How To Calculate A Sling Load
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- čas přidán 4. 09. 2024
- - From MaintenanceResources.com -
Take the guess work out of how much force is exerted on a sling when making a lift with two or more lifting straps. The angles are not always just 45 or 60 degrees as is often listed on the sling capacity tag. Here is an easy way to figure out if it will be a safe lift.
All you need to know are four things:
1. The rated vertical safe working load of the sling.
2. The total weight of the load.
3. The length of the sling from the hook to the attachment point.
4. The vertical distance from the load to the hook point.
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Considering the Safety Factor is built into the rigging, this is a fantastic demonstration.
This is my favorite video on how to figure this out. Years later, I'm back to this no-frills explanation.
Excellent.
I like the way you talk slightly slow sir. It provides me time to take notes 👍 thanks
Effective communication. Thanks for sharing.
your video was very helpful, easy to understand, and well put.
Thanks,
I work construction rigging etc and this is basic thanks teacher you explained it a lot easier than how I learned it on the field lol
But he is WRONG. I have proved mathematically in my other comment.
For learner or safety personnel it's v informative...Thank sir.
Noted ..helped me with my elevator home work . Thank you
Thank u so much for your excellent way of explain for easy understand.
Thank you..very clear explanation🌷
It's really nice video... Because, this video is more helpful for me... Special thanks a lot... ❤️
Excellent way of explaining
Love ❤
Thank your video,really helped me
thanks for posting this, i truly understood now
Thank you sir 🤝
Thank You , very good information .
thank you for your work
I am an Appointed Person, trained to make lift plans.
The only thing good about this video is that you can find out the "sling load" but this should NOT be used to calculate the actual lift, because it is WRONG.
A Load Weight of 12,000 lbs is, 5443 kg so, 5.45 Tonnes. This is very heavy to be using “slings” or better called Webbing Slings. You will be using a sling that it is too wide and may need shackles to attach to the lifting points of the load, making it unreasonable. Red Lifting Slings are for up to 5 tonnes, Brown Lifting Slings up to 6 tonnes, but these are rated for vertical lifts, angled loads require a much higher vertical rating.
Instead, chains should be used in this example. An 8t rated chain can do the job safely. Calculating the Safe Working Load (SWL) - i.e. Rated Capacity - of multi-leg sling/lifting accessory arrangements using Uniform Load Method.
The measurement of the HH (hook height) is a bit ambiguous to say the least. The correct way of calculating the HH is based on the desired (included angle, in the UK, is 90 degrees or lower)
Or up to 45 degrees on the vertical angle from the load point (vertical) to the angle to the hook of the crane.
The most important factor is the desired angle of the chains in relation to the hooking points of the load, which is called (included angle).
In this example, I used my Trigonometry Calculator App and I input the known values that this person in this video gave.
We know that the right angle from the HH to the base of the centre of the load is 4ft which is (a) side. We know the hypotenuse (c) 6ft, with this information we can now know the angles and (b) distance, which is half of the distance of the load.
So, side b is 4.472 ft (1.36 m) x 2 = 8.94 ft (2.72 m) is the total length of the load.
The angle beta, which is the angle between the vertical side of the HH and the distance of the sling is 48,18 degrees, making the included angle of 96.35 degrees. I will refuse or not allow this lift given these characteristics because we don't know the sling tension for an included angle greater than 90 degrees.
Making numbers out is not the professional way to teach lifting operations.
If 4 sling is divided by 4?
Apply resolution of forces..Tension on each sling = 6000 /Sine theta = 6000 /(4/6) = 9000 lbs
Good job cousin
Thank you sir. Thank you very much
Dustin Outlaw, Theknotman1964 is from the UK. When he talks about not going beyond 90 degrees, he means 90 degrees at the hook which translates into 45 degrees from the horizontal.
Tom mMarley
Thank you. Easy to understand
Plz make a video about centre of gravity of a weight.
Thank you. This helped.
