Eaton VIS motor application

[Doug Hanson]

Here is a report on Eaton VIS motor application, specifically grapple rotate motors that drift.
The document link can be found on this page: http://hansonhydraulics.com/wordpress/a ... otors.html
It discusses the possiblility of converting the open loop VIS motor to the closed loop version with HOS valve and using a back pressure check valve.

Feedback is appreciated.

[smedsgenbo]

Hi Doug!

For the fun of the discussion, i have spent some time looking into your case here.
I am not sure it will work the way you think, or hope. My concern is that the, for this application, quite high amount of oil being flushed away, will somewhat affect the directional control valve, which I believe to be a proportional spool valve. Again, I know I'm on thin ice here and haven't got enough information to try and make a simulation.

Why not exchange the Charlynn TIS 45 with a proper purpose built rotator?
Or would it be possible to fit a small on-off valve to the leak oil line, which is being opened with the same signal that enables the directional control valve?

I have also seen solutions where the monkey in the cab was changed out with a man that knew how to drive the damn thing. Meaning that hessitating so long that the rotator starts drifting is simply illiminated. LOL

[Doug Hanson]

I like the last idea The most noticeable instance of leakage is when loading empty trailers back onto trucks, as the trailer is off balance and the grapple rotate is on a vertical plane.

I havn't had the chance to try changing the checks to a Hot oil shuttle. I'm surprised they use the open loop version of the motor as the lube oil for the bearings is taken from the high pressure side, resulting in oil loss like you say, and extra heat buildup as there is a large pressure drop from the high side of the motor to the drain. My opinion is that taking oil from the return side, or low pressure side to lube the bearings would be a much better idea. Less drift, less heat build up, better efficiency. Seems to be a win win. The major concern is making sure there is enough back pressure so that the lube oil supply is not lost, resulting in bearing failure.

Weldco But'n top grapple use two of these motors in parrallel to rotate the graple, I don't know if you could get a rotator like Rotobec Indexator in a displacement large enough. It would require a lot of modification though, the HOS valve swap should be pretty easy to do.

If I get an opportunity to try it out, I will be sure to post the results.