Drag chains

[Aaron]

Using a drag chain to connect to an equaliser strap that is wrapped around a tree trunk to pull it out. Good idea or bad idea? If not a good idea what application are chains generally used in?

[long stroke]

We bought one a little while ago, since then it has been used numerous times Mainly dragging fire wood to the camp sight, pulling tree's of the track etc:)

[Slunnie]

The problem is that all straps, even ones marketted as not being elastic are still elastic. A snatch strap might stretch 15-20% or whatever it is, but a winch extension still stretches about 10%. If you use a strap and a chain, that makes it act like a high power slingshot if anything lets go, and a drag chain is a lot of mass as a projectile.

They're used for dragging stuff. The army also use them for recovery of stuck vehicles - but not to snatch from.

[abaddonxi]

EDIT:

Using a drag chain to connect to an equaliser strap that is wrapped around a tree trunk to pull it out. Good idea or bad idea? If not a good idea what application are chains generally used in?



Pulling down a tree or pulling out a bogged car? It's not quite clear from your post.

Cheers
Simon

[Slunnie]

Sorry.:(

It doesn't really matter what you are loading it up with be it a car or a tree, I guess my point was to not use a drag chain with any strap, even if its being used as a tree trunk protector such as in Aarons case or as part of a vehicle recovery. The chain by itself is fine, but with anything "kinetic" it has the potential to fire away - much the same way as you don't join straps with bow shackles, so that if the strap fails then the bow shackle doesn't become a projectile.

[DiscoStew]

The problem is that all straps, even ones marketted as not being elastic are still elastic. A snatch strap might stretch 15-20% or whatever it is, but a winch extension still stretches about 10%. If you use a strap and a chain, that makes it act like a high power slingshot if anything lets go, and a drag chain is a lot of mass as a projectile.

They're used for dragging stuff. The army also use them for recovery of stuck vehicles - but not to snatch from.

I know a guy who bet most of his spleen on that one. He was quite surprised at how fast a broken chain recoils when it breaks pulling out a tree stump. He was surprisingly chipper about it because his daughter's head was located quite close to his spleen at the time and his relief was winning over the relatively minor inconvenience of living without a fully functional immune system.

BTW he was not using any traps, the recoil was fully from the chain itself. I think it was about his fifth, and last, stump for the day.

[windsock]

Using a drag chain to connect to an equaliser strap that is wrapped around a tree trunk to pull it out. Good idea or bad idea? If not a good idea what application are chains generally used in?

Used my 2 chains (10m and 18m) for all sorts; used to secure a vehicle (mine and others) that is stuck and in risk of falling or slipping further into trouble, used to 'move' an anchor point for a snatch block to change winch angle, used in conjunction with a 60" hi-lift as a winch, used to drag firewood out of river beds, used to fix winch rope to 8x20mm steel rods driven into ground for winch anchor. All in all, both chains are a very useful bit of kit but that is just me. Wouldn't drive in rough without at least one of my chains. Also have several straps and snatch blocks, and other stuff of use too, so these aren't the be all and end all in recovery, just useful.

[abaddonxi]

Sorry.:(

It doesn't really matter what you are loading it up with be it a car or a tree, I guess my point was to not use a drag chain with any strap, even if its being used as a tree trunk protector such as in Aarons case or as part of a vehicle recovery. The chain by itself is fine, but with anything "kinetic" it has the potential to fire away - much the same way as you don't join straps with bow shackles, so that if the strap fails then the bow shackle doesn't become a projectile.

Sorry Simon, I should have quoted, fixed.

Simon

[Aaron]

EDIT:




Pulling down a tree or pulling out a bogged car? It's not quite clear from your post.

Cheers
Simon


Yeah I was pulling out the tree. Pulled It out like a twig.. Complete (thankfully) with half cubic meter root ball. Im sure the rain helped.

So situations where shock loads arent likely are ok for chains? And am I correct in thinking drag chains have the same safety margins as straps?

[Slunnie]

Shocking a chain wont be very good for your chassis

I'm pretty sure chains have a safe working load, where straps have a breaking strain.

