A fuel cell system is disclosed that employs an expander for recovering mechanical energy from a cathode exhaust fluid produced by the fuel cell system to generate torque. The expander is coupled to a shaft of a compressor with a freewheel mechanism, wherein the freewheel mechanism transfers the torque from the expander to the compressor when a rate of rotation of a driveshaft of the expander is greater than the rate of rotation of the shaft of the compressor, and selectively militates against the expander acting as a restrictor to the shaft of the compressor when a rate of rotation of the driveshaft of the expander is substantially equal to or less than a rate of rotation of the shaft of the compressor.