3RRL
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Post by 3RRL on May 10, 2010 14:20:07 GMT -5
I like Rob's stiffening braces, but don't see how they could resolve the problem of the case(s) separation. If you envision a heavy load in the bucket, say 800 lbs, the load is trying to pivot around the front axle, lifting the rear wheels off the ground (this is also true for digging & pushing with the bucket). This puts the top case screws in tension and the bottom screws in compression - just the opposite of what I'm seeing on my tractor with 0.048" gap at the bottom of the cases and ~ nothing at the top. Using the engine & gear cases on tractors for the sole structure of the tractor has been pretty much standard since the beginning of time. My guess is that a) screws were insufficiently torqued or, b) locking means such as Loctite or lock washers were not used, or c) poor quality steel fasteners are used, or d) all of the above. Also, if this were truely a design flaw pretty much all of the tractors out there would have this same problem, but it seems that only a small minority have it, which points to inconsistant quality control more than anything. In the coming weeks I intend to split the tractor & report what I find. In the meantime I am getting my new garage & house sheet rocked. Priorities, you know. Bruce Bruce, Your explanation and logic is right on. But the loader braces to the rear do, in fact, help off set the loads when lifting or digging. They are fit tight enough and set low enough so as to "aid" the top bolts. The loader tube becomes a pivot point and the braces are set below the tube. They don't allow the top bolts to "stretch" out under load because they are "pushing" the bottom of the tractor up to keep the faces of the bell housing and motor block "square" ... at least to some degree. Plus the braces help when pushing the tractor up with the bucket. They help in that see-saw motion, or rocking motion which will eventually loosen or stretch both top and bottom bolts. That motion occurs when digging if you push the bucket down while scooping, trying to fill the bucket with material or dirt. It stresses the bottom bolts. Then you lift it up which stresses the top bolts. I'm sure they offer some support to some degree (at least my humble opinion), or Koyker would not have those braces as part of their stock loader assembly. How much do they help?... I couldn't tell you that, but I'm sure they help to some degree by keeping everything more rigid and connected than without. Given the questionable materials and bolts and quality control, our Chinese tractors need all the help they can get. Rob-
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Post by Rich Waugh on May 11, 2010 8:49:47 GMT -5
I'm going to build the braces because I don't want to have to do this tractor splitting business again for a long, long time and anything that even might help avoid that is worth doing. It certainly can't hurt to have them and if they do nothing else they will help alleviate some of the problems I've had with saplings getting jammed up under the tractor in that area. :-)
The investment in steel is less than a hundred bucks and the time to fabricate, maybe three or four hours, is moderate, too. Seems like a no-brainer to me. Therefore I am eminently qualified to do it. (grin)
The same day I picked up the gaskets at the post office I also mailed out a Priority Mail package to Colorado. That thing got there literally overnight. Stuff coming to me, however, seems to mostly take eight to ten days. Rather it was the other way around. Still waiting on the replacement gaskets, naturally.
I've been running this repair through my little two-circuit brain quite a bit and I'm almost to the point where I'm not too terrified of it. That may be good or it may be bad. :-) No matter though, there isn't anyone else to do it so I'll muddle through.
I sure do appreciate all the support form you guys!
Rich
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Post by shotley on May 11, 2010 13:27:57 GMT -5
You are my teacher! I have read all the postings and can't help but think that poor bolts, washers or failure to torgue them down is the problem. I learned to drive on an H Farmall in the 50's and have driven many old tractors and a few new ones. I had an old Ford 8N for a long time. No one that I know had a tractor coming apart?? I have been looking at books and postings. What is the easiest way to seperate the front drive shaft for the split? I remeber from previous posts, do not lose the balls.
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3RRL
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Post by 3RRL on May 11, 2010 18:43:46 GMT -5
Shotley, If I were you I'd take the front drive shaft completely off. You could leave it attached to either side and only loosen one of the protecting tubes, but then you have to line it up when you slide the tractor back together. It's just another thing to line up and might interfere with the tractor going together. There is a rubber seal that covers the tube(s) which protect the front drive shaft. You have to loosen the clamps that hold it on. Then there are bolts that hold the tubes to the front differential and also to the rear driving unit. Collapse the tube to get at the retainer washer and balls. Remove them to get the shaft out. And like you said, don't lose those balls. Check the splines to see if they are OK. I don't know if you read my thread on repairing Loretta's 284 front wheel drive or not, but I had to repair the worn down splines. I ended up using short dowel pins instead of the balls for better engagement between the shaft and cup splines. It's up to you, of course, but I feel it's a sturdier engagement there. Rob-
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Post by Rich Waugh on May 11, 2010 23:31:24 GMT -5
Shottley,
Yeah, I'm quite certain that the root cause of the failure was poor workmanship and/or materials rather than geometry. So I'll be putting it back together with grade 8.8 or better bolts, same for lock washers or hard washers and I'll verify that there is at least 1-1/2 times the bolt diameter of thread engagement. I'll also be using red Loctite on the bolts and Loctite sealer on the bearing seal. Everything torqued to spec for the fasteners, too.
