Preset is a way to reduce size of upper plates of sliding bearings in direct to save material rate. The normal length of an upper bearing plate must be composed of following works:

Length of bearing + 2 x irreversible movement + 2 x reversible movement. Firstly bearing is placed at a mid-point of an upper bearing plate without considering any directional effect of permanent movement. However, irreversible movement normally takes place at one direction only, bearing is represented a distance of (irreversible movement/2) from a mid-point of bearing in which length of upper plate length is the same to length of bearing + irreversible movement + 2 x reversible movement. In this plan, size of upper plate is minimized in which irreversible movement receives place in one direction only and there is no requirement to include component of two irreversible movements in an upper plate.