Ã…kerman H10BE & H10MBE dipper arm "thinking break"

[Paska]

Hi Swedish gurus. We have 2 Ã…kermans, one with tracks and one with wheels. They both have this same issue: When pulling the dipper arm towards the machine, especially with no load, it pauses for 1-3 seconds when the arm is vertical. So there's air in the cylinder. This is the only move where this occurs.

Is this a feature or a fault, and how to get rid of it? The wheel one doesn't leak from the gland, the track one leaks a little bit.

[Anton]

Kontrollera återfyllnadsventiler

[Paska]

Thanks Anton! where can I locate those valves?

[Anton]

Bomfotlimpa och 4 vägsventiler.

[Paska]

Some pics here from the spare parts catalog if someone else is having similar issues. Took a while of staring to get how it works.

[Anton]

A-A och B-B

[Paska]

I finally tried checking the "Ã¥terfyllnadsventil" for both hoses that go to the dipper arm, I couldn't pull the sleeve out by hand but I'm already 90% confident that they both are in tact as I can feel the spring pressure against the guide being equal in both. Knowing how they work, there's absolutely no chance that the other valves would affect the working of this cylinder either.

So will I have to try harder to pull the sleeves out to verify that the springs are in tact even though they both clearly are doing their job? Or should I move onto checking something else? I personally think it's either air getting into the cylinders while not in use and not being able to escape, or the second option would be that there's not enough pressure in the hose that's feeding the valve block, which I think comes as a branch from the main return line.

Given that most Ã…kermans with this style of anti-cavitation valves seem to have this issue, someone should probably already know what causes it? I don't personally know for sure if it's a feature or a fault because I've never seen one that doesn't do this.

[Paska]

By the way, I think I read on some other thread in here that there would be a process to somehow check these with pressure gauges but I couldn't find any instructions for it. Do you know more about that?

[Paska]

I just realized that there's probably nothing wrong with it. It doesn't have the issue at all with the original Ã…kerman bucket only installed but when I add the Engcon and the heavy grading bucket that are probably 1700kg together it forces the arm to move too fast, causing this issue. There must be already some restrictor that's calibrated for the original equipment weight (judging by the fact that you can't send it down at almost free-fall speed like the main boom) but if it's not adjustable, I probably need to add the "strypbackventil" that some people have suggested in other discussions.

As a side note, the issue actually happens because the return flow from the rod side is insufficient to fill up the piston side through the refill valve. It never happens in the other direction. This is why the dipper arm needs the restrictor and the main boom down movement doesn't.

[nixs]

As a side note, the issue actually happens because the return flow from the rod side is insufficient to fill up the piston side through the refill valve. It never happens in the other direction. This is why the dipper arm needs the restrictor and the main boom down movement doesn't.

More probably due to the fact rod side has less oil volume than the piston side.

[Paska]

As a side note, the issue actually happens because the return flow from the rod side is insufficient to fill up the piston side through the refill valve. It never happens in the other direction. This is why the dipper arm needs the restrictor and the main boom down movement doesn't.

More probably due to the fact rod side has less oil volume than the piston side.

Yes, that's why there's not enough flow to prevent vacuum