Snatch block for winch how large do i need

[Ty Unnos]

I agree with what saying, but what's the safety factor after its been used and abused, got wet, developed wear etc. And lets remember that the 6 ton cable also has a safety factor, and im sure theres guys on here snapped cables myself being one. The SF is there for a reason in respect that your kit is only new when its new:thumbup:

 

Totally agree. The safety factor is there for a reason but you can also use common sense (and a bit of physics!) I am not suggesting you exceed the SWL - just that you can take account of theoretical maximums vs actual loading and size your system accordingly.

 

There is lots of info in here:

 

http://www.forestry.gov.uk/pdf/fctg001.pdf/$FILE/fctg001.pdf

 

The key bit is:

 

Even if a component has a safety factor allowing it to withstand loading above the SWL, the load placed on the component should never knowingly exceed the SWL.

 

So if you use your 6 ton winch and 8 ton SWL snatch block to LIFT a 6 ton object you will have knowingly exceed your SWL. ( The snatch block could be experiencing 12 ton )

 

But if you use your 6 ton winch and 8 ton SWL snatch block to SKID a 1 ton piece of timber you have not exceeded your SWL. Yes you will have to overcome inertia / friction ect but you can be confident that the timber will move and in doing so will not exert a force on the snatch block that is great than the SWL.

 

So if I was going to use the above set up I would make sure I didn’t try and move timber that was too heavy!

 

The other thing is it ain’t the strops and snatch blocks I worry about. I know their SWL and can calculate the force on them. The big unknown is the tree you are anchored on! When you double up using a snatch block you double up on the anchor point as well and pulling the anchor point over is a real possibility.

[mendiplogs]

Totally agree. The safety factor is there for a reason but you can also use common sense (and a bit of physics!) I am not suggesting you exceed the SWL - just that you can take account of theoretical maximums vs actual loading and size your system accordingly.

 

There is lots of info in here:

 

http://www.forestry.gov.uk/pdf/fctg001.pdf//fctg001.pdf

 

The key bit is:

 

 

 

So if you use your 6 ton winch and 8 ton SWL snatch block to LIFT a 6 ton object you will have knowingly exceed your SWL. ( The snatch block could be experiencing 12 ton )

 

But if you use your 6 ton winch and 8 ton SWL snatch block to SKID a 1 ton piece of timber you have not exceeded your SWL. Yes you will have to overcome inertia / friction ect but you can be confident that the timber will move and in doing so will not exert a force on the snatch block that is great than the SWL.

 

So if I was going to use the above set up I would make sure I didn’t try and move timber that was too heavy!

 

The other thing is it ain’t the strops and snatch blocks I worry about. I know their SWL and can calculate the force on them. The big unknown is the tree you are anchored on! When you double up using a snatch block you double up on the anchor point as well and pulling the anchor point over is a real possibility.

 

HI MATE THANKS FOR THAT but im not lifting logs im pulling them thats not the same lifting re anchor point i no what you mine but the winch is a good one thanks jon

[mendiplogs]

Totally agree. The safety factor is there for a reason but you can also use common sense (and a bit of physics!) I am not suggesting you exceed the SWL - just that you can take account of theoretical maximums vs actual loading and size your system accordingly.

 

There is lots of info in here:

 

http://www.forestry.gov.uk/pdf/fctg001.pdf//fctg001.pdf

 

The key bit is:

 

 

 

So if you use your 6 ton winch and 8 ton SWL snatch block to LIFT a 6 ton object you will have knowingly exceed your SWL. ( The snatch block could be experiencing 12 ton )

 

But if you use your 6 ton winch and 8 ton SWL snatch block to SKID a 1 ton piece of timber you have not exceeded your SWL. Yes you will have to overcome inertia / friction ect but you can be confident that the timber will move and in doing so will not exert a force on the snatch block that is great than the SWL.

 

So if I was going to use the above set up I would make sure I didn’t try and move timber that was too heavy!

