Double Rope Autolocking Belay Device

As part of my senior design project for Mechanical Engineering, my group is interested in designing a sort of two rope auto locking belay device. There is a link to a survey below meant to gauge interest and identify design criteria. If you can spare 2-5 minutes, your input would be greatly appreciated.

docs.google.com/spreadsheet…

Luke Engvall wrote:As part of my senior design project for Mechanical Engineering, my group is interested in designing a sort of two rope auto locking belay device. There is a link to a survey below meant to gauge interest and identify design criteria. If you can spare 2-5 minutes, your input would be greatly appreciated. docs.google.com/spreadsheet…

Click here...

I recommend you include comparative belay devices in the weights question instead of just using grams.

The Reverso can autolock two ropes at once. A double rope grigri or cinch would be cool though

"Here's your sign"

milfred wrote:The Reverso can autolock two ropes at once. A double rope grigri or cinch would be cool though

Not always, according to the instruction manual.

This is a common misconception about both the ATC guide and the Reverso.

Matt N wrote:"Here's your sign"

Considering they list the SMART Alpine I believe they are aware of the devices that you have listed. If you read the post, they are looking to design such a device, presumably one that could compete with those you have listed.

Now be nice and answer their questions.

The mammut smart alpine does the job very nicely, and can replace all the other devices if you ask me..

MegaGaper2000 wrote: Not always, according to the instruction manual. This is a common misconception about both the ATC guide and the Reverso.

True. Only double autoblock for belaying the second (and third if at the same time)

Not an autoblock for lead

That CT device sure looks interesting.

The Smart doesn't lock up as reliably as I'd like. I consider it more of a breaking-assist device. Nice for belaying a hangdog, but not the best for lazy aid belays.

The Hewbolt double is the best I've found for autolock with two ropes. Simple and reliable.

Hopefully this can help you out. Lots of interesting designs that have since been discontinued, or were not available in the US.

There's definitely a few that caught my eye

storrick.cnc.net/VerticalDe…

milfred wrote: True. Only double autoblock for belaying the second (and third if at the same time) Not an autoblock for lead

That is not what I am saying.

The Reverso has the potential to only autoblock the second OR the third. If one falls, the autoblock feature can be disabled for the other.

Look at the instruction manual and see for yourself:
petzl.com/files/all/technic…
See illustrations 11a and 11c.

As I understand the picture there, the risk only really occurs if the two seconds are at different angles to the belay device. Then, if one falls, her weight can hold the belay device 'open' - at an angle that prevents the other second's (the 'third' ?) line from autoblocking. Not the world's greatest risk, but something to be aware of, nonetheless.
Illustration 11c in the petzl instructions above offers a specific example of how this could happen.

As I understand it, the same thing goes for the ATC Guide and all other devices that depend on the weight of the falling climber to pull the device into a constricting orientation in autoblock mode.

That, I believe, is why the engineering students are trying to design a new type.

As a very long-time user of double ropes, my primary concerns, in order of importance, are:

1. Adequate breaking power for big falls on a single (relatively thin) strand. I don't care about autolocking per se, an "assisted braking" system is good enough in principle. It isn't clear to me that either the current Reverso or BD plaquettes are adequate for catching big falls on 8.5mm and below strands.

2. Effective handling of two ropes for belaying the leader. It should be natural and uncomplicated to simultaneously---or nearly simultaneously---pay out one strand while taking in the other. The Smart Alpine gets low grades for this in my opinion, and the usual ATC-type devices are slightly better but far from ideal.

3. Effective rappelling. This means adequate friction, smooth operation, and minimal kinking of rap lines. Autolocking on rappel is a plus, but only if it is reliable. The Smart Alpine stinks for rappelling.

4. Construction that does not allow for noticeable changes in performance as the device wears. Altered performance was the worst feature of the TRE Sirius, which was otherwise the best of all devices, current and past, in terms of handing the leader's ropes.

Current fads in belaying notwithstanding, I don't care about special features for belaying the second. If some sort of autlocking second belay is provided, I am unlikely to use it if it doesn't allow for smooth two-way handling of the rope, a feature none of the present systems comes even close to providing.

I would like to see a belay device like an ATC/Reverso that trades support for 11mm ropes in favor of better breaking performance for 9.5-10.2 mm ropes. Current devices seem to let skinny single ropes especially dry ropes slide too easily for my comfort.

climber pat wrote:I would like to see a belay device like an ATC/Reverso that trades support for 11mm ropes in favor of better breaking performance for 9.5-10.2 mm ropes. Current devices seem to let skinny single ropes especially dry ropes slide too easily for my comfort.

I agree with climber pat. I would love to be able to have an atc guide or petzl reverso designed for a max diameter of 9.5mm and better performance for alpine ropes (i.e. 7.7mm twin ropes and 9.0mm singles.)

cool, Luke, got your survey in.

There's a comparison of various semi-industrials and a few papers on recreational devices throughout the ITRSonline archive, though you'll have to fish through. If I remember one, looking for the 'holy grail' in 2009; which may be fitting as well to your quest.

That belay device pictured ^^^ up there looks like an alien spaceship.