Farm pro 2524 / Jinma differential lock problem

[dennyd]

Well at least you got a cure for the goofy handle position, ya in winter time it's a bear trying to get it down to the floor when all bundled up.

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.

 

[kjnwi]

Well at least you got a cure for the goofy handle position, ya in winter time it's a bear trying to get it down to the floor when all bundled up.

Thanks for all the help. I got the new bolt and nut installed and with the back end up on jacks the diff lock works perfectly.

Now on to loader mounting...

 

[Marrow999]

I love this site - there is so much info and so many people willing to help!
Can I attempt please to clarify a couple of points on my Jinma 254....

My issue is the diff lock is permanently on (have done everything suggested on here re back/forward/jam a break on etc but to no avail..)

The lever (and its shaft) are very floppy - is it that shaft that is moving within the assembly or is it more about the "button" and its shaft? Should I be attempting to pull the button out with some grips?

Hope the picture explains all?

Many thanks

Mark

 

[piper184]

The rounded over "button" you see is actually the head of the bolt. That bolt is threaded into the end of the shaft that connects to the shift fork inside.
In normal operation the shaft is pushed out towards the lever by an internal spring. This holds the locking jaws apart and allows the differential to operate.
In your picture the shaft is pushed in all the way and the jaws are probably locked together as you said. To prove this you can jack one wheel off the ground and try to rotate it by hand. It probably won't turn more than the backlash of the gears. Rocking the wheel that is not on the ground back and forth, perhaps rather harshly should cause the locking jaws to release and let the shaft pop out. When that happens the head of the adjusting bolt should make contact with the cam on the bottom of the lever. Looks like you have about 3/8 to 1/2" clearance there which would appear to be about right.
The question is why is the shaft (button) not popping out on it's own? A couple of things come to mind: broken return spring or something jamming the locking jaws inside. To have a look at either situation you will need to remove the seat and the 3point/tank assembly so you can have a look down into the differential.
BUT, it might just be "stuck" from dirt and corrosion on the shaft where it goes through the housing. I would remove the lever (two bolts) and pivot to get it out of the way. Then try to grab the adjuster bolt with something you can pull on. Claw hammer, crowbar, vice grips, pry bar, whatever. The goal is to get the shaft to come out of the housing that 3/8 to 1/2". It is just a round shaft and it is sealed to the housing with an o-ring so it is fine to twist the shaft as you pull. Rocking the lifted wheel might be needed to help jar things loose so you may need a helper for a few minutes. Squirting some rust busting penetrating oil around the jam nut can't hurt either. Also tapping on the end of the adjuster bolt with a hammer (like you are trying to drive it into the differential) might help break up any corrosion or jar something else loose. Tap, don't pound with a sledge hammer.
It is a robust and simple design. The only iffy part is the use of an o-ring as a seal in a wiping situation but they get away with it because there is no pressure on the seal.

 

[Marrow999]

The rounded over "button" you see is actually the head of the bolt. That bolt is threaded into the end of the shaft that connects to the shift fork inside.
In normal operation the shaft is pushed out towards the lever by an internal spring. This holds the locking jaws apart and allows the differential to operate.
In your picture the shaft is pushed in all the way and the jaws are probably locked together as you said. To prove this you can jack one wheel off the ground and try to rotate it by hand. It probably won't turn more than the backlash of the gears. Rocking the wheel that is not on the ground back and forth, perhaps rather harshly should cause the locking jaws to release and let the shaft pop out. When that happens the head of the adjusting bolt should make contact with the cam on the bottom of the lever. Looks like you have about 3/8 to 1/2" clearance there which would appear to be about right.
The question is why is the shaft (button) not popping out on it's own? A couple of things come to mind: broken return spring or something jamming the locking jaws inside. To have a look at either situation you will need to remove the seat and the 3point/tank assembly so you can have a look down into the differential.
BUT, it might just be "stuck" from dirt and corrosion on the shaft where it goes through the housing. I would remove the lever (two bolts) and pivot to get it out of the way. Then try to grab the adjuster bolt with something you can pull on. Claw hammer, crowbar, vice grips, pry bar, whatever. The goal is to get the shaft to come out of the housing that 3/8 to 1/2". It is just a round shaft and it is sealed to the housing with an o-ring so it is fine to twist the shaft as you pull. Rocking the lifted wheel might be needed to help jar things loose so you may need a helper for a few minutes. Squirting some rust busting penetrating oil around the jam nut can't hurt either. Also tapping on the end of the adjuster bolt with a hammer (like you are trying to drive it into the differential) might help break up any corrosion or jar something else loose. Tap, don't pound with a sledge hammer.
It is a robust and simple design. The only iffy part is the use of an o-ring as a seal in a wiping situation but they get away with it because there is no pressure on the seal.

