PDA

View Full Version : Shovel / Loader Bushings



Ian B
05-23-2004, 05:27 AM
Has anyone out there replaced bushes & pins on earthmoving equipment? I'm looking to buy a used 4 ton loader (the sort that steers by pivoting in the middle) and I'd like to know how difficult it is to rebush / repin the bearings on the shovel arms, bucket etc.

I have a decent sized mill, and access to a 12" x 36" lathe, so machining shouldn't be a problem. I'd guess the largest pins are around 2" diameter. I have enough lifting equipment to get the heavy bits off if needed.

What's the usual repair tactic? Is it to:
- machine up new bushes & pins and press the bushes in?
- ream the old bushes in-situ & make oversized pins?

In the case of the first option (new bushes), do the bushes need reaming to fit once in place?

Any recommendations on bush / pin materials? Grateful for any words of wisdom from the group.

Many thanks,

Ian

wierdscience
05-23-2004, 09:26 AM
The best way if it is possible is to line-bore the welded in bushings in place and make press in bushings to bring it back to the original size.You can do this so long as the bushings you have aren't eggshaped too badly.

If they are egg shaped then you will have to do one of two things,either weld up the eggshape or cut the whole bushing out and entirely make a new one and weld it in.

If you decide to cut and weld in new ones the method I use is to cut the weld itself and make the od of the bushings a little larger than the original.When you make the new bushings make the bores about .008-.010" oversized becuase when you weld them in the weld will cause them to shrink slighly.When you set up to weld them make sure that you have both bushings in place on the pin so the pin will keep the alignment,once you have the bushings tackwelded in place in three or four positions remove the pins and finish welding.If you are replacing bucket pins or arm pins where there are two sets seperated by a distance I use a long length of pin material to align all four bushings before welding so when the joint is complete all pins are on the same axis and plane.

The line boring alternative will work best if you can mount bearings (pillow block)on either side of the bushings to be bored and make yor own boring bar to fit,just a toolbit in a crosshole powered by a 3/4 or 1" drill motor.Set it up and take lite cuts.003-.005" per pass,if more than one set of bushings is envolved then do the same as above using a long enough bar to span all bushings.

One word about pin material,don't use cold rolled(1018-1020)waste of time,it is too soft and pounds out quickly.My favorite material is 4140-B7,it is cold rolled and heat treated to 38-40 rockwell c ,it still machines good,but is nearly three times as tough as common colled rolled,another alternative is through hardened hydraulic cylinder rod,a good bit harder than even the 4140,but even tougher.

Make sure the pins are locked stationary to the machine frame and the grease is fed through the working bushing and not through the pin,I have seen through experience that gun drilled pins fail and they always fail in the crosshole.

Ian B
05-23-2004, 01:55 PM
Thanks Wierd,

That's exactly what I was after - I like the idea of using hydraulic rod.

The machine I'm going to look at doesn't look to be too bad, so I'm hoping I don't find severely oval holes (if I do, the rest of the machine is probably shot, and I'll look further).

I'd been thinking that the various holes would have been bronze lined - from what you say, it sounds like this isn't the case. If I need to bore the existing bushes out, is rebushing with hard bronze a good idea?

I was wondering how to line bore the bushes - a 4 ton loader is a bit big to hold in my mill's vice! I hadn't thought of a pair of plummer blocks and a drill.

Thanks again,

Ian

John Stevenson
05-23-2004, 02:47 PM
Ian,
You work in the oil rig game. One of my customers Mirage Machine tools supplies a range of clamp on boring machines that can do this work.
Any chance you could 'borrow' one ?

Also bronze bushes aren't a good idea. They cause the shaft to wear more than the bush in dry applications.
Daft as it sound Devcon plastic bushes last up far better and cause less wear to the pin.
Plus side is they are 'self reaming' if you have a big enough hammer, and can take up ovality by spreading to fill.

John S.

motorworks
05-23-2004, 05:45 PM
"Daft as it sound Devcon plastic bushes last up far better and cause less wear to the pin"

First time I saw large "plastic bushings" was on the back of a deep sea dragger.The shaft was ~10 feet long and 120mm in diameter.The plastic bushings were mounted in a steel
"pillow block".They were about 12-15 mm thick.Ask the chief how they were holding up and he said in broken English 'Great'.
Plastic bushings are used in shrimp and crab plants on stainless shafts.They hold up longer then regular bearings or bronze bushings.But they are still a hard sell to some people.

