How do you make a hydraulic top link float?

[SFish]

Marshall:

That is pretty much what I was thinking. If I were going to put it on my Bush Hog I would just extend the shunt hose a little way up toward the seat and have a pressure rated ball valve to flip instead of an electric valve when mowing. If you want to be sure if the reaction time is quick enough (as per Jeffinsgf above), connect the two hoses together and drive around with the mower before modifying. My top & tilt hoses have male and female ends for each cylinder so I can put them together when they are off the tractor. I can just barely move the cylinders by hand when they are hooked up like this, but I have only tried it when everything is cold, so I think this idea would work.

Steve

 

[SPYDERLK]

"Gut wouldn't the differences in volume caused by one side having the piston displacing fluid make this not work?
Marshall"

Yeah. Good catch. There wouldnt be anywhere for the excess fluid to go when cyl was compressed - and extension would cause a vacuum - and alternate cycles may cavitate.
larry

 

[SFish]

I just went out and climbed onto the tilt link with the cylinder rigged with the up hose quick connected to the down hose and it readily lowered about 6 inches with my (somewhat hefty) weight. If this worked on a top link hooked to a mower I wouldn't be worried about cavitation because the bubbles would be mostly vacuum and would disappear when the cylinder moved back. Even air bubbles would immediatly flush out when the controls were used. I would just give this a try when the top and tilt is in hand to see if the movement is adequate for mowing before spending any money.

steve

 

[bobodu]

Don't know if this would help,but it's what I did on my WC.Haven't gotten around to cross drilling pin holes to stop any travel.

 

[PILOON]

Unless your tractoe is very different from mine---

Does not the factory 3-point not have a 'float' setting? and the hydraulic upper is added for remote adjusting from the seat vs adjusting the screw?
if so it seems that your float setting would be from the setting of the intregal valve all while leaving the 3-pt setting alone.

On my tractor dragging my back blade allows it to float and I screw the upper link to control debth.
So with the hydraulic you'd shorten to limit debth and longer would float unless you lock the intregal control .

 

[mopacman]

Mars:

For the top link put a T at each end of the cylinder and connect with hydraulic line and an appropriate valve. With the valve open fluid flows from one side to the other and the link will float. With the valve closed it acts as per usual.

Steve

I dont think steve's idea will work because their is a different volume on each side of the cylinder due to the shaft. When the cylinder goes in their will be more oil comming out than will fit in the shaft side.
Larry H

 

[herringchoker]

Larry - That's a good point. If the first action after the bypass valve is opened was to extend the cylinder, would it extend and create a vacuum on the side opposite the rod? I don't know. But if it did, would the fluid then have some space to move back and forth and thus allow some float? Again, I don't know. Now this is bugging me!

Marshall - If you try this, let us know if it works.

 

[mars1952]

Hi Piloon: My JD4300 3PH has a float mode but that is for the complete 3PH. I want my lower lift arms to remain in a fixed position and the top link to extend and contract on it's own. If the top link can extend and contract then the rear of the mower can move up and down more to follow the curve of the land. The front of the mower will go up and down with the lower lift arms
Good Luck, Marshall

Unless your tractoe is very different from mine---

Does not the factory 3-point not have a 'float' setting? and the hydraulic upper is added for remote adjusting from the seat vs adjusting the screw?
if so it seems that your float setting would be from the setting of the intregal valve all while leaving the 3-pt setting alone.

On my tractor dragging my back blade allows it to float and I screw the upper link to control debth.
So with the hydraulic you'd shorten to limit debth and longer would float unless you lock the intregal control .

 

[Renze]

Why spend $$$$ on modifying a hydraulic top link ? on my neighbor's pasture topper, we simply use a chain instead of a top link. the chain gives enough play to follow the land, and when you lift it, it leans over about 4 inches until th chains are tight and that's the trick...

Later design pasture topper have the 3pt lift frame attached to 2 pivot points, which are braced by 2 chains to the rear of the mower, so you can use your normal top link, which means no need for a chain with wide enough links on both ends to put a top link bolt through.

 

[Bird]

My JD4300 3PH has a float mode

Well . . ., sort of. There's one major difference. Your front end loader has power in both directions, up and down, in addition to the float position, while the 3-point on most tractors only has power to raise the 3-point, it's lowered only by gravity, so yes, if you have it lowered the all the way you have some float.