New Rock Exotica Pulley

[SomethingWitty]

Has anyone ever gotten any damage from running Atlas in their Omni? It's a little strange that these promo pics feature a rope that isn't within the specs for the product. I just bought an Omni and the Atlas fits in fine but it does seem like the outer edge of the sheave might dig into the rope since it's a little more narrow.

I would guess that the inconsistencies in sizes and claims of sizes that run rampant with rec and pro equipment and ropes, as well as the tendency to recommend things that are definitely acceptable rather than "eh, it could probably work" are to blame.
Half of an inch is 12.7mm. 9/16ths is 14.2mm. I see those two sizes misrepresented constantly.
If the omni 2.6 was honestly more like 13.8 mm safely, long term, with no wear on the side plates beyond what a 13mm rope would cause, then they would still rate it at 13mm.
There's also the matter of loaded vs unloaded lines. As tension is applied and rope elongated, the diameter shrinks somewhere between appreciably and slightly depending on the load and the rope construction.
I'm willing to bet that RE knows what they're doing, even if I don't know exactly what it is.

 

[JeffGu]

Atlas stretches a lot, and drops right down into the sheave tightly when it does. The pictures that RE released when the pulley came out showed it with Atlas rope in the pulley. I figured they probably wouldn't do that if they thought it would be an issue. Under load is where it really matters, and like you said, the 9/16" might be as skinny as a fat 1/2" polyester rope (like XTC) depending on its actual size under load. Most of the rope OEMs that I talked to measured their rope under 40 to 50 pounds of tension. I've found that they're all over the place when you measure them from no load to a couple hundred pounds.

I played with it on a job on an acreage with no targets, and the Atlas seemed fine. I'm not so sure that other 9/16" or 14mm ropes would necessarily work as well. I seem to remember seeing Atlas diameter listed as 13.5mm somewhere.

 

[Tree-Taylor]

I touched based with RE on the matter. They mentioned that using Atlas in those photos was an oversight and is not the size rope they recommend for the device. However, using a slightly larger dynamic rope does not present "any major concern or risk".

 

[colb]

I'm aware of some 9/16ths all gear husky rigging rope that was used over a year or two of time in an omni 2.0 without issue...

 

[SomethingWitty]

I touched based with RE on the matter. They mentioned that using Atlas in those photos was an oversight and is not the size rope they recommend for the device. However, using a slightly larger dynamic rope does not present "any major concern or risk".

If that's the official stance, I'll take it.

 

[oceans]

I’m pretty sure that RE’s Omni series Blocks are under-rated for our environment, but for the company to cross market a particular tool, it’s got to meet criteria we may not consider. These blocks are used by so many industries, I’m certain another took precedence over the labeling spec’s.

That said, let’s not digress into a “pulley vs. block” discussion, and just follow RE’s recommendations on this one. It’s a darn fine piece of kit that I use on a regular basis.

 

[Tree-Taylor]

I’m pretty sure that RE’s Omni series Blocks are under-rated for our environment, but for the company to cross market a particular tool, it’s got to meet criteria we may not consider. These blocks are used by so many industries, I’m certain another took precedence over the labeling spec’s.

That said, let’s not digress into a “pulley vs. block” discussion, and just follow RE’s recommendations on this one. It’s a darn fine piece of kit that I use on a regular basis.

I have Atlas and an Omni. I was hoping to use them in conjunction as shown in the picture released by RE... wasn't anything more complicated than that.

 

[oceans]

I have Atlas and an Omni. I was hoping to use them in conjunction as shown in the picture released by RE... wasn't anything more complicated than that.

No intentions of putting you or anyone off with my previous post. Re-reading, I can see how the second paragraph might, but while writing, I was thinking of an older thread in which people argued over what’s a pulley and what’s a block...and I could see someone chiming in with that since splitting hairs on rope diameter began over a minor oversight by RE. Was meant in good humor.

When I first got the Omni Block from Brandon, I nagged him about the rope spec. The sheave profile radius is far larger, and the cheek plates are far wider than the smaller Omnis, but the rope diameter rating is the same across the board. The 2.6 even nudges you past 1/2” @ 5:1 bend. It was just weird in my mind to release a product that way, but understanding their markets helped it make sense.

Again, my post was just a broad statement to anyone wondering what’s up with the labeling on those blocks, and how it sure looks like 9/16”, or even a 5/8” line might ride nicely in there.

 

[colb]

The 2.6 even nudges you past 1/2” @ 5:1 bend.

I feel like I'm missing some baseline information about ropes and blocks/pulleys. What's 2.6 refer to? What is the significance of a 5:1 bend, and is that a bend diameter:rope diameter ratio?

 

[evo]

I feel like I'm missing some baseline information about ropes and blocks/pulleys. What's 2.6 refer to? What is the significance of a 5:1 bend, and is that a bend diameter:rope diameter ratio?

I think so.. I’ve been taught 4:1 bend ratio but more is better. 2.6 would be sheeve diameter which would get you a 5:1 bend ratio on 1/2 which could be some rescue specs or what not.

Regardless block has bushings and Pulley has bearings.. not black and white across the board, but bushings handle shock loads better. Need to know the basics before you learn what limits can be pushed and what ones cannot.