Cub 149 Loader - hydraulic issue

Palskidoo · #1 01-02-2019, 09:50 PM

Hello Everyone,

Been lurking in the shadows here for a while as I built my loader assembly onto my 149. I started with PF Engineering plans (thank you to them!) and changed a couple things.

Anyways, I finally got it all together a couple days ago and the hydraulics work but they are "jumpy" kind of like there isn't enough oil. (I know for a fact there is plenty of oil so thats not the problem) The cylinders will gradually extend to their full length and then boom-down is fine. This happens for both the boom and bucket cylinders.
The other thing I noticed is the hydraulic oil gets "foamy". the first time I figured its because the setup was new and its just a side effect of the pump and empty lines and cylinders. However she sat all day today and when I got home I fired her up and cycled the cylinders..... still foamy.

Have you guys run into this issue with your FELs? Is there a common cause for hydraulic fluid to get foamy? maybe the pump is running too fast? the oil return from the open center valve runs down a 1/2" line to a 90 degree elbow an into my reservoir. Maybe its a fitting issue? (the oil return is at the lowest point of my oil reservoir and below the oil level, so it shouldn't be getting aerated)

Any suggestions or help would be great I really want to get to using this

PS dont mind the mess in the picture

CADplans · #2 01-02-2019, 11:12 PM

I can not see the "oil tank",,

Foaming can be caused by the return oil going in the tank above the level of the oil.

The return MUST be submerged ALL the time,,

cooperino · #3 01-03-2019, 08:08 AM

How many gallons does the resevoir hold and what is the GPM of the pump? Just having enough fluid to extend cylinders may not mean enough to keep oil cool. I were would check the temp of the fliud after running. Also is your filter on the return line?? Have you changed the filter? Ive seen some pumps sheer fluid if it is old or dirty.

Ok. I just saw you built this. For some reason i thought maybe you bought it. Ok. Lots of questions then. Gpm or pump, psi, rpm pump is spinning, suction side hose size, pressure side hose size, how many gallons is system.??

Palskidoo · #4 01-03-2019, 08:09 AM

The "towers" on either side are hollow, as well as the sub frame box tubing that runs under the frame between the towers. The return is mounted to the sub frame box tubing so it is returning oil to the lowest point where there is always oil.

Palskidoo · #5 01-03-2019, 08:13 AM

Quote:

Originally Posted by cooperino

How many gallons does the resevoir hold and what is the GPM of the pump? Just having enough fluid to extend cylinders may not mean enough to keep oil cool. I were would check the temp of the fliud after running. Also is your filter on the return line?? Have you changed the filter? Ive seen some pumps sheer fluid if it is old or dirty.

the reservoir holds about 4 gallons and the pump is 4 gpm. Also the filter is on the supply line to the hydraulic pump.

ol'George · #6 01-03-2019, 09:10 AM

Foamy oil is caused by cavitation
Jerkey-ness is caused by cavitation.
Noise is caused by cavitation

Too heavy an oil for surrounding temps.
Oil that is restricted on the intake side, like a filter (not recommended) or too fine/small a suction screen.
Piping sized too small for suction side of pump, or pump too large.
Non direct/uphill flow to suction side ( pumps don't suck well)
No vent in reservoir.
Aeration of oil in the reservoir by improper placement of return line.
These are some of the causes of cavitation.

I can only guess what you have designed.

cooperino · #7 01-03-2019, 09:16 AM

Ok.. Many times in low GPM pump set ups if you put a filter before the pump you can actually starve the pump. If you had a larger pump it probably would be ok but that small a pump it could cause the issue you are having. I would suggest you put the filter on the return line. Also. a 4 gallon tank with a 4 GPM pump is really running it lean. That means your cycling your whole capacity every minute. The fluid will get hot pretty quick. Is there any way you can add capacity? Larger tank?

Was typing same time as George..

But what he said and I said.. Oil that is restricted on the intake side, like a filter (not recommended) or too fine/small a suction screen.

I think you move the filter and it will work.

Palskidoo · #8 01-03-2019, 10:20 AM

Thanks for the responses guys!

I have been reading up as much as I can all morning and I will be changing some things around to try and alleviate the cavitation. My first step is to remove the filter on the suction side!

Ill keep you guys posted.

ol'George · #9 01-03-2019, 11:01 AM

Quote:

Originally Posted by Palskidoo

Thanks for the responses guys!

I have been reading up as much as I can all morning and I will be changing some things around to try and alleviate the cavitation. My first step is to remove the filter on the suction side!

Ill keep you guys posted.

It is a good idea to have a suction screen there.
but for tryout you can just move the filter to Rtt ( return to tank)
I think surplus center has suction screens and bigger is always better.
never go smaller.

Palskidoo · #10 01-04-2019, 04:31 PM

update:

Last night I removed the filter from the suction line to the pump and ran the machine a little. The jerky, jumping movement of the cylinders was reduced almost to nothing. It was a night and day difference in the performance of the hydraulics. However I did still get a bit of foaming in the oil. I am hoping that once I install the filter on the return-to-tank line the foaming will be further reduced or cured all together.

I hope to have this completed this weekend.