DIY tirfor winch handle

[5thelement]

32 minutes ago, Haironyourchest said:

Are you sure the maxi flex cable has no memory? It's a steel rope. Maybe you're thinking of Dyneema (Spectra) UHDP textile rope - that has no stretch therefore no (or little) backlash.

Yes, the maxi flex has no memory, no one will be decapitated if the strop comes off.

[openspaceman]

1 hour ago, Haironyourchest said:

Are you sure the maxi flex cable has no memory? It's a steel rope. Maybe you're thinking of Dyneema (Spectra) UHDP textile rope - that has no stretch therefore no (or little) backlash.

Yes one needs to define memory, as @Haironyourchest says no stretch then no way to store energy. Modern steel rope with a fibre core  squeeze the core as it tensions and expands when it goes, normally with no or little stored energy. The problem comes when another part of the system stretches or bends and stores energy when it does, if the rope snaps then it's this which provides the catapult effect.

 

KERR are famous for this when a weak attachment point fails and gets flung into the towing vehicle.

 

Back in the days of 3 strand nylon climbing line a young lad was killed when it was used as a throw line with a weight on the end, this got stuck and the rope was pulled, elongating it until the snagging branch snapped releasing the weight with all the energy in the rope's elastic deformation and striking the bloke on the head. Most ropes used in arb now are "static" with minimal elongation  rather than "dynamic" ropes used in climbing, to absorb the shock of the climber falling on them.

[htb]

Maxi flex has a memory for kinks.

[Haironyourchest]

Quote - ("Yes, the maxi flex has no memory, no one will be decapitated if the strop comes off")


Well, you sound pretty certain of that. Care to test your theory? Set up your tifor with the maxiflex cable/rope at full 20m span, anchor Tirfor and rope hook to immovable objects and tension the rope till you break the shear pin. Now take an angle grinder to the rope just behind the load hook. You'll be perfectly safe - if the rope springs back under tension, it can only spring away from you. Video the test and I'll send you a brand new rope.

Edited September 3, 2021 by Haironyourchest

[roys]

I use my Tirfor on a fairly regular basis and I use the maxi flex rope, I can’t argue one way on the other about its memory but something i was taught back in the 80’s and still do it, is once the rope section under tension is more than about 5 or 6 meters is to put a tarp / salvage sheet or even a big jacket over it. This was in case part of the system failed the flying rope energy would be arrested, no idea if this idea is out of date or superseded.

[harveyWhite]

Thank you very much for all of our advice people . We will definitely be careful . The cable is 16.3 mm diameter and will be anchored around a 300-year-old oak tree. I should have mentioned this earlier.

[5thelement]

2 minutes ago, harveyWhite said:

Thank you very much for all of our advice people . We will definitely be careful . The cable is 16.3 mm diameter and will be anchored around a 300-year-old oak tree. I should have mentioned this earlier.

Don’t forget to use it in exactly the opposite way to what the manufactures who designed it say.😉

[5thelement]

1 hour ago, htb said:

58 minutes ago, Haironyourchest said:

Quote - ("Yes, the maxi flex has no memory, no one will be decapitated if the strop comes off")


Well, you sound pretty certain of that. Care to test your theory? Set up your tifor with the maxiflex cable/rope at full 20m span, anchor Tirfor and rope hook to immovable objects and tension the rope till you break the shear pin. Now take an angle grinder to the rope just behind the load hook. You'll be perfectly safe - if the rope springs back under tension, it can only spring away from you. Video the test and I'll send you a brand new rope.

I’ve got a better idea. Rather than f**k my quality gear up trying to prove a point, why don’t you do it, make a YouTube vid and post it instead, I work for a living.

Edited September 3, 2021 by 5thelement

[Haironyourchest]

(Quote - 5thement) "I’ve got a better idea. Rather than f**k my quality gear up trying to prove a point, why don’t you do it, make a YouTube vid and post it instead, I work for a living."

I only got the China clone with the generic 7x19 strand steel core wire rope. :-( I work too, but not hard enough to afford a genuine Tirfor. I suppose I could stretch (pun intended) to just the Maxiflex rope, for the sake of experiment, but I know how it would end. Steel rope is steel rope, regardless of the construction. There is no such thing as a non-elastic type. All steel ropes are elastic, store energy. Even chain stores energy, and will recoil some when stretched to breaking point. I'd like to know where you got this information that Maxiflex has no memory. I'm guessing its Tractel marketing speak refering to the property of being able to tolerate a smaller bend radius over snatch block shieves without suffering plastic deformation. If this is the case, as I suspect, it would mean the Maxiflex rope is actually more elastic than the bog standard kind, and therefore more dangerous in a breakage scenario...now, as for operating a Tirfor in reverse, this is one of the intended modes of use. Tractel's own literature, and common sense, indicate this. It don't make any difference to the winch whether it's pulling the rope and load through itself, or pulling itself and load, along the rope. In any case, nobody is going to be able to break a medium to large size Tirfor rope in a month of Sundays, assuming the rope, hook etc is sound. The danger is the sling or strop failing, or slipping off the load.

[openspaceman]

31 minutes ago, Haironyourchest said:

Even chain stores energy, and will recoil some when stretched to breaking point.

I think a chain stores more energy than a wire rope  because there are parts of the link that have a bending stress in them as well as pure tension.