Farm pro 2524 / Jinma differential lock problem

[kjnwi]

My new to me Farm Pro differential lock lever is loose- no resistance at all. It falls to the down position and has no effect on anything. My wheels are not locked. I've looked at the parts diagrams but can't figure out how the outside arm connects to the internal shaft/fork/spring.

Any thoughts on what might be wrong and a possible fix would be appreciated.

Do I have to take off the entire housing under the seat to see what's happening?

Thanks

 

[piper184]

There are apparently a couple of different designs for the external lever, but from what I can tell the internal mechanism is the same for both.
In either case both levers have an external cam below the pivot point. When you move the lever the cam pushes on a plunger that is sticking out through the housing just below the pivot point of the lever.
The plunger is the end of the shaft that holds the fork and the return spring. The lever should be connected to a plate that has two bolts connecting it to the housing. You can easily take this plate/lever assy off to get a better look at the plunger. You should be able to force the plunger in a little ways and have it spring back out at you when the pressure is removed.
That is about all you can do from the outside. For anything else you have to pull the seat, then pull off the hydraulic tank/3 point cylinder in order to get a look inside the axle housing.
I once took mine all apart because it would not stay engaged or would "pop out" when under power. As it turned out, the lever pivot point hold down bolts had loosened up and the cam was not pushing the lever in far enough to fully engage the locking jaws.
Another possibility to look for is the roll pin that holds the lever/cam assy to the pivot pin. If that roll pin is damaged it could be allowing just enough play not push the plunger in against the spring.
Hope this helps.

 

[kjnwi]

Thanks for the info. I think the problem is with the lever/cam. I can now see the button and spring underneath, and can push it in slightly, but the lever and cam is too loose to make good contact.
The roll pin looks good so I値l have to unbolt the mechanism to inspect further.

Thanks for the help.

 

[RonMar]

There is also nothing that holds the lever up. It is supposed to be able to fall/disengage on its own as you really only want to be running with a locked diff for as brief a period as necessary to get unstuck. The lever will free-fall but the plunger will not pop out until the claw halves are unloaded and can slip apart.

 

[piper184]

Ron is correct about that. You don't want to be turning tight circles on solid ground with the lock engaged, that puts a lot of stress on the jaws. In some situations (especially icy ones) you have to hang on to the lever to keep the lock engaged.
By the same token, sometimes it is hard to get the jaws to engage. The lever will not come all the way up until the jaws lock together. If the jaws are not lined up completely, one wheel has to turn more than the other before they come into alignment. For testing purposes I would jack up the right side until the tire just clears the ground. You can then turn the tire by hand (or foot) while moving the lever in and out of the engage position.

 

[RonMar]

I can hold the lever up with my leg pushed out to the side so both my hands are free...

 

[kjnwi]

I pulled the mount and lever. The lever is a little sloppy but everything appears ok.
The problem is the cam won稚 contact the spring loaded button no matter how I manipulate the lever.
Either the button is not out far enough or there痴 an issue with the cam and lever. I took a picture of the button but don稚 see how to add to this post.
The button moves a bit with heavy pressure.
The wheels are not locked. If I move 1 the other turns in the opposite direction so I assume the button is out as far as it should be or at least far enough to release the fork.
I may order another cam and pin but was hoping someone ran into this before.

 

[piper184]

To post a picture when you are typing in the reply box look at the little icons just above. The 3rd one from the right looks like a picture screen. Hover over it and it says insert picture. Click that and it will open a little window that lets you browse to a saved file. Don't forget to click the words "Upload files(s)" in order to add the picture to your reply.
As for the button not out far enough. The fork doesn't move far, maybe 1/2" at most. The button is the end of the shaft that holds the fork and it has a spring that should push the shaft outward.
Since your axle is not locked it seems most likely that there is something wrong inside. See if you can get your picture posted and I will compare it to my tractor to see if we can figure anything out.

