Not many 4" tree strap options to pair with ARB 9000 pulley

[GogDog]

Ok, so getting a SSO bumper and a smittybilt x2o 10K winch. Really looking forward to it. And...already started the learning process and been reading a ton. Mainly getting hung up on the multiplying forces when using a snatch block, though I believe I have a good understanding of that now.

I decided to get an ARB 9000, since the working range is 20,000lbs...so 2x my winch. Breaking strength is 38,500lbs. All set there.

However...if I'm using a tree as my recovery point, its all 3 items that really matter:

Snatch block
Shackle
Tree saver

The snatch block is 20K WLL, 38,500 breaking.
Shackle: (I have an alloy 3/4" shackle from campbell), is 14K WLL, but...70K breaking strength (5:1 ratio)

Most tree straps...from ARB, wheelers, etc...are 3" wide, and have a 29-30K breaking strength. So...would pair well with a Arb 7000 pulley (15K working, 30K break strength).

It looks like there are not many 40K breaking strength tree straps. I can only find two ->

Smittybilt 4"x8' tree strap $32 -> https://www.amazon.com/Smittybilt-C...3MJ8/ref=cm_cr_arp_d_product_top?ie=UTF8&th=1
40K break strength
Cons: Its smittybilt....

Bubbarope tree hugger 10' $97 shipped ($79 + $18). 47K break strength!
Not sure how they did this one...since nearly all 3" straps are 30K break strength. Maybe they made them thicker?
Cons: Super expensive

Anyway...am I just overthinking this? Should I just use a normal 3" tree strap rated at 30K instead of trying to get a 40K that "pairs" with the ARB 9000?

 

[FrenchToasty]

Holy sheet that's a lot of K

 

[Peadog]

The snatch block doubles your 10k winch, so the max force is 20k, or am I looking it wrong?

 

[GogDog]

The snatch block doubles your 10k winch, so the max force is 20k, or am I looking it wrong?

No, thats correct. I'm basically looking at the safety factor.

For example...if I had a 8K winch, then having an ARB 7000 pulley which a working limit of 15K and breaks at 30K, would pair well with a 3" tree strap...which also breaks at 30K.

This is a 10K winch, so the appropriate pulley would be a 20K working load, so an ARB 9000 is a good choice. But if you keep the same 3" tree strap, there really isn't much point of going to a Arb 9000 since the tree strap would be the weakest link. A 4" tree strap would be what you want to pair with the pulley. I'm just disappointed in my options.

 

[Peadog]

I understand your looking at safety factor, but your still dealing with 20k on a 3 inch tree protector that's rated at 30k. I would sleep just fine at night with those numbers.

 

[techno]

Couple of things to keep in mind. With the strap around an anchor tree properly, the forces will be divided evenly between the two ends, effectively halfing what each leg sees.
Also, the winch only produces max force on the last cable wrap. A lot of winching is done well below max.

 

[GogDog]

Couple of things to keep in mind. With the strap around an anchor tree properly, the forces will be divided evenly between the two ends, effectively halfing what each leg sees.
Also, the winch only produces max force on the last cable wrap. A lot of winching is done well below max.

Are you sure about the tree strap only seeing half the force on each leg? Actually...you have to be right.

This is all pretty interesting. The best way I found to think of winching is counting "tension" units. So from this image that I modified from 4wheelingaustralia ->

So the purple 1T (one tension) are the tension on each winch line segment. The Red boxes are the tension at each load point. All you need to do is count how many lines are touching each load point.

Therefore, there is 1T at the winch itself, then 2 tension units at the first tree, then 2 tension units at the snatch block that is attached to the vehicle, and only 1T at the second tree.

As an aside, where I see a potential big mistake, is how you connect the second snatch block. For example...I'll be installing a SSO slimline bumper, which has 2 front shackle loops. They are supposedly decently strong. However...if I attach the snatch block to one of those loops, then there is going to be 3T (tension units) all on the front SSO slimline bolts. Someone said there are youtube videos of people getting their aftermarket bumpers ripped off with stuff like this. I assume it would be much better to share the load between the bumper and the normal factory front recovery loops below the bumper.
So, then it would be 1T on the slimline bumper (winch), and 2T on the factory recovery point.

Same thing with the tree. Technically you could put your second snatch block back to the same tree with a second tree recovery strap. But that would potentially put 30K lbs of pressure on the tree (3T on a maxed out recovery), so that better be a big tree!

ANYWAY...getting back to the tree strap. It should be like this ->

The snatch block doesn't move during the winch, which means there is a balance of force (there is an equal and opposite force). So if the winch cables are exerting 2 tension units, that means the tree straps are exerting exactly 2T in the opposite direction. And each "leg" of the strap is only getting 1T.

So....I guess I was wrong. A tow strap, rated at 30K#, really functions at 60K# as a tree strap.