[This message has been edited by motorworks (edited 05-23-2004).]

wierdscience
05-23-2004, 07:57 PM
Ian,most of the loaders I see are in the 6-12yrd bucket variety,it is quite common for them to have hardened steel bushings in them,the mfgs use needle bearing races for their wear bushings.

You might try going to the mfg for the weld bushings and wear bushings,even the pins.I know JohnDeere and Komatsu both supply replacements for their units and they are quite reasonably priced.

One more piece of info that might help,the amount of wear and lubrication the pins recieve is determined by the material the loader will be moving.

For topsoil and clay the normal grease and bushing material is fine,stone,stone dust and river gravel you need extra heavy grease with indicator dye(starts out red and clear like strawberry jam and turns black as it gets dirty letting you know when to grease the joints)for beach,silica and quartz sand you need thin grease and the wear bushings should be the graphite impregnated fiberglass,if you use steel,bronze or mon-poly plastic the silica dust will eat them in short order.

I don't know how much experience you have on these loaders,but believe it or not the operator is at least 50% of the wear on a set of bushings.A good operator can load 8 hours a day for a year or better on a set,a novice can get maybe 3 months.

I'll try and post a link to the bushings I'm talking about.

wierdscience
05-23-2004, 08:08 PM
Look here-

http://www.mcmaster.com/

Page 1008,look for the PTFE/NOMElined fiberglass bearings with the 25,000 pv rating

Hope this helps

sandman2234
05-23-2004, 11:31 PM
Realizing it isn't the same, but a cherry picker they rented at work has a big bronze shaft. About 5" diameter, I wonder if that would work in the right alloy. Probably not for long.
david

AussieChris
05-24-2004, 12:27 AM
When I did this exercise on a Loader/Backhoe I was able to buy 4140 "ground round bar" in the exact size I needed for the pins. This saved a lot of machining as I only had to drill the cross-bolt holes and cut to length. Better finish than I'd get on the lathe. Original pins were quoted at $150 each here in Oz. I bought 3' of bar for $20. I used round hollow section (same material) for the bushes and machined to suit. Still going great.

Chris.

Ian B
05-24-2004, 05:41 AM
Thanks again guys,

It would never have occurred to me to use steel bushes in the pivots, let alone polymers in that service! I'll look at the reinforced PTFE bushes. I can appreciate that the bushes (especially at the bucket end) lead a pretty rough life, and often don't see a grease gun from one job to the next.

John, little hope of finding a bolt-on boring machine here offshore; we might be able to rustle up a gas axe and a 48" pipe wrench though...

Wierd, on the operators - I'm sure that the operators who give the bucket a good hard rattle with the hydraulics to shake soil & clay loose are the ones with machines that eat bushes for breakfast. I'd not heard about different greases for different applications; I'll be digging 'oles in clay & soil. Experience on loaders? Er - about 15 minutes so far...

Chris, how much clearance did you allow between the rod & bush bore?

Great advice, many thanks.

Ian

wierdscience
05-24-2004, 09:29 PM
Actually,the good operators keep the ruts smoothed over and filled in the loading yard,bouncing over them all day beats the pins right out,plus the good operators climb off the machine at the end of the day and walk normally,the novices are huanched over and holding their backs http://bbs.homeshopmachinist.net//biggrin.gif

No you don't ram the pile,and you don't power into it either,both will kill a tranny or torque converter.Best way is to approach in low gear at half trottle with the bottom of the bucket at a 5* down angle,as soon as the edge digs in to the pile you apply power,tilt the bucket up and raise the bucket all at once,by the time the bucket is rocked up on the stops and lifted to daylight your foward motion should be stopped and the engine returned to idle,shift to reverse and back out,don't worry,after you practice 6 or 700 time you'll get the hang of it http://bbs.homeshopmachinist.net//biggrin.gif

