I’ve seen numerous references to putting a pass or two of weld across an old bushing to shrink the OD and ease removal of the bushing. Friend is working on a mini-ex (Kubota 121) and needed to replace the main blade angle bushings (2 piece bushing with a spacer in between). I suggested the welding method which he tried without success. Ultimately, the bushings were cut through with a carbide tipped blade and then driven out. Afterwards he sent me these pics. My question is, why did the welding approach not work here? Based on the look of the weld, my guess is too little heat/penetration of the weld into the bushing which did not produce the desired shrink. Thoughts?
I agree with you. It's usually more effective to weld a circle around the inside circumference because that heats up the entire bushing. The idea is to create a full heat cycle of the bushing metal, and heating the entire thing will produce more shrinkage than just a few cross welds.
I would postulate because the welding is supposed to be done in a circular fashion around the bushing, not up and down as shown in the photo. The whole idea is that the weld melts and fuses to the bush material in a complete circle, then when it cools it shrinks slighlty and pulls the material of the bush inwards just enough to loosen it in the parent bore. All that welding a bead in a vertical orientation might do is to shorten it by a few thousandths.
Thanks for the replies so far! @Nige I found a few threads referencing the circumferential weld on the bushing, that does make sense thanks!
I have done it quite a few times like your friend did it, with good success; though after reading this I might try it going around like guys have said. The way I have done it is weld the passes hot, and then splash the weld with water. If it doesn't work the first time, repeat. Usually I have done a couple hot passes at once, then hit it with the water. I have always thought that shocking it with water is what did most of the trick, but I really don't know that much about the science of it.
I cut them with a torch and scarfing tip myself. That heats and weakens it significantly. I don't cut clear through, just a few slices.
Some of the bushings on my 315c are some kind of stainless alloy, and wouldn't be torched . . .
I have had some in a hole hard to get to. Also welded a big washer or cross bar in them and took an air hammer to them after cool down.
Ive always used used the circular method , 99%success.Today i had a small pilot bearing on the input side of a planetary shaft,the balls and inner race were pieces. It was pretty tight to weld in the way it was reccessed. Torch in one hand sovlent atomizer in the other hand. a couple of quick red spots then hit it fast with air water spray and the race wriggled out.
I use some 3/32 stainless rod that is 120000 lbs strength instead of 70000 rod. It pulls harder when welded around in a circle and the bushing just falls out. Have done many this way but usually put 1 pass near the bottom and one pass near the top. Couple little sections done in the middle works good to help. Warning though, if your not a good welder, maybe don't use stainless as the torch will not help afterwards to cut it out. I can weld it easily with about 80 amps. Have welded out many a wheel bearing race like this. Simon C
As the first two gents to reply suggested circular welds are the way to do it. If it isn’t loose enough after the first weld bead add another one. Option 2 is as someone else suggested… “it can’t be tight if it’s a liquid”! I have found the welding trick works very well on bushes like in the pic and even cups for tapered roller bearings like used in large on road trucks and semitrailers for wheel bearings. The trick for putting them back in is overnight in the freezer or an upside down LPG cylinder to shrink them a bit if no press is available and they are too tight. I assume everyone else does this too??
I have used a freezer, but never tried the upside down propane tank. Never thought of that. I've seen guys use dry ice or liquid nitrogen in a styrofoam box too. I have 8 wheel hubs to pull between our two cultipackers. I'm not sure yet if they just need to be repacked, or if they will be getting all new bearings and cups yet. I pulled the worse one apart and the race just spun inside the hub. I already ordered a new hub for that one as the race fell out once I got the grease cleaned out of the way. If I have to replace a bunch of bearing cups, I'll be trying the circular weld pattern to speed the process.
I have heard about the dry ice and liquid nitrogen but have never seen it used or had access to it. We are a bit remote where I am, but there is always propane bottles around. The first time I tried it was putting wing attachment bolts in my aeroplane, it’s a long story but they were supposed to be tight fit and we had trouble. It was only a small size bolt but we managed to shrink it about 0.001in (might have been 0.002in it was a while ago). Has to be upside down to get liquid out of the bottle instead of gas. I think I know what you mean with your hubs… I could be mis interpreting so correct me if needed! If you need to get it going you could try what we call peening the hub where the cup sits. Involves putting a pattern of dimples with a centre punch and hammer in the loose area. It’s a bit of a last ditch effort, but it can tighten the fit up enough to get another run out of it sometimes. If the hub is buggered anyway you could try it just for giggles. I have found Loctite retaining compound plus peening can be even more useful, I think the truckers of old would have loved the retaining compound. I had to do it to the yoke in a tail shaft the other day as the universal cups were starting to fret, not sure how long it will last yet. Disclaimer this is not an approved repair procedure and for emergency use only
Have done the peening of the race holding area with a center punch, then wipe totally clean with brakleen, then Loctite 601 all around and on back side of race and pound in. Never seen one come loose. Not manufacture approoved, but worked perfectly. Warmed with propane torch to speed up the loctite. Simon C
Have you tried it? Those sintered bushings in the 120 didn't really cut either. I was melting the material and essentially blowing some of it out of there with the oxygen. It was not pretty but it worked. enough metal was removed to weaken it and the heat cycle and following contraction did the job.
