Disclosed are power machines, and drive systems for use thereon, as well as methods of controlling the displacement of a hydraulic drive motor. The drive system includes a drive pump capable of providing a hydraulic power output and a drive motor operably coupled to the drive pump that receives the hydraulic power output from the drive pump. The drive motor has an operating displacement that is variable between a minimum displacement and a maximum displacement and it provides a rotational output member. A shift actuator is operably coupled to the drive motor and it is configured to vary the displacement of the drive motor between the minimum displacement and the maximum displacement. A controller controls the shift actuator to cause the drive motor to provide infinitely variable displacement between the minimum and maximum displacements.