Add More Bucket Curl to Jinma 284

   #1  

3RRL

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I've got a problem with how little Loretta's Jinma284 bucket curls.
When she scoops up dirt or material, a lot of it tends to fall out of her bucket because the bucket does not curl back far enough to make sure it stays in there. Especially when carrying the load low, the material tends to sift out as she makes her way to the dump area. I've read where several other 284 owners have written about the same thing, so I decided to look at what to do about it. My solution is to move the hydraulic cylinder mounts to achieve this goal.

Anyway, here's the problem...not enough bucket curl. You can see the bottom of the bucket is almost flat in the full curl position. As a reference, the Koyker fel and bucket on my Kama curls up at least 30 degrees or more and allows me to carry a heaping bucket full. So I took her bucket off the QA mount to see what (how much) curl to strive for. You can see in the third photo how the back of the bucket should angle vs the first and second photos.
The last photo is the full dump on her 284. That amount of dump is a good thing for dumping at or near full height, but it also represents another problem that I came across.

 
  
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3RRL

3RRL

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When I had the bucket in full curl and dump position, I was trying to visualize where the new cylinder mounting points should be to give her more curl, but still a lot of dump. Looking closely at the full dump position, I came to the conclusion that the Chinese engineers screwed up when they added the QA feature.

First, I noticed in the photos below that the cylinder body was touching the fel arm at full dump. That's bad, but not nearly as bad as the next photos that clearly show the cylinder rod to have a pretty good bend in them now. Crap!
Are any of you guys having the same experience with the new 284's?
Take a look at these...



I looked at the Koyker again to see what their set up was like and noticed they have welded stops that determine maximum bucket curl AND dump. The Jinma loader does NOT. This is a big deal because when I took the cylinder off to straighten the rod, I extended it first to check the over all travel of the cylinder. Man, it is like 4" greater than the mounting points allow. The mounting points from full curl to full dump were 18-1/2" apart, and the cylinder extended 22-1/2". I was not used to this because I set all my cylinder strokes to bottom out in either direction.

I did notice that the Koyker cylinders were not completely sucked back in full curl though. So maybe this is common practice for loader cylinders ... to have have more stroke than needed. But the kicker is the Koyker has a positive metal stop to limit the curl and dump, and the Jinma does not. So that means the cylinder wants to keep extending thus exaggerating the problem. They are lucky the rod did not bend more due to that! If the cylinder kept extending to full length, there would be a good 3" bend in the rod and they would be scrap. This may also be the reason some of us have cylinder leaks down there due to the stress on the seals.

Here is a photo of the cylinder completely extended.
See how far past it is, compared to the mounting hole in the QA? The hole is where the little welded bar is on the plate.

 
  
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3RRL

3RRL

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Well right off, this became another problem I wanted to correct.
That is to put the QA mounting hole high enough to miss the FEL arm at full extension. One mistake I made after seeing that problem was trying to do it all "on the fly" while up at camp last week... to get both more curl and NO interference with the FEL arm. My goal was to do as little sawing as I had to (being at camp) and also to save the holes in the sawed off sections and re-use them.

In hindsight, I should have drawn it out on CAD first (at home) to get the best solution ... that is to get more curl without losing too much dump movement AND miss the FEL arm. I could have "moved" the hydraulic cylinder mounting points around a lot easier in CAD and come up with a solution offering both. But I wanted to get started while up there, so I did do some alteration to her tractor. Not 100% sure it will work out, but when I got home I drew it up pretty much to what I had done at camp, it looks like it will be OK after all. We'll see next visit up?

Anyway, I had to deal with the problem of the bent cylinders right now.
So I took the little Nylon retainer rings off QA mounting hole. Then I flipped the cylinder rod by turning it so the bend was in the opposite direction.
You can clearly see the bend in the rod going up now.



I figured if the bad design was enough to bend the rod in the first place, I could use that same flaw to straighten out the rod.
I used a piece of rebar and also a pipe to get the rods back pretty straight. I know it's not rocket science, but it worked. Might not have been the best thing for those poor cylinders, but hey, they were already screwed, so I didn't really care. They actually came out very straight by applying the dump carefully several times until I got both of them pretty straight.

 
  
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3RRL

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Now to show you what I did so far.
In addition to the problems of getting more curl, trying to keep as much dump as possible AND not bending the cylinders again, I had to keep in mind that the new mounting location on the QA also has to miss the big QA hooks on the back of the bucket too. I had to be sure there was enough room for them to go over the tube but not interfere with the cylinder end.
So I scribed out a bunch of lines trying to visualize what to do. I wanted to move the new holes up, away from the FEL arm enough to accomplish all that. So I picked a spot where I thought the new hole location should be. My scribe lines for the cut out part had to match so when I took the cut off parts and welded them onto the QA plate, they would be in that new location.
Notice the angle saw cut I picked out too.



After about 3 hours of sawing with the Harbor Freight hand held bandsaw and a Saws All and a hack saw, I was able to check the amount of added curl. As you saw in the first photo, the QA was facing sort of forward, not straight up.
Here you can see even with the cylinder removed, the QA plate hit the torque tube and sawing where I did gave me enough clearance where the QA is now past vertical.
That should give me the 30 degrees of curl or more I'm looking for. (I hope)
Notice also that the lower QA torque tube is a natural stop against the FEL arm. I will weld an added stop there to be sure.