This vide is very helpful
Thanks for the clear tutorial. Sub'd to your channel as a result👍🏽
Safety is our top priority..
Sir plz make video on 3 leg and 4 leg tension calculation formula
What happens when lenghs are not equal,how do you calculate
Thank you sir
Hello I appreciate so much this video and can you please add one video for how to pass the interview for crane operator? thank you so muck for anyone who upload.
How can I calculate the breaking strength/force.And how will I calculate or determine if the sling is correct one to use with calculations.
Thanks for video its make me easier to tell
thanks for your information
Do you have the problems that deal with figuring out the valume and weight of tanks, steel pipes beams etc....cant find anything the can help me me on steel pipes for the ncccco test
Great info - thanks!
Awesome
Estou a tirar o curso e o professor pede para assistir esse vídeo, não percebo inglês e não há legendas
hi. thank you for tha video. please could you explain me, when we do these calculations ? because how can we know the distance between hook point and load....
Gabil Gurbanov tape measure
There is a formula to determine the HH (Hook Height) The person in the video is doing in another way, still valid but he is missing the HH calculations.
Thanks
This is part of the test when your doing your Sparrows Stage 2 Certificate in the UK
So thanks for posting it
As for Dragonf1sh below you need to go back to training school if you want to forget about the Angles because the bigger the angle the more weight is on the strop
But 90 deg is the safest angle and i would never go beyond it
Never exceed 90 degrees? You're gonna put a hurting on your company with all of those spreader bars...
It's stupid to forget about the angle! An object lifted by 2 straps with an angle smaller than 30 degrees woulds require straps with more SWL than the weight of the object. In other words: if the angle is smaller than 30 degrees with 2 straps it is saver to use only one strap.
How
good idea
How come you dont compare the 9000 lb answer at SWL 45 degree angle.?
Are all angle loads compared to 90 degree SWL?
In this case. You take the length of your choker and the height to the hook from center... (Basically gives you the angle) then multiply half the load weight. Gives you the tension on the choker... You don't have to know the angle for this formula... Just look at your tag for load limits in a choke, straight, or basket and you'll be good to go... Assuming center of gravity is center of what you're lifting
The step #2, isn't it supposed to be X times N (number of slings) times W instead?
And, how about a 3-dimensional beams, the case with slings with different x-y-z coordinates, can we calculate it the same way?
Are you rigger i want some doubt i want learn possible you teach me
simply calculate 1.4 X single leg swl gives 2leg swl
2.1 X single leg swl gives 3 and 4 Leg swl
Thats all I ever use 1.4 and 2.1 lot easier than this and confusing to people that dont work with cranes at all.
Antony Gilbey 👍🏻😎
How do you calculate the sling loads in a four point system which is asymmetrical i.e. the COG is away from the centre of the object?
Please provide solutions for this if you have.
Thank you
Only 2 legs carry the load!
Grate information, i would like to learn to calculate the load chart of a boom truck40 ton and under with a series 456b with a 18ft jib. ( the gross capacity, net capacity,what does they represent or mean. ) looking forward for another grate class one love thank you.
Look at the load chart of the of the crane. It'll tell you the capacity at the radius of the boom, jib, trolley etc depending on company your with, a lift plan will be needed past a certain crane chart capacity...
@@dustinjones4910 This tells me that he works alone in his lorry, no operator should be necessarily forced to know this information.
There are qualified personnel that make these evaluations and the information is then relayed to the crane operator via a liftplan.
These are the basic principles of rigging operation safetly.
I want to know how to convert this method of reference to metric? Or worse. Where do the number compound to the point that this method is not set in stone. Feet divide into twelve equal parts. Pounds divide into sixteen. Like celcius and Fahrenheit? Only works at -40°. Probably be close for a quick check though. Nice.
Good
So if you use 3 strings instead of 2 to lift the weight it is X times 1/3 of the weight. Or am I reading this wrong?
no. when you do this calculation it's always based on 2 legs.
Sardar Vlogs the third and forth leg are for balance of the load 2 slings have to be able to carry the load by there self. Just like using a 4 leg bridle, 2 of the 4 legs must be able to support the weight.
