Kinetostatic analysis of a roller drive

A roller drive has a topological structure similar to an epicyclic gearing, where both the planet gear and the ring gear have rollers as their teeth. The roller drive thus has the advantages of easy manufacture and low cost. In this paper, the kinematic model based on the vector loop approach is developed, and models for analyzing the kinetostatics and mechanical efficiency of roller drives considering friction are proposed. By using these models, the velocity, acceleration, normal forces acting on the conjugated pairs and efficiency of roller drives can be obtained. An example is given, and experimental testing is applied to verify the analysis results. The results show that the roller drive has a speed fluctuation that corresponds with the number of ring gear rollers, and the magnitudes of the forces vary periodically with the crank angular displacement; hence, the roller drive has an input torque ripple. It is also found that the roller drive has high efficiency under the operation of high speed. Moreover, the influence of the geometric parameters on efficiency and speed fluctuation of the roller drives is discussed.