Why the capacity of wire rope slings decreases when the angle decreases. Example - At the angle of 60 degree it lifts more weight where as at 30 degree its lifting capacity reduces. Why?
Please help me & specify the technical reasons.
From India, Bhubaneswar
Kesava PillaiDear 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.
From India, Kollam
tukuna.mamaDear Pillai sir,
Thanks for your reply. whatever You have explained is absolutely correct. I highly appriciate your example.
But What are the factors I mean the technical reasons behind this. Though I know the formula to calculate the capacity of wire rope slings at different angles.
so far your given example is concerned, In step 1 it is easier and at step 4 it is difficult. Everybody knows it.
My question was what are the technical reasons come into force.
From India, Bhubaneswar
Kesava PillaiDear Santhosh,
You have the formula for calculating capacity of wire rope slings at different angles. You want to know the technical reason!
1. Consider that you are using two slings in vertical position to lift a load. In this case there is only a vertical component. There is no horizontal component. The load on the slings is exactly the same as your load weight.
2. Now consider to flatten out the slings. This time both slings may be at the same angle or different angles depending up on the CG of the load.
In this case the vertical component remains the same, but a horizontal component is added. The load in the sling is the sum of the vertical and horizontal components. As the slings flatten the horizontal component increases, the angle between the sling and the horizontal plane decreases so the load in the slings increase.
It is a function of trigonometry.
I am leaving the load factor, included angle etc. since you already have the formula.
You have the formula for wire rope slings. What about other types of slings? Will there be any difference?
From India, Kollam
dipilDear Kesava Pillai Sir
Thanks for the great inputs from your side again...
To continue the discussion at the point where you stop with a question, whether there will be different formula for different slings... Yes, it is there... I do have a presentation on Rigging which included these different formula... I am attaching the same for your perusal and the benefit of all other members those who not having this...
Please guide further for learning more on the topic...
murdharDear Mr,Kesava Pillai, your examples are down to earth and easily comprehensible by any lay man. However for the technical reasons, there are lot of good books (Ref Statics and Dynamics by Timoshenko and Young) where good theory behind the forces acting is explained well. Sir are you from safety and if so I like to have your contacts (like email id) by which I have can keep in touch with you, incase if it is not possible here. (Ofcourse for technical and safety clarifications only).
Thanks and Regards,
From India, Mumbai
vallibasha76All friends of Safety Professionals of this Forum,
As per my observation from this forum, we have found two Gem of Persons in Safety professionals as you all knowing inspite of my eagerly express my views as member of this forum they are truely GEM of this Forum for helping all needy persons concerned to safety they are.................1) Mr. Kesav Pillai sir.
2) Mr. Dipil Kumar sir.
Really we safety professionals are fortunate to get this Great persons as you know in this world lot of Selfishness prevailling!! such in such situation also these two persons helped by sharing & helping by needful safety information to all this forum members.
I pray to Almighty God behalf of this forum bless with his mercy always.
Thanks for all sharing their views.
With Respectful Regards.
Valli basha Sab.
From India, Hubli
yogitaptDear Pillai Sir,
Thanks to explain the matter in so admirable way .....
Further sir i like to share with you that I am working in a State Level University. Our University is under process to get ISO 9001:2008.
I feel very good to work for & think that it will definitely improve the style of working & uniformity in all aspects. It's giving chance to work other than routine things & gives scope for creativity. I am also very curious about the results of the whole exercise.
Sir, in govt. organization it is very hard to get speedy work from subordinates.
Will you guide me on issue, how to prepare minds of class III & IV peoples to contribute & implementation of the same as well as raise speed & spirit of working?
From India, Nasik
dipilDear Mr. Valibasha
I am not deserving for this much appreciation words from your side... Surely Mr. Kesava Pillai is deserving for the same... Please don't embrace me with this much kind words... I am assuring you to give my best to this forum as this forum helps me a lot to improve my personal and professional life...
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