Hi piper184!
Fabulous explanation - I understand it fully so HUGE thank you. The "win" for me is your confirmation that the rounded over bolt is indeed the lock shaft and that it is in the "in" position.
Have had a wheel off the ground and it behaves exactly as you describe.
Will investigate further and of course report back.
Thanks again
Mark

 

[Marrow999]

The rounded over "button" you see is actually the head of the bolt. That bolt is threaded into the end of the shaft that connects to the shift fork inside.
In normal operation the shaft is pushed out towards the lever by an internal spring. This holds the locking jaws apart and allows the differential to operate.
In your picture the shaft is pushed in all the way and the jaws are probably locked together as you said. To prove this you can jack one wheel off the ground and try to rotate it by hand. It probably won't turn more than the backlash of the gears. Rocking the wheel that is not on the ground back and forth, perhaps rather harshly should cause the locking jaws to release and let the shaft pop out. When that happens the head of the adjusting bolt should make contact with the cam on the bottom of the lever. Looks like you have about 3/8 to 1/2" clearance there which would appear to be about right.
The question is why is the shaft (button) not popping out on it's own? A couple of things come to mind: broken return spring or something jamming the locking jaws inside. To have a look at either situation you will need to remove the seat and the 3point/tank assembly so you can have a look down into the differential.
BUT, it might just be "stuck" from dirt and corrosion on the shaft where it goes through the housing. I would remove the lever (two bolts) and pivot to get it out of the way. Then try to grab the adjuster bolt with something you can pull on. Claw hammer, crowbar, vice grips, pry bar, whatever. The goal is to get the shaft to come out of the housing that 3/8 to 1/2". It is just a round shaft and it is sealed to the housing with an o-ring so it is fine to twist the shaft as you pull. Rocking the lifted wheel might be needed to help jar things loose so you may need a helper for a few minutes. Squirting some rust busting penetrating oil around the jam nut can't hurt either. Also tapping on the end of the adjuster bolt with a hammer (like you are trying to drive it into the differential) might help break up any corrosion or jar something else loose. Tap, don't pound with a sledge hammer.
It is a robust and simple design. The only iffy part is the use of an o-ring as a seal in a wiping situation but they get away with it because there is no pressure on the seal.

So......oops, image is rather large!
I had previously sprayed the area with some lubricant and having just gone out to action your suggestions, lo and behold the shaft has already moved out (in my orig image the nut was flush with the casing.
Unfortunately the differential is still behaving as if it is locked.
Driving in tight circles (on gravel so not stressing things too much, although clearly illustrating the wheels are indeed locked together), reversing, left brake/right brake etc not shifting it....
Based on your experience is there a specific manoeuvre which maybe more effective with regard to loosening it? (eg jacking up one of the wheels etc?)
Or is it more likely that the shaft is actually broken?
Look forward to hearing from you,

Mark

 

[piper184]

This is good news. The spring is on the far opposite side of the sliding shaft and is held on with a nut so I doubt that if anything was broken it would be able to push the shaft out. But then again that might depend on where and how it is broken. Most likely it has not pushed out quite far enough and the jaws are still engaged but just barely.
I can't tell from the photo if the rounded button head is actually touching the cam on the lever. Also is the lever all the way up. It will free fall until it contacts the button. The spring pushing on the shaft moving the button is the only force used to raise the lever. The cam needs to be well lubed for this to happen. I suspect you still have corrosion and grit on the shaft and or the cam.
Take the two bolts off that hold the lever pivot to the housing and remove the lever entirely. Try pulling the shaft out to see if it will come out a little farther. Work it back and forth while squirting more of your favorite magic juice in behind the jam nut.
I would do all of this with the right wheel off the ground and the trans in neutral. That way you can rock the wheel in both directions as you work on the locking shaft. Nice and easy with no power applied will allow things to slip free without doing any damage.
In normal operation when the lock in engaged and with no pressure on the lever, it will release and raise the lever on it's own just by traveling a few feet in either direction. Sometimes it will stay locked until you turn some. But remember that in a turn one wheel is rotating faster than the other so that is keeping pressure on the jaws and that may help keep them locked.
I am betting that the shaft has not come out far enough for the fork to move the right side jaw completely clear of the left one. Keep at it and I bet you get it loose.

 

[Marrow999]

This is good news. The spring is on the far opposite side of the sliding shaft and is held on with a nut so I doubt that if anything was broken it would be able to push the shaft out. But then again that might depend on where and how it is broken. Most likely it has not pushed out quite far enough and the jaws are still engaged but just barely.
I can't tell from the photo if the rounded button head is actually touching the cam on the lever. Also is the lever all the way up. It will free fall until it contacts the button. The spring pushing on the shaft moving the button is the only force used to raise the lever. The cam needs to be well lubed for this to happen. I suspect you still have corrosion and grit on the shaft and or the cam.
Take the two bolts off that hold the lever pivot to the housing and remove the lever entirely. Try pulling the shaft out to see if it will come out a little farther. Work it back and forth while squirting more of your favorite magic juice in behind the jam nut.
I would do all of this with the right wheel off the ground and the trans in neutral. That way you can rock the wheel in both directions as you work on the locking shaft. Nice and easy with no power applied will allow things to slip free without doing any damage.
In normal operation when the lock in engaged and with no pressure on the lever, it will release and raise the lever on it's own just by traveling a few feet in either direction. Sometimes it will stay locked until you turn some. But remember that in a turn one wheel is rotating faster than the other so that is keeping pressure on the jaws and that may help keep them locked.
I am betting that the shaft has not come out far enough for the fork to move the right side jaw completely clear of the left one. Keep at it and I bet you get it loose.

