I feel like an idiot . . .I threw a track on my 312 today while doing -nothing unusual- but cleaning out crossings. Yes, I keep the tensions correct. Yes, I check before putting it to work. RECOMMENDATIONS please - on HOW to put the track back on as I have never thrown a track. It's nowhere near where I can get a large vehicle except my tractor. It's on a sloped area. The track is all the way off the rear but appears to be on the front idler. Plenty of room to swing the boom.
Luckily i have only had to do this a couple times years ago. First thing I would do is call a buddy that owes you a favor. If you can get a skid steer or a tractor with a loader to the machine.... that would be nice. I would release your track tension and probably get the track off of the front idler then put it on the sprocket so you have the ability to turn the track as you work it back on the front idler. Good luck. I have only seen a track come off in the worst possible place never on dry level ground!!! Good luck
Undue the fitting on the track tensioner, get a chunk of 6x6 or a log and place it on the track at the idler end and CAREFULLY AND SLOWLY push with the bucket to collapse the idler and force the grease out. Hook a chain (preferably with grab hooks) to the inside and outside of the pad over the sprocket end and see if you can lift the track with the machine to get it close to the sprocket, if your track chain is stretched a lot you may be able to pull it on without taking off the idler, if not, you'll need to spin around and get it off the idler, use the chain, then spin around and pull the sprocket end on, spin back around and now chain the idler end and get it close ( this is where a helper is handy to tell you what's going on and can also help guide the chain CAREFULLY with a long digging bar) you can also run the track to help get it started. Another machine, like you tractor is handy too, with forks even better. Just don't get to aggressive pulling on the pads with the chain, you don't want to bend or break one....by the way, they never come off in a convenient time or place.... usually in mud, wedged between two trees and a stone wall, where you can't swing around, so at least you have that going for you....
I believe that machine has a master pin with a cotter key in the end. No press fit on the pin so if all else fails, just knock out the master, use the boom and stick as a crutch and move the machine off the track. Stretch the track out flat and set the machine back on it again using the stick boom and swing to position the machine. I had a long piece of wire rope and some chains and would hook onto the end pad and use the bucket to pull the chain back over the sprocket and track frame to the front idler. I would block the opposite pad up to the angle that matched the idler and set the big end of the track onto the smaller end and put the pin back in. You can do that in less than two hours the first time and after that it can be done in less than an hour. As stated above, make sure you release the grease from the track adjuster cylinder before trying to put the track back together.
Sometimes large chain come-alongs are a big help too.
Thanks for all the advice. It sounds like everyone has similar ways to get it back on. . . loosen the tension, work it onto the sprocket first and then work it over the top roller and over the idler. If I'm missing something please let me know. Although I think I'll be able to get the tractor to where I'll need it, if not what is a good method of 'walking' a one legged track hoe? I've got the 'buddy' lined up (but it will cost me more than 'a favor'), I have a tractor with a loader that can be changed out to a hay fork, chain come along, 6x6, sledge hammer, and crossed fingers.
Good news / bad news. Good news: I got the hoe 'walked' to a nice level are. BAD news: I couldn't get the idler pushed in and I found out why I threw the track. The two nuts that hold the idler spring together had come off, so the spring was sprung. Now I have to get it 'pressed back together' and bolted.
Good day Attached may help Kind regards Uffex
Thank you . I welcome all recommendation and suggestions.
Good day CatKC Thanks for the kind comment may I suggest that it would be more beneficial to look at prevention as a best practice, I know fitting thrown tracks is very hard work with little reward may be track guides may help. Kind regards Uffex
Derailer illustration
Thanks again for the information, you always seem to have a wealth of such. It is something I will consider, depending on the cost Etc. I'm not sure what the result would have been in this case as the nuts holding the tensioner spring had come off and likely caused the derailment.
When you say Idler spring you mean the big recoil spring right those things can kill you. Getting tracks back on can be amateur hour time if you are careful but recoil springs are definitely not. be careful and seek out someone who knows what they are doing.
Got that! YES it's THE BIG RECOIL SPRING. As the TWO NUTS came off (which does not make sense to me as the shaft did not break) , I will NOT EVEN ATTEMPT to put thing back together. I am going 400 miles, round trip, and have someone PRESS the assembly back together and then put the assembly back onto the excavator. After putting 'the assembled' idler back in I will 'roll' (as suggested) the track back on over the idler. I am always SAFETY first and I don't see any safety problems in doing this but if you do let me know. - - - If you work for CAT (OR ANYONE ELSE) shoot me a price on the Track Adjuster as from the condition I think it is advisable to replace it.
Good day If you have a similar experience it could be that the package requires replacement, there are many undercarriage specialist out there who are able to supply. Kind regards Uffex
I do work for Cat but I advise calling your local Cat dealer. Their price may be different than mine plus they may have a used parts dept with a good takeoff from a scrapped machine that could save you some money
I think the first thing to figure out is just WHY the nuts came off in the first place. Some photos of the disassembled recoil mechanism would help, as would the machine Serial Number to identify just what type of assembly you have. Second JD's comments about recoil springs. They are known in the trade as Death Springs for good reason.
I've seen the threads on the rod rust off enough to allow the nuts to just get pushed off the end. You will need a new rod and nuts at the least.
SN 9GR00432K 312B - I thought I had supplied the SN but neglected it. I can't supply disassembled pics as I took it to a crawler repair guy and had it re-assembled, as I stood a long ways away. The bolt threads were cleaned / sandblasted and showed nothing abnormal. The nut and 'jam nut' tightened with no problem. It also confuses me and the repair guys as to WHY the nuts came off. Unless there was some kind of a 'twisting action' the nut should not have moved. It's possible someone could have previously 'repaired things' and not correctly put it back together. Maybe if the 'washer' was not put on and only one nut. . . .
In my head the only way I can put that situation together is that the assembly was out at sometime and not put together properly. The tracks were run tight enough to push on the spring which left the nuts loose on the rod and able to back off. Where did you find them sitting when you removed the idler assembly?
That is also my guess. If there was a 'jam nut' properly installed I don't see how it would have come off, I've never had one come off. I did not find the nut (I doubt if two would have fallen off at the same time) when I pulled the idler off. Had I found them it would have saved me some time trying to push the idler back to put the track on. I am going to look for it today in the area where the track came off. I walked/moved the Cat quite a ways to get it out of mud and on level ground.
Nige, is there any significance to the "K" on the end? SN 9GR00432K
Is it stamped like that on the S/N plate with the "K"..? I can't say I've ever seen that before.