So here is my problem. Picked up a case 850 with an 8 way blade on it. The main spherical bearing was completely shot. There was no race, just the inner ball piece that goes on the pin. I ordered up some new parts and pulled the main pin and old parts to see what i was dealing with. By the parts diagram I figure there should be a step or snap ring in the bottom of the bore to hold the bearing race. In the pic you can see i dont have that. There should also be a snapring groove on the top to retain the bearing race. The bore that is there is about the right size, but is egged some. You can see there is some weld at the top of the bore and also the bottom, im thinking it was to hold the spherical bearing in at one point. http://s48.beta.photobucket.com/user/PatF10/media/photo1.jpg.html So here is my plan since I dont have any snapring grooves and the bore is egged. I want to make a new sleeve with either a step on the bottom to hold the race and a snapring on top or two snapprings. Then I would have to grind out the bore to accept the new sleeve, i see this being the hardest part. Then welding the new sleeve in. This would leave me with a good bore and be able to service the bearing again in the future. This is just a farm dozer, it doesnt get used to make money for me. Id like to see what some people think of my plan that work on this stuff, think its viable. I dont doubt my abilities to do this just want some insight.
Pat,I think the best way to fix that and likely as cheap as any is to machine out all that old metal till it cleans up.Pad weld it then machine a new bore to suit the bearing with a step at the bottom and a new groove at the top. About a 6 hour job for a half decent line borer.You have a good as new fix. Putting a sleeve in will work for a while but here is a few issues. You will need something like a 3/4 wall thickness sleeve to carry the bearing (my opinion only) Its a big job to grind out the bore and no matter how good you are its not going to support the sleeve properly. You will be relying on a relatively small amount of weld to hold it. The bearing only has a few thou bore tolerance.They have 2 to 3 thou interference. As soon as you hit the sleeve with a welder its going to distort all over the place. That's my experience. I've also seen a few repairs over the years that should not work but do
Yea i see what you are talking about with my method of fixing it. I am some what curious what a repair like that would run me. Is boring and welding like that something a typical machine maintenance service would do? Something i dont want to spend a ton of money on as it is just a farm dozer pushing some dirt and mostly bushes and trees. The insight is appreciated, gonna have to continue looking into options.
Its easy done with the right equipment. I have done quite a few similar bores in Komatso 475's. They have a larger spherical bearing on the bottom of the blade. You need to find out what line boring contractors you have in the area or alternatively a workshop with a borer big enough to fit the frame on. Pay my travelling and I'll do it for you
So i have been going over this problem in my head for a little while now, and i have one main concern. If i weld in a sleeve, ive decided to go with at least a 3/8 wall. What kind of issues will i have with it cracking. The c frame on the dozer appears to be a cast steel. Any steel/cast welding i have dont was used with nickle rods and preheat, peen the weld as it cools. But i know circular welds tend to crack more. If cracking is going to be to big of an issue, then i need to figure out another way to retain the sleeve. Ideally i would like to have it line bored and re welded, but i dont think i can justify the money into it for a farm machine. That and equipment mechs are pretty busy around here as it is. Gas line/well work has them pretty busy.
We do a lot of these types of repairs here. I agree with RayF. Unless you can get a heavy wall sleeve in there I'd build it up and bore it. Anything thin is just going to get hammered out. This is especially the case if you dont have a perfectly round hole to start with and anything less than a press fit with your sleeve. If you do decide on the sleeve method make it as heavy a wall as you can without thinning the parent material too much. Bore the hole round and bevel the top and bottom edge considerably. Also bevel the od of your sleeve. You'll want a deep "V" to fill with weld top and bottom. As far as welding goes, I would reccomend 7018LH rod. Cast steel is quite easy to weld under the right conditions. I would press your sleeve in and tack into place. Then preheat to 600 or so degrees and weld 2 quarters 180 deg. apart one side. Reheat again and repeat other side. Continue alternating each side till fully welded. The key is to keep it HOT. By this time everything should be up to temp and allowing it to cool naturally should be fine. The cracking occurs when the parent material is significantly colder than the weld which creates a hard brittle spot where the weld meets the parent material. Basically cooling too rapidly. I think boring to size after welding is the best way to go, however I think distortion will be minimal. So if you bore your sleeve to finish size before installing and because the bore takes a spherical brg, I doubt it will be a problem. Just remember to allow for press fit collapse in your finish bore size. Otherwise your brg will be too tight when installed. We have some pictures posted on our Facebook page of a front idler we welded a new center in that we machined here in our shop. Pretty much the same procedure just thinner material. Look us up on Facebook under PD Mechanical or visit our website for a link. Good luck. Steve. www.pdmechanical.com
Thanks for he reply steve. Im curious on your idler repair there, what grade steel did you use for the new center? Seems like it is a similar type repair that i will be doing.
