I had a long post in another forum but thought my question might be more appropriate here. Has anyone ever seen a swing pin wear excessively and leave behind what looks like powdered metal? I replaced the bushings with spring tension bushings because the hole wasn't perfectly round and had new pins made at a hyd. shop. I sprayed some dry graphite but normally spring tension bushing don't require greasing. Some might refer to it as galling but the pin wore about 3/16" deep on the side facing the bucket. The bushing was rough but nowhere near the same amount of wear. I'm wondering if the pin was too soft or maybe once the chrome wore off it acted like an abrasive? I think the pin was made from a cylinder rod as it was chromed. Dug about 150 yards with the new pin and bushings.
I read your other post as well. I'm not familiar with spring steel or how it will offer acceptable performance in a hole that is not the right shape (oval vs. round?). Which particular TLB you are working on may also provide us some clues as well. I have replaced swing fame/swing ram bushings a couple of times over the life of my current backhoe ('97 CAT 416C). On my machine the swing frame is cast iron (which is relatively soft) and I think that this is common among most machines as a harder material is likely to crack in certain situations. I have never had the issues that you are describing, but I have always used OEM parts and have not had an "out of round" issue in the pin holes of the swing frame either. Based on what you are describing I suspect (2) possible issues. First, I've never used a rod from a hydraulic cylinder as a pin before. I would agree that the chrome is very hard but that might contribute to excess wear on the sibling material (the bushing) unless it is also equally as hard. Second, I would be suspect of the base material (what is under the chrome) since the material was not selected based on performing like a pin (side load) but rather a compression and tensile strength like what it would be subject to as a rod. Does this cause the chrome to fail?...Removal of the pin will tell you that (and much more as well). If the chrome is in tact I would suggest that you powder is from the bushing. The fact that the bushing is already showing wear (without even having to disassemble) this would be my primary suspicion. The fact that the bushing is not supported equally around the bore (or boss) concerns me as well. The fact that you have chosen not to apply grease is also concerning. I would imagine that they are out there but I have been running 'hoes since the 80's and I have not seen a swing frame/swing cylinder bushing that does not require daily greasing. We could probably go through many scenarios but I will still have the same conclusion. I suggest, that if the parent metal of the swing frame has enough meat left on it, that you should line bore it back to proper round status. Then have your machine shop build you bushings that will be OEM inner diameter (so that you could use OEM pins, or equal), and press fit diameter for the holes as bored in the swing frame. I would also recommend that the bushing be the same hardness as the pins. I know that this may likely require removal of the swing frame from the machine (maybe not) but it is the proper way to repair the issue. If there is not enough meat on the swing frame to accomplish this....Then it might be time to search for a new swing frame. If the swing frame is cast iron I don't believe that one could weld it up and then line bore it back out. Obviously that brings us back to the replacing the swing frame idea. It may not be what you want to hear but the alternative seems to be what you are already experiencing. I'll be interested to hear what others may come up with. Best of luck!
As for the chrome rod as pins. A good 50 percent of the pins in are fleet are made from old cylinders but are in the standard issue steel bushings and seem to.give just find performance. Could it be the rod they used was not hardened at all thus make the steel smash a bit cracking off the chrome and starting the wear. The rods we always end up using are case hardened. Good luck drilling a hole with anything less then carbite there harder then wood pecker lips.
Yes have seen pins wearing like that and the black/grey powdered metal you describe. It’s chattering as it moves creating the dust. It will wear very fast. Not much you can do but keep it greased as well as you can until you have to change pin out again and do not use the chrome rods again as the chrome is so hard it’s acting like a grinding compound and underneath is weak steel
I've mentioned it a few times, Andy, an extra son bought sight unseen his grandfather's Ford 4500 TLB. When it was shipped here, He discovered the swing tower was badly worn. The bushing was worn through at bottom of the swing tower & the portion integral to the tractor was quite damaged. We TIG welded a good deal of material to bring it back to original shape & he built his own line boring rig. The bushing is non standard OD, so new bushings had to be made. It was a big project. Less severely worn, I've done them on two other backhoes. The hoe must be blocked up to support it in all directions, Hoses removed to allow tractor to be a foot away from hoe. Usual process of welding, or heating with rosebud to loosen the bushing, then drive it out. New bushings need liquid nitrogen, or at least dry ice to shrink them. Liquid nitrogen is twice as cold as dry ice.
It's on a Cat 931B track loader. The swing frame is cast steel. The bore for the bushing is not really out of round, just a little that the OEM bushing wouldn't be super tight in the bore. That's why I used a spring tension bushing. Spring tension bushings are recommended and have been successfully used in applications like wheel loader articulation pivots. They claim they don't normally require greasing but can be special ordered with grease grooves. They are much easier to install than shrinking a standard bushing. They weren't too expensive so that's why I tried them. Cylinder rod is used a lot for pins. I read where someone says a bore can be welded but leave a little at the top of the hole unwelded. Then you can use a hole saw to bore the hole to proper size. Has anyone tried this? Line boring is out of the picture right now. I could maybe very carefully clean up the bore after a little welding with a die grinder and final finish with a flap disc. I'm going to remove the bottom pin and see what shape it's in. The other thing I'm wondering is if the type of steel of the bushing is just incompatible with the steel of the pin???
I've done the hole saw trick on a d4c c frame when I was done the pins where a 4 hit with the sledge fit it was alot of flap wheeling to get out a 1/16 or there abouts
Now I'm totally confused! Where is there a swing pivot on a track loader?
This is a 931 on youtube.
I guess I could have said it's a Cat 5G2150 backhoe but nobody would know what that was. It's a D3B/931B backhoe. It's an improved version of the one shown above.
Are you sure the bore is damaged? or just the bushing? Just looking at the hinge mechanism, my eye says it is undersized. It'll be prone to wear. Likely, you are going to need a weld & line bore to fix it. I'm drawing a blank trying to remember the company makes expanding pins to fix this problem. TD7G had minimal slop in the c arm pins, but tracks were hitting the angle cylinders. The expandable pins cost about what a line bore would. I discovered the track shoes were non standard width, & I cut them down. left the pins alone. I did add a sacrificial pad to the side of the C arm to prevent track shoes from hitting the hydraulic cylinder.
The bore for the bushing is slightly oversize in a couple spots. I previously ripped the the top swing mount off and mistakenly used a flap wheel on the bore for the bushing. Not a lot but not a perfectly round hole.