new bollard/winch for rigging?

[Tony Croft aka hamadryad]

or continue cutting and pasting from wikipedia

 

 

what did you think i was going spout that off the top of me edd! lol:lol:

[Rupe]

breaking load is irelevent , we have to work to safe loads, and i wanna rig loads in excesse of 7kn! snatch a half tone lump of beech on a block say

 

Yes but breaking load is what is written on a karabiner, so you cant compare a 7Kn SWL of a winch to an aluminium karabiner that has 7kn written on the side.

 

I agree its all about SWL. If you want to use a lower SF you can do. 10:1 is really for ropes etc. so you could use 5:1 on the winch if you like, it still aint gonna break.

 

But 500kgs of wood snatched is more likely to exceed SWL on your rope well before it does so on the winch, which is fine as the rope should be the weakest part anyway.

 

I do think the 700kgs SWL is a bit low, and easy to exceed, but it really doesn't matter, if your rope and the tree can take it then go for it. Thats always been my method.

[Tony Croft aka hamadryad]

my steel crabs have a MBS 50 kn, my isc pulley a working load limit of 3000kgs, so isnt the bollard/winch supposed be stronger than the isc pulley?

[Rupe]

So your half ton of beech is less than the SWL anyway, so even if its snatched it will be fine if you groundie knows what he's doing, and very not fine if he doesn't.

[StevenIbelings]

Well dont hang me up on it...but as far as i know it isnt...correct me if im wrong!

[Tony Croft aka hamadryad]

I have had my big rope through that pulley to a leaning pop and a 7.5ton loaded truck whell spinning pulling the tree back into the woodland via the pulley, my rope is a known quantity 7 kn sounds low to me. or maybve im being thick?

[Adam Bourne]

sorry to butt in on the conversation! but why would you have to push you gear to the limits i'm happy lowering 250kg of wood all day because i know i would not be over working my equipment but to snatch load 500kg of anything unless done real well is just burning a hole in your pocket....in my opinion anyway:001_smile:

 

 

 

Adam

[Peter]

my steel crabs have a MBS 50 kn, my isc pulley a working load limit of 3000kgs, so isnt the bollard/winch supposed be stronger than the isc pulley?

 

No, the bollard/winch is only subjected to half the load of the pulley.

[Rupe]

Basically the ISC pulleys are super awsomely strong, and the DMM impact ones are even stronger, they will always be the strongest part of your set up. Like Peter is implying they actually carry double the load (the log on one side PLUS the same load on the other side holding the log in place.

 

So, a WLL of 3000kgs is about right, that means a load of 1500 kgs can be applied to either side, which is double waht the winch can handle which is exactly ok.

 

If the pulley could only handle the same as the winch then you would have problems.

 

I have never snatched anythign like 500kgs, like majestic says 250kgs is ample. We have however lifted 600kgs lumps with no bother but that would be putting 1200kgs of force on the block so a 3000kgs WLL is very comforting.

 

The large ISC actually has a WLL of 4500kgs!

[Paul Smith]

So what dont you like mike?

let me know! maby we can change stuff that you would like too see more...

 

Curious why you dont like it!

 

Steven,

 

Send me one and I'll do s full test and review for you and Arbtalk!! 8)