Snatch block for Tirfor winch

[dereki Member Find all posts View Profile Close dereki]

Hi

I have recently obtained a Tirfor 516D, which has an 11.5mm cable. The instruction manual states in section "Rigging Arrangements" that any pulley must have a diameter of 18 times the diameter of the cable. This means any snatch block needs to have a pulley with a diameter of 207mm... Most are less then 1/2 this. The biggest ARB one is a mere 110mm.

The requirement for the large diameter is because of the stiff nature of the special cable used in the tirfor machines.

So
1. Where would I get such a pulley?
2. Be warned that if you have a hand winch, check the manual to see what the minimum diameter is for your make/model of winch. Otherwise cable damage/weakening may occur.

D

[samo Addicted PP Member Find all posts View Profile Close samo]

Re: Snatch block for Tirfor winch

if yor r after a snatch block that big, try blackwoods or any lifting or rigging shop eg bullivents, but trust me they only say that to cover their arse, been using snatch blocks with tirfors for years and never had a problem yet, when they get that big they get heavy, go with an arb 1 you will be fine, but its up to yourself, these r only my opinions and r not to be taken as gospel. cheers samo

[foxclan Avid PP Poster! Find all posts View Profile Close foxclan]

Re: Snatch block for Tirfor winch

Hi dereki
You could search nsw workcover publications Rigging Guide , part one page 25 - winches,sheaves and purchases for flexible steel wire rope.
Regards Troy

[ozwapet2 Advanced Member Find all posts View Profile Close ozwapet2]

Re: Snatch block for Tirfor winch

Well there ya go, I never heard of such a thing. But there may be a point.
Even the 4WD instructors I've seen use Tirfors and other brands of hand winches with standard sized snatch blocks.

[dereki Member Find all posts View Profile Close dereki]

Re: Snatch block for Tirfor winch

Hi dereki
You could search nsw workcover publications Rigging Guide , part one page 25 - winches,sheaves and purchases for flexible steel wire rope.
Regards Troy

Thanks for the info.

I had a really quick look. I probably missed something, but there is a table there ... light load, once off use, 11.2 x the wire diameter... = 128.8 which is still bigger than the big ARB block which is 110. But it says, that the winches etc are complicated and you should do what your manual says.

Sigh... I might ring a rigging supplier that sells Tirfors and see what they say. The Tirfor wire has apparently got a solid core so it doesn't crush in the jaws of the machine, but winch cables have a soft core so is more flexible and can do around much tighter corners... like the drum on the winch.

Does anyone have a manual for a non Tractel brand Tirfor, like a magnum or something? What does it say?
The reality is I will probably just get a 4wd snatch block, but now I am interested in what is "correct", assuming that the manual is overly safe...

Thanks
D

[samo Addicted PP Member Find all posts View Profile Close samo]

Re: Snatch block for Tirfor winch

funny about the tirfor cable, i went and saw a rigging company about a new steel winch cable and i walked out with 28m of 11mm tirfor cable for my winch, so whats that saying, and that was on this companies recommendations. cheers samo

[dereki Member Find all posts View Profile Close dereki]

Re: Snatch block for Tirfor winch

funny about the tirfor cable, i went and saw a rigging company about a new steel winch cable and i walked out with 28m of 11mm tirfor cable for my winch, so whats that saying, and that was on this companies recommendations. cheers samo

Interesting. What brand of winch is it. It looks like some use 11.5mm and others use 11mm cable. Some have a max lifting load of 1600kg others 1500kgs. In any case, will .5 of a mill matter, probably not unless your at the limit of the system, then it might just slip. Of course, these things have large safety margins. 5 times, I believe.

So to kind of answer my own question...

The block size 18 times rule in the manual is for lifting 1.6t, on a regular basis (building site, every day for example), and with years of service life in mind. ie 1000s of lifts.
For the 1 emergency I might need it for the 4wd block is probably going to be fine...

D

[samo Addicted PP Member Find all posts View Profile Close samo]

Re: Snatch block for Tirfor winch

its an ironman 9500lb winch, and when it comes to a lifting and pulling rating it is different, usually the pulling rating is almost double the lifting capacity. cheers samo

[bgreeni Member Find all posts View Profile Close bgreeni]

Re: Snatch block for Tirfor winch

I would certainly not put a tirfor cable around a small dia pulley. The safest way is to have another more pliable cable attached to the tirfor cable and run that around the snatch block. As stated, the tirfor cable is a special type of cable and does not like sharp bends.

[ozwapet2 Advanced Member Find all posts View Profile Close ozwapet2]

Re: Snatch block for Tirfor winch

I would certainly not put a tirfor cable around a small dia pulley. The safest way is to have another more pliable cable attached to the tirfor cable and run that around the snatch block. As stated, the tirfor cable is a special type of cable and does not like sharp bends.

I've also seen a snatch block / pulley that is wide enough to take a winch extension strap. I have not seen it in use, but i imagine the strap would need to have no twists in it to work effectively,

[winniliss Avid PP Poster! Find all posts View Profile Close winniliss]

Re: Snatch block for Tirfor winch

Your URL link didn't work, try this:

http://www.workcover.nsw.gov.au/form...gingGuide.aspx

[dereki Member Find all posts View Profile Close dereki]

Re: Snatch block for Tirfor winch

I would certainly not put a tirfor cable around a small dia pulley. The safest way is to have another more pliable cable attached to the tirfor cable and run that around the snatch block. As stated, the tirfor cable is a special type of cable and does not like sharp bends.

Actually I was just thinking of using plasma rope instead of a winch extension strap and only running that through the block.

I just checked the price of plasma rope... um... no. :shock:

In all honesty I am getting into the way over equipped stage, and really can't see me using a block. But... for safeties sake I will stick to the rules on this one and either get a 210mm block or some sort of more flexible wire as an extension to run through a standard 4wd block.

Thanks for all the input so far.
D