I am slowly working on getting my used Bobcat 442 ready to dig and noticed the pins and bushings are extremely sloppy. I am used to the pins and bushings on my CAT being extremely tight. Since excavators are new to me, I was not sure if these were designed to have more slop due to the shock forces? The bushings that are in place now are 52MM inside diameter and the new ones claim to be 50MM. The PIN is between 48.5-49.6. Ideally what should these be? I could not find anything in the service manual or the operators manual that specified any of these dimensions and how to check for wear. The bushings I can still get from Bobcat around $73 each and the pins they no longer have. I can get some bushings from McMaster that appear to be the same that are $23 each. Any advice on this? I am inclined to get 4 from Bobcat for now and maybe switch over too McMaster if I find them the same? For Pins, is there an aftermarket vendor that is not outrageous to make these or might have them in stock? Lastly, any special tool or advice you have for removing the existing bushings would be extremely helpful! Thank you!
No, they shouldn't be that loose in my opinion. On my Bobcat (manufactured by Doosan) they design more clearance than I think they should. I had a custom pin made for one of the joints on mine to get it tightened up. I did use Bobcat bushings. That price for the bushings does not seem unreasonable to me. If you can find a reputable machine shop locally that can make pins to tighter tolerances, that's what I would do. To remove the old bushings, weld a bead around the inside of them (will make a smokey mess because of the grease), and the heat cycle will shrink them so they'll almost fall out. You may need to use a hammer and drift but it'll be a lot easier.
Wow, that is a great tip about removing the bushings!!! Thank you! I could make my own pins. The question is what hardness and alloys should I start with? I am tempted to go as hard as I can, but then I wonder if that is not good because the machine will yield before the pins do?
Rockwell C scale of about 45 will be hard enough for the pin surface. Ensure the case is at least .0250" deep or better to allow for some wear before they really start chewing badly. Much harder and they are too brittle to absorb shock.
Not sure what you mean by case? Are you talking about the heat treated depth? Looks like I can pretty easily get my hands on C28, C32, and C59-60 from McMaster.
I received the new bushings from Bobcat and they are not what I expected. Even the bobcat dealer said they had never seen this type of bushing before. Do any of you have some insight as to this style vs the solid ones with the grooves?
I haven't seen anyone use bronze bushings since the days of working on friction shovels.
Hmmm. So I’m guessing that’s a bad thing.
It might be phosphor bronze. Last a long time and the wear goes on the bushing and not so much on the pin. What metal is the original?
Well, these look the same as the original. They look more like copper to me though.
Bronze is an alloy of copper and tin plus other elements likely in this case is phosphorus. There are other elements that can be in there. Sometimes this is also called red brass.
Oh, very cool. Thank you. I did not know that.