mechanical advantage rigging

[jrparbor04]

did a job today and had to pull out the mechanical advantage equipment,,,ie. arborist block attached to adjacent tree with a timberhitch in the direction of fell,,,added a regular pulley attached by a prusik to the rigging line and back to anchored tree,,,only got a 3 to 1 mechanical advantage,,,but anything is better than nothing,,,and oh ya,,,used wedges also on the traditional felling technique,,,it was a 50 ft. pin oak leaning towards a shelter and fell it right between a younger swamp white oak and a play ground,,,never tried the prusik to attach the secondary pulley to the rigging line before,,,always used to use a butterfly not,,,love the new method,,,what ways to y'all use for mechanical advantage?

 

[ddhlakebound]

I do the Z rig like you describe, but I also include a biner holding an additional prussic back at the block, so once you tension the line, you don't have to hold it.

I also started out using the butterfly knot, and switched to the prussic attachment from other posts here. Its nice to use MA on a rope, and wedges to move all that weight to where you want it.

 

[John Paul Sanborn]

I started using a marlin spike hitch, which is basically a slipknot with something in the bight.

I've used a compression rig with prussic, and still do from time to time, but the GRCS with a block over it is so much better.

On simple pulls I'll just use a doubled throwline

 

[TheTreeSpyder]

Can 2Hand a Z rig for 4x pull. The prussik lets you take break and impact the rope too; as you aren't tied up/ are freed up. Can super tighten Z so that it resists bending; then bend it at right time to leverage it. The more force on the hinge, the stronger the hinge in response (given no dutching).

i like calling pulley stuff MA because it is inline; gives arithmetic/additive increase in force and not changing direction. Whereby, bending the tightened line is leveraging/ non-inline, direction changing and working on a geometric/multiplicative power of the bend. Both trade distance for power; need 3 points of force; but leveraging works more on changing angles like wrench etc. IMLHO.

 

[jrparbor04]

I do the Z rig like you describe, but I also include a biner holding an additional prussic back at the block, so once you tension the line, you don't have to hold it.

I also started out using the butterfly knot, and switched to the prussic attachment from other posts here. Its nice to use MA on a rope, and wedges to move all that weight to where you want it.

looks like im gonna have to go buy another prusik rope,,,to hold the line back i normally wrap the anchor tree with the rigging line and tie off two half hitches,,,i do like the another prusik idea though,,easier and faster

and dont have the money to buy a GCRS,,,love to get one,,,big fan of a port-a-wrap also