Dear Santhosh
From the question I take it that you are not from safety, you are not aware of any crane rigging, types of slings, hitches, mechanical handling and so on. However I definitely appreciate your attitude in seeking knowledge and I am always happy to help. My only problem is I do not like to spoon feed. Those who are really interested in learning from me like my attitude because my way of teaching makes them competent in the profession.
On to your query:
Please honestly do the exercise in steps 1 to 4 mentioned below and post your experience.
1. Take a bucket full of water keeping hand close to the body. In this case the angle between 0 and 1 is too small and you could probably lift it easily.
2. Move the water bucket away from your body to position 2 increasing the angle between the body and bucket.. Now, check -how you feel about the weight?
3. Move the bucket away from body to position 3 further increasing the angle. Check again how you feel about the weight?
4. Again move the bucket further away from body and keep it almost to horizontal position.
In all the positions though the volume and actual weight of water remained the same do you feel the load differently?
There are different types of slings; not only wire rope sling. With not only wire rope slings but with every other type of slings the effect of sling angle is the same.
There is a simple formula to calculate the stress on slings at different angles.
I will wait for your post on the result of the above experiment to give you a clear explanation.
Regards,
Kesava Pillai.