DISCOVER

Updated February 21, 2017

Calculate the bearing load on a jib crane to know if its carrying too much weight. Knowledge of jib crane load prevents mechanical failure as well as injury to people operating the machine due to overloading. Jib cranes feature a horizontal arm that may swivel with a length of cable attached for lifting or lowering objects. The load applied to the crane arm equals the tension in the hoisting cable and depends on the weight lifted as well as the acceleration of the cable. Use metric units during the calculation, since the process results from a scientific equation.

Determine the weight, in newtons, of the object held by the jib crane by multiplying its mass, in kilograms, times the acceleration due to gravity. The acceleration due to gravity equals 9.8 meters per second squared and denotes the acceleration of freely falling objects. Assuming a mass of 2,000 kilograms, you have 2,000 kilograms times 9.8 meters per second squared, which equals 19,600 newtons. A newton denotes force or weight and equals a kilogram times meter per second squared.

Multiply the acceleration of the crane cable by the mass of the hoisted object in kilograms. Call this result "x." An upward acceleration is positive, while a downward acceleration is negative. Use an upward acceleration of 3.5 meters per second squared for this example. Now you have 2,000 kilograms times 3.5 meters per second squared, or 7,000 newtons for "x."

Add "x" to the weight of the suspended object to attain the load upon the jib crane in newtons. Performing this step yields 19,600 newtons plus 7,000 newtons, or a load of 26,600 newtons

Convert the load to pounds by dividing by 4.45, because a pound contains 4.45 newtons for force. Completing the exercise leads to 26,600 newtons divided by 4.45 newtons per pound, or 5,977.5 pounds.