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Topic Date User

Solo Top Rope with Mini-Traxion. 26-Aug-2007 At 10:55:10 PM JBM

Message

I'd like to rekindle this debate.

I recently became acquainted with a shunt as an abseil backup during some alpine climbing and have begun using it to self belay on top rope on projects that are still a couple grades beyond me.

Clipping the shunt directly to my belay loop on a 10mm rope seems to work a treat. I weight the bottom of the rope about 1m of the ground to take into account rope stretch and the shunt slides smoothly up the rope with no dramas. I took about 20 "slumps" onto the device today with no obvious rope damage (caused by the shunt, at least) and I lowered off easily with prussic and abseil device.

Is there a better a self belay system out there? If so, I'd like to know about it. Has something better been developed since this debate in 2005?

As an aside: I understand that Dave Macleod used a shunt to work the moves on his E11 Rhapsody.

Let's hear it.

On 22/06/2005 The good Dr wrote:
>There seems to be at times a misunderstanding of what various devices actually
>do, and how they operate.
>
>In terms of the shunt the device is designed to absorb energy by sliding
>a small way down the rope when shock loaded. Some informal tests have been
>conducted on the shunt and other devices (eg ascenders) in terms of their
>shock load absorbtion capabilities. Ascenders do tear sheaths and will
>sever ropes due to the aggressive teath. The shunt does not. One particular
>area where a shunt will fail is if during the slide (up to 60cm) it encounters
>a knot. This transfers the energy back into the casing and may cause it
>to fail. Read the technical information from Petzl to get a clear picture
>of the shunts capabilities. Each of the ascender manufacturers also have
>technical information and they usually say that the device is not to be
>used as a fall arrest device (I have yet to see an ascender which states
>that it conforms to the Australina Standards as a fall arrest device).
>
>The following is also incorrect.
>
>>Even at best industrial shock absorbers are designed to minimise the
>chance
>>of death in a fall, not act like a dynamic rope, ie soften the fall,
>the
>>amount of force needed to deploy one is enough to make you one sick puppy
>>for awhile!
>
>The forces generated in a fall are greater than you think and the body
>absorbs quite large amounts of energy. An industrial shock absorbing lanyard
>is designed to reduce the force transmitted to the body to a maximum of
>6kN. They are designed for a maximum free fall of 5.75m. Smaller falls
>will give partial deployment of the shock absorber. The initial limit of
>deployment for the shock absorber is up to the manufacturer but must still
>be within the scope of the Australian Standards (AS/NZS 1891.1). In combination
>with a fall arrest harness that is correctly fitted the forces transmitted
>to the body are not excessive, though if you do take the full 5.75m fall
>you are sure to have one or two tender spots.
>
>Heresay is not great when it comes to equipment, as each has its design
>purpose and usage restrictions. A lot of industrial equipment failure is
>caused by incorrect usage, not poor design.