Lets say you are calling to get a crane truck to lift something, and they have 3 sizes of crane trucks. 17T (with a 70 ft boom), 23T (with a 101 ft boom), and 35T (with a 115 ft boom).All they ask for is how high you are lifting your equipment, how far over, and how many pounds it is.How do you use this information to calculate which size crane is used?
Use trigonometry, it's a triangle of forces.
I am not sure that you are giving us sufficient information. I presume that your crane truck has the boom hinged quite close to the ground, but I am sure that the specified lifting weights will not be achieved until the boom makes an angle of at least 45 degrees with the ground. The 115 foot boom will then sweep a circle of 115 x cos(45) = 81.3 feet, and lift a maximum of 115 x sin(45) = 81.3 feet above the hinge. If the boom is elevated to a 60 degree angle, the circle swept will be only 57.5 feet, but it will lift 99.5 feet. If the boom is lowered to 30 degrees, the circle swept enlarges, bt the distance lifted drops, and the weight lifting capability will also be derated. If the crane has a tower and the weight rating is for a horizontal boom, the maths are quite different.