Michael Boyer, nope, when you're lifting with 4 slings, you can calculate strength of your lift with 3 slings, not with 2
@@michaelboyer4474 2 "diagonally opposed" legs...
Tq
Nice vide
awesome- thanks
please I need more informaitn about Riggers safety and calculate
Sir i dont know how to calculate "H" please help.
Pythagorean theory my friend
A2+b2=c2
If you’re missing b, subtract a from c
Then use your square root button on calculator on the end sum for b
Same if you’re missing a
Subtract b from c and you’ll have a
I start my apprenticeship with cranes tmr, and have a question, the straps vertical safe working load at 90Deg is 6000K . but on the diagram you draw the straps at 45 Deg. angles. from the hook. does that pose a problem ?
He's telling you towards the end of the video what the stress will be on each leg... Just remember at 30 degrees on a 2 leg lift, if the load weighs 2k then each leg, at 30 degrees will each have 2k lbs on it.
An increase in the calculated load
By the time you figure that out I'll have it lifted already
Pedro Adriano lol exactly.
Its more bout the science and math behind it. We all know the load can be lifted but how do we explain the possibility of it.
U know 75/5=15, but how do you explain it and prove it. Always thought this was funny in construction.
My old boss did what you are talking about, ( shooting from the hip ).
Sling at 80 degrees, load 850 lbs ( 385 Kg ), no chafing gear , STRAP PARTED just before destination. DO YOUR HOMEWORK .
Yeah, that's a great idea if you survive the drop...........
That may be the case, but it would be a Cowboy lift. Totally irresponsible.
The lift plan is done before you do the lift and generally by a more qualified person than you. So you can lift safely.
Please make video, how to calculate load with using block(s)
1. Please don't call them "straps". What you show in the video is a "Web Sling". 2. The Load Angle Factor (LAF) can be calculated by this method from any point on the sling, not necessarily all the way to the hook, (which would be difficult with a very long sling. 3. For practical purposes the rigger should remember the 3 main angles he is concerned with a. 60 degrees is preferred, 1.155 b. 45 degrees is next option, 1.414 and the low limit when going into a hook, and c. 30 degrees which is worst case 2.0 and the low limit going into a shackle or master link.. And for James Kutty Joseph, please do not rig any load until you understand the stress factor. Try holding a 5 gal bucket of water straight down, then at a 45 degree angle and see if your arm feels any additional stress at 45 degrees.
holding a weight at angles with your arm operates under COMPLETELY different principles. Please do not try to correct people with incorrect analogies...
The vernacular difference between straps or web slings is effectively irrelevant. Not to mention the fact that it could be chains, ropes, wire rope (steel cable), etc...
That's an endless not a web sling
@@squirts1 Yes, your arms are not ropes that can only resist pure tension and your joints are not pin connections that can’t resist any torsion.
@@squirts1 There are a couple of issues here, first, that weight is almost 5.5 tonnes, so the webbing sling would NOT be adequate for the lift, Chains would be the preferred method.
Another issue is that that sling had miss information, because 90 degrees, is talking about included angle and therefore Uniform Load Method calculation should be applied. Handwritten information on the sling tag is doggy to say the least.
I get it that the video is 14 years old, and now we have better methods to get a correct calculation.
BTW, Gary was right. His analogy stands because it reflects the extra work the arm has to endure to maintain the angle.
@@LordOfThunderUKThere are no issues with my comment at all.
His analogy is completely incorrect and conflates 2 very different principles. Torque vs tension.
While it is more difficult to hold an object at arms length or at an angle, that is a completely different mechanism than suspending an object between two or multiple points. The application of force vectors is very different.
In his analogy, the biggest factor is reducing the length of the arms to reduce torque or load on the joint. While reducing the length of a sling leg (and keeping the same angles) would have zero impact on the forces.