[Tank]

Chains aren't designed for snatch/shock load, they will take some abuse, if you keep an eye on the condition of your chain you should see the telltale signs of when you should bin it. First if you have a section of chain that is no longer flexible, means the links are stretched and pulled in tight on one another, bent and mishapen links are another sign. A good chain if Rated (SWL/WLL) has the same Safety factor built in as other lifting slings whether wire or straps, always work to the SWL/WLL and not the Guaranteed Breaking Strain (GBS) because one thing you will be guaranteed it will break, use common sense, if it dont look right don't do it, Regards Frank.

[Tank]

Posted by Slunnie. Quote: "where straps have a breaking strain."
Never ever use a lifting or pulling strap to its Guaranteed Breaking Strain, because it will break, there should be a SWL/WLL which is either 5 or 6, which is the Safety Factor (SF), SF's are not put there for your amusement, they are there to compensate for wrongful use and abuse, dirt and grit in the weave, unseen broken strands, in other words so you won't kill yourself or worse, someone else.
This is guaranteed, if you load your well used strap at or above the GBS it will break, of that you can be certain, so if you have a strap that is only rated by it's GBS, divide that number by 6 and you should be safe, i.e. Safe Working Load, Working Load LIMIT, Regards Frank.

[Slunnie]

Absolutely... and use, weathering and wear will significantly reduce the breaking strain in comparison to its rating. I bet very few broken snatch straps had 8000lb of force put through them.

[leeds]

Posted by Slunnie. Quote: "where straps have a breaking strain."
Never ever use a lifting or pulling strap to its Guaranteed Breaking Strain, because it will break, there should be a SWL/WLL which is either 5 or 6, which is the Safety Factor (SF), SF's are not put there for your amusement, they are there to compensate for wrongful use and abuse, dirt and grit in the weave, unseen broken strands, in other words so you won't kill yourself or worse, someone else.
This is guaranteed, if you load your well used strap at or above the GBS it will break, of that you can be certain, so if you have a strap that is only rated by it's GBS, divide that number by 6 and you should be safe, i.e. Safe Working Load, Working Load LIMIT, Regards Frank.


A well used strap can and will break well below its GBS. The GBS applies to a brand new strap and not to a well used strap. A well used strap UTS ultimate tensile strength could easily be 1/3 to 1/2 of or less then a new one. Remember that when these straps are tested the load is applied in a slow steady fashion rather then shock loaded.

When inspecting a strap take particular note of the eye which in a reasonably well cared for strop could be abraded due to the shackle. Covered/protected eyes are good.

Also take note of the stitch block pattern and the webbing there. If the stitching sits proud of the webbing surface the stitches can be easily abraded. Even if the stitching is 'bedded' into the webbing the stitching can be abraded if the webbing looks 'fluffy'

In the UK there is general ignorance between nylon and polyester straps or the difference between snatch/recovery and towing/lifting straps. Many people in the UK believe that a lifting strap is suitable for snatch recoveries as it is strong enough for lifting!

Personally I would like to see all straps clearly marked and advertised as to what material they are made from. I would go one step further and say I believe that straps in the 4 x 4 world should be coloured coded. One colour for towing/tree strops, another for winch extensions and a third colour for snatch/recovery straps.

Regards


Brendan

[Rosco]

I know a guy who bet most of his spleen on that one. He was quite surprised at how fast a broken chain recoils when it breaks pulling out a tree stump. He was surprisingly chipper about it because his daughter's head was located quite close to his spleen at the time and his relief was winning over the relatively minor inconvenience of living without a fully functional immune system.

BTW he was not using any traps, the recoil was fully from the chain itself. I think it was about his fifth, and last, stump for the day.

I'm surprised at that Paul. Don't get me wrong, I don't doubt you. It's just that I always thought that when using a chain alone, in the event it snapped it would merely collapse and not recoil, due to the fact it has virtually no give to stretch. Ya learn sumfin new every day ... ;):D

[BigJon]

I'm surprised at that Paul. Don't get me wrong, I don't doubt you. It's just that I always thought that when using a chain alone, in the event it snapped it would merely collapse and not recoil, due to the fact it has virtually no give to stretch. Ya learn sumfin new every day ... ;):D

I am not surprised it recoiled. Steel is very elastic.

Don't believe me? Drop a steel ball bearing onto a steel plate and watch the bounce!

[Rosco]

I am not surprised it recoiled. Steel is very elastic.

Don't believe me? Drop a steel ball bearing onto a steel plate and watch the bounce!



