For some reason the one track on my excavator got real loose and the adjuster is still adjusted where it was. Anyway, I went to split that chain to find the problem. I grabbed the 15lb sledge, and a shaft (to hit the pin), and a pipe to hold that shaft. I have got the master pin about 1/4 inch outside of the outer rail, maybe I've moved it 3/8 total. It has stopped moving. I hit the thing for about 15 minutes or more with no movement. I know it's not going to jump out of there. Is there something I need to know? This is on a JD790...... So about 50k lb machine. Can they be split with just a sledge and a shaft to hit, or does a guy need special machinery to do it? Rodney
Worn pins can have a bit of a crank in them. Easiest way is pull the links either side of the master pin together then have a go with the hammer. If that don't work get a FBH or better still a press.
A master pin costs about $15. Cut the centers out of each end, let cool and you can knock it out with a four pound hammer. It is not worth the time to mess with them.
Yeah, might have to remove the shoes on either side of the master pin to get at it properly, put something solid behind the link so it isn't bouncing and binding. If the rails are well worn that pin might have a good shoulder pushed up inside the outer links there. A bit of heat never hurt either.
Heat sounds like a good idea..... heat the pin, or the link? Rodney
If you want to save the pin, heat the links. If you pick up a new master pin as John C. suggests and I tend to agree with, then as he says blow the center out of both ends of the pin, let it cool a bit to shrink and drive her out.
I'm not sure about the 790, but the newer 330 size machines have a snap ring holding the pin in and it only comes out in one direction. Additionally the outside of the link on the snap ring side will become deformed over time and you will need to get in there with a die grinder to get it round again before you can get the pin past that point. Most of the time the master pin and link is worn out to the point where you don't have to cut it apart but removing the track pads around the pin for access is a great idea.
As I recall, the early ones would have had the "T" headed pin with a large round bent cotter pin through a hole in the other end. The newer chains would have as you say a snap ring on one end only, I had forgotten about those. For logging applications we always removed the master link and pressed regular pins in, the masters did not live long in the woods.
I forgot about that. This chain did have the snap ring, and I've been trying to take it out the wrong way...... no wonder it's not moving. I know the other side, the master will come out with the 4lb hammer and a punch. This chain is just about shot, but for the little that I use it, I'd like to get a little more life out of it.
View attachment H2 remove track master pin H2201056.pdf Good day Rodney Seems you are making a tough job harder please see attached if we can help further please put in a request excatech.esy.es
Not sure how I was making a tough job harder, other than trying to go the wrong way. However The pin came out with persuasion from the sledge, and the idler is now laying on the ground..... and everything looks OK to me..... what should I look for? I can think of very few things that could possibly be wrong - the track got loose and it came off, and the tension and idler position did NOT move..... Broken pin/bushing/link??????? I was told to look at the idler and the bushing/bearing in it, and I can see that it isn't the problem. I had a good idea that it was not the problem, cause when the chain was on, the idler was not running out of 'center'. Rodney
Did you pull the adjuster and spring assembly out and inspect it? Sometimes the spring can break. and if you're that far into it you might as well reseal the adjuster.
Give the final drive a good look over for misalignment and/or oil leaks, if you lost a hub bearing it could **** and throw the track. Then start looking for broken track pins I would guess.
I did not pull the adjuster and spring assembly, cause the idler was still adjusted to where I had put it - all the way out. The block for the idler rides in it's own track on the track frame, and that was protruding about 1/4 inch before and after the track got loose. I was having lot of trouble with other side coming off, so I was paying attention to it. Would I be able to tell if a pin is broken by just looking at the links, or would the difference be too small to notice? There's no oil leaking from the final drive, but I should check for misalignment. Rodney
If the track stretched enough to come off you should be able to spot broken pins or links pretty easily. As Deere tech mentioned you might want to double check the recoil since you have the idler out already, if something's weak or bent or malfunctioning the idler may have popped back out to it's normal spot after the track derailed?
If the block for the idler was sticking out of the frame by 1/4 then your track chains are pretty worn. Other things to check for wear would be the upper carrier rollers. It sounds like your probably close to being out of adjustment on the adjuster if that idler is out that far. When you go back together with it I would inspect the chain closely for a broken pin and I would probably try to take a link out of the chain to get the idler a little further in the frame rail.
Good day Rodney We have seen some examples of fractures in the bulkhead that supports the adjuster, you can usually see the welds are cracked. Kind regards Uffex
Yea, this U/C is pretty well shot. I think the adjustment is close to the end, if not already there, and that makes me wonder about the pins/bushings. I had not thought about the upper carrier rollers at all - You're concerned about them being not near as tall in roundness as they used to be..... I will have to measure them. I hate to dump a ton of money into this thing anymore..... I think in the last 3 years I've put about 100 hours on it..... I have projects that keep appearing for it..... I guess if I'd factor the cost of repairs with the cost of hiring the work done, then the repairs would become cheap..... Rodney
I'm not really concerned about the height of the upper roller, just the fit of the roller on the shaft if there was a lot of play between the roller and shaft. If your not finding anything then just reassemble it and baby it along. If the chain is shot then you might as well keep running it until you get to the point of breaking a pin. At that point you can decide what you want to do with the undercarriage. It will probably last a lot longer than you think...
The rollers are not sloppy in their fit onto their shaft. I bought this thing for a steal with a tired motor, and it sorta looked like the top rollers were just replaced, but I could be wrong. How does a guy take a link out - Just like the method described before - blow out the center of the pin with a torch on both sides and drive it out? Rodney
It's a little more complicated that than. The bushings protrude from the small end of the links into the big ends of the next link. There is a thread on here where I have photos showing the process on a small excavator.
That's right...... I assume they fit real loose into the next link where they protrude..... So you'd have to get the pin out, and then remove the bolts for the link/shoe on the one side and take it off like that...... can you just cut the bushing with a sawzall then, or does a guy need the gas axe for that too? Rodney
Gas axe or cut off wheel, or just a good grinding wheel, the excavator chains the bushings aren't as hard as on the dozers, but still too hard to cut with a saw blade.
OK I saw John's other post with the pictures, so I understand now. Thanks! Rodney