I know this is an old post, but it's only on the second page of this section, and I thought it might be interesting to some of you if I posted what I've done. Out of laziness, this is copy and pasted from another forum. Because of one of my citations, you should be able to find it if you look, but I'm not trying to plug another forum.
It's copied verbatim, so the audience is slightly different. As reference: A YM2000 is a 20 PTO horsepower 2 wheel drive gray market tractor. The American version is the YM240, different only, in the American version, a 2 speed rather than 3 speed PTO with overrunning clutch, and a reversed throttle linkage.
A couple weeks ago, my girlfriend succumbed to my recent spate of tractor activity, and learned to drive some of my equipment. She really enjoyed it, and has been wanting to grow a "BIIIIIIIIG garden." After she looked some, she now has a YM2000 to do her gardening with! It's all hers, and I'm really proud of her. I think it's kind of redundant, given my plethora of tractors at the moment, but I am NOT going to argue!
The tractor was apparently used at a nursery to pull carts between their rows of plants and do general service/grading type work. It was VERY narrow. A quick test with my smallest disk harrow yielded acceptable results, but it felt really unstable for a new, inexperienced operator, particularly without any ROPS. I wanted to be able to pull my larger disk, though, but it is set up for my larger tractor and is fairly tall on the attachment points for the lower links.
I reversed the rims, and set them out to their widest, which worked much better, but the narrow rice tires combined with the geometry of the disk's 3 point attachment tended to hold the rear end up, and it would easily get stuck, slowly churning holes in the ground, especially when combined with delayed application of the differential lock, and tardy lifting of the implement when the tractor started to slip excessively. (Again, primarily operator inexperience on her part.)
While the correct solution would probably be to replace or revise the attachment points of the disk, and, especially, more thoroughly train the operator, that seemed like a rather boring solution to the problem. I scrounged around a bit, and found some Schedule 80 pipe and 1/4 inch plate. The other addition to this tale is that the girlfriend didn't just get a YM2000. She also ended up with this:
It's a Mitsubishi D1800. (It used to have ag tires on it, but we're getting to that part.) Before all this occurred, I was looking for ag tires or R4 tires for my loader-equipped YM240. I happened to find a set of R4 tires, brand new and never mounted, on (I was told) Kubota rims with a 6 on 6 inch bolt pattern, which won't match my YM240. They do, however, match this Mitsubishi. I had the tire shop swap the R4s for my turf tires on their respective rims, and mounted them up to each tractor. Now I had a spare set of rice tires that were only a tiny bit shorter than those on the girlfriend's YM2000. (Everybody thoroughly confused yet?)
I cut a set of four round plates from the steel plate, and drilled holes to mount to the Mitsubishi pattern wheels in two, and the Yanmar rims in two. Then I cut the tubing, trued it up, and welded them together to get a pair of these:
Sorry for the crummy picture, all I had until this evening was my cell phone for photographs.
After re-reversing the Yanmar wheels to their narrowest setting, I put the spool over the wheel and tightened it up with some longer bolts. Then, I put the Mitsubishi wheels onto the spool, at their widest setting. After it some grunting and a couple trips to the hardware store for fasteners, it looks something like this:
The overall width is just under 64 inches outside to outside. My YM240 (The same tractor) with factory Yanmar turf rims is just under 60 inches. Yanmar originally made this same sort of thing:
(Robbed from California, who cites the optional equipment portion of the operation manual, here:
http://www.tractorbynet.com/forums/y...-narrow-2.html)
When it's all said and done, the outer duals sit up from the ground about 3/4 of an inch on pavement, so there is no additional stress on the axle shafts or bearings whatsoever on hard surfaces. In soft terrain, when tire slippage is an issue, the major force they add is forward as tractive effort.
I don't see any major risks to the tractor's longevity or durability, or, especially, safety. In soft ground situations where they only deliver torque, the tractor is operating with no more load than it would in high-traction situations. Even in soft soil, the additional bending moment of the wider wheels must be virtually negligible anyway, and, besides, the tractor was originally engineered to handle dual rear wheels.
This setup will only reduce the force the tractor would see compared to that. Safety wise, the tractor is wider. That makes it less tippy. This setup isn't as stable as it would be if the tires on the outside were in contact with the pavement, but it's not as bad as the wheels at their narrow setting alone.
The failure mode of this apparatus compared to the regular tractor without duals would be to lose the outer wheel(s). The spool is bolted to the hub over the original wheel, so whatever happens, the inner wheel will stay put. Breakage of the inside wheel, or the hub would/will occur, but with no greater likelihood than without the duals, since realistically speaking there is no more force than in the original engineering specification, and, in fact, this design actually would be less than designed for.
Even so, a disclaimer: Please, please, please, nobody look at this project and decide that since some stranger on the internet did this to their tractor it must be a good idea for you to do the same. This has not been engineered beyond literally scratching soapstone onto concrete and mulling in my head. I am a competent weldor, and this will not break my tractor. I have no idea about you, or your abilities or tractor's capabilities. I used what I did because that's what I had. That is not how you should do it. If you need some stranger's advice on how to do something that puts yourself and others in jeopardy, you shouldn't try to do this yourself. If the factory didn't think it's something you should do, you ought not do it.
I'm interested to see how much better it works. I ran out of daylight before testing it out, but I had a really productive and fun afternoon, since I also built a three point adapter for a two point tiller I picked up a few days ago. Here is a shot from the front:
I need to turn out the front wheels to make it look a little more balanced. I still can't decide if it looks cool, or stupid with the duals on. The ultimate test of that will come in the morning, when SHE takes a look at what has happened to her baby.... Is anyone interested in a Mitsubishi D1800 on turf tires? It's a nice driving little tractor.
Since those pictures have been taken, I've revised the mounts on the little disk