Pulling stumps

[Anonymous Poster]

Re: Pulling stumps/Chain Energy

Thank you Professor Rob.

I love this stuff.

By the way, how many credit hours is this course worth?

 

[RobertN]

Put an old sleeping bag over the chain or cable, about half way down the length of the chain.

It it breaks, the old sleeping bag will help dampen the chain. If it does hit you, it's better to get hit by that than the bare chain. It's a old trick 4-wheelers have used for years.

RobertN in Shingle Springs Calif

 

[Anonymous Poster]

<font color=blue>Put an old sleeping bag over the chain... half way down the length of the chain. </font color=blue>

Robert,

I've heard that through the years...

That's great if the chain is trained and always breaks under the sleeping bag/coat/etc...but...

What happens when the chain decides to break in a randomly different area?

 

[RPM]

Re: Pulling stumps/Chain Energy

Huck,

If one side of that bottom link breaks first - then yes, you'll see a good degree of whipping around.

It's just the same behavior as if nothing was on that chain - and you walked up and gave it a good crack - just like a whip - then immediately let go. The chain is tethered at one end and you'll see a nice ripple go through it as the free end whips around.

Of course, it's hard for a human to do this to a heavy chain - but the forces are proportionally large enough when a heavy chain breaks that it happens easily.

 

[DrDan]

Personally my favorite way to remove stumps is with a 1 1/2" auger six feet long and a stick of 1 1/4 X 6" 60 percent dynamite. Hell it hardly even is audible if set right and it just lifts them 2 to 4' stumps about 6" in the air and they settle back down into soil that looks like it had been run over by a tiller. Then all ya have to do is go pick it up with an end loader. With all the bombing freaks it may be a little more difficult to buy dynamite now, but as far as I know it is still legal to purchase. Some states require a blasters license which is pretty easy to get. Just take a short course and a fairly easy test. Of course you can't do this in suburbia, but out on the farm that's how the big ones are removed.

Use Mr Dupont - He's tireless

Dr Dan

PS You should see what the ripper on a Cat D-9 does to a 4' stump. Wow what a machine. I have a friend that has one as a toy. He'll let it go for $30,000 but heck with my 2 1/2 acres I couldn't really get into it, but looking at 75 acres that need clearing. Mmmmmm - holds 400 gallons of fuel. May suck up a bank account pretty fast, but what a rush!

 

[ddl]

Re: Pulling stumps/Chain Energy

The problem with the whipping action is that each link is a seperate unit, with stored energy depending on the forces of the link connected on each end of the link. If a link breaks, most of the stored energy is released in the breaking of the link, any movement will be caused by the energy left in the link. But since the link broke and deformed, most of the energy has been lost. For everytime a material changes shape, the Y modulus changes. Also remember that the forces on the chain is eaual in each direction, if a link breaks, the whole chain will relax and the mass of the chain reduces the stored energy. The whip many be a little but not the force of a cable expanding and contracting as forces change in a cable. The whole idea of a chain is the rlease of energy in the relaxing tension. I enjoy this discussion, keep it going. The only thing betteer would be decuss the programming of a microcontroller.
Dan L

 

[MJB]

Re: Pulling stumps/Chain Energy

<font color=blue>The only thing betteer would be decuss the programming of a microcontroller.</font color=blue>
Now there is an off-topic discussion!/w3tcompact/icons/laugh.gif I did a fair amount of microcontroller programming back in my college days, mostly Intel 8051 and 8096 stuff. I am not sure if I remember enough about it to carry on a meaningful discussion though./w3tcompact/icons/frown.gif

Computers don't make mistakes.... What they do, they do on purpose.

 

[RPM]

Re: Pulling stumps/Chain Energy

Naah - fundamentally as soon as the link fails this is a kinematic / dynamic problem. Have to get past the static load failure analysis and think about the dynamics of the problem here.

Perhaps I should pose the question this way instead - some of the respondents think that the chain just goes limp when it breaks. How can you explain anecdotal evidence such as below if you believe that the chain releases in such a low energy mode? ...

1. Tractor towing information from North Dakota State University
2. Dozer Accident at the Ontario Forestry Safe Workplace Association
3. Death of farmer on tractor at theMinnesota Department of Health


(By the way, some good info with regard to tipping the tractor:
4. A good warning on tipping the tractor from the NIOSH
5. Death of a farmer uprooting a tree in Wisconsin)

I'm telling you ... following the initial failure of a link there is a tremendous amount of energy released. Since it is typically one side of the link that breaks first it creates a whiplash effect down the chain. /w3tcompact/icons/shocked.gif

 

[RichS]

Even if it breaks close to the tree it will help dampen the recoil. If you need, put a couple on the chain.
It is not perfect but it is a definite help.
The only place where it does no help is if the chain breaks on the tractor side of the bag/tarp/blanket.

Rich S.

 

[Anonymous Poster]

Without a doubt, any type of cloth material would be a “dampener”…

I guess, I’m really trying to say… not to put all your stock on that blanket/tarp/etc. in case the chain breaks, kind of a false sense of security that’s all.

In my potential disaster, my brother-in-law made a mistake by stomping on the gas, violently jerking the chain {fairly new} causing the chain to shear and setting up a “chain reaction” of recoil chain almost taking my head off… {…and his coat was wrapped in the middle!}

On a lighter note, I sure hope all our resident TBN engineers get this chain/cable thing figured out, so they can get some sleep…./w3tcompact/icons/wink.gif