Abstract: A hydraulically powered implement is designed for use in connection with a tractor that has a hydraulic pump that supplies pressurized hydraulic fluid to the implement. The implement includes a variable displacement hydraulic motor, an operative element driven by the hydraulic motor, a speed sensor configured to measure the rotational speed of the operative element and output a speed signal representative of the measured speed, a shift module that adjusts the displacement of the hydraulic motor in response to a shift command signal, and a controller. The controller sends the shift command signal to the shift module in response to speed signal output by the speed sensor.