I replaced the bushings and pin at the end of the dipper arm last winter. I noticed that the bushings that the pin that holds the bucket on goes into were kind of loose so I tried to shim them. Didn't work. One of the bushings slid inward and blocked the area were the grease comes in. Is there a way to secure the bushings so that they don't move? Maybe some kind of adhesive? I also thought about grinding a few little grooves into the end of the bushings and frame then welding them in place. Any ideas? Thanks, Doug
Another thought I had was to rough up the outside of the bushing for maybe an inch or so and do the same to the frame and put some JB weld on it.
Oversized bushings? I replaced the loader linkage bushings on my 580M a couple months ago; two of the bushings were completely missing and the bores in the loader arms were worn eccentric. The aftermarket bushings I bought were oversized (not intentional on my part but beneficial it turned out). I ground them by hand to fit the eccentric bores, still leaving enough interference so they would stay in place. There was about 50 thou clearance so a little misalignment wasn't a big deal.
Thanks for the reply. I measured the opening on the loosest one and it varies from 57.32mm to 57.41mm. The bushing (aftermarket) is supposed to be 57.15mm but is around 57.12mm. Another issue is that the bushings are pretty long, 94mm and I assume that the wear in the bore isn't consistent. There is around a 2.5" wide cavity between the bushings when they are where they're supposed to be. I am thinking about taking things apart and maybe welding some nubs to keep the bushings from moving into the center cavity. Maybe I can reinstall the bushings with some very thin shim material? I just want to be careful and try not to f it up more. I've only been putting about 150 hours a year on the machine so it doesn't get a lot of use. Although if I wasn't afraid of it breaking so often as it does I'd probably be putting closer to 300 to 400 hours on it.
I'd try to get oversized bushings and hand grind them for an interference fit. Someone on this forum could recommend a material. A machine shop can make them any size you want. Years ago, a mechanic at one of my plants had the machine shop make some oversized bushings for a home backhoe project using the materials they had on hand. We checked the original bushing with a material analyzer and it was a hard steel alloy (don't remember how hard). He tried some of the hard bushing materials we had but ended up going with a hard bronze. The bronze was softer than the original but he didn't use the backhoe much but I don't remember him having any problems.
If the gap is small you could use Loctite 660 on the bushing. If there is a grease hole, don't put the Loctite there. LOCTITE 660 - Retaining Compound - Henkel Adhesives (henkel-adhesives.com)
Sounds a little more complicated that I'm capable of doing. What do you do, just keep grinding it a little at a time and checking the fit? Pounding it into the hole and then out? Some of the other bushings that I replaced had to be pressed in and/or cooled with dry ice then pounded in with a large hammer. Until about a year or so ago I don't think I've ever dealt with bushings.
Thanks, I've ordered some. I put one of the bushings back in using some shim stock. It seems to be very tight, at least for now, It took a 10 lb. sledgehammer to get it all the way in. I'll do the same with the other one and if they get loose again I'll try the loctite. If that doesn't work I'll try the oversized bushings like Bote suggested.
Split tension bushings go in fairly easily because they can contract. I just put a flat plate over them and pounded them in with a normal ball pain hammer. I let the Loctite cure for 24 hours before I started putting the boom back on.
Interesting, I hadn't heard of a split tension bushing. I installed the second bushing today with the shim stock. It was not nearly as tight as the first one so I assume that both will probably need replacing soon.
I put an old standard bushing in the bores and measured the gaps around the circumference with feeler gauges. I made a sketch of each bore from this data. I added .08 all around for interference fit. I used a belt sander to duplicate the profile of the sketch. I sledge hammered the bushings into the bores. On assembly, one side was too tight meaning the bore centerlines weren't aligned perfectly. I applied dykem blue to show where the contact was and opened it up with a round file. This is obviously not a precision repair but has worked fine for 25 hours. The bushings were totally gone before repair so it was definitely an improvement.
I like this approach. The bushings I used were already oversized so there was no additional cost. I see McMaster-Carr carries a bunch of the split bushings. Where do you get yours?
I got mine at hyd. shop but they had to order them. I think they were Hercules.
Sounds like you know what you are doing, unlike me, lol. I like the idea of the split bushings and will likely try them if I have trouble again.