Au contraire ... ;)

Not very elastic at all. If you have a peek at the stress v strain curve, the elastic range is very small whilst the yield range is very large. Very small strain (elongation) for a very large stress, which more or less flattens out abruptly through yield until it breaks. I tried to paste the graph but failed :(.

[Slunnie]

https://www.aulro.com/afvb/images/imported/2009/05/183.jpg
A -Elastic Limit
B - Upper Yield Stress
C - Lower Yield Stress
D -Ultimate Stress
E -Breaking Stress

[Rosco]

https://www.aulro.com/afvb/images/imported/2009/05/183.jpg
A -Elastic Limit
B - Upper Yield Stress
C - Lower Yield Stress
D -Ultimate Stress
E -Breaking Stress


Yep ... that's the one ..:thumbsup:

[Blknight.aus]

bonus points for anyone who can explain where on that graph a bolt that you tighten to a fixed torque sits (which is generally one you can re-use) and where one that you tighten using the angle torque method sits (ones you cant re-use like td5 head bolts)

[Slunnie]

https://www.aulro.com/afvb/images/imported/2009/05/183.jpg
A -Elastic Limit
B - Upper Yield Stress
C - Lower Yield Stress
D -Ultimate Stress
E -Breaking Stress


bonus points for anyone who can explain where on that graph a bolt that you tighten to a fixed torque sits (which is generally one you can re-use) and where one that you tighten using the angle torque method sits (ones you cant re-use like td5 head bolts)

Its before the yield and the 2nd is at the yield.

[Rosco]

bonus points for anyone who can explain where on that graph a bolt that you tighten to a fixed torque sits (which is generally one you can re-use) and where one that you tighten using the angle torque method sits (ones you cant re-use like td5 head bolts)

1. Between 0 and A
2. Between A and B

1st still in the elastic range
2nd just beyond
Anything past B ... it's stuffed

[Slunnie]

bonus points for anyone who can explain where on that graph a bolt that you tighten to a fixed torque sits (which is generally one you can re-use) and where one that you tighten using the angle torque method sits (ones you cant re-use like td5 head bolts)
I've never really understood why you would tension a bolt beyond its elastic limit - especially a head bolt.

[Rosco]

Its before the yield and the 2nd is at the yield.


No room for error if you go all the way to B.

Tis a fine line between pleasure and pain ... :o:D;)

[Aaron]

Thanks for the help guys!

[clean32]

I've never really understood why you would tension a bolt beyond its elastic limit - especially a head bolt.

There are a couple of reasons, by taking the bolt ( actually usually the Nut in construction) to its elasticity point ( a bit past it actually)
Will deform the threads ensuring the maximum contact area between the bolt and nut.

That understood. If a nut and bolt plotted you tend to get a double parabola. The first as any high points are stressed out into there elastic limit point and the second when maximum contact area is achieved.

The main advantage of this is when bolting different materials with different expansion rates together or where a range of temperatures will be experienced. Because the clamping force is within the elastic range the nut can in effect move up and down the bolt maintaining the same force. Where an bolt ( presumably larger) will increase its clamping force as temperature rises as well as reducing as it cools. the case of bolting a alloy head to a cast block, this could lead to movement between the head and block faces, IE dead head gaskets.

Most steel bridges are built this way

[BigJon]

That graph shows a lot of elasticity to me...

[Rosco]

That graph shows a lot of elasticity to me...


Not really, the limit is A. Relatively little strain (elasticity) for the amount of induced stress. After A it will not return to zero with the stress removed, hence it is all yield.

[Aaron]

Well I just went and got my chain. Does anyone spot anything strange about this picture?


https://www.aulro.com/afvb/images/imported/2009/05/176.jpg

[series3]

One of the linkages doesn't look particularly strong...

[BigJon]

8th link looks like a winner :eek:.

[BigJon]

Not really, the limit is A. Relatively little strain (elasticity) for the amount of induced stress. After A it will not return to zero with the stress removed, hence it is all yield.


Anything up to A is elasticity.

Anything after B is plastic deformation and therefore throwaway.

Much more useable strength in the elastic range than anywhere else.

That is how I see it.

[steveG]

Well I just went and got my chain. Does anyone spot anything strange about this picture?


https://www.aulro.com/afvb/images/imported/2009/05/176.jpg

That link looks a bit ordinary - maybe the equivalent of a shear pin in a hand winch :p

I'm also not sure about the marking on the hook - "forged China".
Which meaning of forged applies? I'd be worried that its not the "heated and stamped" one!