Errol
05-24-2004, 09:58 PM
Wierdscience, you must have run a loader in your past life. Everything you have been saying on this thread is soooooo true!!! I built a miniature bulldozer in 1986 with a front end loader on it, steel pins and bushings. The undercarriage didn't last long, so upgraded to plastic type [Redco 750] bushings for much improved life. A few years later, I built a backhoe using steel pins and steel bushings. Yes, I use the Extreme Pressure grease, and yes, if you don't pay attention, the pins will break. In fact right on the pre drilled grease cross hole, just like you said. Anyhow, heres a picture of my machine in action on the side of a mountain. http://img45.photobucket.com/albums/v139/RedEyes/misc0012.jpg The footprint on my machine is 36" wide and 60" long. Still runs great with over 1000 hours on it. Anyhow, I just had to tell you wierd, that you are right on..... as to all the tips re pins and etc....

Peter S
05-24-2004, 10:42 PM
Errol,
You built that!? I'm impressed, do do have any more photos and info?

AussieChris
05-25-2004, 12:02 AM
Ian, I think I made the holes in the bushes .010" bigger than the pins. I have no idea what the clearance should be, but I had no trouble with fit after welding the bushes in place and it was a heck of a lot better than before (one pin was broke!).

Chris.

Errol
05-25-2004, 12:48 AM
Peter S, Here'a another one for ya. My daughter splitting wood back with my wood splitter just built last winter. Powered by remote hydraulics from the bulldozer. To give you an idea of size... the pads are 6" wide. total width of machine is 36". http://img45.photobucket.com/albums/v139/RedEyes/Cassie_splitting_firewood_01.jpg

wierdscience
05-25-2004, 07:06 AM
Errol,"pastlife"? http://bbs.homeshopmachinist.net//biggrin.gif Sometimes when I go out on service call to a dredge operation,I'll be sitting around with noting to do waiting on parts to show up,so I'll just help myself to a loader and load trucks while I'm waiting,that way I'm not bored while waiting http://bbs.homeshopmachinist.net//biggrin.gif

Neat job on the loader!I have been wanting to build a mini-excavator(track hoe) for awhile now,I ran a small one made by Samsung,it was only 36" wide and 48" long on the treads and had a turntable,arm and bucket just like the big ones do,the neatest things about them where they would fit through a small yard gate and becuase the digging arm was offset to one side it could dig right up to the edge of a foundation,really handy.

Thats one industrious young lady you have there,not many girls would split firewood for the oldman now a days,you must be proud.

audrey
05-25-2004, 02:17 PM
Nice Dozer. I saw a miniature one at a machine shop years ago. It had been made by a couple of older brothers and it was slick. Are there any decent plans for a mini dozer available out there somewhere? Thanx Audrey

Ian B
05-25-2004, 02:28 PM
Impressive, Errol - and to think I was worrying about making pins for one...

Thanks for the tips, Wierd, hopefully the shovel will lead a fairly easy life, shifting soil & compost. I saw the bushes you referred to in McMaster; looks like a good solution (easier than working with hardened steel bushes).

Amazing what you learn on this board...

Ian

spkrman15
05-25-2004, 04:53 PM
AH-HA!! I knew you had to be Canadian Errol! A bulldozer and a wood splitter. That says it all. Great work. I really like the table idea for the wood splitter. I personally have been thinking of building a conveyor to carry the split wood away from the splitter. Tripping over the wood as i split it really drives me up the wall. This way i could split the wood and just let it fall into the truck.

You know i really should get going on that idea......tomorrow

Rob http://bbs.homeshopmachinist.net//smile.gif

Errol
05-25-2004, 06:59 PM
spkrman15, Yes, I'm another Errol named after Errol Flynn, the movie star all our mothers were swooning over some 50 years ago.

You are the only one of hundreds who have seen my wood splitter who actually recognized this important feature. This is why I built it this way. I originally looked at dozens of ideas, but all the splitters let the pieces fall back to the ground so you end up working twice as hard as you needed to. This wood splitter has the working height table which allows you to work the wood until the right size, then into the wheelbarrow to the woodshed. The table is made of 11 gauge, actually two tables, one on each side, each hinged, and fold up vertically so the whole unit can pass thru a small gate, also small footprint for storage.