 

The other thing is it ain’t the strops and snatch blocks I worry about. I know their SWL and can calculate the force on them. The big unknown is the tree you are anchored on! When you double up using a snatch block you double up on the anchor point as well and pulling the anchor point over is a real possibility.

HI MATE THANKS for that thats the other things just cut it up small and can use the block on single line too just to get the timber out can some time be a night mere thanks jon

[3dogs]

But there will be a 12t pull on the snatch block...

 

Do we both agree that a 12 ton block is required?

[3dogs]

So if you use your 6 ton winch and 8 ton SWL snatch block to LIFT a 6 ton object you will have knowingly exceed your SWL. ( The snatch block could be experiencing 12 ton )

 

But if you use your 6 ton winch and 8 ton SWL snatch block to SKID a 1 ton piece of timber you have not exceeded your SWL. Yes you will have to overcome inertia / friction ect but you can be confident that the timber will move and in doing so will not exert a force on the snatch block that is great than the SWL.

 

So if I was going to use the above set up I would make sure I didn’t try and move timber that was too heavy

 

I totally agree with what you say and have no issue with that. However you would have a winch setup that could potentially overload the block, and when whole tree skidding that is all too easy to do and believe me a six ton cable in face hurts I've got the good looks to prove it:blushing:

 

There are many on here that may not fully understand physics!

 

So to maintain industry best practice 6ton winch = 12ton snatch block = 12ton+

Strop or choker.

[Eddy_t]

Just remember - the weight stated on the winch is ALWAYS the maximum weight for PULLING ON A LEVEL SURFACE! On my 1.2 tirfor the lifting weight is about 2/3 of the weight, also you need to check the limits on the strop, certain ways of wrapping lower the draw weight

 

 

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[mendiplogs]

So if you use your 6 ton winch and 8 ton SWL snatch block to LIFT a 6 ton object you will have knowingly exceed your SWL. ( The snatch block could be experiencing 12 ton )

 

But if you use your 6 ton winch and 8 ton SWL snatch block to SKID a 1 ton piece of timber you have not exceeded your SWL. Yes you will have to overcome inertia / friction ect but you can be confident that the timber will move and in doing so will not exert a force on the snatch block that is great than the SWL.

 

So if I was going to use the above set up I would make sure I didn’t try and move timber that was too heavy

 

I totally agree with what you say and have no issue with that. However you would have a winch setup that could potentially overload the block, and when whole tree skidding that is all too easy to do and believe me a six ton cable in face hurts I've got the good looks to prove it:blushing:

 

There are many on here that may not fully understand physics!

 

So to maintain industry best practice 6ton winch = 12ton snatch block = 12ton+

Strop or choker.

HI MATE thanks for that jon

[Ty Unnos]

So here is a question.

 

I have this type of snatch block:

 

4.5" 4 Ton Heavy Duty Lightweight SNATCH BLOCK Swivel SAFETY HOOK Lifting Pulley | eBay

 

It's WLL is 4000kg. It is solid and I trust it. But it is heavy for what it is.

 

Then I see these:

 

Bushranger Snatch Block - 7000kgs

 

Which is a 4x4 recovery style snatch block - also designed for wire rope.

 

It's WLL is 7000kg and it is much lighter!

 

But is it suitable for working in the woods?

[Big 'Ammer]

Mendiplogs, if you are using the snatch block only as a means of an offset pull, then a six tonne strop and a six tonne block will suit a six tonne winch.

 

If you wish to double the power of your winch by fastening the end of the cable back to the tractor and fastening the block to the timber, then you will need a twelve tonne block and strop.

 

But the winch will probably break doing that....

[difflock]

The winch wont break, but the tractor might?

If the free end is secured back to the tractor (note! not the winch)

Say hook it to the tractor drawbar with a length of suitable chain below the winch anchor blade.

6 tonne pull on the winch, but 12 tonne pull on the tractor.

If hooked back to the winch the most likely failure points are the winch end top link mounting, followed by possibly the lower link arms pins or fixings( at the winch end)

Cheers

M