Arborist SRT systems
Many of the devices used by arborists to work on stationary rope will be familiar to rescue operators . Products such as the Petzl RIG or I ’ D are used as belay devices at basal anchors or as part of personal work positioning systems .
A wide range of SRT work positioning devices are now used by climbing arborists . Almost all of these are designed to be multi-function ascenders and descenders .
As can be seen in the image , the rope tail exits below the device , unlike with traditional descenders where the tail exits at the top of the device . This allows arborists to use foot and knee ascenders to ‘ rope walk ’ rather than using sit-stand ascent setups .
There are too many arborist-specific SRT devices to detail in this manual , and the pace of development would make any such effort rapidly obsolete .
Most of the available devices use some variation of a camming system , whereby the weight of the operator forces an orientation of the device which increases the compression applied to the rope . Most such devices can be actuated by using one hand to open the device , usually by depressing the top handle or plate . Do not attempt to actuate an unfamiliar device without first securing the casualty ! Few arborist devices have fail-safe or panic functions , and some will drop the climber very quickly if opened aggressively .
Another type of arborist-specific SRT system uses an additional friction device attached above or below a friction hitch . Several of these systems are commercially available and vary in appearance ; all are designed to remove the additional friction when the hitch is advanced during ascent , and then automatically apply the additional friction when the system is loaded .
The additional friction prevents the hitch from binding and allows the arborist to descend smoothly by opening the hitch .
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