Pulleys and strops to use with a Tirfor?

[Stephen Blair]

The shear pin should be the 1st thing to let go. Everything else needs to be rated higher than the winch. With vehicle recovery it's extremely difficult to calculate the forces involved, a good resource is 'Winching Operations In Forestry - Tree Takeown and Vehicle De-Bogging'

 

http://www.forestry.gov.uk/pdf/FCTG001.pdf/$FILE/FCTG001.pdf

 

I don't work with things with shear pins, if you don't know what you are doing then the last thing you want is a system seized up under tension!

The winch should never be the weakest link, if you don't know what to do, get taught how to.

[Matthew Storrs]

I don't work with things with shear pins, if you don't know what you are doing then the last thing you want is a system seized up under tension!

The winch should never be the weakest link, if you don't know what to do, get taught how to.

 

Iv got the Tirfor TU16, despite having a shear pin, i have on occasion given it nearly my all with the handle fully extended- I must say i wince/cringe whilst doing it when theres that much tension despit having well over rated stops etc. The pin has never sheared so they must take a hell of a lot of strain before they do. A mate was helping me out once and made the mistake of releasing the handle when it was still under tension- it hit him on the head and he saw stars but i think he was lucky it didn't crack his skull to be honest.

[R Mac]

I don't work with things with shear pins, if you don't know what you are doing then the last thing you want is a system seized up under tension!

The winch should never be the weakest link, if you don't know what to do, get taught how to.

 

I did, kind of, winch use is taught on CS-32, as I understand it the shear pin of a Tirfor type winch should break 1st but the winch will still hold the load, the handle has the fail safe on a Lugall, I don't see how the winch shouldn't be the weakest link, are you suggesting that the strop/shackles/etc should break before the shear pin?

 

What would be the point of having a shear pin if the rest of the system was going to fail 1st?

 

Here's an excerpt from the pdf I linked to.

 

"When making up winching tackle for debogging

or tree takedown operations, care must be

taken to ensure that all components are rated

appropriately to cope with the anticipated

force under which they will be required to

operate. The safe working load of a system is

that of the lowest rated component of the

system. If any of the components in the system

has a feature which will prevent overload of

the system or failure, e.g. sheer pin in a hand

winch, then that element of the system should

have the lowest safe working load (SWL) of all

components (see page 10). Wire rope should

have a SWL that is compatible with that of the

blocks, shackles and other components used."

[maria warwick]

I have snapped the shear pin on my winch. I have one of the cheaper versions. Was pulling out some conifer stumps and there was two of us on the winch lever , so quite a lot of muscle ! I would rather the shear pin go , than the cable. Shear pins are easy to pick up off the internet ( pack of 10 ) !!

[Haironyourchest]

Woodworks, if you haven't bought the tirfor yet, consider a ratchet lever hoist as an option. They come in 500kg, 750, 1500kg, etc similar to the tirfors. Same price as the tirfors for the same pulling power, or maybe a bit cheaper. The advantage they have over the tirfor is they are chain not cable, so much much easier to store, to clean and to transport. Also more compact. Chain also "less" dangerous if it fails. They come with a really short chain, but rated chain in common sizes is cheap. They have an overload clutch option as well, for extra bucks. One of them with a dyneema extension rope "might" give you more versatility.

[drinksloe]

I thought winch cable now should have a rope? core so no longer snaps back the way it used too.

 

Knw ive seen/had a few cables snap on me from tractor winches and just lay flat even when under big tension.

Nothing like the old wire rope which would come back to meet u. Dodgy stuff.

 

I too was under the impression the sheer pims has to give first. If it is not the weakest link means the rope/shakle/strop will give so wotever ur winching is about to fall back to original position. Not good.

Most tifors have spare pins in the handle

[Stephen Blair]

I did, kind of, winch use is taught on CS-32, as I understand it the shear pin of a Tirfor type winch should break 1st but the winch will still hold the load, the handle has the fail safe on a Lugall, I don't see how the winch shouldn't be the weakest link, are you suggesting that the strop/shackles/etc should break before the shear pin?

 

 

 

What would be the point of having a shear pin if the rest of the system was going to fail 1st?

 

 

 

Here's an excerpt from the pdf I linked to.

 

 

 

"When making up winching tackle for debogging

 

or tree takedown operations, care must be

 

taken to ensure that all components are rated

 

appropriately to cope with the anticipated

 

force under which they will be required to

 

operate. The safe working load of a system is

 

that of the lowest rated component of the

 

system. If any of the components in the system

 

has a feature which will prevent overload of

 

the system or failure, e.g. sheer pin in a hand

 

winch, then that element of the system should

 

have the lowest safe working load (SWL) of all

 

components (see page 10). Wire rope should

 

have a SWL that is compatible with that of the

 

blocks, shackles and other components used."

 

 

Do you know the weight of everything you are pulling or lifting?

Why pick up a 2 ton strop or a 3 ton strop or even look at the numbers on things unless you know for sure.

Reasons I don't want the weakest link being the winch.

1, it's the most expensive piece of kit.

2, I will be standing beside it so don't want the massive twangy movement beside me.

3, if something else fails I can still rectify the situation easier than if the winch fails.

I don't like shear pins, they can get stuck, they are something tiny that get misplaced easily, dropped at your feet in short grass never to be seen again and if I'm taking something with a shear pin it's not up to the job.

I work with the biggest thing I have to hand, I have no idea the pressures, weights and forces in numbers, what I do have is years of experience where my brain recognises a big lump of wood, a strop, shackle and chains and says' well it didn't break last time and it was bigger '

[drinksloe]

How can u rectify pulling a heavily leaning tree over if strop fails? Or lifting something?

 

tree springs back to where it wants to be or falls where the wieght is. Not sure how u can rectify that?

 

If a sheer pin fails, not ideal but with tirfor type u can ease of 1 or 2 clicks but everything should still hold. So u can then decide how ur going to get out off it. Extra winch or using a snatch block.

Also if shear pins fails first u shouldnae have any 'twanging' as everything else is designed to hold

 

 

Same with the strops etc, it dosenae really matter as long as ur strop is plenty strong enough, just like u know roughly the size of chain u need.

[Stephen Blair]

You can't think of situations where your way could be wrong, I know the situations I've been in that worked out OK after something has failed and it's not been the winch .

No point going round in circles here.

[R Mac]

The winch doesn't fail when a shear pin breaks, that's the whole point.

 

I agree that you can't exactly know the amount of force you're going to need in every situation, especially debogging but that only means that you should choose the highest rated equipment that you can reasonably use, the heaviest part of the system will be the winch but that still isn't a reason to use strops/shackles rated lower than the winch itself. If a strop or shackle fails the system has failed catastrophically and you've just lost all control of the object that you're pulling/lifting, you also run the risk that the cable suddenly relieved of the significant amount of tension placed on it will whip through the air like a guillotine with a shackle on the end carrying enough momentum to kill on impact. If a shear pin breaks you still have a degree of control. As for loosing a shear pin, you should be carrying spare shear pins and a means to remove a broken one.

 

Finally I can't think of a situation where I'd want a strop/shackle etc to fail before the shear pin (shear pin designed to prevent you overloading the system) so give me an example.