L3800 hydraulics

F2036

Member
Jan 25, 2014
76
2
8
Bondurant Ia
When I bought my L3800 I had the dealer put hyd. couplings on the back so that I could use hyd. clyinders for 3pt or towed implements. He put on two couplings to I could use double acting cylinders, which works fine.
My problem is that when using my disc mower with a one way cylinder, it will not stay in the positation that I put it in, it will gradually loose its height and settle down.
No I haven't taken the cylinder apart to see if that is the problem, I am thinking it is okay since it is a brand new cylinder from John Deere, maybe this is where my problem is starting :)
Is there any adjustment on the L3800 to seperate operation between double and single acting cylinders???
 

Vlach7

Active member

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L47 305DT JD500C
Dec 16, 2021
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Frazier Park Ca
Disconnect and cap the lines and see if it still drifts down to isolate it to the cylinder, I just did that with my FEL bucket cylinder at 300hrs, just rebuilt it. much better.
 

TheOldHokie

Well-known member
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Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Apr 6, 2021
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Myersville, MD
windyridgefarm.us
When I bought my L3800 I had the dealer put hyd. couplings on the back so that I could use hyd. clyinders for 3pt or towed implements. He put on two couplings to I could use double acting cylinders, which works fine.
My problem is that when using my disc mower with a one way cylinder, it will not stay in the positation that I put it in, it will gradually loose its height and settle down.
No I haven't taken the cylinder apart to see if that is the problem, I am thinking it is okay since it is a brand new cylinder from John Deere, maybe this is where my problem is starting :)
Is there any adjustment on the L3800 to seperate operation between double and single acting cylinders???
Single acting cylinders can't leak down internally.

Edit: Whoops - I see these mower cylinders are pull type - single acting in the retract rather than extend direction. They can leak down internally. If you put a shutoff (e.g ball) valve on the cylinder you can "lock" the cylinder in the up position. If it drifts down when locked the seals in the cylinder are leaking.

If its a new cylinder my money would be in the control valve rather than the cylinder. How quickly does the mower drop?

Question below still needs an answer.

How are you using a double acting valve with a single acting cylinder?

Dan
 
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F2036

Member
Jan 25, 2014
76
2
8
Bondurant Ia
Dan, I'm just plugging the cylinder hose into one side of the hyd outlet. I can use the cylinder to raise the disc mower just fine, it is just that it won't stay at the height I set it at, it wants to leak down.
The next time I mow hay I will put a valve inbetween the tractor and the hyd cyl tosee if it is the cyl that is leaking back.
 

TheOldHokie

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L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Apr 6, 2021
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3,213
113
Myersville, MD
windyridgefarm.us
Dan, I'm just plugging the cylinder hose into one side of the hyd outlet. I can use the cylinder to raise the disc mower just fine, it is just that it won't stay at the height I set it at, it wants to leak down.
The next time I mow hay I will put a valve inbetween the tractor and the hyd cyl tosee if it is the cyl that is leaking back.
When you use just one of the outlets with a SA cylinder you are deadheading the pump against the unused outlet everytime you lower the boom. That is not good for the pump or the relief valve. The other outlet should be connected to tank to provide a path for the pump to unload.

That has nothing to do with your leakdown issue but its how you use a DA valve with a SA cylinder.

Dan
 
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