Recovery Ring- (Pulley Block alternative) (1 Viewer)

[SOAZtim]

I sat down with Andy of 7P chat about these and we did a full line pull. It's not really a review, but more of a walk through since there is so little info on these still.
We're spending a year driving to South America and decided to use 2 of these to replace our older Arborist style aluminum pulley blocks.
(Full disclosure: I have no direct financial interest in these selling, but work for Overland Expo and 7P so there is bias)
Cheers,
Tim

 

[cruiserpilot]

Switching to synthetic line and the weight savings get real. Impressive. I wonder now, throw in
some real crap swamp mud, sticks and contaminants -
How about a video redo real world that's not desert dry?

 

[woodsman 44]

I think its a great idea but just not for a lot of use....I use arborist block for 2 to 1...tree work is what I do for a living

 

[SOAZtim]

Switching to synthetic line and the weight savings get real. Impressive. I wonder now, throw in
some real crap swamp mud, sticks and contaminants -
How about a video redo real world that's not desert dry?

Good call. An abrasive material like Sandy mud on the ring would do damage over time!

I think its a great idea but just not for a lot of use....I use arborist block for 2 to 1...tree work is what I do for a living

Why not a lot of use?

 

[Crusha]

Pretty cool, but takes up a lot more room than a snatch block...if that's an issue in your rig.

I do like the simplicity of it.

 

[SOAZtim]

Assuming you already use soft shackles it takes up a whole lot less room.

Pretty cool, but takes up a lot more room than a snatch block...if that's an issue in your rig.

I do like the simplicity of it.

 

[renago]

Good idea , but ...
The biggest enemy of Dyneema fiber is heat .
A long, or heavy pull will generate a high ammout of friction on the ring , and conseguently heat .
Worst Thing is that the heat is building up on the same point of the soft shackle .
This will lead to a constant degrading of the fibers in the friction point .
If we add mud , dust , sand , we will need to change the soft shackle pretty often ,in order to stay sufficiently safe .
The idea is however interesting ,must be developed .

Bye Renago

 

[gnob]

Itd be an easy mod to add a bearing in the center

 

[SOAZtim]

Good idea , but ...
The biggest enemy of Dyneema fiber is heat .
A long, or heavy pull will generate a high ammout of friction on the ring , and conseguently heat .
Worst Thing is that the heat is building up on the same point of the soft shackle .
This will lead to a constant degrading of the fibers in the friction point .
If we add mud , dust , sand , we will need to change the soft shackle pretty often ,in order to stay sufficiently safe .
The idea is however interesting ,must be developed .

Bye Renago

You'd think heat would develop, but due to the line speed it doesn't seem to happen. We did a full line pull on a solid hill with my foot on the brakes to keep the winch just above stall speed and the ring wasn't even warm. Still, I could see those competition winches going so fast that they develop plenty of heat.

 

[renago]

For those who want to learn more on Dyneema heat reaction
https://www.dsm.com/content/dam/dsm...hes for studying UHMW-PE thermal behavior.pdf

For those that trust my opinion and experience, I would comment :
Dyneema melts at 135/140C.
But as all thermo plastic fibers , the more near you reach the melting point , the weaker fiber becomes.
Must say that the system is very interesting, adding a large bearing could make the system almost perfect .
For small loads and short pulls can work as is .

Bye Renago

 

[Jetboy]

These are commonly used in sailboat rigging. Low friction rings are a fine substitute for a block in a lot of scenarios. As long as you recognize that they're "low" friction not "no" friction. IF they're sized appropriately they could be a much lighter weight alternative to a traditional block. The price is right too. They're typically around $20 ea in the sailing hardware world.

I would think it would be frustrating to keep the line in the ring when setting up the pull though since it's not captured like it would be in standard block. Also testing compared to ball bearing blocks shows that the rings have about 30% more friction than a ball bearing block. What that means in this case I have no idea. Would the friction be higher than a steel on steel bushing? Does it matter? Maybe not.

Also FWIW - I've seen them used both ways. They're not normally used in that orientation though. Most commonly they are setup like this where the moving rope is sliding on the inside of the ring, not using the ring like a pulley block:

 

[SOAZtim]

For those who want to learn more on Dyneema heat reaction
https://www.dsm.com/content/dam/dsm/dyneema/en_GB/Downloads/Articles/New approaches for studying UHMW-PE thermal behavior.pdf

For those that trust my opinion and experience, I would comment :
Dyneema melts at 135/140C.
But as all thermo plastic fibers , the more near you reach the melting point , the weaker fiber becomes.
Must say that the system is very interesting, adding a large bearing could make the system almost perfect .
For small loads and short pulls can work as is .

Bye Renago

Good info, if there was heat. Lol. Try one out first.

These are commonly used in sailboat rigging. Low friction rings are a fine substitute for a block in a lot of scenarios. As long as you recognize that they're "low" friction not "no" friction. IF they're sized appropriately they could be a much lighter weight alternative to a traditional block. The price is right too. They're typically around $20 ea in the sailing hardware world.

I would think it would be frustrating to keep the line in the ring when setting up the pull though since it's not captured like it would be in standard block. Also testing compared to ball bearing blocks shows that the rings have about 30% more friction than a ball bearing block. What that means in this case I have no idea. Would the friction be higher than a steel on steel bushing? Does it matter? Maybe not.

Also FWIW - I've seen them used both ways. They're not normally used in that orientation though. Most commonly they are setup like this where the moving rope is sliding on the inside of the ring, not using the ring like a pulley block:

Yep, easy to keep in the channel. Not that high of friction in this orientation. The rope doesn't slip it just runs along the channel as the ring spins. Only friction is on the soft shackle and that's why they use a large diameter to minimize it .

 

[half k cruiser]

Any idea how much mechanical advantage you lose going with the ring vs a snatch block ?

 

[woodsman 44]

Any idea how much mechanical advantage you lose going with the ring vs a snatch block ?

With ring Its still 2 to 1 but your dealing with friction on the dyneema soft shackle (not sure how much) versus a greased snatch block pulley....

 

[half k cruiser]

With ring Its still 2 to 1 but your dealing with friction on the dyneema soft shackle (not sure how much) versus a greased snatch block pulley....

Correct, like making a 2:1 with a carabiner. There's definitely some advantage there, but it's not fully 2:1. I guess the same would technically be true for the snatch blocks as well. There's no way they are running 100% efficiency, but it's probably close enough to not even be a factor.

 

[e9999]

what is this 2:1 advantage you are talking about, exactly? We're talking about one device here, correct? Or do you mean something like a winch and the line back to the bumper?

 

[SOAZtim]

what is this 2:1 advantage you are talking about, exactly? We're talking about one device here, correct? Or do you mean something like a winch and the line back to the bumper?

I assume they're talking line back to the bumper. We've used ours to recover some trucks off the side of a jungle track where we would otherwise get pulled down into the jungle and then to move a tree. All good so far.

 

[half k cruiser]

what is this 2:1 advantage you are talking about, exactly? We're talking about one device here, correct? Or do you mean something like a winch and the line back to the bumper?

Correct, snatch block to the load for 2:1

 

[ntsqd]

Any friction in the system doesn't subtract from the mechanical advantage. It subtracts from the overall line-pull. Say an M8 actually pulls 8,000 lbs. single line. Then doubled back it pulls 16,000 lbs. Only the pulley has a 1% loss due to friction. That means that the doubled pull max effort is only 15,840 lbs. I'm pretty sure that I'd never notice the difference between 16,000 lbs and only 15,840 lbs., even if it landed on my foot.

I'm tempted to buy one of these and try it:

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