A Hybrid Transmission for SAE Mini Baja Vehicles

This paper describes a hybrid transmission consisting of a Salsbury style rubber belt continuously variable transmission (CVT) and a two-speed manual transmission. Rubber belt CVT transmissions are used extensively in the Mini Baja competitions. Although widely used, rubber belt CVTs have a limited torque ratio range, and teams must reach a balance between top speed and pulling or hill climbing capability. The hybrid transmission described in this paper provides a wider range of torque ratios by combining a CVT with a two-speed manual transmission. Included is a description of the major components, a derivation of the equations used to model the primary pulley in a simulation used to select the desired gear ratios, and a summary of performance characteristics obtained from testing.