A Design Scheme for Multidisk Beier Traction Variators

Abstract

The unique design feature of the Beier traction variator is that it can provide a higher power capacity per unit volume by using multiple thin disk pairs in a planetary system. Operating with a single effective traction contact and with the absence of idlers and dummy elements, promises for high efficiencies are also encouraging. In this paper, a design scheme for such mechanical drives is developed. Kinematics and kinetics of the rolling sliding disks are presented yielding actual performance ratings. Geometrical slippage in the Hertzian contact areas is considered for evaluating power losses at different load levels and transmission ratios. A torque sensitive pressure device which automatically creates contact forces is incorporated in the analysis. Constant traction coefficient pertinent to the boundary lubrication mode nearing thin fluid film friction is adopted for actual performance estimates. Among the different geometrical parameters, the bead radius of the input disk flange was found to play a major role in limiting contact stresses and torque capacities. Efficiencies of transmission, excluding shaft support bearing losses, are above ninety percent for a power of one kilowatt per contact.