The main difference between trapezoidal screws and ball screws in servo electric cylinders is the way they carry loads between moving surfaces. Ball screws use circulating ball bearings to minimize friction and improve efficiency, while trapezoidal screws require low friction coefficients between sliding surfaces. Therefore, trapezoidal screws generally cannot achieve the efficiency of ball screws (around 90%). A simple analysis of the frictional mechanism (studying wear and friction) reveals that the predictability of sliding friction is inevitably lower than that of transmissions using cyclic ball technology. The fatigue life equation (such as L10 life) is very reliable within its applicable range. In summary, due to differences in predictive performance and lifespan, trapezoidal screws have basic differences in their application scope. Although ball screws and trapezoidal screws have various advantages (load, stiffness, efficiency, load cycling, predictability), their cost is relatively high. Although they have a high cost-effectiveness compared to other translational linear motion plans, the design of the ball screw is more complex, requiring a finely hardened bearing surface and a ball circulation installation. The size of the trapezoidal screw is very small, designed to be very sensitive, and has low noise when used correctly. It has good corrosion resistance and can be equipped with self-locking function to meet the needs of vertical applications. Therefore, when the electric cylinder needs to be self-locking in a vertical position, the trapezoidal screw is selected. They play an important role in many application areas, but of course they also have some limitations.