Post by neil on Mar 6, 2013 6:35:56 GMT -5
[glow=Orange,2,300]SNATCH BLOCKS[/glow]
I'm going to show you a few of the different designs of Snatch Blocks, but I really want to focus on how to work with and around them safely.I also want to show you the many things they can be used for and how.
I'll talk about the safe zones/death zones in the use of snatch blocks,which also coincides with some of those same zones winching.....Period.
I don't want to spend a whole lot of time on the snatch blocks themselves, because in my opinion, those made specifically for the uses that we as wheelers would use them are not really up to the industry standards.Therefore I feel that the safety aspect is much more important.
The Snatch Blocks developed for the industry(I'll post pics here later),I'm sure we have all seen. ARB probably has the most elaborate looking one. What I want to bring to light, is that these snatch blocks are not rated by the industry standard with a WLL(working load limit), which means there is no safety factor built in.
Generally speaking, the load limit listed is the [glow=red,2,300]Breaking limit[/glow].
Also take note that the way in which the Snatch Block is loaded also affects it's WLL. Both lines running in and out of the snatch block at 90deg yeilds 100% of the WLL. Lines positioned at 45deg reduce the WLL by 50% or more.
Just for instance, if you do a search you will find that the heavy duty Smittybuilt snatch block is only WLL rated for 3.5t or 7000lbs. with a safety factor of 5. That puts the failure at 36,000lbs. This is the SWL (safe working limit) according to marketing. Just beware it is a MAX limit.
Common sense will tell you that something doesn't add up when you look at industrial snatch blocks.....their weight(very heavy), their size(quite large),and last but not least their cost (alot).
A typical industrial snatch block rated with a 8t WLL will run roughly around $600 and weigh 20#+. Not something the average wheeler is going to buy or cart with them. Hence, this is why I want to talk about use and safety.
[glow=Orange,2,300]Using your Snatch Block[/glow]
Snatch Blocks are very useful in technical recoveries where a straight line pull may be impossible, or you have to side shift your ORV, or your winch just doesn't have enough oomph.
Say that your stuck in mud up to the bumpers and there is just no more movement. So you look at your buddy in the passenger seat and ask him nicely if he wouldn't mind jumping out and hooking your winch line up to the nearest tree with the appropriate tree saver strap and shackle( Besides....he was the one egging you on into the mud hole in the first place ;D).
After hooking everything up, and your buddy standing clear, you begin to winch. The Jeep moves all of about 3 inches and the winch grinds to a halt.
Now you have to come up with some more pulling power. You take the snatch block and attach it either directly to the tree strap or by way of a shackle. (The shackle needs a WLL of double your winch capacity at this point).
You thread the cable thru the snatch block and return the cable to a shackle attached to your bumper. Now when you pull with the winch, two things have happened.....
1. You have spooled more cable off of the drum of the winch.
This means that you are getting closer to the acctual max capacity of the winch.......if you are on the very first wrap, you are at the max capacity.
2. By going thru the snatch block and back to the bumper you are cutting the line speed in half. It's like putting your jeep in low-range.....Think of the gained power.
This is a 2:1 ratio effectively doubling the pulling power. A 9K lb winch on the first wrap of the drum passed thru a snatch block and returned to the vehicle is now capable of 18k lbs of pulling force. Here is where you will find out how well your bumper is made, or it is fastened.
Bystanders beware of flying winch/ bumpers.
This is where you have to be very careful.
1. Is the tree or anchor point good enough to support that kind of pull?
2.The tree strap needs to be up to par. This is probably only an issue if your not using an acctual tree saver strap, as many are rated 40k-60k lbs in the 3-4" wide strap range.
3. If a shackle is used, is the WLL correct? This particular senario would require a WLL of 9.5t or 19k lbs.
4. All bystanders should stay far left and right of the cable, never inline with it. It may not be a bad idea for the driver to stay ducked down in the seat in case of a component failure.
This is a fairly common us of a snatch block.
Other uses would be for getting good rope position for winching another vehicle from around a corner in a matter of speaking,where a straight pull would otherwise cause a roll-over for the recoveree.
Or winching someone from behind or ahead of you.
Where possible, if you could fasten a snatch block to the bumper of the ORV, you could use it to redirect the cable pull and drag the front to the left or right without bunching the rope on the winch or crushing it on the fairlead.
In this same setup your rigging can accomodate many different actions, like rolling your own vehicle back over,or side shifting the rear or front of the jeep.
A simple yet strong attachment made for the front bumper just for this purpose could be very useful.
Don't laugh to hard at my quick illustrations
Here is an example of a snatch block being used to double the pulling power of the winch.
The orange shaded area is where nobody should be positioned while winching.
The yellow arrows in the next two pictures are the direction of travel that the wire rope will travel depending on where the break occurs. Assuming that it would be at a point of attachment and not the rope itself.
Here is using a snatch block for redirecting the line of pull. Remember to take notice to all possible directions of travel in the event of a rigging failure.
It takes a millionth of a second when a failure happens for someone standing within the DEAD ZONE to be mortally wounded or killed.
