Jinma 284, bent left side lifting cylinder.

[BobbieNicole]

Pictured below is the rod from my left side lift cylinder. On top of that, this is the third time I've done this, and I am not aware it happens until I try to lift the FEL. I was extending pretty high to dump a load of branches and tree debris on to a high pile. As all hydraulic actions on this machine tend to be a bit jerky, maybe curling the FEL down caused it to go out of alignment and lowering it just slowly bends it. Always on the left side. On the plus side, I've now replaced all the original cylinders (lift and curl) with aftermarket ones (about $220 ea), so it won't hurt so bad if it happens again.

Any ideas?

 

[piper184]

Do you still have the original bolt on bucket?

I replaced mine with a quick attach setup, but I didn't install a torsion bar between the two sides. When I would change attachments, I noticed that the left side moved slower than the right side. This was a pain when hooking up as the two sides were always out of phase. So I welded in a torsion bar. It was the best piece of square tubing I had on hand. It was not sufficient and I twisted the tube. Then I had another problem to deal with in the dead of winter. I used a hack saw and cut out the tube. Now I am back to the issue of the two sides being out of phase.

I think that this contributed to the twisting of the tube and I won't bother replacing it until I figure out what is going on. My current working theory is that the left cylinder is farther away from the control valve and the internal friction/restrictions of the fluid flow caused the left to move slower.

Following this line of thinking, it would seem that you have some sort of similar problem. Perhaps some kind of restriction in one of the hoses or pipes between the right side and the left. The right side is retracting faster than the left and is putting undue pressure on the rod, causing it to bend.

Or, perhaps there is something else out alignment on the left side which causes the left cylinder to bind while retracting. Perhaps the loader frame itself is twisted or one of the mounting points is out of alignment.

Since this has happened multiple times, I would start with a flow test at each cylinder. Maybe just take all the lines loose at all the fittings and blow them out with air. Not definitive but may lead to a clue.

Also block up the loader on the stands and figure out a way to check the alignment of all the pivot points.

If you put the tractor on a flat surface and lower the bucket, do both sides make contact with the ground at the same time?

 

[piper184]

PS. Please post info on the after market cylinders you are using.

 

[BobbieNicole]

Do you still have the original bolt on bucket?

I replaced mine with a quick attach setup, but I didn't install a torsion bar between the two sides. When I would change attachments, I noticed that the left side moved slower than the right side. This was a pain when hooking up as the two sides were always out of phase. So I welded in a torsion bar. It was the best piece of square tubing I had on hand. It was not sufficient and I twisted the tube. Then I had another problem to deal with in the dead of winter. I used a hack saw and cut out the tube. Now I am back to the issue of the two sides being out of phase.

I think that this contributed to the twisting of the tube and I won't bother replacing it until I figure out what is going on. My current working theory is that the left cylinder is farther away from the control valve and the internal friction/restrictions of the fluid flow caused the left to move slower.

Following this line of thinking, it would seem that you have some sort of similar problem. Perhaps some kind of restriction in one of the hoses or pipes between the right side and the left. The right side is retracting faster than the left and is putting undue pressure on the rod, causing it to bend.

Or, perhaps there is something else out alignment on the left side which causes the left cylinder to bind while retracting. Perhaps the loader frame itself is twisted or one of the mounting points is out of alignment.

Since this has happened multiple times, I would start with a flow test at each cylinder. Maybe just take all the lines loose at all the fittings and blow them out with air. Not definitive but may lead to a clue.

Also block up the loader on the stands and figure out a way to check the alignment of all the pivot points.

If you put the tractor on a flat surface and lower the bucket, do both sides make contact with the ground at the same time?

I am thinking along the same lines, the FEL does look a bit wonky. I did think to get it on a level surface to check height on either side. Also, the hood doesn't close without banging it past a bar on the FEL. It does have the skid stir attachment which changed the geometry enough that at full curl it will bend the curl cylinders over the frame. I used a "field fix" to keep going the first time but eventually replaced those cylinders with a pair from Surplus Center--I then used the take outs as lift cylinder replacements (maybe a contributing factor to their later failure).

The original lift and curl cylinders were identical, but I went with a shorter (20") cylinder for the curl and a 24" cylinder for the lift which was a closer match. The tang is shorter on the replacements, so I added 4 fender washers to fill the gusset. Also needed to replace the mount bolt to 3/4", fortunately they're slightly smaller so fit without drilling. I have come across specs that call out the original cylinders as 2" bore, but while the outer diameter of the cylinder is 2" the inner is 1.5" so I went with that. I've posted an image of the receipts, you can see my hose shop (which is damn good) couldn't adapt the fittings without making new hoses, but now that they have all been replaced, if this failure is persistent at least it will be a quick, $250 job.

 

[zzvyb6]

Chinese steel from same junk that the rebar came from that failed in the Bangkok State building collapse. It's called "tofu steel" over there.

 

[piper184]

Please post a photo of the bucket and curl cylinders.

Chineesium steel is always suspect. However, I have done some really sketchy things with my OEM loader and never had a problem. I even put enough twist on it to twist a 1-1/4" heavy wall square tube that I put between the two sides. One of my curl cylinders is leaking at the gland end so I have ordered a repair kit to have on hand when I have the time to fix it.

It sure sounds like something is amiss on your FEL, especially since this has happened more than once. Maybe if I see how it is set up I can offer more insight.

 

[BobbieNicole]

Here are the two profile views.

 

[piper184]

This is strictly a guess on my part, and in no way is meant as a criticism, but I think I see your problem. Part of it at least.

The quick attach setup has moved the bucket quite a ways forward of the cylinder connect points. This adds a lot of extra stress. That combined with the additional weight of the grapple, quick connect and extra reinforcing puts even more stress on the cylinders. Force X length, moment arm and all that.

I know it doesn't seem like much and the loader will lift it but the bucket cylinders are the weak link, especially in this setup.

This is one of the reasons that adding a snow blade that angles to the front end loader can quickly lead to disaster if you are not careful.

I can see where if you were applying down pressure via the bucket cylinders, especially if the bucket was tilted down and you were driving forward the added force when hitting something could easily over power the cylinder rod. For example, you have the grapple open, the bucket tilted down (maybe all the way) and drive into a pile of limbs. The forces seen at the cutting edge are transferred back to the tractor by way of the bucket cylinder rods. Any misalignment or twisting of the frame and even more force can be put on the rod. Once it gets even a slight bend or even flex, it basically becomes a noodle under compression forces.

As for a cure, stronger/larger cylinders for sure, but that just pushes the forces back to the next weak point.

For reference, here are a couple of pictures of my quick connect. I actually cut the brackets off of the bucket and welded on the universal plate. The welded the adapter to the brackets once they were bolted back to the frame. I don't think this whole setup added more than about an inch to the "reach". It isn't perfect, but it also is more likely to "pop loose" than to bend the frame or the cylinder.

I hope this helps you figure out what is going on with your loader.

 

[BobbieNicole]

All good points, still it is curious that it is always the left side that fails. I will check the alignment out when my crazy summer life gives way to a more sedate autumnal life. I doubt I will do anything about the bucket attachment. Probably I'll just try to remind myself to take it easier, maintain a relationship with Surplus Center, and remember bulldozers have tracks not wheels!