 

[kjnwi]

Pictures of the button

 

[piper184]

Interesting. I don't remember exactly what mine looks like. I will try to get a picture this afternoon.
Can you get ahold of the shaft (button) with a pliers or vice-grip and pull it out any?
How far can you push it in?
Does it spring back out on it's own?

 

[piper184]

Here is a scan of my parts book. The page numbers are a little hard to see but #141 is a nut.

This jogged a memory. I think you can screw the Stud (#142) or nut to adjust the length. I don't remember exactly what I did as it was several years ago. Since the stud and nut are shown outside of the o-ring, you should be able to pull them out of the housing.

View attachment 2006 284 Diff-lock parts.pdfView attachment 2006 284 Diff-lock.pdf

 

[piper184]

OK. NOW I remember. I also see what is wrong with yours. You are missing the stud and nut. Take a look at this photo, you may have to zoom in. There is a stud (basically a bolt) that threads into the end of the plunger (shaft). This is where you adjust the length so it contacts the cam on the lever. The lock nut keeps it all in place.
My problem was the fork was not engaging the jaws far enough. I took it all apart only to discover that there was nothing wrong. I then took the lever off of the housing and discovered the adjustment. From there it was easy.
My lever looks different because I added an extension to get it into a more convenient place for me.

 

[piper184]

PS, pardon the mess. I overfilled the hydraulics earlier this winter and it overflowed. Can't pressure wash in these temperatures.

 

[kjnwi]

I’ll have to get in there closer. All I saw was the cap and maybe 1 turn of the spring. It gave a little when I pushed on it but it’s hard to push. I don’t remember seeing a nut on the outside. Would that be under the end cap on the the outside end of the spring?

 

[kjnwi]

Ok that sounds like the missing link. So the cap on mine has to be pushed back in and the bolt and locknut thread into the end that you see in my picture? I’m not at home but I thought that was a solid cap.
Once this is fixed I’d be interested in your lever design as mine hits me in the leg too if I hold it up.

 

[kjnwi]

I appreciate all your help. I’ll order the bolt and nut.

 

[piper184]

You shouldn't be able to see anything on the outside of the housing except the end of the shaft and the o-ring. The shaft should have a hole in the end that is tapped to a 10MM thread. The book does not specify the pitch but I would bet it is 1.0. Spray some brake cleaner or carb cleaner into the hole and see if you can expose the threads.
I would be tempted to buy a few different bolts that are 10MM in different lengths and thread pitches if available. That way you can see which one fits best. Once you figure that out, you might want to grind the head of the bolt into a slightly dome shape to make it engage the cam more smoothly. It might be a good time to put a new o-ring in there as well. They don't last real long in this kind of application. Mine probably is part of the mess you see in the picture.
I bet you don't have anything wrong inside. It is fairly robust and Ronald at Ranch Hand once told me he had never seen an internal part fail.

 

[dennyd]

Funny that my handle has to be pushed down to engage.

You guys all have to pull the handle up? So mine is backwards? I have to grab the handle and push down with my right hand and but my foot against it to hold it there.

A stupid design because lots of times we don't have an extra right hand to push down or pull up with. I wonder if I can reverse mine so I can pull instead of push?
Any body know?

 

[kjnwi]

Mine is definitely push down as well. And it’s a tight fit by the seat. Would be nice if they would have allowed more room for my seat.

 

[piper184]

Yes, mine is push down too. Sorry I miss-spoke earlier. I must have had the PTO lever in my head at the time.
Look at my picture above and you can see that the direction the cam must travel in order to push the shaft inward toward engagement.
There were two reasons I extended the lever towards the fender. First it was hard to get to when bundled up for winter snowplowing, which is where I use the lock most of the time.
Second, the handle threads into the casting that is the cam. There is a jam nut that is supposed to keep the lever from turning. On my tractor the handle threads were shallow and the nut stripped them out. That had to be fixed so I added and extension at the same time. Has not come loose since.
In operation the weight of the handle is not sufficient to hold the lever in the engaged position. The force of the internal spring pushing the shaft against the cam is enough to keep the lever up.