The forces that are offset (cantilevered) from the bearing centers of mechanical components producing uneven loading on the bearings. Uneven loading means that some bearings are supporting more of the load than others. Moment forces are categorized by the direction in which they act: pitch, roll or yaw. When loading results in moments acting in only one of the moment directions, it is called a single direction moment. If it is in more than one direction, it is referred to as compound moment loading.