Bearings are designed for specific L10 life hours, and when additional load is applied, the bearing life is drastically shortened. For example, a 25 percent increase in load causes a 50 percent reduction in bearing life. Seals and other critical component parts requiring accurate alignment, such as gear teeth, are also subject to failure because of overhung loads. Clearly, excessive overhung load can cause serious equipment failures and lead to significant downtime. However, it is possible to calculate and anticipate excessive overhung loads.
Most equipment is designed by manufacturers to accept certain levels of overhung load.
Manufacturers' catalogs for gear drives or motors specify the acceptable amount of overhung load and how to calculate it. I should mention here that the best time to calculate overhung load is when specifying and selecting your drive system equipment. Doing this prior to equipment selection will ensure that your equipment will be capable of handling the load it will receive. However, if the overhung load was not considered prior to equipment selection, and if system components are experiencing excessive overhung load symptoms, the calculations can be part of the trouble shooting process. The load connection factor, or FC, describes the type of sheave, sprocket, or pinion mounted on the shaft.