Properties of electrically preloaded rack-and-pinion drives

Ball screw drives are very common in industrial applications and, therefore, thorough analyses of their characteristics exist. Rack-and-pinion drives are a good alternative, if large travel ranges and high dynamics are required. However, they are not scientifically and systematically analysed. Nowadays, either constant mechanical or electrical preload is often used in industrial applications to reduce the backlash of a drive train (Weck and Brecher in Werkzeugmaschinen 3: Mechatronische Systeme, Vorschubantriebe, Prozessdiagnose, 6th edn. Springer, Berlin, 2006). This paper describes the investigation of an electrically preloaded rack-and-pinion drive in an experimental rack. The focus is on backlash, stiffness, friction losses and bandwidth of the examined feed axis dependent on the preload. An open controller allows online variations of the drive system’s preload. The resulting effects are investigated experimentally. The paper shows that increasing preload reduces backlash and increases stiffness and bandwidth, but friction losses raise as well.