Instead of an intermediate medium between the moving element and the fixed element of the linear guide, a rolling steel ball is used. Because the rolling steel ball is suitable for high-speed movement, small friction coefficient and high sensitivity, it can meet the working requirements of moving parts, such as tool holders and carriages of machine tools. The basic function of the fixed element (rail) of the linear guide system is like a bearing ring, a bracket for mounting a steel ball, and the shape is a "v" shape. The bracket wraps around the top and sides of the rail. In order to support the working parts of the machine tool, a set of linear guides has at least four brackets. Used to support large work pieces, the number of brackets can be more than four.

The steel ball has a diameter tolerance of ±20 μm, and the steel balls are sorted and classified into 0.5 μm increments, and are respectively mounted on the guide rails. The magnitude of the preload is determined by the force acting on the steel balls. If the force acting on the steel ball is too large, the steel ball is subjected to the preloading time for too long, resulting in an increase in the kinematic resistance of the bracket. Here is a problem of balance; in order to improve the sensitivity of the system, reduce the resistance to motion, correspondingly reduce the preload, and in order to improve the accuracy of motion and the accuracy of the accuracy, it is required to have sufficient pre-added negative numbers, which is contradictory aspect.