A power machine having an engine and a drive system configured to effect travel of the power machine, the drive system comprising: a drive pump driven by the engine, the drive pump capable of providing a hydraulic power output in response to a drive signal; a drive motor having a rotational output member, wherein the drive motor is configured to selectively operate in a low range mode having high-displacement and in a high range mode having low-displacement, the drive motor being operably coupled to and receiving the hydraulic power output from the drive pump and having an operating displacement that is variable between a minimum displacement in the high range mode and a maximum displacement in the low range mode; a gearbox that selectively operably couples the rotational output member of the drive motor to one of a plurality of gear reduction sets; a shift actuator operably coupled to the drive motor and configured, in response to a variable electric signal, to vary the displacement of the drive motor between the minimum displacement and the maximum displacement; a controller operably coupled to the shift actuator; a gear sensor in communication with the controller and configured to provide to the controller an indication of which of the plurality of gear reduction sets is selected; wherein the controller is configured to select a control curve for controlling the shift actuator based upon which of the plurality of gear reduction sets is selected, the controller being further configured to provide the variable electric signal to control the shift actuator to cause the drive motor to provide infinitely variable displacement between the minimum and maximum displacements; and a power source operably coupling the controller to the shift actuator, the power source being configured to receive the variable electric signal from the controller and to responsively control an amount and direction of power provided to the shift actuator in order to control the drive motor to provide the variable displacement. a drive pump driven by the engine, the drive pump capable of providing a hydraulic power output in response to a drive signal; a drive motor having a rotational output member, wherein the drive motor is configured to selectively operate in a low range mode having high-displacement and in a high range mode having low-displacement, the drive motor being operably coupled to and receiving the hydraulic power output from the drive pump and having an operating displacement that is variable between a minimum displacement in the high range mode and a maximum displacement in the low range mode; a gearbox that selectively operably couples the rotational output member of the drive motor to one of a plurality of gear reduction sets; a shift actuator operably coupled to the drive motor and configured, in response to a variable electric signal, to vary the displacement of the drive motor between the minimum displacement and the maximum displacement; a controller operably coupled to the shift actuator; a gear sensor in communication with the controller and configured to provide to the controller an indication of which of the plurality of gear reduction sets is selected; wherein the controller is configured to select a control curve for controlling the shift actuator based upon which of the plurality of gear reduction sets is selected, the controller being further configured to provide the variable electric signal to control the shift actuator to cause the drive motor to provide infinitely variable displacement between the minimum and maximum displacements; and a power source operably coupling the controller to the shift actuator, the power source being configured to receive the variable electric signal from the controller and to responsively control an amount and direction of power provided to the shift actuator in order to control the drive motor to provide the variable displacement.