Wow wow wow! Thank you for this great detail and the apparent optimism! Will persevere and report back!

 

[Marrow999]

This is good news. The spring is on the far opposite side of the sliding shaft and is held on with a nut so I doubt that if anything was broken it would be able to push the shaft out. But then again that might depend on where and how it is broken. Most likely it has not pushed out quite far enough and the jaws are still engaged but just barely.
I can't tell from the photo if the rounded button head is actually touching the cam on the lever. Also is the lever all the way up. It will free fall until it contacts the button. The spring pushing on the shaft moving the button is the only force used to raise the lever. The cam needs to be well lubed for this to happen. I suspect you still have corrosion and grit on the shaft and or the cam.
Take the two bolts off that hold the lever pivot to the housing and remove the lever entirely. Try pulling the shaft out to see if it will come out a little farther. Work it back and forth while squirting more of your favorite magic juice in behind the jam nut.
I would do all of this with the right wheel off the ground and the trans in neutral. That way you can rock the wheel in both directions as you work on the locking shaft. Nice and easy with no power applied will allow things to slip free without doing any damage.
In normal operation when the lock in engaged and with no pressure on the lever, it will release and raise the lever on it's own just by traveling a few feet in either direction. Sometimes it will stay locked until you turn some. But remember that in a turn one wheel is rotating faster than the other so that is keeping pressure on the jaws and that may help keep them locked.
I am betting that the shaft has not come out far enough for the fork to move the right side jaw completely clear of the left one. Keep at it and I bet you get it loose.

100% Correct!!!
I removed the lever and a bit of gentle persuasion resulted in the attached (will clean up & grease). The spring is clearly alive and well as the shaft now pops back out when pressed in.
I now have a tractor that turns corners!! I seriously cannot thank you enough..... as Christmas approaches I would, as a thank you, like to make a donation to a charity of your choice?
Please private message me (or stay public if it means someone else might do similar....!) to let me know which charity that would be?

Let us hope our "conversation" and pics help someone else too!

Huge thanks

Mark

 

[jacquesss]

Good day to all. Im from south Africa a bought myself a jinma 250.. the previous owner only used it for pulling a trailer... So he removed all the levers, pto engaged lever, pto speed lever and the differential lock lever... I tried to engage the the pto but it only made funny sounds.. so i google assist me and i was able to take off the hydraulic box and the pto engaged system was just not at the right place... I have made 2 bushings and wil just weld a flat bar on to the bushings and then put a pin in to hold it in place so if ever i need to strip it again it will be easy...

So i have sorted both the pto engaged lever and the pto speed lever... Now i need assistance in how can i make something that will work on the diff lock lever... I have the rond bolt sticking out and the housing that is hold down by 2 bolts... But i believe as i have read your previous messages i have a tipe of cam or something that is missing... My housing only have a pin coming out of it and a hole in it...

Could someone please send me some photos of how the cam is supposed to look like maybe a can masjien something at work... I will add photos if i get home... My hydrolic box is still off so for interested sake I will also take some photos of the inside of the gearbox so for future it would be easier to refer to how it works inside.

Thankz to all... Its amazing what you can actually find on the net if you spend time...have a wonderful day

Ps. If you would like me to also add photos of the pto enough magnesium and the pto speed selecter on the inside please indicate so then i will also add it

 

[piper184]

Does your tractor look like the picture in post #29 just above your post?
If so, the differential lock works by the cam on the lever pushing the rounded bolt/shaft inwards. This shaft has a fork attached to it that slides the jaws together which locks the axles. The shaft has a spring on it which pushes it back outward and unlocks the axles.
The lever has a cam built into it that forces the shaft inward as the lever is pushed down. The rounded button (bolt) is threaded into the end of the shaft and is used to adjust the length of the shaft so it contacts the cam properly. The jam nut is there to lock the bolt once it is adjusted.

You can see a parts diagram here: Drive Gearbox - 18-28HP Tractors
Note that there are images on this page and the one with the diff lock is the one on the right hand side. Also if you hover your mouse over the image it will show a zoomed in version that your can scroll around to get a closer look.
Part number 131 in the middle of the picture is the fork that slides the claw. As you can see it is connected to the rest of the assembly shown just below it.
Part number 139 is made of cast iron and has the cam molded into it.
Part #138 is the bracket that bolts to the gearbox.
If you scroll down the parts list on the right until you get to #138, click on the part number and it will open a picture of that part.
It appear that Jinma used a couple of different designs of how the lever was attached to the tractor. If you could post a picture of the outside (button end) of the shaft where the lever was removed it would help identify your setup.
In any case, you could probably fabricate something that would bolt to the two tapped holes in the gearbox housing then make a pivot so that it pushed the button inward when you wanted to activate the diff lock.

 

[jacquesss]

Good day
Thankz alot pipper184 for your assistance i believe it is part 139 that is missing

I have added some photos for future reference to explain it..

I will see how i can make something that will work in the same principal and also share it if it works..

Again thankz alot for the assistance