G.A. Ewen
05-25-2004, 09:32 PM
Very impressive machine Errol. I have dreamed of building a small crawler. What did you use for track chain and drive sprockets?

Arcane
05-26-2004, 01:35 AM
I came across thi s (http://www.antiquetractors.com/cgi-bin/photo_pic.cgi?pic=http;//www.antiquetractors.com/gphotos/7645.jpg&firstrec=64&lastrec=79&Parameter=cub%20cadet&mode=All&what=gphotos) while surfing one day. The little crawler is a very impressive piece of work, isn`t it?

[This message has been edited by Arcane (edited 05-26-2004).]


[This message has been edited by Arcane (edited 05-26-2004).]

Errol
05-26-2004, 01:38 AM
G.A. Ewen, The chain is standard type 81-X chain with a 2" pitch [commonly used in sawmills on "green chain" and lumber conveyer applications]. Each pad is simply a 6" length of 1/4" x 2 1/2" flat steel, which is bent in a jig, so that every one overlaps the next. The pads are then welded onto the 81-X chain. The grousers are simply a 6" length of 1/4" x 3/4" flat steel, one welded to each pad.
http://img45.photobucket.com/albums/v139/RedEyes/Misc0007.jpg
As for the drive, rather simple, just std flame cut sprockets, welded to a standard [Dodge type]taperlock hub. Hard surface (Stoody) rod to all sprocket surfaces, and reshaped with a jig in a grinder. I learned not to get "real fussy", because with all of this running in muck and dirt, the sprocket kind of "hobs" in to the right shape in a few hours.

Evan
05-26-2004, 02:17 AM
Errol,

I welded up a "table" on one side of my wood splitter also, big enough to stack several good size logs waiting to split. Very handy. I used expanded metal for for the table.

wierdscience
05-26-2004, 06:59 AM
Arcane,that is neat,shows lots of dedication,that guy must have not wanted to touch antoher piece of steel for a while when he finished that one http://bbs.homeshopmachinist.net//biggrin.gif

Errol,I hope you had a MIG gun for those tracks http://bbs.homeshopmachinist.net//biggrin.gif I wish I could find a set of the new rubber track-belts at auction,if I did I would start on that mini-excavator.

What kind of power did you put into your machine? I have been thinking of a 3cylinder Perkins diesil,lots of power and durability I think.

Errol
05-27-2004, 12:40 AM
Yes wierdscience, rubber would be a good way to go, but the tradeoff may be less pushing power, but an indefinite life on the tracks. I am on the third set of tracks now. The engine is an 18 hp kohler gas, which has been very reliable, and sips fuel at less than a gallon an hour.
http://img45.photobucket.com/albums/v139/RedEyes/rhs_bulldozer.jpg
As you can see from this photo, I built the machine as inexpensively as possible, yet to be as effective in doing work. I designed the machine in order to build narrow trails up the sides of mountains which are required for motorcycle racing.

I agree. Arcanes machine is totally a work of art by comparison. The pads on his machine aren't even scratched! They must have set it down for the photo with a crane. I notice these things, because everytime I move mine, it gouges the concrete and things everywhere.... Another good reason to go rubber....

Arcane
06-01-2004, 03:32 AM
I found another link (http://www.ihcubcadet.com/crawler100.htm) to the little crawler, if anyone is interested, and I also found this site (http://members.aol.com/pullingtractor/tips.htm) which deals with small pulling tractors and has some rebuild information specific to Kohler engines.

thistle
06-01-2004, 09:31 AM
this company advetises in hsm and mw


http://www.cadplans.com

their plans/kits are for the wheeled digger

i kind of prefer the tracked version in theposts above .

i have built 4 boats in the last 10 years maybe its time for a mini bull dozer- for those days when you cannot gofishing..........

[This message has been edited by thistle (edited 06-01-2004).]

G.A. Ewen
06-01-2004, 10:15 AM
Errol,
81-X!!!! That is lighter than I would have expected. This encourages me as I got 40' of conveyor chain last year at an auction that is heaver than 81-X.(not sure what number it is)

http://img4.photobucket.com/albums/0603/GAEWEN/698c3f05.jpg

A small crawler could be next winters project. http://bbs.homeshopmachinist.net//biggrin.gif