Dude....maybe that is why bubbarope is claiming their 3" Tree hugger is rated at 47K break strength, while every other 3" tow strap is rated at 27-30K. Note the wording on their site ->

--------------------
We made The Tree Hugger™ super strong with the breaking strength of 47,000 lbs. when wrapped around a tree or some other stationary object. (bold added)
---------------------

That is some clever marketing/choice of words.

 

[GogDog]

Actually...I found some good info from sling rigging diagrams.

So...here is a 500# rated strap. If "towing" (vertical in the diagram), it can only withstand 500# of force.

However....in a perfect world where you had a 90° angle and two shackles, it could hold 1000# of force.

In a tree strap setup...where the angle is at least 60°, you get a 75% increase in load.

Thus...for the bubbarope.....if you take a normal 27K 3" tow strap, use it as a tree strap...it goes to 47K break strength. Wow...I'm glad now I didn't buy that bubba strap. Through some clever wording they are taking a normal 3" strap and selling it for double the price!

Now....I can't explain it where if the angle goes to 30° or lower that your strength capacity goes back to 100%. Nor do I really have to understand it...I just have to trust science. I'm sure it has to do with a bunch of sin/cos calculations and stuff that I don't have to do anymore because I already graduated.

 

[tb-av]

That is some clever marketing/choice of words.

No, it simply describes the strength by it's intended use. They publish all the specs for their snatch straps as well.

It's a tree hugger. How else would you attach it to a tree except by wrapping it around. ... and after it's wrapped around wouldn't you like to know it's breaking strength?

It's not a tow strap, a snatch strap, or anything else. It's a tree wrap strap.

 

[GogDog]

No, it simply describes the strength by it's intended use. They publish all the specs for their snatch straps as well.

It's a tree hugger. How else would you attach it to a tree except by wrapping it around. ... and after it's wrapped around wouldn't you like to know it's breaking strength?

It's not a tow strap, a snatch strap, or anything else. It's a tree wrap strap.

Yeah, I get that. Its just that its not industry standard.

ARB ARB730LB 3" x 10' Tree Saver Strap - 26500 lbs Capacity
TGL 3", 8' Tree Saver, Winch Strap, Tow Strap 30,000 Pound Capacity
Rhino USA Tree Saver Strap 3" x 8' -Lab Tested 31,518lb Break Strength
smittybilt is the same, warn is the same too, though warn is slightly different because their "epic" metal shackle ends actually make the ratings go DOWN, which is dumb for them to do.

And it shouldn't justify the doubling of the price. Its fleecing unsuspecting customers when they can get a high quality ARB tree strap for half the price ($40), and generic ones for $25. Same straps and capacities.

And up until about an hour ago...I was one of the unsuspecting customers. By the bubbarope description, they make it sounds like the actual quality of the strap is what gives it the extra strength...and...justifying the price increase. But in reality...the only differentiating factor was their wording. Snake oil.

 

[tb-av]

Granted they all have just about the same break rating.

They are not all made the same though.

So one may be more long term durable than another. Hold up to the elements better, etc..

But if the price bothers you then buy the $25 one if you think they are all the same. Because by breaking strength alone they are.

Bubba Rope prints it right on their label. Three configurations, three breaking strengths. Not sure how they could be more clear about it.

 

[techno]

This is a good vector diagram showing the effect the leg angles have.
Always good practice to keep it as low as possible, especially for the health of the tree, haha.

 

[GogDog]

Bubba Rope prints it right on their label. Three configurations, three breaking strengths. Not sure how they could be more clear about it.

Perhaps...show a picture of their label before you buy it? I think that would be more clear about it.

Its ok...I think they are being deceptive with their marketing, but you don't and thats fine. I'm just glad I caught it. They are not lying technically.

But you are right....there are quality differences between the different companies, and yes, the bubbarope does have a cordura covering over the entire length. Arb only has some smaller moveable protectors (as does wheelers brand), and some don't at all (like rhino).

 

[Lindenwood]

Actually...I found some good info from sling rigging diagrams.

So...here is a 500# rated strap. If "towing" (vertical in the diagram), it can only withstand 500# of force.

However....in a perfect world where you had a 90° angle and two shackles, it could hold 1000# of force.

In a tree strap setup...where the angle is at least 60°, you get a 75% increase in load.

Thus...for the bubbarope.....if you take a normal 27K 3" tow strap, use it as a tree strap...it goes to 47K break strength. Wow...I'm glad now I didn't buy that bubba strap. Through some clever wording they are taking a normal 3" strap and selling it for double the price!

Now....I can't explain it where if the angle goes to 30° or lower that your strength capacity goes back to 100%. Nor do I really have to understand it...I just have to trust science. I'm sure it has to do with a bunch of sin/cos calculations and stuff that I don't have to do anymore because I already graduated.

Great diagram!

