Petzl Basic Modification

[potholer]

Apart from possibly the odd one with a recent Croll, the only Croll disconnects I've had in a hybrid frog/ropewalking setup were with the ~1984 bar-and-pin catch model.
The subsequent Croll catch designs (flat or twisted metal 'D' plate with thumb loop) would seem likely to have been fairly immune, but I wasn't really doing much apart from frogging when I had one of those.

I think the current plastic design is probably at least a bit better than the ~1984 one, which could pretty much be 'wiped' open with the base of the thumb when doing changeovers.

[Tim White]

Has anyone experienced this with the older designs of the Petzl Croll and/or Basic? None of my caving group using the older designs has ever experienced this type of failure.

I’ve seen the new Croll open and come off the rope as you describe a number of times. It has always been under they type of circumstances that you describe. They come off of the top climber who is using a rope-walker on a tandem climb.

My simple analyses... With only normal rope weight below, a climbers feet and legs are in a natural position for that person (about shoulder with apart) while climbing rope. But adding the weight of the tandem climber below, the rope is now in a very taut position below the top climber. This position forces the top climbers feet and legs close together when stepping in the rope-walker. In this situation, the climbers boot sole, bootlace, pants cuff, or other simply part catches the protruding plastic latch on the Croll and opens it. I’ve never see this happen other than on a tandem climb.

Remember, the Croll was not designed to be attached to ones foot or knee in a rope-walker system. Down at you foot/knee level, out of sight and reach is beyond the manufactures design and intended use of these items. But we American TAG pit bouncers do use them in that manner.
Be aware of the conquences of how you use you gear.

I just glad that Berta and I have a supply of old style Crolls.

[NZcaver]

:!: Remember, the Croll was not designed to be attached to ones foot or knee in a rope-walker system.

--> Nor the Basic, or the Ascension. Only the Pantin.
I concur with Tim's analysis on this.

The Petzl ascenders coming off rope issue does not have to be linked to draging the ascender against any rigid surface such as rock... I personally saw a climber have two of the newer Petzl ascenders come off rope THREE times each within 5 minutes... I saw nothing that made me believe there was any outside influence on the ascenders...

What about the ascender catch rubbing against boots, clothing, straps etc while being raised (as Tim mentioned)?

As I posted earlier in this thread, the instructions that come with your ascender(s) actually warn you about this:

Specific Information (Ascension and Basic)
http://en.petzl.com/ProduitsServices/B1 ... 502-F1.pdf

Precautions
Guard against anything that could accidentally open or
block the action of the cam or the safety catch (webbing,
clothing, pebbles, twigs...)

Specific Information (Croll)
http://en.petzl.com/ProduitsServices/B1 ... 500-03.pdf

Safety Instructions
Guard against anything that could block the
action of the cam (pebbles, twigs...)
Beware of catching the safety catch in clothing
and webbing.

Plus Petzl describes (and shows) the Croll ONLY being used as a "chest ascender" - attached to the seat harness via a half-round maillon rapide.

Of course, we cavers always come up with our own ways of doing things - and a toothed-cam ascender is definitely more efficient and easier to open/close intentionally than a lever-cam (ie Gibbs) ascender anyway. Suggestion - modify your ascender safety catches per what Scott and Hank posted, or find some of the old-style models.

[Scott McCrea]

Here's another potential way to not die if your ascender cam comes open. I would never do this while caving, but it would work. It would very inefficient, but it would work...

I had an Arborist in my practice tree today--practicing vertical caving stuff, not working. He is new to vertical caving and instictively used some arborist techniques. One was a 5mm accessory cord tied to the lanyard of his QAS, tied right into the knot at the bottom of the ascender. The cord then went up the outside of the ascender. A friction knot (I think it was a taughtline) was then tied to the rope just above the ascender with as little slack as possible. So, when the ascender was pushed up, it would push the friction knot up with it. And, in theory, if the ascender failed, the friction knot woud catch.

I asked him why he used this. He said that when climbing up thru tree branches, it's possible to catch the cam on something and pop it open.

Not real efficient, but if having the cam open is a common problem, I suppose it might save your hide.

[potholer]

The old Petzl Expeditions, where the catch was a bar with had interchangable pins sticking out (short for cavers, long for winter mountaineers wearing mitts.
When pins unscrewed and got lost, some people threaded a little string through the hole, and had a small (1-2") loop with a knot they could pull down to open the catch.
When Crolls moved to the D-shaped metal catch plate with the thumb loop, and before the plate was twisted to make it easier to open, some people used a small string loop there to give something to get hold of.

I dare say using a Dremel to do a mod like Scott's (taking off most/all the lip of the 'thumb bucket' on a modern Croll's plastic catch, or shaving down the catch on a Basic), and then drilling a small hole through the catch for a string thumb-loop might make it much less prone to opening yet still leave it easy to open (even wearing gloves) by pulling the loop. If wanting to leave a really smooth front surface, two holes could be drilled, with the hanging loop exiting at the back of the catch, and the flush-fitting front loop smoothed over with epoxy.

[NZcaver]

Here's another potential way to not die if your ascender cam comes open. I would never do this while caving, but it would work. It would very inefficient, but it would work...

But - your ascender cam is not going to come open if it has your weight on it anyway! So what really kills you is inattention - not noticing that your unweighted (solo??) cam has come off the rope, before applying your full weight to it.

If that arborist is using a single-ascender technique, and he likes the functionality of a handled ascender combined with the security of a trusty hitch for backup - then sure. More power to him. Still I think it would be more efficient and no less convenient to just ditch the ascender and use the old tautline hitch, or a VT with a small pulley on the bottom. That seems to be how many (most?) arborists do it.

Otherwise, if he's using a 2 ascender system (like a Frog etc) - what's the point? You already have your redundancy built-in.

[caverd]

I’ve seen the new Croll open and come off the rope as you describe a number of times. It has always been under they type of circumstances that you describe. They come off of the top climber who is using a rope-walker on a tandem climb.

My simple analyses... With only normal rope weight below, a climbers feet and legs are in a natural position for that person (about shoulder with apart) while climbing rope. But adding the weight of the tandem climber below, the rope is now in a very taut position below the top climber. This position forces the top climbers feet and legs close together when stepping in the rope-walker. In this situation, the climbers boot sole, bootlace, pants cuff, or other simply part catches the protruding plastic latch on the Croll and opens it. I’ve never see this happen other than on a tandem climb.

Remember, the Croll was not designed to be attached to ones foot or knee in a rope-walker system. Down at you foot/knee level, out of sight and reach is beyond the manufactures design and intended use of these items. But we American TAG pit bouncers do use them in that manner.
Be aware of the conquences of how you use you gear.

I just glad that Berta and I have a supply of old style Crolls.

[/quote]
Very good points presented by Tim.

It is very possible that the foot ascender, as it is being pulled up the rope by the bungee cord, could rub against the other foot. The only thing that the knee ascender could have rubbed against would be the side of his pants. I did not see any interference from anything during the climb, but that doesn't mean it didn't happen.

I spoke with Bruce Smith (On Rope 1) about this issue earlier this year. He was not aware that it was happening. I understand that each of us assumes some level of responsibility when using this type of gear. Is there any potential risk to vendors who design and sell climbing systems that incorporate this equipment that we now see failing under specific circumstances? I would also like to learn more about the history of the development of the Petzl ascenders. I know they were designed for cavers. Were the initial designs intended only for specific climbing systems (frog system as currently illustrated in Petzl literature)? If Hank is following this, can you chime in?

I too am glad that I have a few of the older Petzl's to use (as well as Kong's). Mine have been going strong for 15 years.