Take a moment to carefully asses where everyone is standing before winching. Some pulls are very light and not likely for anything to happen, but if your in the habit of practicing safety, your alot less likely to have an accident happen.
This picture is to show you one of many ways to redirect your line of pull by extending the snatch block further away from the first tree with a longer strap.
Here is a bunch of pics (10) of various snatch blocks and descriptions, along with a couple of use pics.
Here is a typical ARB example
A typical warn example
This snatch block is designed for synthetic rope use only, and you will see on the lable that it has a max rating of 15,000 lbs.
These 2 are like the smittybuilt HD's..one has a WLL of 4t and the other is WLL 6t. I still have not found a higher max rating on this style than 36k lbs.
Here is an example of the fancy ARB style, but this paticular one is the acctual manufacturer's.
I included this one because it has KN ratings on it. KN's are acctually a sustained force rating, not acctually a weight rating.It's acctually a kenetic force rating like droppoing 180 lbs 3ft will generate a lb rating of 5K give or take. There are formulas on line to deturmine the weight rating....if I remember correctly 22kn is equal to roughly 6500 lbs.....but don't hold me to that.
Here is a ARB being used to doulble the winch power. Notice how the shackle is placed. This is correct.
Here is another pic of use. Again, the shackle is being used correctly, but the chain in the background is not.....The chain should not be wrapped or twisted (links should be in line). The shackle on the background pic is backward, and the chain should loop thru the bow and not hooked to it. It's hard to tell, but I also think that the chain is fed thru the strap eyes. This also is a major NO-NO as it ruins the strap and greatly reduces the strength of it.
I'm not 100% on this picture, but I believe that they are winching another vehicle up the hill. They are not currently winching because you can see the line is slack. The winch line has a damper thrown over it,the tree saver,shackle, and snatch are all correct.
Where everyone is positioned is what is in question. The safest place to be is behind the hummer. Second safest place is to the uphill side of the cable(left). Ten foot away from the hummer and cable. No closer than 2/3 of the lenght to the first anchor point(Snatch Block).
Both men to the right of the cable are both in the DEAD ZONE!
Her are a couple pics of industrial style Snatch Blocks.
Here is one that is designed for vertical lifting only.....You can tell by the shackle.....if you read the shackle post.
There was two other pics but photobucket it being fusy.
They both have hooks on them, one with a safety,one without. When using hooks, always try to place the hook's open end facing up, in the event that it breaks it will throw the hook towards the ground.
If using a industrial style snatch block with a built in attachment point, a shackle with a threaded pin is preffered.
I'm going to show you a few of the different designs of Snatch Blocks, but I really want to focus on how to work with and around them safely.I also want to show you the many things they can be used for and how.
I'll talk about the safe zones/death zones in the use of snatch blocks,which also coincides with some of those same zones winching.....Period.
I don't want to spend a whole lot of time on the snatch blocks themselves, because in my opinion, those made specifically for the uses that we as wheelers would use them are not really up to the industry standards.Therefore I feel that the safety aspect is much more important.
The Snatch Blocks developed for the industry(I'll post pics here later),I'm sure we have all seen. ARB probably has the most elaborate looking one. What I want to bring to light, is that these snatch blocks are not rated by the industry standard with a WLL(working load limit), which means there is no safety factor built in.
Generally speaking, the load limit listed is the [glow=red,2,300]Breaking limit[/glow].
Also take note that the way in which the Snatch Block is loaded also affects it's WLL. Both lines running in and out of the snatch block at 90deg yeilds 100% of the WLL. Lines positioned at 45deg reduce the WLL by 50% or more.
Just for instance, if you do a search you will find that the heavy duty Smittybuilt snatch block is only WLL rated for 3.5t or 7000lbs. with a safety factor of 5. That puts the failure at 36,000lbs. This is the SWL (safe working limit) according to marketing. Just beware it is a MAX limit.
Common sense will tell you that something doesn't add up when you look at industrial snatch blocks.....their weight(very heavy), their size(quite large),and last but not least their cost (alot).
A typical industrial snatch block rated with a 8t WLL will run roughly around $600 and weigh 20#+. Not something the average wheeler is going to buy or cart with them. Hence, this is why I want to talk about use and safety.
[glow=Orange,2,300]Using your Snatch Block[/glow]
Snatch Blocks are very useful in technical recoveries where a straight line pull may be impossible, or you have to side shift your ORV, or your winch just doesn't have enough oomph.
Say that your stuck in mud up to the bumpers and there is just no more movement. So you look at your buddy in the passenger seat and ask him nicely if he wouldn't mind jumping out and hooking your winch line up to the nearest tree with the appropriate tree saver strap and shackle( Besides....he was the one egging you on into the mud hole in the first place ;D).
After hooking everything up, and your buddy standing clear, you begin to winch. The Jeep moves all of about 3 inches and the winch grinds to a halt.
Now you have to come up with some more pulling power. You take the snatch block and attach it either directly to the tree strap or by way of a shackle. (The shackle needs a WLL of double your winch capacity at this point).