Seriously though, thats scary stuff. Any particular brand?

Steve

[Shonky]

Is that link completely unwelded? :o

:eek:

[Aaron]

Yep the link was missing a weld. Another had a weld that hadn't been cleaned up and another was welded but the joint was pretty off center.

Its TJM brand. They're sending it back to get it looked at, they've never seen it before. To their credit though, their service has been great as always (Caboolture store)

[steveG]

I guess there's a bit of a lesson to be learned - just because its new doesn't mean its OK.

Personally, I'll be giving any recovery gear I buy from now on a good going over as soon as it comes out of the packaging.

Steve

[JohnF]

not too long after I first joined this forum I put a a thread where while pulling a large fallen tree the chain let go and ended up flying over our RR roof. Only the roof carry bars stoped this chain from smashing the roof in.

[Tank]

That chain should be in a rubbish bin, a few tips, the hook should have the size of the High Tensile chain e.g. 8mm and WLL, also the pin in the hook should be a larger dia. than the links of the chain and it must be Good Quality. Dont go for pretty, shiny links, look for good fusing of the link joins. Go to a Rigging supply company or a reputable Truck Spares supplier, make sure you ask for hi-Tensile chain. That chain you bought could kill someone, I would insist that the company you purchased it from withdrew ffom sale and recalled all of that chain, I'm sure you didn't buy the only crap bit of chain they had, I would report them to consumer affairs for selling such crap, Regards Frank.
P.S. check out my chain below, note how the links are much shorter and the fused welds are much stronger.

http://www.aulro.com/app/data/686/medium/DSCN7851.JPG

[Aaron]

I just went down to the local truck center and picked this one up. The quality just looks so much better. 1 meter longer, but 20 dollars cheaper, though it doesn't come with a pretty bag...

new one
https://www.aulro.com/afvb/images/imported/2009/05/175.jpg

and to compare with the old
https://www.aulro.com/afvb/images/imported/2009/05/176.jpg

[Rosco]

I just went down to the local truck center and picked this one up. The quality just looks so much better. 1 meter longer, but 20 dollars cheaper, though it doesn't come with a pretty bag...




That doesn't surprise me. 4WD shops are, in the main, rip-off merchants.
A few years back I was after a Donaldson pre-cleaner. The local 4WD mob wanted about $120. Got one from Diesel Spares for about $40.

[Aaron]

I remember reading a post on here ages ago in regards to spotlight prices. The member said they bought theirs at a truck spares place and it was much cheaper. I never gave it a second thought until today. I didn't have time to look around much, but they did have some pretty cool AUX fuel tanks that I caught out the corner of my eye.

[Tank]

I just went down to the local truck center and picked this one up. The quality just looks so much better. 1 meter longer, but 20 dollars cheaper, though it doesn't come with a pretty bag...

new one
https://www.aulro.com/afvb/images/imported/2009/05/175.jpg

and to compare with the old
https://www.aulro.com/afvb/images/imported/2009/05/176.jpg
Just look at the difference in quality, note the shorter links on the "real" chain, I wonder how many bought the crap chain from TJM, Reagrds Frank.

[Tank]

8th link looks like a winner :eek:.
Well the 9th. link takes the prize, Regards Frank.

[windsock]

Other configurations of chain I have found very useful are...

https://www.aulro.com/afvb/images/imported/2009/05/170.jpg

...and...

https://www.aulro.com/afvb/images/imported/2009/05/171.jpg

The top one is the longer chain and it can be shortened to the required length simply using the snig hook along the length anywhere. I use this a lot in conjunction with the 60" hi-lift jack used as a winch.

The bottom chain is my standard drag chain. I also carry a spare hook in case I need to swap over to a two-hook set-up for either chains.

Important to look out for rated chain vs unrated. Most rated chain over here in NZ is identifiable with the rated stamp on it. This was all obtained from a rigging wholesaler.

https://www.aulro.com/afvb/images/imported/2009/05/172.jpg

[BigJon]

Well the 9th. link takes the prize, Regards Frank.

Obviously counting isn't my strongest skill :eek::p.

[Slunnie]

That graph shows a lot of elasticity to me...
I thought the curve up to D was over exaggerated compared to testing which I've done.