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Discussion Starter · #1 ·
Do you guys who have hydraulic top links prefer one with or without a check valve? I understand it prevents leak down but also prevents you from using a float function and may make minor adjustments harder. What other factors are there to consider?
 

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Why would you want a float function on the top link?
 

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I wondered this myself.
I have a deere 4400 and I believe the valve has a built in check. So I ordered a cylinder without and works great.
So I guess it depends on what type of valve you have.

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Why would you want a float function on the top link?
Some guys like to run their bush hogs with it in float. I've been wondering which way to go also, when I finally decide to get a hydraulic top link.
 
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I've run my neighbors bush hog in float. Follows terrain much better. I've heard of people unhook the top link if you know the field or area you cut really good.
 
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Discussion Starter · #5 ·
Why would you want a float function on the top link?
Having the top link float reduces the impact of even ground by allowing the attachment to ride up or down as necessary. That's why guys occasionally use a chain rather than a rigid manual link. I've done it and it can make a difference in some situations.

I have a JD 3rd SCV on the rear of a 4200. I don't know if that has a built in check valve or not.
 

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So it depends on the implement?
 

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Discussion Starter · #7 · (Edited)
So it depends on the implement?
I'd say it depends more on the ground. Three point attachments do exactly as the tractor does so if you have a lot of dips and bumps the bush hog, for example as mentioned above, will rise up when the tractor climbs a small incline leaving the grass taller just before the hill. It will drop down all the way when the tractor goes into a dip which causes scalping. Unhooking the top or using a chain is basically a poor man's "float" allowing the implement to follow the contour it is on rather than the one the tractor is on. I've never unhooked but have used a chain on badly rutted or washed out drives with a box blade. You could do it with a rake or straight blade too. You set the maximum down with the chain but the ground can push the implement up rather than forcing it's way through the material you may not want moved or stopping you altogether. The example mentioned above likely refers to a bush hog with a rear wheel so it's still riding on three points of contact.

Giving up the float option is not great imho but having the attachment leak down isn't great either. Just trying to determine which is preferred. If the valve has a built in check the decision is already made.

Does anyone know if the JD OEM 3rd SCV on a 4200 has a built in check valve? I called my dealer but the guy answering the phone was in pre-k when I bought this thing and I might as well have been asking my dog. He has no idea what I'm asking. ☹
 

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What about a box blade? Seems to me you'd want that held in a fixed position fore & aft.
 

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What about a box blade? Seems to me you'd want that held in a fixed position fore & aft.
A box or rear blade, yes, you'd want that fixed as that determines the aggressiveness of the cutting edge. Something like a land plane though, which has its own skids to ride on could benefit from the float function as you want it flat to the surface it's riding on, not necessarily the orientation of the tractor.
 

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I have one with a check valve, and I've been told by friends that have one without that will indeed leak down after a little time, mine has held position for weeks at a time. The valve definitely doesn't hurt anything by being there, so didn't see any harm in getting with it.
 

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Discussion Starter · #11 ·
I have one with a check valve, and I've been told by friends that have one without that will indeed leak down after a little time, mine has held position for weeks at a time. The valve definitely doesn't hurt anything by being there, so didn't see any harm in getting with it.
Are you saying theirs leak down when the tractor is running? I know it would leak when the tractor is off but with the pump on I don't see why it would.
 

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I don't have one. If I am plowing I have notices it will lengthen but like a 1/4" over an hour. Could be the cylinder, probably is the control the valve though. I prefer having the float ability but it really doesn't matter both types work well.
 
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Are you saying theirs leak down when the tractor is running? I know it would leak when the tractor is off but with the pump on I don't see why it would.
You've never had your bucket leak down while running? I know mine will, I would assume the rear remotes would be the same
 

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Having the top link float reduces the impact of even ground by allowing the attachment to ride up or down as necessary. That's why guys occasionally use a chain rather than a rigid manual link. I've done it and it can make a difference in some situations.

I have a JD 3rd SCV on the rear of a 4200. I don't know if that has a built in check valve or not.
I think you meant to say 'Uneven Ground'.
As far as those who know the land well they are mowing you might get away with unhooking the top link or using a chain for a top link but what are you gaining by doing either one?
Uncharted territory I want total control of my brush cutter. Should I hit a hidden pile of rocks or that hidden partially rotted stump I don't want the front of my brush cutter lifting up and putting me in the line of fire when the blades start throwing rocks or wood out the front of the mower. If I hit something unseen I want to be able to grab my 3 pt. control and lift the mower straight up while slowing the engine and mower down.
 

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I think you meant to say 'Uneven Ground'.
As far as those who know the land well they are mowing you might get away with unhooking the top link or using a chain for a top link but what are you gaining by doing either one?
Uncharted territory I want total control of my brush cutter. Should I hit a hidden pile of rocks or that hidden partially rotted stump I don't want the front of my brush cutter lifting up and putting me in the line of fire when the blades start throwing rocks or wood out the front of the mower. If I hit something unseen I want to be able to grab my 3 pt. control and lift the mower straight up while slowing the engine and mower down.
This is why you see the flat stock that connects the 3 point to the rear of the brush cutter replaced with chains, it can tip forward, but can't tip back.
 

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I have them on mine. Didn't matter either way for me, don't need float. If a hose blows it won't crush me or rip my rockshaft arms off the tractor when I have 1500lb ballast box on. I can switch it though if I need as the valves are added to the cylinder. They can be removed.
 

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The check valve is solely to slow the down the travel of the top link to make it easier to get the setting you want. It has no other purpose.

Dave
 

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The check valve is solely to slow the down the travel of the top link to make it easier to get the setting you want. It has no other purpose.
Dave
It does have a purpose. It is a European safety standard. For front three points they have a lock out so if they blow a hose something doesn’t drop while traveling on the road. It would work the same for this one.
 
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