Cat 953C 2ZN I am having trouble keeping the mounting bolts on my bottom rollers tight. Last fall I took both roller frames off and replaced all broken bolts. Every bolt was replaced with new Cat bolts. Bolts from the rear track guides to the front idler come loose. Any ideas on what to do?
A quick search revealed this
How worn are your track chains, and are you doing a lot of high-speed travel? If your track chains are severely worn, with rails "scalloped", and roller flanges are hitting the pin bosses, the hammering caused by the scallops and the rollers hitting the pin bosses, will make roller bolts come loose - and you'll never keep them tight, until you invest in new undercarriage.
I was told by a shop to put blue Loctite on roller bolts. It helps keep them tight and also helps prevent them from rusting in place.
Did you remove the paint off the mounting surfaces
Flat file both mating surfaces. If there is a high spot when you bolt down, your holding the tightest on that high spot. When things start pounding it can flatten out that ding on the surface and the mounting bracket may work loose.
I'd use a flap disc in an angle grinder to clean both surfaces and ensure they're flat.
Gentlemen, TY for all your replies. Much appreciated
If you have the room try Bellville waters under the bolt head. In essence they act as a spring to keep tension on the bolts. We used them a lot in Potash mines for equipment where there were bolt loosening problems.
Keep in mind that grinding and sanding discs change the whole surface. Big high spots will push back on the grinder and you may not remove all of it. On a fairly big flat surface a sharp file layed flat on it with no handle that is pushed accross it won't bite into it if there is no high spots. I use a file that way to check for high spots. (a file thats sraight will rock on a convex surface and bight the edges on a concave surface). I use a carbide scraper or spot grind big dings then finish with a file. I use paint remover, scrapers, wire wheels and scotch bright pads quite a bit for paint and rust removal. A flap disc is a good tool, maybe check your work with a file when your done.
The surfaces should be reasonably flat to begin with. You can check with a file for flatness but rails are higher hardness so won't file too easily if there's a high spot. Usually it's just taking paint off and just takes a light dressing.
You can buy Nordlock wedge-lock washers that are specifically designed to prevent bolts from loosening in high vibration environments. NORD-LOCK® ORIGINAL WASHERS Secure bolted joints exposed to extreme vibration and dynamic loads. Available in multiple materials and coatings. www.nord-lock.com
There's also Nord-Lock extreme that are dished like belliville washers.
We had those all over radar antennas in the drive sections. They do work well keeping fasteners tight. Prior to gearbox changeouts using another vendor, the capscrews were always a maintenance item to retorque. With these and single use retention fasteners, loosening was history. Lots more vibration from wind loading, gear mesh, bearing rotation, frequency vibration, and harmonics of the same than one would ever imagine. I don't see why they wouldn't solve this problem with to roller carrier retention bolts working loose unless the threads have been pulled, or stretched during a prior install.