As to the 30-degree mark, that is simply because Sin(30)=0.5. Without going crazy drawing diagrams, this means you are effectively halving the force of each rope in the pulling direction. Total tension is still 500lb in each line, but much of it is wasted pulling against each other. Going below 20 degrees would actually result in exponentially less towing capacity.

Also, companies aren't really allowed to straight-up lie about things like ultimate breaking strength.

However, there are several characteristics that absolutely will differ between manufacturers. Namely, elongation and durability are probably the most significant among them, with durability arguably breaking up into factors like heat tolerance and abrasion resistance. So, a cheap strap will be technically just as safe out of the box and with occasional light use, but will likely degrade more quickly with UV exposure and use. The aforementioned strap covers on higher,end products are an obvious example, but they might also be made of inherently more resilient materials.

That said, I have never had issues with cheap stuff that would have left a higher-end model still usable (like having a strap drag under a tire and fray).

 

[GogDog]

Great diagram!

As to the 30-degree mark, that is simply because Sin(30)=0.5. Without going crazy drawing diagrams, this means you are effectively halving the force of each rope in the pulling direction. Total tension is still 500lb in each line, but much of it is wasted pulling against each other. Going below 20 degrees would actually result in exponentially less towing capacity.

Also, companies aren't really allowed to straight-up lie about things like ultimate breaking strength.

However, there are several characteristics that absolutely will differ between manufacturers. Namely, elongation and durability are probably the most significant among them, with durability arguably breaking up into factors like heat tolerance and abrasion resistance. So, a cheap strap will be technically just as safe out of the box and with occasional light use, but will likely degrade more quickly with UV exposure and use. The aforementioned strap covers on higher,end products are an obvious example, but they might also be made of inherently more resilient materials.

That said, I have never had issues with cheap stuff that would have left a higher-end model still usable (like having a strap drag under a tire and fray).

Thanks for the math! I knew it was just going to be a sin/cos calculation. The explanation is helpful though.

And yeah...I think I did right by buying cheaper tow straps (rhino usa). They can get used/abused so a high end strap would likely not lasting much longer than a cheaper strap when getting it dragged through the dirt.

I did buy higher quality shackles (campbell alloy), snatch strap (arb usa), snatch block (arb 9000) though.

 

[Lindenwood]

On a moderately related note, there are significant gaps in understanding of breaking strength and WLL / Safe Working Load. Breaking strength is an emperically-derived value that must be rigorously verified across multiple product runs. Safe Working Load is almost 100% arbitrary (I say "almost" because occasionally there is actual math involved for a specific load or load type). Generally speaking, most steels have a yield strength of 50-70% of breaking strength, which means you arent going to really start fatiguing the metal until you reach 50-70% of that MBS. However, most safety organizations specify a 1/4 or 1/5 safety factor to cover as many bases as possible.

Case in point, the 5/16 steel cable that comes with most winches technically has a WLL of about 2500 lbs and a breaking strength that barely exceeds the winch capacity (it varies based on the specific cable composition).

However, how often have we seen people argue that because they are pulling with a 9k winch, they need shackles with a >9,000lb WLL? Even basic 3/4" shackles are actually rated at 38,000lb minimum breaking strength, so it is kinda overkill when you do the actual numbers.

However, I do still use 3/4" shackles because an abrupt jerk with a chain can indeed approach 40k lbs of force (if I remember right, a 5,000lb vehicle going from 5mph to 0mph in 4 inches, like somebody pulling a slacked chain taught, will exert about that much force). Of course, that is kindof a worst-case scenario for me. I use a 1/4" Gr70 chain for my hi-lift winching kit because it still has a 12,600 MBS and saves me about 30 lbs of chain to haul out of the mud pit holding my rig. But, I use snatch straps for vehicle-to-vehicle pulls.

 

[GogDog]

I wonder what the breaking strength is of the smittybilt x2o synthetic line I'm getting...

But yeah...I read somewhere that you want the winch line to be the weakest link in the system, so if something happens the line breaks before...a shackle. And, even if the breaking strength is much less, when you add snatch blocks and double/triple line pulls, the line's "strength" increases by 2 to 3 times, but the shackles/snatch blocks still receive the same stress, so those do need to be more overkill.

And yeah, it does seem arbitrary for the WLL vs breaking strength. For example....Wheelers straps are made by Safeway, and are meant for overhead loads. So, Wheelers advertise their straps as ->

-----------
These straps are continuous duty rated at 13,500 lbs, the material itself is rated at 27,000 lbs break strength.
------------

However, the label on the strap is ->

Which.....shows the WLL used "vertically"...(i.e. straight), is 4800lbs. So for lifting, the strap's WLL is 4800, breaking is 27,000, so thats a 5.6 to 1 safety factor. Wheelers is advertising a 2 to 1 safety factor for towing. Its all arbitrary. Thats why its nice to know the breaking strength of items, because then you can give your own WLL based on whatever safety factor you want.

 

[Lindenwood]

+1 to all that!