Aircraft air cycle machines include a housing, a shaft arranged within the housing, and a first wheel assembly operably coupled to the shaft and arranged within the housing. The first wheel assembly is configured to rotationally drive the shaft. A second wheel assembly is operably coupled to the shaft and configured to be rotationally driven by the shaft. A magnetic assembly is arranged within the housing and along the shaft. The magnetic assembly includes a stator assembly fixedly connected to the housing and a rotor assembly rotationally coupled to the shaft. The magnetic assembly is arranged along the shaft to provide a gear ratio between the first wheel assembly and the second wheel assembly.