Characteristics and mechanical efficiency of roladrives

This paper analyzes Roladrive reducers and tests their mechanical efficiency. A Roladrive is a planetary gear train that employs rollers instead of cut gears and has multiple teeth (rollers) meshed while operating. The speed ratio is independent of the pitch diameter, but it is dependent on the number of the pin-teeth and rollers. Moreover, Roladrives can be designed for noninteger speed ratios easily. When the speed ratio is greater or equal to 1 and the basic ratio is near to 2, the theoretical mechanical efficiency reaches the optimal values. Mechanical efficiency of a Roladrive is greater than 0.9 as speed ratio is less or equal to 26. The theoretical mechanical efficiency can reach as high as 0.988 when the speed ratio is equal to 2. Experimental results show that the slopes of the theoretical and measured mechanical efficiencies are very close. In conclusion, this paper provides the foundation to use the theoretical mechanical efficiency to predict the real mechanical efficiency of Roladrives.