Video instructions and help with filling out and completing Why Form 8815 Calculators

Instructions and Help about Why Form 8815 Calculators

Today we're going to learn about how to calculate the load on each sling when we make a lift we can take the guesswork out of it by looking at four easy steps we know from the strap the safe working load of each of these is right on the tag here's an example of what you might see on a strap tag one of the things you need to know is the vertical safe working load of the sling and that can be from the tag that's right on the sling itself the angles of the slings are not always just 45 degrees or 60 degrees so to figure out the stress that is on each of these slings we just need four things one thing we need to know is the vertical safe working load of each strap the second thing is the weight of the object you're lifting the total weight the third thing is going to be the length of each strap and that's from the hook to the connection point so that is the length and the last thing is the distance or the height above the load that the hook is so here's how we go about calculating the force on each sling divide the leg length by the vertical height that the hook is above the load so we're going to take L divided by H that's the first step then the second thing we do is take that answer and just for practical purposes we will call that X and we will take that answer X and multiply it times half of the weight the answer to that is how much force is exerted on each of these sling legs that means there's that amount of force on this sling as well as that same amount of force on this sling if this answer of the force that's needed or that's exerted on each sling is higher than the safe working load then it's not a safe lift so to review the four things we needed to know was the vertical safe working load from the strap itself the weight we're going to call that W the length of the strap which we're going to call L and then the height which is the distance above the load that the hook is so we'll put some real numbers on to this let's suppose that the load has a total weight of 12,000 pounds we have to six foot straps L and the distance the hook is above the load is four feet which is H so step number one was to take L the length of strap divided by H the height above the load that the hook is so in this case we would have 6 divided by four and that equals one point five the second step was to take that answer 1.5 and multiply it times half of the weight 12,000 half of that is going to be 6,000 pounds and the answer to that is 9,000 pounds that is the force exerted on each of these slings when you would be making this lift so the last thing we have to do is compare the 9,000 pounds with the safe working load on the tag of the strap at 90 degrees so in our case 9,000 pounds if the safe working load at 90 degrees was 10,000 pounds this would be a safe lift because the force is not more than the rating of the safe working load in the case of this strap that we showed you at the beginning this will lift 6,000 pounds at 90 degrees is that strong enough to support our example of a 12,000 pound load no it's not again it's very important to make sure that the strap is able and capable of lifting the amount that we calculate you have to be safe and safety is a very high priority