What causes the swing bearing bolts to break and snap off at the threads? Just got it into the shop and giving it a once over and fixing things and noticed some bolts missing out of the swing gear housing underneath, after some investigating, they snapped off at the threads, the machine has about nine thousand hours on it and I'd guess its time for the bearing assembly as well, but how do you get the broken bolts out, the upper structure off and why did the bolts snap off in the first place? I've seen a few places on the forum where the upper structure was lifted up and the slew bearing replaced, but not a thread specifically dedicated to it that I could find, anyone done this and want to explain it to a backyard mechanic as to how to go about it and how extensive the job is? Any insight and advice is appreciated.
What machine?
Either tired or overstressed from overloading. Failure to check and tighten leading to uneven loading will cause this also. Drill and easy out, typically the broken ends will spin right out. Use a left hand twist drill bit with a reversible drill, probably spin them all out with very little drilling. Replace them all while you're at it, get OEM if possible and whatever flavor machine it is, ask your local service department if there's a service bulletin concerning the bearing and/or bolts. If it doesn't have tube spacers under the bolt heads with long bolts, it should. The longer the bolt the more stretch it has under load before it deforms or fractures, thus the logic behind long bolts and tubular spacers.
Good day Randy We have seen this issue on a few occasions the problem was identified in those case's as two most probable, 1/ the bed was deformed by weld repairs at the turret this had distorted the actual bed causing uneven loading of the bolts. 2/ the machine had been strapped down to a barge when digging below water the extra weight of the barge overloaded the bolts. We would endorse Lantraxco comments suggesting complete replacement of the bolts and the addition of torque tubes extra care pulling up the bolts with a wrench measuring the tightness. On file we have some information from a slew ring bearing manufacture if you believe this may be helpful drop me a email via the forum. Minor distortion can be corrected with special bedding compound. Kind reagrds Uffrex
Its a smaller size hitachi that 120 size machine, the table has never been welded on and all the remaining bolts are tight, I'd figure the bolts in the back or front would be the first to break, the bulk of them broke right under the cab, there are six out there with two remaining and the others are broken on the opposite side. Will a worn swing bearing also contribute to this happening? I've noticed some slop in the bearing the last year or so and was thinking now would be the time to replace it. As for getting the drill the bolts out, even with a angle drill head I'm not sure I can get it up in there to drill them and to eze out them out, I was thinking the upper structure would have to come off and lift it up enough to get at the broken off bolts to drill and get them out and replace the swing bearing at the same time. As for hard use, I'd venture a guess it gets used far too hard, has for decades but there has only been welding done on the thumb and stick on this machine, nothing else. I'm late for my latest ice storm and have to run..................or crawl to get to started on dealing with the ice issues of the day, thanks everyone for now and will talk later.
What is the exact model number and how many bolts are remaining? Deere/Hitachi does not put bolts in every hole on the swing bearing. If I remember right there are several holes not used under the cab and also on the opposite side. Check your parts book but I think most 120s used 36 bolts.
I finally found the service manual for it, there are supposed to be 20 bolts in it, one in every hole and there are five in a row missing and one bolt in and another one missing on one side and two side by side on the other side missing, one in and another missing. Called the dealer and the service department told me the swing bearing is worn enough to cause stress on the bolts and to replace the bearing, all the bolts and start over new, about what I was thinking, found the name tag and its a 100-2 grey market machine. They are trying to tell me to pull to pull the sun gear out of the finals and put H beams across the front and back, jack on four corners after removing the center joint, swing motor assembly and unhooking hoses and unbolt the upper remaining bearing bolts and jack up the upper structure enough to pull the lower assembly out, replace the swing bearing and use a mag drill to drill out the broken bolts and as they say just repeat the disassembly process and should be done before I know it..........................................
I would have changed about 30 to 40 swing bearings on excavators ranging from Hitachi 120 through to CAT 245 size, I never pull out the Carbody I just jack under the the frame bellow the counter weight and press down with the arm, it is the easiest and safest way, I have tried it with removing the carbody but found it to be a waste of time also putting more risk to the task, I have posted pictures in the Shop Talk slot under Caterpillar Sprocket removal, having posted pictures in the past with good detail on this Forum, I near always do them by myself unless I am showing other fitters how to tackle the job in a safe fast way, lots of snapped off bolts I manage to weld to and get out from the thread end of the bolt, this might involve removing a fuel tank or battery box what ever, anything beats drilling but sometimes you have to. good luck tctractors p.s. pulling centre gears in f/drives can cause issues Hy-Dash drives are timed up gears, get it wrong lets it fly!!
