Pulley with Guide-mode belay?

Has anyone experimented with integrating a pulley into guide mode belays?

Seems to greatly reduce friction when pulling ropes which would be great when pulling lots of rope or fatter ropes. Other than some extra weight and setup time, I can't think of any drawbacks.

Really?  Not even one?  

Okay I'll start:

YER

Isaac Mann-Silvermanwrote:

Okay I'll start:

YER

Gonna

lolz.

Double Jwrote:

Really?  Not even one?  

Ok, I’ll take the bait. Is the issue that it also reduces the (highly desirable) friction from the climber strand cinching down on the brake strand if the climber falls, which is literally the whole point of guide mode?

Assuming Taylor is not trolling, or at least that someone else reading might not suspect a problem …

A rule of thumb for a loaded rope running over a biner is that the load is reduced ~30% by friction.  Assuming that, and when instead catching a fall with the pulley which eliminates that reduction, there is  30% more force towards causing the brake strand to start slipping through.

That is a significant increase. 

To put that in terms of all the variables, adding the pulley would increase the percent of circumstances when guide mode will fail to stop a fall.

And I doubt one could wholly make up for that increase in failures by going to fatter ropes without gaining back more handling resistance than was avoided by using the pulley.

Taylor Petersonwrote:

Has anyone experimented with integrating a pulley into guide mode belays?

Seems to greatly reduce friction when pulling ropes which would be great when pulling lots of rope or fatter ropes. Other than some extra weight and setup time, I can't think of any drawbacks.

The ONLY drawback is that you have the locking gate of the blue biner rubbing against the tree and if that gate unscrews the whole system will quit working as desired.

Edit: have you filed for a patent?

If you’re only belaying one follower (aka: one rope at a time) using a Gri Gri greatly reduces the friction from pulling the rope through the device.

If you must belay two followers simultaneously, switching to a Kong Gi Gi or Camp Ovo with a nice large round stock locker is much more efficient than using an ATC.

The question becomes when is it worth it to carry two Gri Gri’s instead of a GiGi?

Bill Lawry wrote:

Assuming Taylor is not trolling, or at least that someone else reading might not suspect a problem …

A rule of thumb for a loaded rope running over a biner is that the load is reduced ~30% by friction.  Assuming that, and when instead catching a fall with the pulley which eliminates that reduction, there is  30% more force towards causing the brake strand to start slipping through.

That is a significant increase. 

To put that in terms of all the variables, adding the pulley would increase the percent of circumstances when guide mode will fail to stop a fall.

And I doubt one could wholly make up for that increase in failures by going to fatter ropes without gaining back more handling resistance than was avoided by using the pulley.

Braking in guide mode is achieved by the climber’s strand pinching the brake strand due to the orientation from which the device is hung. Does braking have enough to do with the friction around the carabiner that exchanging it for a pulley would cause that pinching action to stop working on its own?

Taylor, you're so close to inventing the MicroTraxion. Which in the olden times consisted of a pulley+ascender to catch the rope.

I have seen a few guides top belaying with a Microtrax to save their arms. You need to keep the rope tight so the teeth don't damage the sheath on your rope.

...

P.S. I don't think I'd recommend this technique for the general public. Pulling up rope isn't that bad! If you're too pumped from belaying gotta hit the gym ... haha ....

Alex Fletcherwrote:

Braking in guide mode is achieved by the climber’s strand pinching the brake strand due to the orientation from which the device is hung. Does braking have enough to do with the friction around the carabiner that exchanging it for a pulley would cause that pinching action to stop working on its own?

It’s not the pinching action that changes. That stays the same - as I think you suspect.

What changes is how much pull force is on the brake strand. With the pulley, there will be more force encouraging the brake strand to slip under the still-same pinching action of the load strand. 

I have definitely heard of guides using micro trax to top belay.

what is the public opinion on this? Petzl gave us testing and some notes about it.

Should it be widely accepted? Should it be for guides / advanced users only? Why? Should it be discouraged and not recommended instead?

in terms of rescue, it would be easy to lower someone in conjunction with a Gri Gri to the belay loop. Belayer sits back and disengages the micro’s teeth, lowering carefully from the Gri Gri on the waist.

If you needed to get the micro out of the system first, that would be obnoxious but doable using a short block and tackle haul.

Bill Lawrywrote:

It’s not the pinching action that changes. That stays the same - as I think you suspect.

What changes is how much pull force is on the brake strand. With the pulley, there will be more force encouraging the brake strand to slip under the still-same pinching action of the load strand. 

Given that the pulley has a much larger diameter than the blocking biner normally used. the climber's rope may exert significantly less downforce on the "pinching point".

This set up COULD have potential for solo lead belay.  Maybe.

Gunkiemikewrote:

Given that the pulley has a much larger diameter than the blocking biner normally used. the climber's rope may exert significantly less downforce on the "pinching point".

True about larger pulleys, maybe.  Hadn't considered.  And that will still depend on the length and depth of the slots.

So it goes from bad to maybe worse in terms of intended use of original engineering. Still, could address the large pulley diameter with one of those small plastic REI pulleys?  Or a carabiner pulley?