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More tests required on toothed-cam ascenders

Richard Tregoweth - Monday, February 13, 2012

The 'frog' single line ascent system configured using a hand, chest and foot ascender is considered Standard Operating Procedure for most kiwi arb companies installing access lines. The system is also accepted at ITCC events.

Until the DB Tree drop tests last month there was no New Zealand data available questioning the behavior of these devices when dynamic forces were applied.

Below is a comment by Jordan Glassop from Jords Climbing Corner in response to the 'top holes on hand ascenders' blog post last week.

Jordan makes a number of interesting points along with a reference to more drop testing on toothed ascenders (highlighted in bold) so we have included a YouTube video (below Jordo's comment ) for you to consider.

The demonstration in the video depicts a 'rescue' situation using typical height safety back-up devices. You could argue the gear is operating outside of spec and not all the devices have toothed cams but it is an interesting video nevertheless.

The DB Tree drop tests produced similar results seen in the video. Drew used a Petzl Croll and Petzl Ascension on Yale Blaze with 80kgs of weight dynamically loaded - the sheath stripped to the core on impact - relatively easy.

There is no doubt, more drop tests with toothed-cam ascending devices is required.

"Yeah I would like to seek some feedback from the ISA technical committee on some of these questions we have been putting out lately... See what their outlook is. After seeing some interesting testing lately it seems to me there is no easy answer that's for sure.

Ascenders on there own without absorbers are stripping ropes relatively easy, due to the toothed cams, and prussiks aren't biting well once a rope is stripped.

If you ask me the Rope Wrench with prussik below has looked to be the most successful during a drop test (shock load) thus far. It will be good to see a longer video of this test Drew produced for us earlier, in the future sometime.

The wrench may be a winner again over toothed ascender positioning?

But the question on how to configure some of our equipment at times and what is acceptable still remains.

I can't wait for the day a team such as Petzl start running programs to investigate the "tree climbing" arena further!

I have one last question. Why aren't Petzl labeling their equipment, stamping  the rating on the relevant parts of their items.

For example if the top hole is not being tested and is not rated, then stamp that on this part of the ascender.

I like the way pulleys show how the rating applies to the way you would like to configure it.

A little more ink or another stamp would eliminate a lot of confusion at times.

Let the progression continue! :)

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