 
  
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3RRL

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Another thing I wanted was to keep the little welded pieces which key the pins towards the outside.
That is the reason for that angled saw cut in the above photos. I figured I could swap the sawed off pieces from the left QA over to the right side and get the holes where I wanted and also still have the welded key locators on the outside. Realizing I had 4 extra inches to work with, I also set the cylinders about 1-1/2" from being completely sucked up, much like on the Koyker set up. The QA holes are far enough from the FEL arm to not interfere in both curl and dump positions now. I figure there is also a slight mechanical advantage from this new position resulting in a little more curl and dump force, but that remains to be seen.
Here's what all that looks like welded up now.

 
  
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3RRL

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The last part I got done before going home was to saw off the top cylinder connections and relocate them to suite.
What I did there was cut them off and swap the rights for lefts like on the QA, and flipped them so the pivot is at the top of the arm instead of below. I will have to space them enough so as not to interfere with the bodies of the cylinders since the pivot is narrower than the body. But that is no big deal.
I also have to choose how far up the FEL arm to weld them. This will be determined on how much dump I get. If I don't get enough dump, I have that 1-1/2" to suck up in the cylinder and move them lower, allowing for more dump at full extension that way, or I might have to lower the QA holes a bit. That remains to be seen. I will tack weld them in place and try it with the bucket on first. Also, those pieces that stick out I will saw off if Loretta wants me too, but she said they look pretty cool like that.:)
Anyway, that's all I got done so far.

 
   #7  

Eagleview

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It's hard believe but it seems everything you buy these days has to be modified just to make it do what it was supposed to be able to do in the first place . I dont know how many times ive had to do simillar to what you have just done . Your obviously very handy with your hands . Just one thing , and you have probably allready checked it , is the angle of the bucket at full lift . It's probably where it was supposed to be in the first place but may not be the case and something could roll over the back and onto the bonnet . I'm having trouble trying to imagine how they could screw up that bad . Is it possible that the hose bracket was welded onto the wrong cross tube and the hitch is upside down ?
 
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RedDirt

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Rob, you are simply amazing. I'd no more attempt a 3-fix-at-once modification with out the benefit of a full CAD study than volunteer to raise a teenager. Did you do any measured drawings or mock-ups? Or just use rough sketches? Hope it works out well. Looks great so far.

I too am disappointed in the amount of curl of my BX. If I get to doing a QA next build season I'll address it then.
 
  
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Iron Horse said:
It's hard believe but it seems everything you buy these days has to be modified just to make it do what it was supposed to be able to do in the first place . I dont know how many times ive had to do simillar to what you have just done . Your obviously very handy with your hands . Just one thing , and you have probably allready checked it , is the angle of the bucket at full lift . It's probably where it was supposed to be in the first place but may not be the case and something could roll over the back and onto the bonnet . I'm having trouble trying to imagine how they could screw up that bad . Is it possible that the hose bracket was welded onto the wrong cross tube and the hitch is upside down ?
You know, I can't believe it either.
My Kama does not have any "engineered" problems like that. Yes, I planned on fixing some stuff because perhaps of inferior quality or poor quality control, which could be reflected by the cheaper price I paid for a Chinese tractor, but not a bad engineering job like this. The QA is not upside down because the big "hooks" on the bucket would not go over the other cross tube. Where they fit it is necked down to accommodate the hook size. And I made and welded the hose bracket on myself when I installed her home made grapple, so it is not factory.

The big problem (I'm guessing) is 1) there is no positive stop for maximum dump or curl thus allowing the cylinder to keep extending even after the rod hits the FEL arm ... resulting in the bend. 2) They did not take into consideration the loss of curl when they designed the QA. I was looking at it and IF the bucket were mounted directly to the FEL arm points (like my Koyker without QA), then it would have plenty of curl. I think they overlooked it on both ends.

Also, thanks for the tip about the high lift. I've instructed my wife to use the dump while lifting high to avoid roll back and she is aware of it. Plus she has the grapple attached which (sort of) acts like a guard. But nevertheless, it was worthy mentioning it and I appreciate it. And yes, I'm lucky to be sort of handy with my hands.
 
  
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3RRL

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RedDirt said:
Rob, you are simply amazing. I'd no more attempt a 3-fix-at-once modification with out the benefit of a full CAD study than volunteer to raise a teenager. Did you do any measured drawings or mock-ups? Or just use rough sketches? Hope it works out well. Looks great so far.

I too am disappointed in the amount of curl of my BX. If I get to doing a QA next build season I'll address it then.
Thanks Ray,
Like I said in one of the posts above, I should have measured and made a CAD drawing first, but lol ... it looked like what I was doing would work. When I got home the sketch I did was only guessing at the dimensions of where the pivot points are. Since I didn't take any dimensions, I did it only to see how bad I screwed up, but it is not definitive enough to tell. It looks OK just from the non-OK sketch though.:D hahaha.
The only way is to tack weld the upper cylinder connections and try out the curl and dump. If I am WAY off, I will measure everything and draw it up at home.
lol ... Backwards, huh? Then go up to fix it proper. I'll post back in a week or so, depending when we go up again.
Thanks for checking this thread out.
 
 
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