Old Excavator Dropping Steel Track Occasionally

[GHDirect]

Hi All

I would appreciate feedback from any member who has knowledge of this type of steel track device or new ideas that could improve this problem. Sorry it a bit long.

I am a self builder and have had this Circa 1985 JCB 802 (3.25 Ton Steel Track) past 5 years. I think its a Kubota chassis with a JCB cab as they didn't have a factory model at that time. Mine (knicknamed Daniel Digger) came well used! as anything that could fall off had but the engine, pump, rams and hoses have required little attention in my time and it has dug, pulled, pushed and trundled well. Except when you're not expecting it can throw a track (about 8 times in 5 years) and they are 2-3cwt each being heavy for a single person to refit although in time I have become more competent.

Rear drive sprockets do not look that worn. All guide pulleys turn free.
I have no knowledge of manufacturers track tension so with track off ground pump them up so there is about two fingers width between lower pulleys and track. This seems reasonable as it limits the tracks ability to pull out from rollers sideways when doing a turn. If it does this it certainly means a track dump.

I thought I had solved the issue as the sliding pusher forks that hold the front wheels aligned were designed in a thin steel and both had become bent in time which changed the front wheel alignment. Over the term I have stripped these out, remade/welded then out of 10mm steel so wheels are now aligned. Front wheel bearings seem good with very little side play.
However the other day it dumped a track and I have no idea why.

I attached picture of Daniel, track to idler distance (with track off the deck.) Rear Sprocket and front wheel.

Ideas welcome

 

[Furniss]

Which end are they coming off - idler or sprocket ?
Looks like sprokets are pretty worn to me ?

 

[Scoff]

Which end are they coming off - idler or sprocket ?
Looks like sprokets are pretty worn to me ?

My thoughts also,it's got teeth but the sides are worn.

 

[JD450A]

Sprockets are worn, I expect bottom rollers will be fairly worn too.

 

[GHDirect]

FYI It used to favour coming off the idler, but having fixed the pusher last time it came off the sprocket.
Never seen a new sprocket so difficult to judge the wear area, but could well be the cause.

 

[CPS]

FYI It used to favour coming off the idler, but having fixed the pusher last time it came off the sprocket.
Never seen a new sprocket so difficult to judge the wear area, but could well be the cause.

Is the idler sitting in to the chain correctly? It looks like the centre ridge is to high for the chain.

 

[Regy53]

do you have the pictures individually . ? may help @GHDirect

 

[GHDirect]

Is the idler sitting in to the chain correctly? It looks like the centre ridge is to high for the chain.

I assume you are looking at the top idler. Admit this is not at its best, well worn so can't say what it originally looked like.
You note has made me think should it have a much deeper centre ridge that sits in the chain like the lower ones, and over the years its worn away to look more rounded. I'll have a close look at that idler for further clues, ideally need a picture of a new one or something with similar track design.

 

[GHDirect]

Picture of track off the ground.

 

[GHDirect]

Rear Sprocket

 

[mart1602]

id put a bit more tension on the tracks than you have,sproket is worn but see a lot worse are your tracks holding tension or do you need new seals in the piston?

 

[GHDirect]

id put a bit more tension on the tracks than you have,sproket is worn but see a lot worse are your tracks holding tension or do you need new seals in the piston?

Seals are O/K, don't need pumping up every minute. This model comes with a two speed pedal. If I put to much tension on the track and you engage the higher speed the extra tension sucks the power and the hydraulic motors struggles. I have experimented over the years but generally two fingers width below a lifted track allows the higher speed to function and limits track dumping.

Its been earning its keep today loading soil into my dumper, I needed to do some careful low speed shuffles to get through the soil pile and at one point it did try a track dump this time on a front idler, luck was on my side as one a loud clonk and it click back inline.

I had a good looked at the top idler. It could well have had a much deeper centre when new and this would have acted as a guide to the chain.
In its current state the chain is free to move over it and anywhere else tension takes it.
So accepting the forum are saying sprocket and lower idlers, the top idler is also a likely contributor.

