Tree remover

[MossRoad]

Think about that... you put a long lever on the end of the pt and start prying on it. Heck, I've bent my forks several times by prying on stuff and they are only 3' and a lot thicker steel than the mini hoe.

 

[J_J]

Think about that... you put a long lever on the end of the pt and start prying on it. Heck, I've bent my forks several times by prying on stuff and they are only 3' and a lot thicker steel than the mini hoe.

David is right. Consider this, a 10 to 1 ratio on the 425 with a lifting force of 800 lbs, and a good lifting arm. You now have 8000 lbs of lifting force. However, if the object is 9000 lbs, the PT rear end will lift.

 

[sawdust_maker]

With the foot on the tree remover, you have leverage and the 800 pounds of lift from the pt will be multipled by a factor or 3 or more. No loads will be put on the minihoe that are greater than normal because you are limited by the PT weight or the relief valves.

A multi-thousand pound load on the tree trunk does not mean that your pt will be lifted from the ground or tipped over. Its a lever after all.

http://math.nyu.edu/~crorres/Archimedes/Lever/LeverIntro.html

And its not the load on the mini-hoe that is the problem. The arm of the hoe is a box beam, with relatively thin sides as I recall from other threads. (1/8 inch steel?)

You have a beam with a large load on it in the center of that beam. The load can be large, since you have leverage working against you here. This beam was not designed to take a serious load at that point. Buckling will indeed be a real threat. My guess is a crumpled mini-hoe arm soon.

John

 

[BobRip]

A multi-thousand pound load on the tree trunk does not mean that your pt will be lifted from the ground or tipped over. Its a lever after all.

Archimedes' Lever

And its not the load on the mini-hoe that is the problem. The arm of the hoe is a box beam, with relatively thin sides as I recall from other threads. (1/8 inch steel?)

You have a beam with a large load on it in the center of that beam. The load can be large, since you have leverage working against you here. This beam was not designed to take a serious load at that point. Buckling will indeed be a real threat. My guess is a crumpled mini-hoe arm soon.

John

Almost all of the force will go to the foot on the tree puller, not the PT.

 

[J_J]

A multi-thousand pound load on the tree trunk does not mean that your pt will be lifted from the ground or tipped over. Its a lever after all.

Archimedes' Lever

And its not the load on the mini-hoe that is the problem. The arm of the hoe is a box beam, with relatively thin sides as I recall from other threads. (1/8 inch steel?)

You have a beam with a large load on it in the center of that beam. The load can be large, since you have leverage working against you here. This beam was not designed to take a serious load at that point. Buckling will indeed be a real threat. My guess is a crumpled mini-hoe arm soon.

John

When a PT exceeds it's lifting capabilities, the back end starts to rise. This is the same as the tree and the lever lifting principle. If the machine can not lift the tree, and you keep adding hydraulic fluid to the lifting cylinders, guess what. You have just made the PT a lever by rotating the PT on it's front wheels, and the rear end will come up. Have you ever seen that tool that they use to move a train car, years ago, and they might still use it. It looks like a long pole with a wedge on the end, and one man can move that car by the lever principle.

What's that old saying, If you give me a lever big enough, I will move the Earth.

 

[3238dpw]

Consider this, a 10 to 1 ratio on the 425 with a lifting force of 800 lbs, and a good lifting arm. You now have 8000 lbs of lifting force. However, if the object is 9000 lbs, the PT rear end will lift.

JJ I agree that if you need to lift 9000 lbs the PT rear end will lift, but I would be pretty happy being able to pull out a tree that requires 8000 lbs of lift. Right now i can only pull a tree that needs 800 lbs of lift. To me that sounds pretty good or am I missing something.

 

[RegL]

This has all been interesting but did anyone look at the specs? The tree jack alone weighs over 1200lbs. with most of the weight several feet out from the attachment plate. You would have to use some kind of space age materials to build one long enough to have any real leverage and also light enough to lift with a pt425.

 

[J_J]

JJ I agree that if you need to lift 9000 lbs the PT rear end will lift, but I would be pretty happy being able to pull out a tree that requires 8000 lbs of lift. Right now i can only pull a tree that needs 800 lbs of lift. To me that sounds pretty good or am I missing something.

Scott. As you know, the 425 can lift around 800 lbs. If you use this leverage in a lever situation, you should be able to lift quite a bit more. You probably already know about lifting with a boom pole. The further out you try and lift, the less you can lift, but if you add some weight to the rear end, you can lift more.

A simple lever would be something like a seesaw. Equal weights on each end of 100 lbs, and you have balance. Now, move the fulcrum toward one end with a 10 to 1 ratio, you should be able to lift 1000 lbs on the other end.

Someone mentioned the weight of the tree puller in the skid steer add. The weight of the tree puller has to be including in the weight of the pulling force.
Actually, it could be lighter and stronger and still do the same job.

 

[Marks481]

Actually, it could be lighter and stronger and still do the same job.

Definitely. I bet if you built it out of a 4x4 1/4" box beam, it would have more then enough strength for the job.

Alternatively, you could make it attach to the end of the minihoe with a swivel, so you get extra lift height at the PT end of the prybar. This will not damage the mini hoe (I have picked up the back end of the PT with the minihoe when prying on rocks with it, and didn't change the shape of it). This might make it more complex, since either you will have an extra arm flopping around or need another hydraulic cylinder.

 

[sawdust_maker]

JJ I agree that if you need to lift 9000 lbs the PT rear end will lift, but I would be pretty happy being able to pull out a tree that requires 8000 lbs of lift. Right now i can only pull a tree that needs 800 lbs of lift. To me that sounds pretty good or am I missing something.

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