Forestry Winch SWL

[ps9]

So a new 4t winch comes with 10mm steel wire rope. The safe working load [SWL] of 10mm swr is only 1.25t. What am I missing that makes it ok to use wire of this diameter?

[Peasgood]

No expert but you sure you are looking at pulling rather than lifting?

[Khriss]

Hmmm 7x19 10mm minimum break load is 6.5ton in my book, if it came with the new winch, then you will have a manual with it. 1:5 swl would be abt 1.25 ton. Wot you using it for? K

[Paddy1000111]

MBL of 7x19 10mm is usually ~52 to 64 kN depending on the producer but its SWL is a lot lower like you say as it's usually 1/5th minus 10% for an assembled winch cable. I'm not sure about the rules about winch cables and how the MBL and SWL works though. As they aren't suspending a load I don't know what their requirements are. 

[woody paul]

Got a winch on land rover rated at 12500lb pull and its got a 9,4mm multi strained cable rated at over 7ton.

Edited February 19, 2021 by woody paul

[ps9]

Thanks for the replies. I don't have the winch but looking to buy, hence trying to understand. A 4t winch can presumably load a wire up to 4t so my numpty brain would expect it to come with a steel wire with a safe working load of 4t. But that's going to be in the region of 18mm and I don't think anyone is using wire of that size on a small logging winch. The Minimum Breaking Load of 10mm [7x19] is 6.5t so it all seems a bit tight. Is that just the norm?

[Paddy1000111]

Pretty much. I've got a 4.5 tonne winch on the landy and that's a 10mm cable

[Peasgood]

I've used a 10mm wire to pull things with a tractor (not winching, just pulling). You can break them but you have to be doing something a bit daft, tractor normally loses traction way before the cable breaks.

 

What winch are you looking at? I am toying with the idea too. I have a load of 100' leylandii I would like to drop but only own the land one side. Was thinking a winch encourages them to go the right direction.

[Dan Maynard]

No expert but you sure you are looking at pulling rather than lifting?

This.

SWL is for lifting operations so the safety factor is nice and high. The winch is not rated for lifting - in general if you are dragging and the cable breaks then no disaster, the object just stops moving.

[ps9]

40 minutes ago, Dan Maynard said:

..in general if you are dragging and the cable breaks then no disaster, the object just stops moving.

Perfect Dan, that's the bit I was missing. Was expecting an overloaded / snapped cable [when dragging a load] to twang like a big elastic band back towards the operator. You are saying it will just flop to the ground hence less need for safety factor.

@Peasgood the ones from Wirax in Poland seem very well priced if I can get delivered to the UK.