If a straight down cut will take a bushing out, some 3/32 size chamfer rod would cut it out. Once first cut is done the bushing would be a lot looser. Simon C
I did try it, but they were pretty big bushings and I found I was just making a big mess and not getting anywhere. Your machine was probably a different alloy, I suppose . . .
That is berry good farmer! Did you wire weld that with flux cored, gas or both?
I think both simple hard wire. I don't use cored,,, nothing against it but my stuff is so simple and limited that I use 2 sizes wire in the shop with a few sticks to use free rods mostly and for field work.
I have never had an issue removing wheel bearing cups with a punch and hammer, they usually just tap right out. Bushings on the other hand are a totally different game.
Canned air upside down if the fit isn't too tight. Find a container just big enough for the bushing. Canned air upside down will come out liquid. Fill the container with the bushing in it. It'll boil like crazy! It still isn't as cold as dry ice, not near as cold as liquid nitrogen.
That's all I did. Degrease, then 4lb hammer and hefty drift punch to send them out.
gouged a bit and loosened up.
On ConMet aluminum drive axle or steer axle hub factory installed are real tight. I always run a bead around the race and even then it might take some force. But when done that way the surface the race sets in ends up less scared and makes for a better install. But that's aluminum hubs, cast steel can be the same.
I think welding beads the width of the bushings could work if they were done on opposite sides or in 3 or more places so the entire bushing got hot enough to shrink. One bead is only going to heat a small portion of the bushing in one place. The opposite side of the weld won't get hot enough.
I’ve used a cutting torch quite often to remove old bushings. Much easier than some of the other methods. To get by if the bearing race was loose a center punch usually makes the race snug and will hold for many years on farm wagons.
I've read all of the threads above for busing removal but I'll be darned if I can figure out how to remove the upper and lower king pin bushings on my TB016. Can't drift the top one down because the bottom one stops it. Haven't tried yet, just theorizing that it would. And the same from the bottom up - don't even want to try that due to liuitle room to swing the hammer. Tried using the dremmel tool approach and someone should go to prison for even suggesting that. I'm to the point now of using a torch but really don't want to gouge them out either. Never used a spilt bushing remover though and heard that may work. Anyone out there like to throw in some useful information to help this old man out? I'd really appreciate it.
While I'm on here, I would like to find some opinions on attaching a thumb to my TB016. I am assuming the activator would be the left foot pedal? And is a hydraulc thumb welded to the dipper preferred over a stationary one? Thanks.
Maybe your bushing can be welded out easily with stainless rod. Post a picture and maybe we can advise. Simon C
What is a TB016? The hardened bushings used in heavy equipment cut OK with a very skilled hand & an oxy acetylene torch. I did have one once over shoot the bushing & burn a bit into the bore. I welded it up & ground it smooth with a die grinder. I prefer heating only. I use a welding tip on an oxy acetylene torch. I heat strips lengthwise of the bushing, at least three places. After it cools, usually beat it out with an old socket.
It's a micro excavator. "TB" stands for "tiny baby"
Also known as a “worm digger”. But hey, anything beats a shovel!
1.6 metric tons? Fits in an F150 short bed? I sure could use one, it'd have to be a second machine. Mrs. B. could use it to plant posies.
I would need a bit of education. Some very small backhoes on compact utility tractors use only DOM (Drawn Over Mandrel) sleeves, without bushings. To refresh, you weld in new DOM pieces. In many ways, they are easier to freshen up, no high tec processes needed. I did have one from a Massey CUT come loose. It flew past my ear making a buzzing sound. I figure an inch one way, I'd have lost an ear.
I did this one on steel. Parts were , none or outrageous and even a deal was 60$ from dealer and 2 at auto parts.