This SAE Standard provides a uniform method to calculate the lift capacity of knuckle-boom log loaders and certain forestry equipment. It establishes definitions and specifies machine conditions for calculations. This document applies to knuckle- boom log loaders as defined in SAE J 1209 and SAE J 2055 and certain forestry equipment defined in SAE J 1209 that have a rotating upper-structure such as feller bunchers, forwarders, harvesters, and behind the cab or rear-mounted knuckle-boom loaders not having their own power supply. It does not apply to harvesters that are incapable of lifting a tree or log completely off the ground. This document applies to those machines that are crawler, rubber-tired, and pedestal or stationary mounted. The purpose of the SAE document is to establish a consistent, repeatable means of determining the lift capacity for the types of equipment contained therein.