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Bearings in tail wheel of bush hog

Richard Rogers

Titanium
Joined
Nov 27, 2001
Location
Bentley, Louisiana
Or "brush hog" to you fellows up north. Anyhow, the rear castor on a bush hog has always been difficult, for me at least, to keep bearings in. The shaking and beating back there just gets them. If you've owned one of these mowers, you are aware of what I mean. On the last one I had, I put heavy bronze bushings, and I was pretty happy with that. Didn't keep it long enough (for reasons I won't get into) to decide if I would do that again, so I didn't get to see the bronze bushing experiment through.

This brings us up to date. I am building a 7 foot bush hog for a 55 hp tractor. This is mine I'll be using myself. I have the gearbox coming, I've made a category II three point hitch, and now I'm making a hub for the castor, into which bearings will go. What is a sensible way to do the bearings that will last? I haven't ruled out the heavy bronze bushings this go-around, but if someone can tell me something I would really like for an idea, I still can change it at this point. Also, what size axle would be good to have in this castor? Heck, anything else for a tip is appreciated too. I'm building my own because all the factory ones I see are very expensive, and are light, at least in my eyes.

I expect to be finished with this project in a few weeks, so I will try to post pics when I'm done. I work on this one after hours, and catch-as-catch can. Been kind of fun so far. The hitch turned out beautifully.

Thank you, and have a good weekend.

Richard
 
have you tried plastic?(you must be talking about a crazy wheel that pivots and keeps the blades out of the dirt.)

just like in a rod weeder wheel, you never grease it and will outlast bronze running dry in the dirt all day.

more farmers have found out that for some jobs plastic saves them time and money.
 
I was thinking plastic also. Be sure to provide as much bearing contact area as you can so loading is light. This means a generous shaft diameter as well as width. It is low speed so it probably could be effectively sealed with O-rings. O-rings of a lubricated material if you want to get fancy. Or no seals at all if dirt intrusion is not a big issue. Use a SS shaft and away you go. I am thinking of graphite filled Nylon or Polyethylene (UHMW) for the bushings.

Randy
 
IMHO plastic is not going to hold up for any length of time.Just look at the plastic bushings on riding mower wheels.A couple of years back I replaced the whole assembly on a 7' bush hog.I used the spindle of a truck as the pivot and used tapered roller bearings to match the spindle.Capped it off with seals top and bottom and put two grease fittings on it top and bottom.The guy who owns it is still amazed to this day.Hasn't had a problem with it since I did it and he's brought me more work,as a result,than I really want.Why want folks let me retire.I supposed to be.
 
I was thinking plastic also. Be sure to provide as much bearing contact area as you can so loading is light. This means a generous shaft diameter as well as width. It is low speed so it probably could be effectively sealed with O-rings. O-rings of a lubricated material if you want to get fancy. Or no seals at all if dirt intrusion is not a big issue. Use a SS shaft and away you go. I am thinking of graphite filled Nylon or Polyethylene (UHMW) for the bushings
-------------------------------------------------

no seals no grease at all, plastic(the right grade) will last twice as long, if you add grease all you get is dirty.

farmers have gotten smart and save money, the hired help wont grease anything unless you babysit them.
you know I live in dry land farming area in eastern washington and the use of plastic works very well.

I make plastic thrust washers for no till drills that have a tounge that puts 20,000 lbs downforce and they last a season.

plastic works great on on things that are neglected, when wore out you knock the bushing out and pound in a new one and for $10 it is good as new.
 
Richard, there's two choices for this application. One will last, but the other one is just about perfect. Aluminum bronze is amazingly tough in impact type situations. I've got a set of guides I made from aluminum bronze running in one of the largest jaw crushers in the US right now that have outlasted the original 660 bronze ones by a factor of 7 to 1 and they still show no significant signs of wear. However, the ultimate bearing for this would be Garmax, made by Garlock. It's a steel backed bushing with a reinforced self lubricating matrix of some kind of polymer stuff, and is specifically designed for impact loading.

Ditch Witch has used Garmax bearings in all the pivot points on their trenchers, etc for years, and if you take a look at the next Ditch Witch you happen to see, there are NO grease fittings. Their pivot points will outlast the typical bronze bushed greasable ones by several times over.

When I was at Michelin, we had problems with large bronze bushed shafts which mounted heavy truck tires for machine testing on roadwheels with "bumps" made from attaching half sections of 3" round stock to the roadwheel. Tire loads ranged up to 6000kg (13,200 lbs) and speeds up to 60 mph. We continuously were making new bushings and dragging lube grooves into them. We decided to try the Garmax for its impact properties, and found it would outlast 660 bronze by roughly 10 to 1 in our application.

These bushings are available in common sizes to interchange with many other standard diameter and wall thickness bushings, and while they do cost more, in an application like this they're by far the cheapest solution in the long term.
 
I this application that is no speed to talk about. What you are looking for is stability, wear resistance and shock capability. Chilled iron bearing will work well in this situation on a hardened shaft. We used them in screw conveyors moving very abrasive material and they held up very well.

Hope this helps.

Joe
 
Ray has it. The one's that last have "wheel bearings" with grease seals. Just like an automotive front axle. Standard 1" trailer axle bearings and matching grease seals will out last your deck. A slight preload is ok since there's hardly any rotational speed.
 
I have a Ford 910 mower that's been sorely abused for over 35 years, nearly everything else on it has been rebuilt or replaced, and the tail wheel is still as good as new. It has tapered timken bearings in it and lip seals, gets greased once a year. The pounding it gets is incredible, I thought it would be the first thing to go.

I think the Garlock bushings would be the next best choice, and easier to install.
 