AND I'll be fabricating and installing the loader braces. They can't hurt and they certainly might help a lot. Hell, I'll glue a lucky rabbit's foot to the bell housing it it helps! Anything to avoid having to do this again someday.
Rich
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Post by stumppuller on May 12, 2010 0:28:50 GMT -5
OK, this is getting interesting, so let me be the devil's advocate here for a moment. Let's say you make up a frame as best you can & install it. Now we all know that the frame will not be a perfect zero-clearance fit up. All manufacturing requires some assembly & manufacturing tolerance range with precision machining being in the realm of say +/- 0.003" (machine tool work), simple weldments being say, +/- 0.040" & large scale weldments or complex weldments maybe +/- .125" or more? The point is, is that if you are going to assemble it, you will need some "slop". And the "slop" will most likey be mitigated by clamping a flange down hard with a bolt & lockwasher (over your nice thick coat of paint, no less), but the potential for movement is still there none-the-less. So the question is: Did you really make the tolerance & fit up so fine, so tight, that once all the cumulative "slop" of each & every bolt hole is taken out under high load, the case bolts will still see no load? (don't forget that in addition to the tolerancing slop, there will be material flexing & stretching as well) Even with Rob's fine machining & fabrication skills, I doubt that he has reached a state of tractor Nirvana. That flawless design might possibly come about if the sub-frame were actually made as a true floating frame with the tractor axle housing somehow only providing a thrust force (& perhaps a counter torque as well) but this is now getting to be quite an exotic design. So, should you make a stiffening frame? I don't know... if it makes you feel good about it, then do it! Now I will take off the devil horns and resume kicking my tractor. Bruce
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red
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Post by red on May 12, 2010 7:21:45 GMT -5
Good points Bruce!
Think the biggest advantage is it reduces the amount of Flex. If you watch someone else run your machine you would be amazed on how much flexing occurs. My neighbor works for the local utility and when I got my machine I explained the reasoning behind me taking it easy with the machine. He understood and told me that he's seen a new kid tear up and break a new utility BH at work.
-Ed
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Post by shotley on May 12, 2010 8:32:44 GMT -5
Stumppuller, I thought the same thing you did about the external bracing. Perhaps an adjustable slide that could be tightened down would solve it. I plan to just make sure I have good bolts in and put it back together.
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Post by Rich Waugh on May 12, 2010 11:54:53 GMT -5
Bruce, I think your reasoning is on the money. There's no way to "splint" the tractor without having close-tolerance fitments all the way. I don't think that makes the loader braces a waste of time and materials, though. While they can't relieve the stresses on the bell housing completely I think can reduce them some. Every little bit helps. And having the braces there will certainly provide a safety margin if you should stress the bell housing joint sufficiently to stretch the bolts or pull threads - might be the difference between something you can repair and something that would literally trash the block or bell housing beyond redemption. Besides, they're real macho. Not totally sexy like a bucket grapple, but way better than a cup holder. :-) So- now that you've taken all the magic out of my loader braces project what are you planning on de-bunking next? Gonna tell me there's no Easter Bunny or that Dolly Parton is really a guy? Rich - who has no illusions left
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3RRL
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Post by 3RRL on May 12, 2010 13:38:57 GMT -5
Bruce, I give... My statements repeatedly said, they will "aid" and help "to some degree" because they add "more" rigidity than without, "IMHO", etc...etc. I was hoping to make that part clear. Never did I say they take "all" the stress away and are the answer to all problems.
There is a given amount of flex and stress the tractor makes, depending on what it's doing. So when you steal some of that "given amount", it has to go somewhere else. The idea is to "transfer" some of the flex and stress from one point to another "to some degree" (not ALL of it). Preferably, to one that can withstand the stress more than where it's at right now. Or at least to one that is more desirable ... one that can be easily repaired or maintained or is more accessible or will have less impact which otherwise leads to a major repair. Or in this case, to one that is designed to "aid" in relieving the stress. My opinion is that the support brackets do just that (to some degree, of course, and not 100%). They "aid" by absorbing some of the stress and flex loads the tractor sees. By doing so, they relieve the other bolted up connections of "some" stress. Which without them, would normally see 100% of the stress. So I stand by what I wrote. Rob-
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Post by Rich Waugh on May 12, 2010 17:30:32 GMT -5
Thanks, Rob. I feel a little better now. Still a bit shaken, but now I think I can rise above it and carry on. As long as I don't find out Dolly is a guy...
I'm in favor of any and all reinforcement that can be done to offset the possible consequences of soft steel, brittle castings and weak fasteners, to say nothing of marginal engineering in some areas. Loader braces are one way, counterweights are another, replacing weak parts where feasible, etc. I plan to do all of them that I can.
