DK45 Hydraulic Top Link

[CajunRider]

I would like to put in a hydraulic top link for my DK45. What's the correct size and type of cylinder? I'm thinking 3"x10"x1.25' (18.25" - 28.25").

Thanks for your help

 

[gladehound]

All I can offer is that a 3 inch cylindar is big!

Assuming 2500 psi system pressure, 2500x3.14x1.5^2 = 17,600 pounds of force. I think it is overkill. Don't know if you would be at risk of breaking anything.

 

[gladehound]

Thinking about this more... you just want to tilt an implement without snapping it in two, or bending it in half, in the event that you tilt too far, come to the end of your 3 pt float travel and lift the back of the tractor off the ground.

With a DK45, you have a ~2500-2600 pound 3pt lift capacity 24 inches behind the links. I would match that so that you can tilt anything you can lift. If the verticle distance between lower 2 links of the 3 pt and the upper one is 24", then you need a cylindar that can generate 2500 pounds of force. If you have 2500 psi operating pressure (just a guess). You need 1 square inch of surface area on your cylinder. To get this you need a 1.13 inch cylinder. You could go with a 1.5 inch cylinder to be sure in case you have lower system pressure or impliments with shorter vertical distances between the upper and lower links.

Let's say you have lower system pressure and less verticle distance between the upper and lower attachment points. The 1.5 inch cylinder, you get 2600 pounds of tilt 2 feet behind the links if the verticle distance between upper and lower links is 18 inches and the system pressure is 2000 psi.

Now if you want to make a big 3 pt hook to lift just about anything huge with, you could use that 3 inch cylindar, fill your bucket with weight and lift until the front is sky high, the 3pt breaks, or the tractor breaks in half. This is probably what I would do. But the 1.5 inch cylinder is probably the more sensible choice.

 

[kentrodngun]

Now if you want to make a big 3 pt hook to lift just about anything huge with, you could use that 3 inch cylindar, fill your bucket with weight and lift until the front is sky high, the 3pt breaks, or the tractor breaks in half.

Made my day Gladehound although I've been doing free taxes for the elderly all week, so I'm easily amused

 

[PAB_OH]

You need 1 square inch of surface area on your cylinder. To get this you need a 1.13 inch cylinder. You could go with a 1.5 inch cylinder to be sure in case you have lower system pressure or impliments with shorter vertical distances between the upper and lower links.

Some random thoughts, I'm getting tired sitting here in the hotel room...

What about the rod diameter. You have to be able to handle all the force the 3PH will see through dynamic loading. And if you have a 1" diameter rod then you reduce your piston area by that amount on the return stroke.

Most of the top link cylinders I see are 2"+ diameter. I'm betting it has to due with the required rod diameter to handle loading and the effective area you're left with to lift whatever implement you have hanging of the back.

 

[gladehound]

Good point. I didn't think about the fact that when a cylinder pulls it has less surface area for the pressure to push against due to the rod. So you do have to go bigger to get the required lift. Thanks for the correction. Shock is another consideration.

A 1 inch rod reduces surface area by 0.79 square inches. So a 1.5" cylinder with a 1" rod would exert 1.77 x system pressure on the push stroke but only 0.98 x system pressure on the pull stroke. So with 2000 psi you get about 2000 pounds of pull.

The list below gives an idea of how much weight you will be able to tilt up with different cylinders at a distance behind the links that equals the distance between the link attachment points. This doesn't take changing angles into acount and assumes a right angle between the cylinder and a line drawn through the link attachment points. In reality, you will get a little less than these numbers because you wont be at a perfect right angle.

A 1.75 inch cylinder with 1" rod gives ~3200 pounds of pull with 2000 psi
A 2 inch cylinder with a 1" rod gives ~4700 pounds of pull with 2000 psi
A 2 inch cylinder with a 1 1/8" rod gives ~ 4300 pounds of pull with 2000 psi
A 2.5 inch cylinder with a 1 1/8" rod gives ~ 7800 pounds of pull with 2000 psi
A 3 inch cylinder with a 1 1/4" rod gives ~ 11,700 pounds of pull with 2000 psi

Since your 3pt is rated around 2500 pounds, if it were my tractor, I would probably go with the 2 inch bore, 1 1/8 inch rod. I would get one that could handle a 5000 psi shock load which would equate to over 10,000 - 15,000 pounds depending on the direction of the shock load.

