Z pulley VS. 2:1 Ratchet ?

Setting up a Z pulley with a Tibloc, DMM revolver and another pulley on the master point seems to me like the easiest and simplest way to set up a mechanical advantage. But everything I research online suggests that the 2:1 ratchet is the preferred method. To my novice eyes it seems like carrying the Tibloc, DMM Revolver and a extra pulley is less of a process than carrying the 2:1 Ratchet system around.

So something like this (with another pulley on the master point for another advantage)

imagine there is another pulley on the master point

(Deleted)

Thought he was talking bout crevasse rescue.

I should have clarified I'm referring to simply hauling a bag on big walls.

Yes, a 3:1 is way overkill for most wall applications. A 2:1 should be sufficient. Try hauling with a 3:1 and you will find out soon enough that it just takes way too long to haul a full pitch.

Fringepaste wrote:Setting up a Z pulley with a Tibloc, DMM revolver and another pulley on the master point seems to me like the easiest and simplest way to set up a mechanical advantage. But everything I research online suggests that the 2:1 ratchet is the preferred method. To my novice eyes it seems like carrying the Tibloc, DMM Revolver and a extra pulley is less of a process than carrying the 2:1 Ratchet system around. So something like this (with another pulley on the master point for another advantage)

Between the irritation of moving the tiblock down the line over and over, the inefficiency of a dmm revolver as a pulley, and the mistake of thinking an extra redirection pulley on the master point adds mechanical advantage, my advice is to try a pitch of hauling with both systems and your answer will be clear as to why one is superior to the other.

And while you're doing that and have both the ratchet and the tibloc/z-pulley/revolver side by side you'll be able to see that you're trying to compare basically the same thing, one you have to put together each time you use it, the other being self-contained and easier to setup and start using. Score another one for efficiency being the more important consideration on a wall

I'm definitely going set them up side by side to see the difference. I think the source of my confusion stemmed from thinking you need less gear for the regular Z pulley right? Even if you replaced the revolver with another pulley you wouldn't need that extra cordallete setup.

Using the Z-cord is an extra piece of gear, but I don't think there is any reasonable way around it if you want a 2:1. Plus, it is just a piece of cord. I'm pretty sure you'd need the same number of pulleys and rope capture devices to do what you propose, if i'm reading you correctly. On the plus side, because it is independent of the rope, you can put the whole system, already set up, in a small bag and clip it to your harness with the haul line. It's super easy to just whip the whole thing out and little assembly is required.

A separate question.

For the 2:1 I see allot of people using the petzl basic ascender. I already own a petzl croll ascender. Would there be any difference between the two for this ratchet set up? Or would you recommend using neither and just inverting my normal jugging ascenders?

I hate to ask this (because I think I'm supposed to know this) - exactly what is the difference between 2:1 and 3:1? I've seen diagrams and photos of rigging that looks identical referred to by both terms. In light of that, I think a lot of climbers get confused and call a 2:1 a 3:1 and vice versa.

A visual answer is probably better than descriptive.

pictures

petzl.com/en/Sport/Crevasse…

or, if you're looking for a little more
alpinerecreation.com/mechan…

Anyone have experience using the croll instead of a basic? Would it make a difference? Or is it smarter to just save weight and use a normal ascender?

yukonjack wrote:pictures petzl.com/en/Sport/Crevasse…

Now I'm really confused. The image posted in the OP is referred to as a 3:1 and the one with the cordlette involved is referred to as 7:1 !

Marc801 wrote:I hate to ask this (because I think I'm supposed to know this) - exactly what is the difference between 2:1 and 3:1? I've seen diagrams and photos of rigging that looks identical referred to by both terms. In light of that, I think a lot of climbers get confused and call a 2:1 a 3:1 and vice versa. A visual answer is probably better than descriptive.

The ratchet system and other system op posted are theoretical 3:1 advantage systems. In general the friction in the parts of the system don't allow for full efficiency so the 3:1 is called a 2:1 as that's pretty much what it's good for in practice, (is my understanding)

Fringepaste wrote:Anyone have experience using the croll instead of a basic? Would it make a difference? Or is it smarter to just save weight and use a normal ascender?

Any rope grab device will be fine as long as it flows easily over the line as you're resetting the system. Croll vs basic vs ascender is no real difference

Marc801 wrote:I hate to ask this (because I think I'm supposed to know this) - exactly what is the difference between 2:1 and 3:1? I've seen diagrams and photos of rigging that looks identical referred to by both terms. In light of that, I think a lot of climbers get confused and call a 2:1 a 3:1 and vice versa. A visual answer is probably better than descriptive.

This is a 2:1
climbing.com/skills/tech-ti…

As you can see the differences to a 3:1 include - use of a separate thin non-stretching cord. Being thin, the pulley efficiency is increased. The trax is not loaded during the pull stroke.

David Coley wrote:use of a separate thin non-stretching cord. Being thin, the pulley efficiency is increased.

How does the width of the cord have an effect upon the efficiency of the pulley?

(Not a passive-aggressive or sarcastic post, interested in the mechanics of the statement)

How long do you recommend I cut my cord for the ratchet?

kevin deweese wrote: The ratchet system and other system op posted are theoretical 3:1 advantage systems. In general the friction in the parts of the system don't allow for full efficiency so the 3:1 is called a 2:1 as that's pretty much what it's good for in practice, (is my understanding)

Not true. The 2:1 is indeed a 2:1. I'll admit it's a bit tricky, but the easiest way to convince yourself is to think what happens when you haul X inches. How much does the load rise?

If you go through this exercise for the 3:1, you'll see that if you haul 3 inches, the load rises 1. Doing the same thing for the 2:1, the load will rise X/2 (1.5 inches).

kevin deweese wrote:The ratchet system and other system op posted are theoretical 3:1 advantage systems. In general the friction in the parts of the system don't allow for full efficiency so the 3:1 is called a 2:1 as that's pretty much what it's good for in practice, (is my understanding)

They do look very similar to the 2:1, but count the strands that are actually lifting the load. In a 3:1 you are pulling on the same rope attached to the load. In the 2:1 systems a separate ratchet line is used, and the rope attached to the load just builds up slack until it's pulled through. (Unless a second person hauls on it, of course.)

kevin deweese wrote:How does the width of the cord have an effect upon the efficiency of the pulley? (Not a passive-aggressive or sarcastic post, interested in the mechanics of the statement)

The greater the bend in the rope the lower the efficiency; thus the ratio of pulley sheave diameter to rope diameter matters. One random source suggests a 4:1 ratio is enough to make the efficiency losses insignificant.

Fringepaste,
Ideal length for the hauling ratchet cord would be about 8-10' on the short side, 15' is probably getting a little long. You will want to tie a big knot in the end of the cord, to keep it from pulling back through the top pulley. Then, when you are ready to operate, you will tie into the pull cord at whatever the appropriate length seems to be for that station. This allows the operator to customize the ratchet length to account for the specific layout at each belay as well as for different sized operators.

The ideal location will be the one that puts you in the most efficient location to work the inverted ascender. When I find the right location, I prefer a clove hitch here, sometimes I clove an extra biner into the hitch to make it easier to untie from the pull cord.

I prefer to start with the pull cord a little long. Once the cord starts to wear out, you can either cut some off or swap ends.

happy hauling