You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
GOOD SLINGING PRACTICE<br />
BASIC RULES ... 4<br />
4.4. SAFE WORKING LOADS - THREE-LEG SLINGS.<br />
Three-leg slings need special consideration, because rarely do all three legs take an<br />
equal share of the load. It is best to assume that only TWO legs are sharing the load,<br />
with the third leg only acting as a "balancer".<br />
Using our Riggers' Guide, we find for<br />
this system:<br />
1. the SWL = 4500 kg.<br />
2. the WLL of each sling = 3200 kg.<br />
3. the load in each sling leg will be<br />
the actual load x 0.7.<br />
4. the SWL = WLL of ONE sling leg<br />
divided by 0.7.<br />
If loads are critical and equally shared we can find accurate<br />
sling loads by calculation - e.g; using the same scenario,<br />
10mm chain slings with a WLL of 3200 kg and effective 90°<br />
included angle has a SWL of (3200 / 0.7) = 2286 kg per leg.<br />
= 6857 kg for the three legs.<br />
As an example:<br />
Sling legs are 3m long.<br />
Pitch diameter of the sling attachments is 3m.<br />
The effective included angle is 60° (30° from<br />
vertical).<br />
Using the approximation method, we assume the<br />
load is taken on two legs only. Therefore, from our<br />
Riggers Chart, we find the sling load at 60°<br />
included angle will be 100 kg x 0.58 (60° load<br />
factor) = 58 kg.<br />
Assuming the load is equally distributed between<br />
the three legs, we find that the sling load =<br />
100 kg x 0.58 (60° load factor) x<br />
2 legs<br />
3 legs<br />
= 39 kg.<br />
Assumed included<br />
angle = 90°.<br />
= 45° to vertical.<br />
Load = 100 kg.<br />
10mm chain<br />
slings<br />
CRANEAGE - SLINGING: BASICS PAGE 5
Change language