for using an implement. He said it worked correctly after the valve was installed. He used it for a few years and then parked it under a shed roof for 15 years only firing it up a couple times a year maybe to run a bushhog. He said this lift problem started about 6 months ago.

I got it back a couple months ago and have been working through a bunch of issues: noisy hydraulic pump caused by clogged screen, fuel issues with leaking lines and clogged filter, bad seat, no working lights, bad throttle friction disc. I have it just about sorted except for this lift issue.

On my tractor the feedback disc/rod (#34) only contacts the push valve lever (#5) when the arms are all the way up. Shortening the rod will make it contact sooner but it still will not contact #5 at all when the arms are being lowered as it will actually be pulled away the lower the arms get.

The additional manual is much better than my factory Deere shop manual. It has none of those diagrams even though it is about 3" thick! There was mention of a neutral position at 10 degrees from the top for use with implement B. The stop valve is hard to turn but would the lift not work at all if the stop valve is closed? Mine does go up and down, just not according to the position of the hand lever.

 

[winston-HT]

Is spring #7 in place? Is your feedback rod in the correct hole? <LINK_TEXT text="https://www.tracto...nts/587946-feedbackrod-jpg.33833/</LINK_TEXT>

 

[jrappl-HT]

Yes, my spring is in place. I did have a problem where the spring was overpowering the handle tension and always pulling the arms back to the top position - especially from vibration while in use in the field. I cleaned the rust/dirt from the tension screw/spring and tightened the nut to apply more tension and it works better but not great. I think there is a friction washer on the lift handle that I should replace. At least I see one available from Hoyle.

My setup is not exactly like the one you pictured. On my tractor there is only one hole on each side for the feedback rod.
I'll try to posts some pictures later today.

 

[jrappl-HT]

Here's a short video of the issue. I start with the arms fully up and move the lift handle forward a little, arms should drop a little and stop but nothing repositions the valve to the center location and they drop all the way to the ground. When I pull the handle back to raise the arms you can see once the arms get to the top the feedback rod causes the collar with the small rod to push the valve to the center position and stop movement. I don't see anything that would cause the feedback rod to push the valve to the center stop location for any other lift arm position.

Video:
<LINK_TEXT text="https://drive.goog...rW6vKwG20sxWuVxX/view?usp=sharing</LINK_TEXT>

 

[winston-HT]

I think #34 should be free on the shaft. Is it? Your already looking at it but a good picture of your setup. The nut holding the spring on hand control should be able to put more tension on your handle. https://www.ebay.com/itm/283559053471

 

[jrappl-HT]

#34 is not free on the shaft and I do not believe it should be, in fact it has a spring pin going through the collar and the shaft to lock it.

 

[winston-HT]

<QUOTE author="jrappl"><s>

</s>#34 is not free on the shaft and I do not believe it should be, in fact it has a spring pin going through the collar and the shaft to lock it.<e>

/e></QUOTE>

My bad, I'm old. I meant #5. #34 on the Yanmar parts drawing is #5 on the John deere parts drawing. https://www.hoyetractor.com/CTGY/20003PTCONTROL.htm

 

[jrappl-HT]

I get that being old thing and wouldn't it be nice if Deere and Yanmar used the same diagrams!

The handle is connected to the lever that pushes the valve (#5 in the first diagram) so it can't be completely free but I do see that there is a an offset rod/pin going through it with a snap ring holding it all together. That is likely seized and maybe it is suppose to be able to turn. I'll pull it apart tomorrow and get it turning and see if that changes anything.

 

[jrappl-HT]

Fixed! Thank you winston.
The pin from shaft #9 in the original (Yanmar) diagram was stuck/seized in lever #5. It is suppose to turn freely.

I pulled the whole control lever and brackets, took it apart so I could get at the stuck piece and had to drive the rod out. A little wire brushing and some lube, put it back together and it works great!

That job could have been a lot easier with better bolt placement and using something instead of spring pins...

 

[winston-HT]

Glad to hear your on the road again.