What is the crane capacity calculation formula for an overhead crane

The lifting capacity of an Overhead Traveling Crane is determined by the design of the structural components. Where the crane beam was fabricated the neutral axis and the second moment of area (Zxx) had to be calculated to determine the amount of compressive stress could be applied to the top of the beam to stay within the stress rating of the steel measured in megapascals (Mpa). This stress determined the load that could be lifted.

Steel has a lower failure point in compressive stress than it has in tensile stress.

There are many factors involved in the calculation including dynamic forces, end carriage design, runway design etc. When using prefabricated section such as universal beams the values of Zxx and Zyy are provided by the manufacturer. Crane runway design usually involved welding a channel section with the flanges facing downwards to improve the lateral stress (Zyy) of the universal beam used to support the downward forces.

The actual design calculations were more complicated than described above.

This was the old way of approaching design, today finite element design process are used.

The specific calculation is as follows: support reaction force FA=P/2, FB=-P/2; maximum bending moment Mmax=Pl/4; (for the formula, refer to Mechanical Design Manual Volume 1 1-125) The point of maximum bending moment is the center of the girder

In fact, it is more complicated