Try page 42 as this is drilling bolts, there is other excavators in bearing change mode on other pages, note how it's cribbed up with long timbers and short cross timbers, this will keep you safe so study and understand it, you remove all the hard to get at bolts by swinging the top about, then crib up your timbers, don't use steel as things slide easy, you will need to drop down your rotary coupling blanking off the pipe ends with steel blanks, oh and vent your hydraulic tank and leave it venting before you touch any pipe work. tctractors
Ex 200 -5 started popping bolts at around 15000 hours . Nice rock in the bearing . Changed the lot . Problem solved . The sheared bolts came out easy thanks to all the oil leaks over the years . I swung the machine across the tracks , jacked it up and got the L90 shovel and dragged out the undercarraige . My first and only time doing such a job but it worked out fine .
Tctractors, I must have flipped through a couple hundred pages looking for that post, I knew I'd seen it just couldn't remember where or who put the photo's on, thanks for the page and thread. You mentioned removing the fuel tank to get at the broken bolts and the photo shows a mag drill hooked upside down, how do you remove them from the top side with the fuel tank removed, could you explain this in more detail. Also, what would happen if the hydraulics leak down or sag, with the boom holding so much of the weight and so few of cribbing in the front, will it tip off the back blocks you have setup in the photo's on page 42? Is there a way to crib up the front side even more? I've made a dozen phone calls today alone trying to figure out how make this whole job safer, and I might have found a large crane I can rent for a few days really cheap and was thinking about cribbing and hooking the 30 ton crane to the lift points on the sides of the boom and also to the top of the counterweight to help stabilize it some more along with cribbing, any thoughts on this idea? I might also be able to rent a 65 ton crane as well if need be, the crane rental was a fraction of what the local shops wanted just for labor to do the job and my thoughts were it would sure help with a safety, but I've never done this job before?
Randy, if you block it tight the way Tony did in the photos in post #621 it will never move.... All it needs is some good hardwood cribbing. HeavyEquipmentForums
A sloppy bearing will point load the bolts causing them to break in sequence. I've also seen the carbody flange warped likely caused by the bad bearing. I've also seen where the machine was being moved on a truck and the boom hit a bridge causing the bottom of the house to be warped. I've only known of one person in my area that had the tools and knowledge to check and mill those areas flat.
No Crane needed, just follow the picture, to get the bolts out of the top side try welding a washer to the top of the bolt then weld a bolt to the washer, don't make things harder than it is, do it yourself and don't involve other kit or people as it's less to go wrong, all the people that pull out the Carbody are not doing it to earn money as it's a waste of time. tctractors
I did my first swing bearing ever,and it workd out.I'm not giving the 'right 'way 'or anything to do one,but here is a visual look through a video.it was an economical way in my case with what was available.Hopefully it helps a little. https://youtu.be/gKUrPUB0eXQ
Honestly if I'd had that amount of machinery available I might have seriously considered doing it that way also, but if all that's available is the excavator itself then by using a couple of good jacks at the back the way Tony does it is a viable alternative.
Only reason to yank the bottom out usually is if the bearing support flange needs machining flat.
Agreed.
How do you make sure that the pinion gear teeth line up with the ring gear? Are they beveled to slide together? Seems like one tooth could come down right on top of the other.
Leave the swing motor hooked up and just touch the swing lever when the house settles back down on the ring gear.
Just checking in to see how your job went? Did you get it finished? Did you take any pictures?
Three of us did this weekend, now waiting for seals and some small parts to get in so I can button it up and move it out of the shop. First off I'll admit, I was very hesitant of doing this job, but thanks to Nige and Tctractors I decided it must not be as bad as I was thinking [the safety issue] and the parts finally showed up so we did it this weekend. I have to thank you guys especially Tctractors who suggested cribbing up the upper structure and leave the undercarriage alone. We took our time, as in slow as a snail to make sure it was safe, had about four times more cribbing than was needed just to be sure we didn't run out, added extra cribbing everywhere to add safety to this job, and in less than six hours we had it done. I'm not sure how much faster we could have changed the bearing if we'd have known what we were doing and had done one before, but I'm sure we could have done in far less than six hours, that's for sure, we spent more time studying if it was safe and with every move we made, that it couldn't move on its own, etc, etc, etc. I'll also admit, I had a crane as a backup in case we thought it might not be safe or might shift, but never needed it at all. The cribbing, the way Tctractors does it, is the slickest and simplest way of doing this job ever and I'll have to admit, once its done, was also the safest by far. It took some doing to get the upper structure aligned to get all the bolts in, but once we had one in, most of the battle was done, we just used a chain binder to slide the upper structure the last partial inch to get things lined up. It didn't take much to get the broken bolts out, and there are some holes not used, not sure why they were not tapped, shorter bolts could have been put in those holes with no issues, but according to the book they are not supposed to have bolts in them. Again thanks to everyone who helped me out with this, and for anyone reading this and thinking about doing theirs on their own, its not that bad of job and just study the cribbing Tctractors used and how he did it and take your time and go slow, but its essential to have help, leave one in the cab and at least one more doing the bocks and giving instructions. As for pictures, I'm sorry we were stressed enough and never gave it a thought till we were done.
Caterpillar Sproket Removal (also Komatsu)