rotten lime dismantle

[jojam]

Just a little pointer, not critisism of the original post.

 

For anyone using such as a vehicle to pull over large lumps, especailly on a tree showing basal decay, you must be careful on guaging how much pressure you are exherting on the stem.

 

Remember the stem is a lever, if you pull a given force on that lever, the longer the lever the more the force at the base. A small force on the top of a 40ft stem will exhert tremendous pressure at the bottom.

 

The base or soil level of the stem becomes a fulcrum point and theoretically, 100kg of force applied 40ft up a stem can be as much as 4000kg at the base.

 

Not good with basal decay.

 

I personally only ever pull over lumps I'm cutting with a rope by hand. Unless it's a felling cut and the whole stem is coming over.

 

Be very careful using techniques above, you really do need a good understanding of the forces involved.

i'll second that.had a nasty experience with a beech-fell in the tree.Stretchy poly prop rope tied onto my valmet and an oversized hinge.The don't make a good combo!Classic barbers chair.Yes you certainly do learn by your mistakes.Sometimes you need things like that to keep yourself real

[scotspine1]

For anyone using such as a vehicle to pull over large lumps, especailly on a tree showing basal decay, you must be careful on guaging how much pressure you are exherting on the stem.

 

Very good point Dean

 

 

The base or soil level of the stem becomes a fulcrum point and theoretically, 100kg of force applied 40ft up a stem can be as much as 4000kg at the base.

 

Dean, get what your saying but from what I remember from engineering classes at school you can't mix metric with imperial, it doesnt mean anything. If you'd said 100kg of force is applied 12 metres up a stem the torque at the base will be roughly 1200Kns...about a ton.

 

 

 

techniques above, you really do need a good understanding of the forces involved.

 

Very true.

[Dean Lofthouse]

Only reason I've done it like that Tim is because each unit multiplies and I was taught in feet and inches

 

Ie: If side A was 1ft and side B was 40ft

 

Then A would be 40x B

 

As below:

[Dean Lofthouse]

Just another point, the fulcrum takes the combined force of a and b .

 

In the case of a tree stem, the fulcrum would be soil level so my example above is incorrect, the force on the fulcrum would be double, it would be 8000kg, not strictly accurate because soil is soft and would give but the principle is there.

[scotspine1]

Just another point, the fulcrum takes the combined force of a and b .

 

In the case of a tree stem, the fulcrum would be soil level so my example above is incorrect, the force on the fulcrum would be double, it would be 8000kg, not strictly accurate because soil is soft and would give but the principle is there.

 

Dean

 

The rope is not pulling at 90 degrees to the stem so not all of your 100kg of applied force is being used.

 

You are applying a moment to the tree (rotational force) on a hinge (backcut). You can find what force is really applied on the horizontal vector, from this vector tool = 71kg

 

So the correct answer would be 71 x 12m = 852Kn metres

 

The most important thing this tells you is that the further back you stand from the tree with the pulling rope - the easier it will be to pull over.

[Stephen Blair]

i learnt this when i was about 10, i had a goat that wouldnt ever cross a burn, if i extended its lead to about 30 feet ang gave it a good pull, i would drag its awkward arse over it no bother

[tommer9]

Thats like the beginning of some weird and slightly spooky childrens story......"go on grandad, tell us the one about Steve the Giant and his 30 foot goat puller":001_smile:

[Mesterh]

i learnt this when i was about 10, i had a goat that wouldnt ever cross a burn, if i extended its lead to about 30 feet ang gave it a good pull, i would drag its awkward arse over it no bother

 

[testcricket01]

im totally lost with all this angles talk now lol

 

surely its not putting much stress on the tree because its just pulling against whats left of the hinge,

[Tommy_B]

I should think you are lost, You've been thinking about it for a year!!!:lol: