hello. we have a CAT d6txw high track dozer that we bought new approx 5 years ago. we have broken more track bolts than i can count in that time. we work in salt which is crushed down to -3/4" roughly and it is not very abrasive, almost creates like a graphite dry lube. cat has been here multiple times and has even replaced the chains and pads but can't provide us with any reason for our issues. any ideas would be much appreciated. thank you.
Are bolts rusting from salt?
My guess would be that the salt is wicking its way in to the bolt threads and eating away at them. Has any kind of Locktite been used on them ? Did you ever consider welding the the nuts to several new, properly torqued bolts just to have a comparison to the others.
Does the tractor have heavy duty or System One undercarriage.? If you are not sure just post the Serial number, I can figure it out from that. What width of track shoes are fitted. ? Does the terrain the tractor works on cause any sort of flotation issues.? In other words does the tractor have a tendency to sink.? EDIT: Do you have any good close-up photos of the fracture face of one or more broken bolts.?
Reminds me of reading this story about a Belzona repair to keep track pads on an excavator. https://khia.belzona.com/en/view.aspx?id=41
Just a thought: https://en.wikipedia.org/wiki/Stress_corrosion_cracking
I believe there are three track gauge models denoted by XL (narrow gauge), XW (mid width gauge) and, LGP which are the really wide tracks. I used to see a lot of broken bolts in wider gauge tractors using wide pads and working in any type of rock at all. What generally went with that is a big reduction in track chain life as well. Usually broken pad bolts happen when pieces of rock get stuck on the edges of the pads forcing them apart as they move through the bend at the sprocket or idler. I've seen plenty of issues as well when the initial installation of the pads wasn't done properly. Paint not cleaned off, bolts not cleaned before installation or the bolts and nuts not torqued up properly. Salt can also have a lot to do with it but in my experience there is a big reduction in the bolt head size from corrosion before they actually break. Usually the bolts that haven't broken will take a half size smaller socket in order to get enough grip to turn them loose.
What I have read about SCC is that it will take a part that otherwise looks good and just cause it to break for no immediately obvious reason. So it sounds plausible in this situation, maybe.
That's why I asked if the OP had any photos.
Weld the pads on the outside edges with a couple 2" inch welds 2on each side with 7018. A little preheat would help. Pads are probable shot if they are loose and never stay tight. If they are still good easy to grind the welds on the outside of links and get them so they can be reused. I welded a stripped master link to get more life out worn out chains. Continued on next page. Nurse came in.
If want better corrosion protection use a 312 stainless or specialty rod for difficult to weld steels or unknown steels. They are similar to 312 but usually easy to find. Supermissel weld is an example. They are stainless based with high tensile 120-130,000 but have really high ductiilty (I think it's ductility) like 32%. Using something like a 11018 is too brittle for the application and may crack. Dual shield Flux-core could be used but I wouldn't use Mig or any other stick rods like 6010/6011, 6013 or 7014. They are not for the type of loading on a track. .
I posted a response to the wrong post. I don't know to change it. Look under excavators.
Komatsu PC60 rebuild thread. Hate the small letters with fat fingers.
Darn phone.
As a project manager , my observation would be that the salt is wicking its way into the bolt strings and consuming them. Has any sort of Locktite been utilized on them? Did you at any point consider welding the nuts to a few new, appropriately twisted fasteners just to have a correlation with the others.
Welcome to HEF, Devon !
I mentioned the salt wicking into the treads in post #3. I'm probably wrong, but my I was thinking that not only was it corroding the threads but at the same time causing a swelling of them that would perhaps increase the tension on the bolts.
do you think that might be the latest spambot?
Still waiting for photos.........
Boy, the near word for word regurgitation of Tinkerer's post sure makes it look suspicious. Still, it was just a little different. If I were a teacher I'd be wondering if somebody's being a copycat. To give Devon the benefit of the doubt for the moment, I'll just post a reminder of the Forum Rule on advertising: Devon's introductory post elsewhere counts as that ONE permissible post. The link posted in this thread makes it smell kind of spammy. To bring Devon into compliance, I'll just go and edit that link out. You won't mind, will you, Devon?
Digger most of the project managers of Devon's level that I've dealt with know their way around dozer undercarriages working in a salt storage facility.
Could one of the moderators please move my 2 posts from the excavator forum on Kom. PC 60 to this thread. I think it might be a good solution. Thank you
Yes, of course they do. I need to learn to not be so cynical. Dave, I assume those are the two posts you meant.
we The 2 posts about welding the pads on a kom.PC60 undercarriage rebuild thread. Thanks