Loader bucket pauses

[BobReeves]

Ford 3000 with loader running off tractor hydraulics. The loader bucket pauses at the same place everytime I dump. If I hold the valve open for 15 seconds or so it goes ahead and moves the bucket to the stops and doesn't pause on return. I can live with the slowness due to running off the tractor hydraulics but this pause is aggravating.

It has done this every since I bought it even though I rebuilt the lift cylinders, replaced most of the hoses and changed fluid. I didn't remove the curl hoses or mess with the bucket cylinders as they look good and don't leak. Could this be air trapped in the curl cylinders? The way it's configured it sure looks like it would be easy to get air trapped in the curl hoses as they go down before they go up. However I don't see any good way to bleed it off if this is the case.

Any ideas?
Thanks

 

[JackIL]

Bob,

You are probably experiencing "cavitation." Air gets drawn into the cylinders when either: (1) the heavy load in the bucket is trying to pull the bucket down faster than the hydraulic pump can fill in the oil void on the back side, or (2) back blading.

The primary remedy is to operate the engine at full or almost full RPM so that the pump is doing as much as it possibly can. If you are operating at a very low engine RPM, the pump may not be able to "keep up" leading to cavitation.

JackIL

 

[BobReeves]

Thanks,

Next time out will kick up the RPM and see what it does. Have been running about 1500 when working with the FEL.

 

[jinman]

Bob, my loader has a "regenerative" function that makes it pause momentarily, but more like a second or two than 15 seconds. When the joystick is pushed all the way to the right, the curl circuit function is connected through the joystick and does not have to go through the pump. In other words, both sides of the cylinder are connected together so the weight in the bucket can cause the bucket to dump more quickly than when powered. The flow from the pump is still isolated to the dump side of the cylinder and it will eventually catch up to the regerative function. I always run my tractor at least 2,000 rpm when doing loader work and this makes the function work very well. At 2,500 it works even better. You might try higher rpm also.

 

[plowrup]

Bob,

I would highly recommend you disconnect the Cylinders, and rotate the Bucket to ensure that you do not have a mechanical problem, as yoiu are saying that this occurs only at one specific place, correct? If this is true, air or caviatation is not the problem as your Hydraulics would exhibit this sll the time, not at just one spceific place on one specific circuit. If you do not have a mechanical issue, I would fill the bucket and cycle the bucket many times, then feel you cylinders-if you feel any hot spots you have a internal leak in the Cylinder-

 

[3RRL]

Bob,
I think Jim and Jack are correct in their assesment of your problem.

My loader did exactly the same thing (not 15 seconds) but a couple at least. I always run the tractor less than 1500 rpm (usually only 1000 to 1200 rpm) because it handled most loads. I discovered this "lag" in bucket movement when the load dumped and I wanted to cul the bucket even more. That is, my pause occurred when the bucket teeth were pointing straight down and I wanted to curl more than that to smooth with the top edge of the bucket.

Is that when your "pause" occurs?

Well, I ended up taking a big bite and had to kick up the rpm quite a bit to about 2000 rpm to pick up this load. When I dumped it and culed further to smooth, the hesitation was gone. So upping the rpm was the answer in my case. I'd try that for sure. Also, I don't think it's mechanical because you said the bucket curled after 15 seconds. So I don't think there's a mechanical restriction or it would never curl farther.

 

[Charolais]

I'm on my second loader. Have seen the same problem with both. Not 15 sec. but maybe 3-4 sec. More RPM's takes care of it.

 

[HEC]

I'm on my second new m series tractor and both of those loaders will pause when you try to curl it completly back to where it hits the stops to loosen and dump any left over material in the bucket.Like said before it takes some time for the pump pressure to catch up to go completly back to the stops.I don't exactly how long it has taken mine but I would guess about at least 5 seconds.