A home built 7" bush hog will likely be so heavy you will need a heavy built caster. I would use tapered brg's or ones for a frontwheel drive car that are sealed on both sides. No adjustment needed just a press fit. You will probably need some weights for the front of the tractor also.
 
Gawd, what a lot of old school answers. Plastic will out-last metal bearings 10/1 in low-load low-speed applications if designed accordingly. Add a grease fitting if you want just so you can purge dirt and water. No other reason for this. Also allow generous surface contact so specific loads are low. This is important! If your yard tractor eats plastic wheel bearings it is not the plastic that is at fault (probably), it is inadequate bearing surface contact that chews them up. Timkins?? Bronze?? Chilled iron?? Sheese. Build a lathe with these.

Randy
 
I left right after posting last night, and got back to computer this next morning. Thanks for all the answers.

The comment about a home-built 7' bush hog being heavy is probably right. I have a very heavy duty tail wheel I found laying at a friend's place. It's twice the size of my present 6' hog's tail wheel. I have a pretty heavy Allis Chalmers D17 diesel tractor and I do hope I wouldn't need front weights, but if that's what it takes......

Tattoomike's kinda right about farm work. Let me tell you my experience growing up around my father's medium sized sawmill. Slow turning heavily loaded bearings that experienced shock were always much more prone to going out than higher speed bearings with equalized loads. I was taught this early, and it's been the case in all my first hand experiences. I think I'll be dealing with it on this project.

While all the ideas are appreciated, and each has its own merit, I am inclined toward that Garmax stuff metlmuncher mentioned. I'll do some checking up on it before I decide. It's been my experience (which in no way encompasses the whole world!) that timken tapered roller bearings used for this kind of job want to spread out and apart once any slack develops. I know, I know, if you keep them adjusted.....but I'm really going to be whipping this thing's ass out there mowing uneven terrain, bushes, shrub, snakes, armadillos, unseen stumps, you name it, and that's what gets the bearings.

If I were doing pretty even terrain, I'd probably go Timken, but I've been there before. I can always machine the hub later and go with them, so it's not a bridge I'm burning anyhow. Next would be plastic, but again, the shock I'm talking about would make short work of UHMW, expecially after the inevitable play develops between the axle and busing, allowing a stroke for the hammering effect, which would get bigger quick once the slack developed.

I'm going heavy, but not ridiculous, but still a 7 foot bush hog ain't gonna be light.

By the way, what about the "chain" design I've seen? Instead of rigid braces going from the 3-point hitch back to the deck frame, I've seen chains that allow the bush hog to flex and follow you if you go down into a ditch or hole. I've even seen chain used for the top link from 3-point to tractor. Good design? Drawbacks? Pluses?

Thanks for the input very much.

Richard
 
tattoomike68.you're probably right,many of us don't have a clue about farm work.Who ever said that bush hogs where resticted to the farm.You see them along the roadways,on golf courses,just about anywhere a large area needs to be mowed quickly.They aren't efficient but they get the job done.The tail wheel on these things is only one of their weaknesses but IMHO it's the most previlent.Anyone trying to improve on it could make a million bucks if they come up with a pat solution.Maybe Richard will.I certainly hope so.Then I can retire.We at PM may not have clue to farm work but we have an idea about machine work.GET IT? Bush Hog=machine.
 
Richard,
I think your D-17 will handle the weight fine unless you build the deck out of 1/2" plate ;)

You definitely want some float in the 3pt. mast, but I question using chain, in case of a freak accident like catching the front of the mower on a stump and summersualting the mower forward and wrecking your driveline, or you if you dont have a ROPS on the tractor. We have a Woods mower that uses a hinged 3pt. mast with a strut attached to the deck via a swinging link to limit travel.

Scott
 
Scott,

Can you post a link maybe to a mower like you're talking about? I agree, that D17 Allis is a good heavy tractor. Gotta adjust its valve lash next week. Great motors they made. Don't worry, the deck won't be 1/2" (but I may wish it was!) One thing I'm leaning toward doing is making the deck in sections, with the body framed out of suitable angle iron. That way, rust, dents, holes, whatever can be remedied by changing the panel in question. Just finished the hub maybe 30 minutes ago. Probably do some more Monday night. Again, catch-as-catch can on this project. The grass around here is about quit growing anyway, so if I am building it faster than it comes back, I'm okay.


This whole project is driven by the fact that since I was 12, the bush hogs I've run are all pieces of shit. I'm making one that is the way I'd "like" one to be. I'm almost 36 now, so the wait is, I hope, over.

Richard
 
I have/ had a chain on a Woods 8' that goes to the top link, not a replacement for it, it bolts to one of the holes under the link. The only thing I find it handy for is repeat seatings of the height.
 
I think a slotted top link is the way to go....give you some float but enough to pick the thing up.

I too have heard all the stories of bush hogs coming over backwards. Not sure if they are ole wives' tales or not but it sure makes you think.

I cut a 40 acre field about 4 times in my high school summer jobs. I really miss the powerful smell of that fresh cut grass and the purple martins zig-zagging in back of the tractor's "wake" to maximize on bug intake.

-Matt
 
I don't understand what you mean, Matt, about a bush hog coming over backwards. Sounds pretty nasty! How's it reputed to happen?

I also wonder one other thing. On this machine with an 84" cutting circle, would overall width of deck from side to side and all around underneath of say 90" give me enough clearance? 3" per side? Sounds good to me, but asking since I can take advantage of whatever info I could to avoid a mistake. That's what this board can be so good for. I've put chains on the inlet/outlets before to keep from throwing missiles at everyone. Anything to tell me about that that common sense wouldn't? (except that I need to keep them short enough the blades can't strike them. Nah, never made that mistake :D )

Thanks again,

Richard
 








 
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