As far as the type of sling used... There absolutely are web/strap slings rated for and capable of holding that load. Although, didn't say anything about the type or rating of sling. It's an irrelevant comment in which you try to imply "problems" with my reply.
This is not a 90°lift, right?
Ok.... So not confuse anybody when you do the calculations for foce of each sling, and compair it to the safety rating on the sling (weight) I and it falls short, of safety for a single sling,...... But you are using 4 slings instead of the single so u got the single sling rating ×4 will that be considered a proper and safe lift ...........🤔
Can't you just multiply by the sine of the angle? Say a vertical sling is considered to be at 90º and you have two slings at 30º and each sling has a SWL of 1000lbs; you would calculate the sine of 30 (0.5) and multiply it by the SWL, giving you a SWL of 500lbs per sling.
Is this accurate?
It's accurate but useless unless if you don't know the angle. In this video he does not assume you know the angle.
1cy3
But can't the angle be easily measured?
You can do it with one sling , 1.4 times the SWL of one sling gives you the answer for 1to 2 slings for 3 to 4 slings use 2.1 thats what most of us riggers will do.
if the horizontal angle of ur sling is 60 degree....then we should multiply 9000 with 1.155( loade angle facto for 60 degree). the answer would be bigger than SWL OF WEBSLING IN verticle position.am I right or not?
agreed! but great video
that calculation was already made, he just used a different method to get there.
and using 4 legs slings?
divide by 4 instead of 2 basically.
How you know weight is 12000?
Examples
How to get the sling height
Tape measure.
or presumption
THANKS ... I thought it will actually reduce force when it is at an angle ..still i am not convinced , the resultant force should be the wt of the load , and the sling would divide the total wt of the load in to half ... sharing ... where this extra tension comes from ? since there is no horizontal component in a vertical load!!!!
90 degrees is verticle and that's the rating for the sling. You go off center and the weight dynamic is different
ok thank you ,
james kutty Joseph The extra tension comes from the effect of horizontal load that comes from the slings not lifting vertically (90degrees). If the angle is 60degrees the sling is pulling sideways on the anchor and vertically. A 170degree angle could put as much as 1153% of the total sling load weight on each anchor. Try holding a 30lb weight straight above your head, then try holding it straight out in front of you or straight out sideways.
+james kutty Joseph the best way to understand this is to hang from an object with both of your arms straight up at first, then with your arms spread as far apart as you can reach. You will feel more strain with your arms spread.
Lucas Howard GOOD EXAMPLE...THOUGH
Not understand last point.
Sr. Why do you ad 1000 lb to 9000 lb. Thanks.
To work in x,y,z plane I have to vectorize the forze on each componentes, and if I require a dinamic movemen i have to consider the graivity force. Isn´t it?
And Thanks for all.
he did not add 1000 lbs... the 10,000lb number is the example safe working load limit of the sling legs. The force applied by the load in his example is 9,000lbs per leg. thus, the load is safe.
How to get height between hook and load?
Tanongin mo daw yong isang safety ja
you did not calculate the sling angle inorder to determine the exact force on each leg, and that my friend is a deadly mistake.
yes he did... his example is using 2 sling legs.
I dont understand
wrong computation
I really want to know all of you...
Q:what is the meaning of injection molding machine clamping tonnage 1600KN??
plz give ans and calculation. help me
KN is newtons 10 kn = 1000kg they now put this on all ratchet straps for securing loads !
Each SWL of your slings should be at least equal to or more than the full load at 90 degs...................forget working out the angle!!
That's a lazy ass comment. Ignorant as well. Take all of the thought out of it? Jesus...
Correct then just use 1.4 and 2.1 method on one sling
tanxx
So rigging is liiiike a box of chocolates?
#accesstoenergy
I really want to say u unstand whatyou said
Presentation is very slow and poor
geeesh can you talk any slower and dry
Geesh, did you want the Avengers theme playing in the background? Maybe that would make it more exciting?? This stuff is brain dead easy stuff anyway but most wanna be operators have to have it broken down to the lowest and slowest in order to understand.
Thanks