Base anchor pulling capability’s vs isolated fork

[TTownsend]

 
Wrong. 
 

How come... ?

[scotspine1]

16 minutes ago, TTownsend said:

How come... ?

 

With the rope base tied through a union your pulling force angle will be along the red line, so less leverage, makes it harder to pull over. 

 

 

 

 

[carlos]

we nearly always throwline through a fork and tie down the back at the base, seems to work fine and a lot easier than climbing.

[scotspine1]

36 minutes ago, carlos said:

we nearly always throwline through a fork and tie down the back at the base, seems to work fine and a lot easier than climbing.

 

Same here but on critical, large or back leaning trees it's worth keeping in mind you'll need more pulling force with a base anchor tie off than you would with an isolated  fork. 

 

[Dan Maynard]

I agree it is possible to sum the two rope force vectors to get the red one, but as this is the sum of two forces the red force is bigger than the rope tension.

The force across the stump to pull the tree over is exactly the same.

I would consider it from the digger end, a certain pull on the rope has to be resisted by the tree no matter how it's tied on, what changes is the loading within the wood.

[Mick Dempsey]

8 hours ago, scotspine1 said:

 

With the rope base tied through a union your pulling force angle will be along the red line, so less leverage, makes it harder to pull over. 

 

 

 

 

Had often wondered about this, thanks.

[Mark Bolam]

See Tim, we were both right!

 

I must admit when we were pulling some big leaning pops over beside a caravan park each tree was climbed and the wire chokers placed round the stem at exactly the point directed by the bloke with the 35 tonne winch.

 

No margin for error or snap outs.

[difflock]

To me as a non-Arb person, a world of difference in these 2 techniques, in that I would not dream of flipping a line through a crotch/fork and tying off at the base, I dont know why, but I would always, but always climb, however inelegantly, and most probably using ladders and tie off at the choosen pulling point.

Simple farmers son applied mechanics at work.

[Mark Bolam]

Spoken like a true non-arb person Marcus!

[Mark Bolam]

I think Dan summed it up best earlier.

If the winch is pulling 3t at the point where the rope is in contact with the tree, it’s pulling 3t, however the forces spread out in the tree.