When I first got the tractor I figured that my uses of it would be so far below the design limits that I couldn't possibly hurt it. I know better now. I'll beef it up where I can and back off on the forces where I can't beef it up. And hope a lot.
All of the give and take here is really valuable to help me clarify my thinking and bring out aspects of things I might not otherwise see. That's a good thing, I think. With any luck I might have actually learned something in a year or two more. :-)
Thanks to everyone!
Rich
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Post by stumppuller on May 12, 2010 22:22:35 GMT -5
Hmmm.... I don't mean to rain on anybody's parade, just offering my perspective as some one who has to fix a problem. Since the cases have separated, the bolts are at fault (under torqued, crappy steel, no anti-vibration locking...whatever). I'm not so sure about flexing of the cast iron frame - meaning the gearcases, engine block & bell housing. Cast iron has very limited elasticity. When loaded in tension it fractures rather stretches, unlike worked steel products. I'm aware of only one failed cracked bell housing.
My reasoning is this: If the castings are underdesigned then just about all the Jinma 284's should be failing, but I don't think this is the case. Only a few "lucky" ones are. And when I look at all the other inconsistant quality issues we have ie: electrical, leaks loose bolts, missing parts, etc. I begin to see a pattern. It's not hard to imagine that they screwed up assembing the bellhousing & no one caught it because no one was looking for any problems.
I don't have the equipment, time, skill or energy to make subframes, so I will be investing in cleaning & examining the failed parts. Determine what went wrong & replace the failed items with higher quality, properly torqued / adjusted parts.
Rob, I'll be using your excellent documentation as my tear-down guide. Thanks for all your inputs.
Bruce
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Post by Rich Waugh on May 13, 2010 1:59:55 GMT -5
Bruce,
I didn't read what you said as raining on anyone's parade at all - I thought you made some very logical points. I also think Rob has a good point that the braces can certainly help the tractor to resist stresses in that critical area.
At the outset of all this I was pretty sure that the issue was poor workmanship and/or poor fasteners, and I still think that's the most likely cause. The bell housing casting on my 304 is way beefier than the ones on the 200 series tractors and I sincerely doubt it could be cracked, though I suppose it is a remote possibility. I talking with my brother tonight he mentioned one other possibility that hadn't previously occurred to me, that of the bell housing having warped. I know with some castings that they need to be "seasoned" before being put into service so they can equalize/relieve stresses built up during the cooling after casting, but the more I thought about it I don't think this is likely in this case. I don't think Jinma does their own casting in-house and that bell housing shape is not one that would be prone to stress warping. Nope, I think the most likely culprit is fasteners of low quality that were not properly torqued or with insufficient thread engagement (somebody using ones that were too short because they ran out of the right ones). The gasket couldn't reasonably have failed because there's no pressure to speak of in that sump area.
Since I have all the goodies to make the braces and that's the sort of stuff I do for a living, I'll go ahead and make them. If I couldn't do that I doubt that I'd lose a lot of sleep over it, but I know I'll feel better with them on there. Especially when I'm working the loader pretty hard which I plan to do when I start clearing my new land.
I'll do my best to examine everything very closely and take as clear pictures as I can to illustrate my findings when I open this thing up. I'm hoping there will be some fairly obvious indications of the root cause of the leak so we can get some solid facts to work from. I do think that what I see is going to verify just what we're all thinking, though. I'm not expecting any big surprises, nor do I really want any!
I just really hope I don't find out Dolly is actually a guy... :-)
Rich
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Post by stumppuller on May 13, 2010 22:50:05 GMT -5
Rich - There's that Dolly again. I was also thinking of getting a dolly for this project. Harbor, Northern, Kragen & others sell a hydraulic motorcycle lift that is kind of a cradle affair which looks as though it would fit nicely under the gearcase or engine block to support it during separation & realignment. She costs around $100 & has about 1,000 lb capacity. That's a lot of bang for the buck!
Bruce
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3RRL
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Post by 3RRL on May 13, 2010 23:05:22 GMT -5
Those Dollies would work good for splitting the tractor. Probably better than the (2) floor jacks that I used. Fortunately, they were able to roll nicely and didn't come off the tractor halves. If those dollies could cradle the halves better, holding alignment better, then sliding the tractor back together would be much easier.
Don't forget to block up the front axle, or the front part will swivel over and perhaps fall off the jacks or dollies. Also, make or buy a pilot bearing tool for re-assembly. Have lots of empty containers to drain out fluids resulting from having to disconnect lines for the split. Also check the condition of your clutch and see if the throw out bearing is in good shape and greased...and the fingers. It would be a good time to set the clutch pack. I've split my tractor several times now, so if there are any particular questions, I might be able to help. Rob-
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