A 3PT mystery

[skylarkguy]

So, I recently received a tiller to use on my MT372. It is a little Kubota branded tiller, with a 40 inch till width. It is my first tiller and it worked awesome. I had to shorten the PTO shaft which I read about in some other thread on this board. Great!

But here is the mystery. The tractor can pick up the tiller no problem when directly attached to the 3pt. Later after disconnecting it I put it on a pallet so I can move it around the barn with my pallet forks. The 3pt barely lifts it off the ground in this configuration. The additional weight of course is the wooden pallet, and the forks, but I can't imagine it exceeds the capacity of the lift.

What gives here? I also tried to pick up a pallet of flagstone (no idea how heavy) and it couldn't do it. All I can figure is that the pallet forks move the weight so far from the tractor that it is a huge lever arm, but that seems really out there.

Any thoughts guys?

 

[johnrex62]

Sorry, I am a little confused by your write up. You have pallet forks on the 3pt?

I am used to pallet forks being on the FEL, which has less lifting power than the 3pt end, so it might be possible that the fel does not have enough power to lift the tiller when the 3pt has plenty. If you do actually have pallet forks on the 3pt, then the only reason I can think of for the lack of lift would be that your tractor is really small and the pallet forks and pallet weight are the straw that broke the camels back in this case.

I do not know the specs of the tractor or tiller so I cannot make any specific determinations of the situation.

 

[k0ua]

I think you kinda answered your own question, as I am guessing your 3pt lift is probably high 700 maybe low 800, based on the weight of your tractor at less than 1200 lbs, so if the tiller weighs 500+ (tillers are pretty heavy and your now have forks and a pallet under it, that is probably another 200 or so. and it is further from the rated lift point stuck out there. so yes just like you said, It is having trouble lifting it. There are limits to any tractor, and I think you have found the limits of your 3pt.

James K0UA

 

[skylarkguy]

Yeah, I don't have an FEL. My Pallet forks are mounted right to the 3 point. So it only lifts that high. According to the Kubota folks the Tiller weighs about 400 lbs.(it is the smallest one they made apparently).

My tractor is pretty small (is it polite to ask about the size of ones tractor) So the rough math you provided kind of makes sense. Is there some math to do to actually figure out the capacity of the 3pt? In my squishy brain I think it has something to do with volume of the lift cylinder amount of travel and the distance from the lift point...but I haven't gotten my head totally around it.

 

[284 International]

Does the valve squeal when you try to lift it? That's the bypass, when there is too much pressure building in the system. That means it IS too heavy. If it's just not lifting it, or not lifting it very quickly, you might have a leaking lift cylinder. Does your three point hitch slowly drop when a load is on it and lifted?

Lifting ability has to do with the surface area of the lift piston, hydraulic pressure, and the ratio of the lower arms to the upper arms and their attachment points.

 

[wushaw]

My 372 will pick up 650lbs, I haven't tried anything bigger.

 

[skylarkguy]

When the load is lifted it stays lifted, no leak down. It sounds like I have simply found the limit of what it can do. Some day I'll try to find some stuff of known weight figure it out more exactly. Thanks for the help.

 

[ArtMech]

In my squishy brain I think it has something to do with volume of the lift cylinder amount of travel and the distance from the lift point...but I haven't gotten my head totally around it.

First of all, you need NOTHING TO MODIFY ON YOUR TRACTOR. It operates perfectly. Each modification may lead you to the big trouble!!!

If you can find hydro specs of your tractor (Operators Manual), you will read exact digit of lifting capacity of the rods at the ball points. The attachment is always further from the balls, that means the further the load, the lighter it must be. Yes, as you and other TBN'ers mentioned, if directly connected tiller is being lifted easily, it may be, that the forks+pallet+tiller+additional-lever-arm is too much for your tractor.

This phenomenon I meet every time, while working with 3ph bucket. The buzzing reduction valve always informs me when the load is too heavy. Like you, I can't load the bucket at full desired rating in my case of gravel or stones. And that is normal.

So there is no mystery ...

 

[skylarkguy]

thanks saracenas i won't be making any modifications. that bucket on your thumbnail is impressive. My tractor is much smaller.

 

[ArtMech]

thanks saracenas i won't be making any modifications. that bucket on your thumbnail is impressive. My tractor is much smaller.

Thank you. The matter we are talking about doesn't depend on the size of a tractor. I just think, I'm much concerned with an "issue" described by you. So why not to share our thoughts.