If I went bigger, I don't know if I could restrain myself

 

[CajunRider]

Thanks everyone for your input.

Yes I realize it's a bit much, but I got it for cheap 3x10 hydraulic toplink complete with double pilot check valve set up similar to what I see on Carter & Carter Machinery. I paid $110 bucks to a friend who bought it for his JD but decided he doesn't need it.

I checked and find out I can put a bushing in the eye and install it on my tractor. I guess if I want to use it I must be extra carefull with the control.

 

[gladehound]

Well heck, if you alreay have the 3 inch cylinder put it on! You'll be fine as long as you don't get hydaulic power fever!

 

[CajunRider]

Got it installed. I had to buy a 3/4" - 1" bushings and actually had to grind off a little bit off the side of the eyelet to get it to fit. Now it works like a charm. As you said, I have to watch it a bit but I finally begin to get the box blade to behave the way I want.

 

[coolslug]

I have a DK45se with a backhoe. I am curious about the hydraulic top link that you are discussing. What is a hydraulic top link? I have two hydraulic hoses in the back of my tractor that are hooked up to my backhoe. Are those hydraulics what you are talking about?

I am new to tractors so I have a good excuse for my dumb question.

 

[DK35vince]

I am curious about the hydraulic top link that you are discussing. What is a hydraulic top link?

The standard top link is replaced with a hydraulic cylinder. With a hydraulic top link you can make adjustments to attachments on the 3 point from your tractor seat while on the go.
Makes a huge differance when working with attachments like boxblades, backblades, Etc.

 

[coolslug]

Thank you for your response to my question Vince. I read a bunch of posts here that mentioned this but until your reply with your pictures I had no idea what it was. Once I get more used to my tractor I will look into getting a hydraulic top link to use with my new box blade.

Don

 

[CajunRider]

Here's my oversized top link. It's a lil big but it works fine for me. I don't have the side hydraulic cylinder so no tilt for me yet.

 

[KIOTI D]

Another newbie question how is this top link controled,i just bought a DK35

 

[rd_macgregor]

My DK45 came equipped with a single pair of rear remotes, controlled by a detented lever just forward of the FEL control. I use the rear remotes in the summer to control my grapple and in the winter to control the chute on my snowblower. Theoretically, I could get by with the single set of remotes, I guess, but adding hydraulic top cyclinder would certainly require adding another remote...two if I wanted both top and tilt cylinders.
Adding remotes is expensive, and I don't feel competent to do this myself. I wonder if adding several at once is more cost effective than just adding one...that is, would the additional ones be a lot cheaper per each if, say, three were being done at once...or, is most of the cost in parts?
BOB

 

[rd_macgregor]

If you put in a cylinder with an oversize bore, you might want to be sure that the control lever is NOT detented; you don't want it to keep extending after you let go of the lever!
BOB

 

[KIOTI D]

My DK 35 came with the single rear remotes and detent control vale, the owners manual does not explain how it works very well . So i should be able to run a top link with what i have. Thanks for the info.

 

[rd_macgregor]

You can run a hydraulic top link with what you have, but the drawbacks will be that you can't use something else hydraulic at from those remotes and you run the risk of extending or retracting the top link more than you wanted to by accidentally clicking into the detent positions. I do this all the time with my grapple and with my snowblower chute rotator; the result with these implements is irritation, but it might be a more dramatic effect with a box blade.

BOB

 

[KIOTI D]

Thanks RD,l hooked up the cylinder and it works great, i do have to watch that it does not go into the detent position.

 

[Kiotisooner]

I installed a hydraulic top link on my Kioti Dk50. I didn't like the way the detent valve worked, so I made the valve a non-detent valve. It works great now and doesn't lock in.