Using Figure 8 to lower branches...

[sprung22]

Does anyone know the max weight I could put on a figure 8 to use as a lowering device...Using 1/2" double esterlon and a 1/2" cmi pulley up top

 

[TimberJack_7]

I think my aluminum one is rated for 10,000 but I would not put that kind of weight on it.

What do you have? Steel or aluminum?

I have used figure 8's before as light duty friction devices but for some reason I always kind of forget about using the one I have.

 

[TimberMcPherson]

Keep in mind that they get really hot, like dangerously hot. Alot of friction over a small diameter of metal so rope strength will be GREATLY compromised (look up bend ratio). Light stuff in short or infrequent lowers, no worries, other than that, not advised.

 

[sprung22]

I think my aluminum one is rated for 10,000 but I would not put that kind of weight on it.

What do you have? Steel or aluminum?

I have used figure 8's before as light duty friction devices but for some reason I always kind of forget about using the one I have.

Steel

 

[arborsoldier]

Keep in mind that they get really hot, like dangerously hot. Alot of friction over a small diameter of metal so rope strength will be GREATLY compromised (look up bend ratio). Light stuff in short or infrequent lowers, no worries, other than that, not advised.

I agree completely with TimberMcPherson. I had done it in the past, but I would seriously encourage you to not use a Figure 8 to lower branches. It really isn't designed for that purpose. Very often there is a shock load applied. The true design was to lower people in a very controlled and not shock applied manner. If you are dead set on this device, Steel is your best bet. The Port-A-Wrap certainly costs more, but is so much more versatile. You can even attach something like Fiddle Blocks and use it as a lifting device.:agree2:

 

[treeslayer]

as much as the rope will hold, and it will get hot enough to glaze the rope.

 

[sgreanbeans]

:agree2:

Bend ratio is something you need to learn. Bad for da ropes. I will use them on small stuff or a redirect to keep ropes clear. Aluminum will wear faster aswell.

 

[sprung22]

Thanks for the replies.Im not looking for the pros and cons of figure 8's,I know what they are.I have other lowering devices that I use.I was more or less just looking for the WLL of one...Out of curiosity as I couldn't find it anywhere online...So what's the max weight you have put on one?

Thanks Steve

 

[Damon]

to the best of my knowledge allluminum 8's are rated at 25kn or somewhere around 5600lbs breaking strength which gives you a WLL of around 560lbs, however these devices are designed for life support not rigging. Steal 8's are rated at 50kn or aprox 11000 pounds breaking strength with a max WLL of aprox 1100 pounds, as far as shock loading goes they are designed to be shock loaded to an extent however falls on rope that is essentially static like we use for rigging generated extremely high force so it wouldnt take much of a drop in a medium sized round to generate the kind of force required to break the rope or the 8 because of the extremely high bend ratio and small heat dissipation factor, Now as an example I used to belay rock climbers on steel 8's alot using 9.8mm heat resistant rope from mammut one day climbing in mexico i repelled at such a high rate of speed to escape from some kind of particularly menacing newt or gekco or man eating lizard that gave me a nasty look when i topped out on a ledge that upon hitting the ground my rope partially melted through the outer shell before i could remove it and upon dumping a bottle of water on it it warped from the rapid cooling. At this point i had never lowered a log or a branch in my life but i assure you i often lower them on the porty at a much much higher rate then i was traveling that day.

So the answer is this: can you lower a load on one that is shock loaded? Yes? can you push them to there rated capacity without failure? sure. Can your rope handle the same kind of abuse? probably not for long. Is it a good idea? in my honest opinion for what little that counts for absolutely not.

 

[sprung22]

Thanks Damon

 

[treemandan]

Does anyone know the max weight I could put on a figure 8 to use as a lowering device...Using 1/2" double esterlon and a 1/2" cmi pulley up top

It will tell you the rating, stamped on the unit.

 

[fireman]

Steel 8 is rated G or 22,000 lb.You will melt the rope or sheath if you lower fast or the more weight you put on it.But the worse thing it will do is twist the rope on long lowers.It will work have used it several times in emergency situations.

 

[TimberJack_7]

Well I got curious and went to see what my aluminum 8 was rated for. It had 40 KN stamped in it next to one of the ears which converts to 8992 lbs.


Question for everybody else - Wouldn't an aluminum figure 8 dissipate heat better than a steel figure 8? If you look at the aluminum Port-a-wrap on Wesspur's website they make mention of it's "excellent heat dissipating properties".

 

[flushcut]

Steel 8 is rated G or 22,000 lb.You will melt the rope or sheath if you lower fast or the more weight you put on it.But the worse thing it will do is twist the rope on long lowers.It will work have used it several times in emergency situations.

:agree2: I would never use a figure 8 for a lowering device.

 

[Slvrmple72]

Aluminum will dissipate heat faster but also will get hotter more quickly than steel for that fact. Best bet is to have a groundie pee on it while lowering heavy stuff just make sure he minds the rope and has good aim.

I usually like to use my 8 w/ears up in the tree for tagline control while the ground guys lower the main weight of the limb on the porty or if I am lowering a small limb and don't have a crotch nearby to run the rope through.
Makes for a nice quick exit out of the tree, clip it to the saddle with both halves of the rope through it and whoosh!