I know you can't buy them from JCB, and being an old machine I must watch the budget. But design wise the idler is simple and the sort of thing we made to pass City and Guilds exams in the 60's with a couple of stock bearings. Just need to scrounge time on an old centre lathe somewhere. Feedback appreciated GHDirect

 

[Shovelhands]

Someone like EVANS & Reid may well still stock chains, sprockets and top and bottom rollers for that. Or be able to supply something that could be made to fit.

I understand that it’s an old girl and you are cautious about over spending, it’s time to have a think, if you really want to sort it out, then it’s going to cost a few quid no doubt, if you don’t want to spend on it, then maybe it’s time for an upgrade to something newer? If that is not on the cards at all, and budget really is tight, then some homemade track guides may do the trick. Look at a bigger machine, 13 tonner for example, it will likely have at least one track guide, fabricating something similar, even if it’s just welded to the track frame, will kept it from throwing a track so easily.

The tracks are worn, that’s the long and short of it, in conjunction with the sprockets and all the rollers.
It needs new tracks and sprockets at a minimum really. Not sure if they could be replaced with a rubber set? Is it really worth doing that to it?...only you have the answer.

I think I’d keep her plodding on and fit some track guides myself. It will help to stop the chan getting alongside the bottom rollers and then ultimately walking off the chain, although I am a little surprised it has a tendency to come off the idler end? Chains must be very worn for that to happen, walking off the sprocket is commonplace with worn tracks.

Don’t worry about the top roller not having a ridge in the middle, I have two machines that have smooth top rollers, no ridge or lip at all.
Incidentally I think CPS’s question was about the idler, not one of the rollers, it looks like the chan rail is not in contact with the idler, I think it’s only one link though in the pic, that’s being held away by the next link on the chain which is in contact with the idler.

 

[Smiffy]

If they are kubota parts try a kubota dealer i put a new idler carrier on a similar size and age kubota and was amazed at how cheap it was so it may be more viable to replace parts than you think

 

[GHDirect]

Hi Members. Thanks for all your contributions. I think I have enough feedback/ideas on what needs to be done. FYI I am only building one retirement bungalow in my life, I am 71 and been at it 5 years and we should move in within next 6 months having done 80% myself and unlike "Grand Designs" I am about on budget.
Overall this digger has served me well and there is no requirement beyond the build to own one. So its patch it up so it can finish any landscaping and then accept it is close to scrape value.

 

[doobin]

Hi Members. Thanks for all your contributions. I think I have enough feedback/ideas on what needs to be done. FYI I am only building one retirement bungalow in my life, I am 71 and been at it 5 years and we should move in within next 6 months having done 80% myself and unlike "Grand Designs" I am about on budget.
Overall this digger has served me well and there is no requirement beyond the build to own one. So its patch it up so it can finish any landscaping and then accept it is close to scrape value.

Wont be scrap value, a working old digger is a working old digger.

 

[Brendan]

If it digs and tracks generally worth at least 5k on ebay

 

[Mogman]

If it digs and tracks generally worth at least 5k on ebay

Well his digs not too sure on the tracking front

 

[GHDirect]

Well his digs not too sure on the tracking front

Advert should read. "For Sale Old Digger excellent on Roman Roads"

 

[Scoff]

Hi Members. Thanks for all your contributions. I think I have enough feedback/ideas on what needs to be done. FYI I am only building one retirement bungalow in my life, I am 71 and been at it 5 years and we should move in within next 6 months having done 80% myself and unlike "Grand Designs" I am about on budget.
Overall this digger has served me well and there is no requirement beyond the build to own one. So its patch it up so it can finish any landscaping and then accept it is close to scrape value.

My dads the same age and just finished his bungalow,he's also got an old digger (airman ax30) in reality he'd be better off selling it now and hiring in a digger to finish his job,but he does an hour here and there because he can.

My advice would sell your digger now and hire one in,mainly because lanscaping you need to track about far more than digging footings.