Loader question

[Shuboxlover 478]

I have a question about the loader on my D-160

 

With the motor running, PTO (loader pump) engaged, the bucket will sag down.  The lift arms of the loader won't sag, but the bucket will...and rather quickly.  If I move the buck to the "up" position, it will completely (or nearly completely) sag all the way to the dump position in a matter of 10-15 seconds.

 

I hope this makes sense, does anyone have any idea why this would be?

 

Thanks

Tyson

[benji756 341]

sounds like ether the cylinder is bypassing internally or the valve isn't holding

[KC9KAS 4,741]

[953 nut 55,065]

7 hours ago, benji756 said:

valve isn't holding

If the lift cylinders are working well and the cylinders on the bucket aren't leaking fluid the only other component that could do this would be the spool valve "O" Rings leaking by. Should be a simple fix.

[maxiblue 352]

sounds like its a bad hose most likely, those cylinders only use "O" rings no so called packing easy to rebuild done those a few times. But for the bucket to sag like that my guess it is a hose problem because one cylinder could hold the bucket up, has be a major leak and that would effect both cylinders not to hold the bucket up. Only other would be a bad spool valve maybe. Spool valves also have only "O" rings in it.

Edited October 18, 2016 by maxiblue

[pfrederi 17,663]

Spool valve for the curl function.

[Snowmobileaddict 403]

The spool valve, or control valve does have O-rings.  However, they are only there to prevent external leakage of hydraulic fluid while its on its way back to the reservoir on the low pressure side or return circuit.

 

The spool valves are precision machined and matched for maybe a couple thousandths of space in their fitment.  So, if you park the loader, with the bucket up in the air and the boom up and the spools in their normally closed, middle position and you see the bucket or the boom dropping, there is either an external hydraulic leak in a hose or cylinder packing, internal piston packing leakage on 2 or 4 cylinders or internal spool valve leakage between one or more spools and the valve body.  The external leaks are easy to spot, because you can see the drips or spray.  An internal control valve leak caused by worn spool valves (scoring, dirty fluid etc) can only be remedied by replacing the control valve.  If you try to dress the spools or valve body with ultra fine grit emery paper or sandpaper, you will likely introduce more space into their precision fitment, thereby making any internal valve leakage potentially worse.   

Edited October 18, 2016 by Snowmobileaddict

[smoreau 658]

Replace thespool valve. Mine will sag a little after 5 min.  These systems that do not have a filter will have metal shavings run through the valves and add ware to them. That is most likely your problem. 

[tbarnhart 240]

I'd repack the cylinders first. After working on ag equipment and all their hydraulics for many years, I can tell you that a spool valve would have to be severely damaged to drop that fast. If you pull the bucket all the way to the top and hold the lever back for a brief moment, you may be able to hear the oil leaking past the piston in the cylinder. Listen for a rushing sound from the bucket cylinders. You may have to get help to hold the valve and listen closely. You can also feel the cylinders while you hold them against pressure. Don't hold it there long, as the system will heat up quickly as it pumps against the relief valve, but it may tell you where the problem is and which cylinder is leaking. If one is leaking, you would probably be time and money ahead to get them both redone.

[Shuboxlover 478]

OK.....new info.

 

Not only does the bucket sag, I can't lift the arms past about mid way....even without anything in the bucket.

 

Does this point to the 2 spool valve or the pump?

[lynnmor 7,302]

4 hours ago, Shuboxlover said:

OK.....new info.

 

Not only does the bucket sag, I can't lift the arms past about mid way....even without anything in the bucket.

 

Does this point to the 2 spool valve or the pump?

Is there enough oil in the system?  Is the pump sucking air?

[pfrederi 17,663]

If you have enough fluid have you checked the wire mesh suction filter for blockages/restriction.

Edited December 7, 2016 by pfrederi

[Shuboxlover 478]

I didn't even know it had one or where that's at...so no.   Where is this located? 

[pfrederi 17,663]

The line out of the bottom of the loader frame feeds the pump.  Inside the upright (reservoir) is an mesh screen leading into this hose..  Bad news you have to drain the reservoir to get at it  (I assume this is an Arc 500 loader

[Shuboxlover 478]

Yes,  Ark 550....

 

I'll drain it,  check it,  and report back

 

Thanks 

[pfrederi 17,663]

Screen is inside the upright at the bottom in the picture.  Also I would install a real filter on the bypass line out of the control valve to the top of the reservoir.

 

Please no comments about the plumbing of the filter I used what I had lying around

Edited December 7, 2016 by pfrederi

[Shuboxlover 478]

OK, so I finally got back around to messing with the loader again.

 

I drained the reservoir and found no metal mesh screen.  The fluid was clean, but red.  I was under the assumption that these were supposed to use 10W-30 or 10W-40.  Anyway, I took the two lift cylinders off, tore them apart and found that the piston guide (I don't know the exact term for it) but it is the part that goes into the wide groove of the piston (not the seal) was completely missing on one and 70% gone on the other.  The seals definitely looked used.   Stupid question, but what I'm describing, could this even be possible...would the cylinder work at all?  The loader would barely go up.  And where did these pieces go?  So I am going to tear into the bucket cylinders after I get these back together, Need to talk to a local hydraulic shop in town first unless someone has part numbers.

 

Thanks