Hydraulic Cylinder Slop

[Hilbilly]

I don't know how else to describe the condition that occurs with my tractor and skidsteer, other than slop. Essentially what happens is that when the curl cylinders are at rest I can grab the bucket and tilt it up freely for a short distance. There is no resistance other than the weight of the bucket. As I understand the way double acting cylinders work, there should be hydraulic fluid on both sides of the piston seal and both sides should be under pressure. Is this right? If so, the cylinder should not be able to be moved by hand, only by applying hydraulic pressure on one side of the piston or the other. So what is causing this "slop"? Could it be air in the lines, a problem with the pump, the control valve, any / all of the above or something else?

 

[J_J]

You are right in the fact that if the cyl is full of fluid you should not be able to move the bucket.

If you have good cyl, leak free, then any slop in the cyl is air.

Usually caused by the bucket descending to fast for the flow coming into the cyl.

Regen is supposed to prevent that by almost doubling the flow rate into the cyl.

The air will purge by using the cyl .

It is possible you have a suction leak, allowing air to build up in the cyl.

 

[Hilbilly]

Thanks JJ.

I just bought the old skidsteer yesterday and am now discovering some problems. This is the smallest issue so far and there are some much bigger ones I will need to deal with. In any case I used the machine for about 2 hrs yesterday and the slop never went away, suggesting that if it was air in the cylinder, it was not purged at any time.

I did a google search for suction leaks on hydraulic cylinders / systems and it appears there are several locations where this can occur but I couldn't find a method to check for the leaks. Rather than ask for any further help on this issue now, I think I will leave this and focus on the bigger engine issues. At some point in the future I may come back and ask for your help / guidance. Or if you know of a link that I could bookmark for later referral I would appreciate it.

John

 

[Mace Canute]

It's an OLD skidsteer so it's likely to be wear in the bucket pivots causing the slop.

 

[J_J]

Raise the bucket up and check the pivots mounts for slop as Mace suggested.

Try and move the bucket by hand and see if it feels spongy.

If you don't get rid of the suction leak, you will continue to have air in the system.

You can maybe look in the tank and see if there ae bubbles.

You can try heavy grease on the suction tube and clamps.

To find external leaks, Napa sells a fluorescent dye that will fluoresce/glow with a black light.

 

[Hilbilly]

It's an OLD skidsteer so it's likely to be wear in the bucket pivots causing the slop.

Right you are!!!! I did some further checking and found lots of slop in the tilt cylinder pin. Pulled the pin and couldn't believe the wear. Turns out there was supposed to be a bushing in there and it was gone. Installed a new bushing which got rid of most of the slop. There is still some at the ends of the pins and I may try to come up with a fix for that later but for now it's much MUCH better. Looks like the cylinder is ok. There's also some wear in other pins but not too bad for an old machine.

Now I just have to learn to use it. I'm use the excavator and find myself trying to curl the bucket by pulling sideways on the right hand motion control lever (or whatever it's called).

 

[SPYDERLK]

... So, the cylinder rod itself was not moving?

 

[Hilbilly]

... So, the cylinder rod itself was not moving?

The cylinder seem to be tight. There is slop in the pins and the pin mounts. I think the cylinder itself is ok. I had to drive the bushing into the lower cylinder opening. Hoping the top is the same. Pins and bushings are cheap .......... cylinders not so much.