paulspage2018.jpg

​No.20  Midline Drift Anchor

The midline drift anchor is an easy way to move tree sections over a long distance.

It works by winching the section up to an anchor and then releasing that anchor toward the next one, continuing on until you reach your drop zone.

We moved the small trees in the middle of the photograph, through the air, to point G.

We chose to rig this system because the slope was steep and slippy and we felt that, although the trees were not large, it would cause an excess amount of cutting with unsure footing. This system gave the team less effort, less exposure to the chainsaw on the slope, no dragging and throwing and only 1 cut to remove each tree.

mlda_1.jpg
mlda_1_2.jpg

Components

Portable Winch and Hitch System

3000 Portable Winch

Portawrap and sling, 10mm class 2 double braid rope, Pinto Pulley, Karabiner and 10mm prussik loop.

 

Anchoring

Small Impact block/16mm deadeye

2 x small ISC block 16mm deadeye

X Rigging Ring deadeye

 

Friction

Portawrap

Natural

 

Re-directs

Sling, Pinto pulley and steel oval karabiner

Rope

1/2” double braid - winch

1/2” double braid - drift anchor

1/2” 16 strand - control rope

A Portable winch

B Drop Zone Anchor

C Drift Anchor

D Drift Anchor Friction Point

E Control Rope

F Control Rope Friction Point

G Drop Zone

mlda_2_2.jpg

Drop Zone Anchor

mlda_3_2.jpg

Drift Anchor

Winch line running off to left and drift line is attached to lowest block.

mlda_4_2.jpg

Drift Anchor Friction Point

mlda_5_2.jpg

Control Rope

mlda_6_2.jpg

Control Rope  Friction Point

mlda_7_2.jpg

The winch rope is pretensioned and then left to hold by the prussik only.

The winch should never be shock loaded.

スクリーンショット 2021-12-19 14.24.18.png
mlda_8_3.jpg

The tree is pulled toward point C. The long distance is controlled at point E.

mlda_9_2.jpg

Point D

mlda_10_3.jpg
mlda_11_3.jpg

The tree is lifted by the winch and then drifted at point C/D toward the drop zone.

Once the tree is in the drop zone the drift pulley is reset and the rigging is repeated.