I believe it was 4140.
PatF10 I see your in my area if you would be interesed in a fab shop taking a look at it give me a PM. I have a few that might be able to help you.
This is our general setup to rebore the bore. Finished bore repair sleeve without the bearing. We heated the sleeve froze the bearing and it slipped right in. Basically finished, just a little more welding to do. Got it all buttoned up and it working well so far!
Good job
You will be glad you put the effort into doing it right. A nice tight blade lets you be a better operator. That point on a blade take a real whupping when you get to hitting things hard.
It was the best i think i could pull off. The sleeve is made of 4140 and has a slip fit into the dozer where it was welded. The bearing if I remember correctly has about a .003" press fit. So long as the welds hold up the bearing will be serviceable. The boring bar is actually made of centerless ground Titanium (was laying around the shop). Used the EDM to cut the square hole in it for the carbide cutters. Was able to get the mag drill on loan from a maintenance guy at work. Got some pillow blocks and mounted everything and away i went. The setup wasnt perfect, the bore is slightly off center, but i think it will do. There are a couple other pins and bushings that are loose but just fixing that made a night and dat difference in how the dozer pushes dirt.
Very nice work....good penetration on the welds. Interesting boring bar to say the least.
old bore the dozer
That's good work with the mag drill, get'er done! Nice chrome stack, too.
PatF10, I've got the same dozer as you, with nearly the exact same condition. I would like to repeat your process! What bearing did you use, and did you machine the sleeve yourself? Did you allow the zerk to grease the new bearing when installed?
Yair . . . That looks a nice little tractor. A spherical bearing seems like a lot of fragility built into a nice heavy "C" frame system just to allow blade to pitch . . . or am I missing something? Cheers.
That's CASE for ya... no offense intended, lol
Its not only Case unfortunately. I've bored quite a few Komatsu 475 dozers that use spherical bearings in the blade set up. They are around the 10 or 12 inch diameter but fail often and usually take the bore out with them.
Our d6k has That problem it breaks the race. Last time I changed it got lucky and the bore was ok.
I got a new spherical bearing from case. I then made a sleeve with a snap ring groove. I cant remember how tight a press fit i did. I can see if i still have my CAD drawings. The new sleeve i welded in. And i left a hole through it so the grease fitting would work.
Yair . . . The point I was making in my post #18 was that the standard heavy bushed hole through the "C" frame with heavy eyed pin onto the blade set up was rugged and, as far as I can see, did everything the spherical bearing does except provide for pitch. Even pushing sand and slop on canal development they lasted tens of thousands of hours and were cheap to fix with a grinder and a welder. Sure, they could get sloppy but our blokes used to spread sand ready for topsoil with eights and nines . . . precision engineering has its place but surely not on the "C" frame of a dozer? Just showing my agin'. (big grin) Cheers.
Scrub, it's all about the money. A single pivot point with a cheap spherical bushing is much cheaper to manufacture and assemble than some of the more complex systems that allow angle/tilt/pitch using multiple rotating joints. It will usually last through the warranty, yeah?
Yair . . . . Yeh lantraxco Gotcha . . . you're even more cynical than me! (big grin) Cheers.
I had to drive a half hour to the dealership on a weekend for a customer several hours away with a then new 988 G or F, anyway was back around the turn of the century the model had just changed. This brand new very expensive machine was the lead loader in a rather large pit feeding a really big project that eventually ended with fresh asphalt on many miles of four lane highway. Operator, good old hand, grey hair, solid as a rock, smooth as butter.... was working along like a well oiled machine with his right hand on the lift and tilt controls, when the loader hit a bump in the road. Snapped one of the levers off... about three or four inch tall *PLASTIC!!!!!* control lever. SAY WHAT????? Operator was panicking, said he was just sure we wouldn't have it because the model was so new, gonna be down two or three days... nope sez I, would you believe I got a half dozen in stock? Only been out a few months and already we're stocking them by the handful. Now who the hell thought that was a good idea? Probably saved ten cents a machine or mebbe a quarter. End of story it only cost the guy a day's drive to town and back and they were making little rocks out of big ones again on Sunday. I got cynic right up to my eyeballs, LOL