Old JCB 801 track removal, adjuster won't move.

[charentejohn]

Can anyone advise please.
The answer may be just to use a bigger lever but before I shear the bolt.......................

This is an old levers on the floor model but in good general condition, tracks aren't great and one was slower than the other but all I needed as just for home use.
I got something caught and the track has jumped the runners and now stuck on the inside, too tight to move it at all. The motor cog is out of the channel it is meant to be in so not moving anywhere.
So I took a look at the mechanism and tried moving the adjusting bolt at the rear, behind the cover plate. Won't move at all, used wd40 two spanners and a bit of heat but no go.

Someone said there may be a locking mechanism somewhere ? Doesen't look like it but thought I'd ask just in case.
Tomorrow I will apply more heat and try harder to shift it, what are my chances ? and any tips appreciated.
I assume the full mechanism is the front idler wheel on a U shaped slider pushed forward by this bolt ? Slider looks ok.

How long is the threaded tube the adjusting bolt goes into as if long it may take a bit of freeing, also does it just push the U shaped slider or could it be seized in a cup there too ?

Digger is currently in the middle of a field and I have general workshop tools/sockets etc, nothing massive, and some long metal tubes as extensions, but woried about shearing the bolt.
Any help appreciated John

[Muz]

Hi John welcome to the forum
The only 'lock' I've seen on other types of machines is a secondary lock nut on the tensioner bolt, if that's not there, then I don't think there's anything else that holds it, that said I've never owned a JCB , so can't be specific. Normally the idlers are bolted to a carriage that sits inside the leg against which the bolt pushes against. Have you jacked it up and looked from the underside to see what's there ? (Don't go under without securely supporting the digger and don't relie on hydraulics to hold it up )

[charentejohn]

I do believe you are right, I will know tomorrow.
I found a post elsewhere that mentioned the lock nut, this is probably what I thought was the tubed piece welded into the frame, not tube just a locknut covered in dirt and rust.
The adjuster on this machine has a pin through the adjuster, I guess to stop people putting a ring spanner on the locknut without thinking.

I will post details once I have tried this, for any future dazed and confused person. The friend who was with me guessed there was something, we just couldn't see what.

[2414.ginger]

According to the manual the pin on the head of the nut should locate into the cover (when fitted back on) this prevents it from unscrewing.
So I think you just need a bigger lever.
By the way welcome to the forum

Pete

[charentejohn]

That makes sense as I wondered why the cover had a piece welded inside it.
So there is no locking nut ? better if there is, I will find out tomorrow, as it would mean more chance of moving it.

If push comes to shove I may have to make an inspection opening with an angle grinder so I can see inside the side cover. My friend here is a welder so could put it back.

[Muz]

That makes sense as I wondered why the cover had a piece welded inside it.
So there is no locking nut ? better if there is, I will find out tomorrow, as it would mean more chance of moving it.

If push comes to shove I may have to make an inspection opening with an angle grinder so I can see inside the side cover. My friend here is a welder so could put it back.

Just be sure the nut you see isnt welded to the frame .. since it may be the method the ' engineers' ..( I use the term loosely).... at JCB secured the tensioning bolt to the frame with

[charentejohn]

Well, just tried again and no go. Used a long lever and heated the bolt base as best I could (enclosed area).
I did remove a section of the side so I could see if all was rusted inside, it is all fine, good clean thread and I can see the spring on the back of the front tensioner.
The bolt goes through a threaded tube welded into the frame (about 2cm long) and no lock nuts or similar.
I even tried removing the rear sprocket (2 allen bolts) but they won't budge either even with an impact wrench.

I have sprayed both sides with WD40 and will leave it an hour then try heat and levers again.

The track has come off on the inside front and rear so is very tight, can't move it at all, so it may well be putting pressure on the spring.
I will have someone lever the spring off a little but don't know if this will help.
The thread I can see has some brown stuff on it, could be fine rust but thinking somebody may have used loctite or similar ?

[charentejohn]

Latest update, still can't move the adjustment bolt. Bending spanners now so searched the net for an alternative.

Found an option to remove the sprocket wheel by removing, in my case, the two allen bolts holding it on.
Tried this and so far so good as it does move. Bad news is they designed it so that it is holding in the hydraulic fluid......
So when part way off out comes the fluid, so I put it back quickly and will get more help to remove the track quickly and hopefully lose less fluid that way.

Anyone got any idea if the fluid loss will stop quickly after I remove the sprocket wheel ? If I work on the main pump I lose a little fluid then it stops, will this be the same ?
If it is only a cupful or so I can take my time refitting and won't need a large tray to catch the spilt fluid. Any advice appreciated.

[charentejohn]

Just a note to say it is now fixed (sort of) so this may help others with a similar machine.
Removed the sprocket and eventually the track. Only minimal oil loss, realised can only lose what is in the lines and motor as valve closed.
Not easy to get back on and took three of us to do it, track is heavy and not easy to manouvre but we managed.
The track was loose afterwards but tightened as it was driven a bit, I guess the movement allowed the adjuster to return to normal after being compressed when the track came off.
One guide in the track came out (the metal bits embedded in the rubber) and 2 are thinking about it. I think I will just bolt them in again for now, drilling through the rubber track and the guide as I don't use it much so no massive strain, I can be careful. I may sort out new tracks later once I get the adjustment bolts moving.

On the locked bolt, still won't move so will try Acetone, to eat Loctite, and acetylene torch if really needed, it will move I am sure just won't be easy.
At least the digger is movable and now safely home, thanks for all help and support.

[Muz]

Sorry John I was out of commission yesterday due to travel ... glad you got it sorted ... and more that you returned to give your helpful explanation of how you got around the problem This will indeed help others, so thanks for that

I'm a bit mystified as to why your tensioner bolt wont undo though ? .. usually the hot spanner frees everything .. now that you are sure of whats in the area perhaps you can get it right hot and cherry red ... no rust or man made substance will resist that

[801_user]

I am way too late replying to this thread, although you have done the same as I had to do with the same machine. My bolt was also seized with "rustlock" I cut a square out of the side to access the other side of the thread and after heat, a socket with a huge length of scaffold pole and some serious swearing at it, I did getting it moving. Very poor design as there is so much thread that you can't get at.
Good news you got it done, although if you didn't free the bolt how can you alter the tension?

Sorry don't have an answer, although I know how frustrating it is.

[charentejohn]

Back again, I haven't tried the Acetone yet but will do and report any results, could be a couple of weeks as other jobs more pressing.
The tracks do need adjusting, especially this one needs tightening, good news is that after the tension of the jammed track was removed, and after applied low heat, I did get a slight click when I tried again with ring spanner on a ring spanner type leverage.

Could be heard and felt, maybe only a fraction of a degree but it is there. As Arnie said in Predator, if it bleeds we can kill it. And if it goes click it is moving so can move some more. Next is acetone and then try to find acetylene torch I can borrow.