You thread the cable thru the snatch block and return the cable to a shackle attached to your bumper. Now when you pull with the winch, two things have happened.....
1. You have spooled more cable off of the drum of the winch.
This means that you are getting closer to the acctual max capacity of the winch.......if you are on the very first wrap, you are at the max capacity.
2. By going thru the snatch block and back to the bumper you are cutting the line speed in half. It's like putting your jeep in low-range.....Think of the gained power.
This is a 2:1 ratio effectively doubling the pulling power. A 9K lb winch on the first wrap of the drum passed thru a snatch block and returned to the vehicle is now capable of 18k lbs of pulling force. Here is where you will find out how well your bumper is made, or it is fastened.
Bystanders beware of flying winch/ bumpers.
This is where you have to be very careful.
1. Is the tree or anchor point good enough to support that kind of pull?
2.The tree strap needs to be up to par. This is probably only an issue if your not using an acctual tree saver strap, as many are rated 40k-60k lbs in the 3-4" wide strap range.
3. If a shackle is used, is the WLL correct? This particular senario would require a WLL of 9.5t or 19k lbs.
4. All bystanders should stay far left and right of the cable, never inline with it. It may not be a bad idea for the driver to stay ducked down in the seat in case of a component failure.
This is a fairly common us of a snatch block.
Other uses would be for getting good rope position for winching another vehicle from around a corner in a matter of speaking,where a straight pull would otherwise cause a roll-over for the recoveree.
Or winching someone from behind or ahead of you.
Where possible, if you could fasten a snatch block to the bumper of the ORV, you could use it to redirect the cable pull and drag the front to the left or right without bunching the rope on the winch or crushing it on the fairlead.
In this same setup your rigging can accomodate many different actions, like rolling your own vehicle back over,or side shifting the rear or front of the jeep.
A simple yet strong attachment made for the front bumper just for this purpose could be very useful.
Don't laugh to hard at my quick illustrations
Here is an example of a snatch block being used to double the pulling power of the winch.
The orange shaded area is where nobody should be positioned while winching.
The yellow arrows in the next two pictures are the direction of travel that the wire rope will travel depending on where the break occurs. Assuming that it would be at a point of attachment and not the rope itself.
Here is using a snatch block for redirecting the line of pull. Remember to take notice to all possible directions of travel in the event of a rigging failure.
It takes a millionth of a second when a failure happens for someone standing within the DEAD ZONE to be mortally wounded or killed.
Take a moment to carefully asses where everyone is standing before winching. Some pulls are very light and not likely for anything to happen, but if your in the habit of practicing safety, your alot less likely to have an accident happen.
This picture is to show you one of many ways to redirect your line of pull by extending the snatch block further away from the first tree with a longer strap.
Here is a bunch of pics (10) of various snatch blocks and descriptions, along with a couple of use pics.
Here is a typical ARB example
A typical warn example
This snatch block is designed for synthetic rope use only, and you will see on the lable that it has a max rating of 15,000 lbs.
These 2 are like the smittybuilt HD's..one has a WLL of 4t and the other is WLL 6t. I still have not found a higher max rating on this style than 36k lbs.
Here is an example of the fancy ARB style, but this paticular one is the acctual manufacturer's.
I included this one because it has KN ratings on it. KN's are acctually a sustained force rating, not acctually a weight rating.It's acctually a kenetic force rating like droppoing 180 lbs 3ft will generate a lb rating of 5K give or take. There are formulas on line to deturmine the weight rating....if I remember correctly 22kn is equal to roughly 6500 lbs.....but don't hold me to that.
Here is a ARB being used to doulble the winch power. Notice how the shackle is placed. This is correct.
Here is another pic of use. Again, the shackle is being used correctly, but the chain in the background is not.....The chain should not be wrapped or twisted (links should be in line). The shackle on the background pic is backward, and the chain should loop thru the bow and not hooked to it. It's hard to tell, but I also think that the chain is fed thru the strap eyes. This also is a major NO-NO as it ruins the strap and greatly reduces the strength of it.
I'm not 100% on this picture, but I believe that they are winching another vehicle up the hill. They are not currently winching because you can see the line is slack. The winch line has a damper thrown over it,the tree saver,shackle, and snatch are all correct.
Where everyone is positioned is what is in question. The safest place to be is behind the hummer. Second safest place is to the uphill side of the cable(left). Ten foot away from the hummer and cable. No closer than 2/3 of the lenght to the first anchor point(Snatch Block).
Both men to the right of the cable are both in the DEAD ZONE!
Her are a couple pics of industrial style Snatch Blocks.
Here is one that is designed for vertical lifting only.....You can tell by the shackle.....if you read the shackle post.
There was two other pics but photobucket it being fusy.
They both have hooks on them, one with a safety,one without. When using hooks, always try to place the hook's open end facing up, in the event that it breaks it will throw the hook towards the ground.
If using a industrial style snatch block with a built in attachment point, a shackle with a threaded pin is preffered.