Conceptual Design for a Coaxial Ratcheting Continuously Variable Transmission
Kuen-Bao Sheu, Shih-Yuan Lai

Abstract
A ratcheting continuously variable transmission (CVT) comprises a ratcheting drive unit, an output drive unit and a speed control unit. This study uses creative design methodology to design a ratcheting drive unit for a coaxial ratcheting CVT. Current designs for a ratcheting CVT are categorized in terms of topological characteristics to determine the design requirements and design constraints for new designs. Number synthesis is used to determine all of the feasible generalized chains for a ratcheting drive unit, including a three-bar to five-bar mechanism with one degree of freedom. Specialized chains are then specified, subject to certain design requirements and constraints. Each specialized chain is then particularized and a schematic diagram of each chain for the ratcheting drive unit is presented. Ten new designs of coaxial ratcheting CVT are then generated using the output drive unit and speed control unit. A kinematic analysis of an example design uses the vector loop method to verify the feasibility of the design.

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