Tree remover

[MossRoad]

5. Yikes, I got it! Now what?

...which was my point.

Oh, I know you got it... now you gonna get it some more!

So I think we all agree that it can be done, thin wall tubing probably won't work well, the lever will have to be long and heavy, so long, in fact, that the PT425 may not be able to lift it, especially with a load, and if it does lift it, it may not be far enough to accomplish much without having to re-gip every couple of inches.

Hmmmm. Someone should make one anyway and see how it works. Any takers?

 

[3238dpw]

Are you guys really talking about try to pull a tree out of the ground with a PT-425? A tree that weighs more than the tractor?

Well are we really talking about a tree that is heavier than the tractor? Not really. A tree requires a lot more force to pull it out of the ground than it actually weighs.

I'm pretty sure you could pry up an 8000 pound load with a PT425 IF, and only IF, the lever you are using is sufficiently strong enough to support 8000 pound loads. With proper leverage anyone can move anything. As mentioned earlier, I have used pry bars to move rail cars by myself. I had a job in the mid 80's driving and loading millitary vehicles from A.M. General's plant in South Bend, In to rail spurs around the area. We had to install the plates between the rail cars to drive from car to car and sometimes the cars were too far apart for the plates, so we had this big pry bar thing and one person could move a huge, double height rail car by themselves.

The real questions are:

1. How long of a lever would you need to move/pry that 8000 pound load out of the ground with only a 5' (or less) lift? You may only get a few inches of movement 10' out from the PT lift arms.
2. How strong would that lever have to be?
3. How heavy will that lever be?
4. etc....
MossRoad

The 8000 pounds of lift was just hypothetical. What is the real question is, is how much bigger of a tree can you pull out with a lever of resonable size than you can without the lever, useing say the 4in1 bucket? My guess would be a lot bigger tree or at least big enough to be worth it.

 

[KentT]

As I understand the Pythagoreum theory (and vector theory, BTW) from long ago, the mechanical advantage provided by this lever would be:

(a) Distance from lift cylinder pins (where force is applied) to the center of the tree trunk DIVIDED BY (b) the distance from the center of the tree trunk to the end/pivot pin of the footpad of the lever

or simply a/b = m, the mechanical advantage

Assuming that the PT could lift 800 lbs at its lift cylinder pins (it will certainly lift more at that measuring point), the lifting force applied to the lever itself (and the tree) would then be 800 lbs x m (stated as feet) = ft lbs of force

Am I thinking correctly? It's been a long time...

 

[ponytug]

Of course you are thinking correctly!

You have the lever part spot on. But Pythagoras usually refers to the length of the sides of a right triangle, a*a +b*b=c*c... The lever ratios were also covered in a prior email by somebody...

As an aside, if the PT is prying the tree out of the ground, it could easily pry out a tree that was heavy enough to tip it after the tree was no longer a vertical dead weight. i.e. As soon as that tree is loose from the ground, you probably want to pop open the jaws holding the tree, so that the tree doesn't apply Archemedes lever principle back on to the PT and you.

All the best,

Peter

As I understand the Pythagoreum theory (and vector theory, BTW) from long ago, the mechanical advantage provided by this lever would be:

(a) Distance from lift cylinder pins (where force is applied) to the center of the tree trunk DIVIDED BY (b) the distance from the center of the tree trunk to the end/pivot pin of the footpad of the lever

or simply a/b = m, the mechanical advantage

Assuming that the PT could lift 800 lbs at its lift cylinder pins (it will certainly lift more at that measuring point), the lifting force applied to the lever itself (and the tree) would then be 800 lbs x m (stated as feet) = ft lbs of force

Am I thinking correctly? It's been a long time...

 

[3238dpw]

Well peter I agree with you about the Archemedes lever principle. If you notice even with the skid steer in the video the tree jack is not used to carry the tree, just to pull it out. The skid steer lets go of it after it is lifted out of the ground. That says you are right about that possibility. So you would need to drop the tree and come back later and pick it up with another tool. Too bad about all that seat time

 

[BobRip]

What you are missing is the same thing that several other responders are missing.

IF you can apply 8000 pounds of lift to a tree, then there is also an 8000 pound load applied to that point on your minihoe arm, acting in the opposite direction. Since the arm is apparently a thin walled box beam, it is likely not engineered for loads of that magnitude at that point, and in that direction. It may well crumple, like an empty aluminum soda can. Once the arm has buckled, it is likely that the mini-hoe will be less usable than it was before you tried to pull that tree. It will be far more flexible of course once it has buckled, so you could even use it to reach around corners. Just think of the new uses you will find for your PT then?

John

John, if 8000 pounds is going to the PT, does that mean there is no weight on the foot (the actual fulcrum) of the tree puller. This foot is the fulcrum and it will carry most of the 8000 pounds and put it right into the ground next to the tree. If it does not, why have it. Me version will and the PT will not be hurt.

 

[BobRip]

Sigh. It is not the PT that I'm expecting to tip over. Assuming that the PT mini-hoe arm is truly a thin walled box beam, it is not designed for significant transverse loads along the beam. Say, as some have suggested, that you will be able to apply a load of 8000 pounds of lift to a tree. Then you must also apply an 8000 pound load at that point on the beam, even though the pt itself will not tip over, since it only feels an 800 pound load. If the arm is not capable of supporting this load, then it will likely fail. The failure, when it occurs, will be rather unpredictable - buckling is often so.

It is your equiptment of course.

John

Our messages must have crossed. The PT will not lift beyond what the minihoe is designed to support, the relief valves will see to that. Now if there are side forces, (I think that is what you mean by transverse forces), this might be unpredictable, but I have had tranverse forces on the arm before and did not damage it, the PT did roll towards one side, and if they got great enough, the PT might roll on the side. Perhaps a rotating joint is needed so that the tree will fall left or right without twisting the minihoe. Is this your point.

 

[BobRip]

Oh, I know you got it... now you gonna get it some more!

So I think we all agree that it can be done, thin wall tubing probably won't work well, the lever will have to be long and heavy, so long, in fact, that the PT425 may not be able to lift it, especially with a load, and if it does lift it, it may not be far enough to accomplish much without having to re-gip every couple of inches.

Hmmmm. Someone should make one anyway and see how it works. Any takers?

MR, this sounds like it's worth doing. Remember the lever arm has it's greatest stress at the fulcrum and could be thinner the further you get back from the fulcrum. I don't know how to do this yet. Was the railroad lever something like that? Do you have pictures or a link?

The other thing which I don't think has ben discussed is that the foot cannot be too close to the tree or it will sit on roots and maybe hold the tree down. This could seriously reduced the mechanical advantage. Heck though, even 2000 pounds of force would help with a small tree.

 

[J_J]

MR, this sounds like it's worth doing. Remember the lever arm has it's greatest stress at the fulcrum and could be thinner the further you get back from the fulcrum. I don't know how to do this yet. Was the railroad lever something like that? Do you have pictures or a link?

The other thing which I don't think has ben discussed is that the foot cannot be too close to the tree or it will sit on roots and maybe hold the tree down. This could seriously reduced the mechanical advantage. Heck thought, even 2000 pounds of force would help with a small tree.

Bob, This is a picture of one man moving a railcar with the railcar mover.

 

[MossRoad]

Ye, it was something like that. A pry bar with a foot that would rest on the track. When you pushed down, it would pry the railcar wheel up, making it roll away from you.