Machining a new bushing out of bearing bronze when factory bushing was steel ?

hd28vsb · Oct 25, 2014

I am working on a front idler off a John Deere 350 dozer undercarriage . The bushing were completely gone and the idler bore worn out of round . I bored it round and was going to machine a sleeve out of steel , press it in and then press in the factory bushings .

Just realized that I am out of stock large enough to machine the sleeve out of . I do have plenty of 660 bearing bronze that I could bush both sides back with . The JD bushings are a steel bushing with a grease groove in it . I know a dozer sees a lot of rough work so I was wondering if the 660 bronze would be a suitable replacement ?

Thanks

randyc · Oct 25, 2014

John Deere has been doing this for a l-o-n-g time. I think that I would be inclined to place my trust in the material selected by their engineering staff.

snowman · Oct 25, 2014

Are you sure it's steel, not iron impregnated bronze? (still magnetic) or even just cast iron? Just better suited for wear

I make decisions like that based upon expense of downtime vs ease of replacement.

johnoder · Oct 25, 2014

I was wondering if the 660 bronze would be a suitable replacement ?

Certainly not for steel loaded in bearing

The softest steel (about 30,000 psi yield) is at least twice that of 660 Bronze

Mike C. · Oct 25, 2014

Also need to check to see if the shaft is hardened or possibly the bushing. One is going to be harder than the other to prevent galling. If you put a soft bushing in where it should be hardened, it will be VERY short lived.

millermachine · Oct 25, 2014

you might use preheat treated 4140

I have seen allot of steel bushing in earth moving equipment. The pins are normally deep case hardened and show little wear. The bushings are worn, egged and smashed out. I do not know what the factory used. But I have found preheat treated 4140 that is 28 to 32 Rockwell to hold up to the job. It machines pretty easy and almost any metal supplier will have it on hand. As john stated bronze is very soft and will probably wear out quite fast. Good luck
Brian

Tony Quiring · Oct 25, 2014

Check with the local dealer as this may be a common issue and someone already solved it.

Deere may hsve a bushing like you are looking to make.

Also look for forum for deere equipment...

traditional-tools · Oct 25, 2014

Doesn't Bronze require lubrication? Typcially there's an oil groove with the ability to lubicate, where a steel bushing wouldn't be like that, would it? If you did replace with Bronze you may need to plan for the lubrication.

4GSR · Oct 25, 2014

If it's anything like the bearing and shaft used on the clothes dryer drum roller. Both the shaft and sleeve bearing are harden like glass! Only about a .001" running clearance, no lubrication either! Probably coated with this

Nedox®

Similar situation on this equipment, both pieces apparently hard, maybe not "glass hard" but in the upper 30's into the 40's.
Pieces coated with something equivalent to this...

Hi-T-Lube®

Mike C. · Oct 25, 2014

Hold up, just re-read the OP. He's going to use the factory WEAR bushing, but needs to bush up the remains of the idler bore to take that bushing. Definitely use steel. I'd bush it for a press fit, press the bushing in and TIG weld the ends, then bore the part for the factory bushing.

IronReb · Oct 25, 2014

It would be better to lose the job because you don't have material than have the job come back on you when the bronze bushing gets spit out.

Not many places for bronze bushings in the under carriage of a bulldozer.

janvanruth · Oct 26, 2014

Mike C. said:
Hold up, just re-read the OP. He's going to use the factory WEAR bushing, but needs to bush up the remains of the idler bore to take that bushing.

Not exactly what the OP stated.
He WAS going to use the wear bushing, found out het didn't have the steel to make the sleeve and wondered if could use bronze to bush as a REPLACEMENT for the steel bushing.
Have a look at the title the OP gave to the thread.

Mike C. · Oct 26, 2014

OK, was a little confusing on both reads, lol. At any rate, I think it is generally agreed that the undercarriage of a dozer is NOT the place for bronze bushings in any form.

hd28vsb · Oct 26, 2014

Mike C. said:
OK, was a little confusing on both reads, lol. At any rate, I think it is generally agreed that the undercarriage of a dozer is NOT the place for bronze bushings in any form.

Thanks for all the replies .
I ended up finding a piece of steel large enough to make a sleeve out of . And then pressed the factory bushing back in .

Vancbiker · Oct 26, 2014

Repaired lots of ag and mining machinery parts with similar issues. We usually welded up the bore then re-machined to fit the original bushing or bearing. Most of the cast parts are cast steel, not iron, and weld easily too.

9100 · Oct 27, 2014

An experience I had, not directly applicable but illustrates the point that these things can be unpredictable, many of locomotives use Viking or Tuthill gear pumps to pump Diesel fuel from the tank to the injectors. I rebuilt a lot of them, mostly failed because the idler gear bronze bushing wore to the point that the idler mover over and locked up. I noticed that some smaller pumps had steel idlers with no bushing which held up better. I modified a larger one with a hardened dowel pin replacing the idler shaft and a 12L14 bushing. We ran the test unit at the rated pressure until we got sick of listening to it, and found there was no apparent wear. I sent out a lot of pumps modified that way with serial numbers stamped on them so I could track them, but was unable to because not one ever came back. The railroads kept sending other pumps in for repair, so they must have been happy with them.

I am not even going to guess why leaded screw machine stock running on a dowel pin holds up better, but it did meet the requirement of hard with a high polish on soft with a cross hatched honed bore.

In this case, I come down with the folks who say the factory has had plenty of experience and probably has found the best combination.

Bill

magneticanomaly · Oct 27, 2014

Factory may know best, but remember they 1) like to sell parts, and 2) stand to save a lot of money if they make 100 000 bushings out of steel instead of bronze.

I know this is hard to tell once the bushing is long gone and wear is into the parent part (typical), but I would ask myself if it failed due to metal-to-metal wear, wear by grit ingress, or pounded out by overload.

If it failed by metal-to metal wear, IMHO hard steel on bronze will wear longer than steel on steel. Neither will last long without lube

If it failed by grit, maybe hard steel on hard steel is best.

If by pounding, hard steel on softer steel.

I would choose aluminum bronze. Much stronger than SAE 660, still a good bearing. I think OP said there was a grease groove. You can make sure there are seals. You can make sure the lube fitting is still there, passage unblocked. You can't make the owner use it.

dsergison · Oct 27, 2014

hard steel bushings and pins in pretty hard welded bores are the norm in undercarrige. anything less hard is short lived. a mild steel filler bushing with the factory hard steel bushing pressed inside it will get extruded from the hammering.

I would not make anything from less than 4140 rc30 to go any where near an undercarrige or linkage.

greggv · Oct 27, 2014

I'm sure that brass or bronze will "beat out" under the pounding of earth moving equipment. Cat uses hardened steel for bearings, and they work well.

JS · Oct 27, 2014

You would be surprised what bearing bronze will handle. One extreme the tracks on the carrier for the space shuttle. That being said factory materials are the best choice, if you need it repaired now and can't wait, then someone needs to make the call. Personally, I use 660 bronze on lots of things here in the mine, most of the machinery here is over 70 years old, so its either Babbitt, Bronze, roller beaings with some old wood bearings in between.

fix it once, fix it right.

Machining a new bushing out of bearing bronze when factory bushing was steel ?

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