Skate block ( casualty )
A skate block system connects the casualty to the tensioned main line using a suitable pulley and adjustable connector . As the casualty is lowered , they are simultaneously moved away from the tree toward the lowering anchor .
This technique is a simple and efficient way to extract a casualty from a tree with dense lower branches , where there is a suspended load or other aerial hazard , or where there are hazards such as steep terrain that make a direct lower undesirable . Vertical rescue teams will be familiar with this approach from training in cliff , tower , and structure rescue systems .
When using skate block or similar techniques during tree rescues , care must be taken to limit the force applied to the tree ’ s structure .
Where the tree structure is not sufficiently strong to sustain the force that would be applied , the top pulley for the skate block line should be installed as a floating anchor ( as pictured above ) with the anchor line passed through a suitable fork of the tree and secured to a suitable anchor away from the tree in the same plane as the skate block ground anchor ( pictured above ). The resulting force on the tree will be reduced in magnitude and will act vertically downward as compression force .
Skills that may be required for skate block :
Technique
Description
Evaluating tree anchors Chap . 2.3
Skate block Pg . 175
Floating anchors Pg . 170
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