working out WLL from MBS

flying_kiwiman

flying_kiwiman

Location
Utrecht, Holland sometimes Dunedin NZ
On some pulley's they only give you a MBS ( max breaking strength )rating . Is there a standard factor you can use to work out the WLL ( work load limit )??.

On the ISC pulley's the give a factor 5 ( WLL 2000kg, saftey factor x5 ). Does this apply for all pulley's?? What factor do you use to work out the WLL if you only have the MBS??

cheers Jelte
 
That's a good point. The problem I've also seen is that some will give a WLL of 5/1 but don't also split that in half. What I mean is, I like how some co.s like Petzl who will mark each side with a WLL. For example, the little Fixe is labeled for 11KN each side, or 22 KN total.

I think that it is pretty standard to have a 5/1 safety factor over minimum breaking strengths for hardware.
 
Yesterday i did a pulling test on a CMI swingcheek pulley with a MBS rating of 71kn ( there was no WLL rating on this pulley ).

At 1200kg there was no sign of any stress or deforming. I went a little further and pulled until 2800kg. At this point the pulley was not looking so good...:)

The cheek's of the pulley were starting to bend outwards at the point where it was attached to the carabiner, also the wheel in the pulley was slightly pulled diagonally.

So i guess the 5/1 ratio is quite correct, in this case it would be about 1400kg
( which i exceeded ).

anyway, that pulley be f@*ked!!

happy rigging, jelte
 
Some manufacturers use differect SWLs. I've seen everything from 2:1 to 20:1. I wish manufacturers would just give us the MBS and let us decide.

love
nick
 
[ QUOTE ]
[ QUOTE ]
Safety Factors

I use 10:1 for rigging equipment

and 5: 1 for climbing equipment

[/ QUOTE ]

I use the reverse. 10:1 for life support and 5-7:1 for rigging.

[/ QUOTE ]

Norm's is the norm.
 
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