In some embodiments, the present invention provides a mower including a frame having a front portion and a rear portion, at least one front wheel coupled to the front portion of the frame, and two drive wheels on substantially opposite sides of the rear portion of the frame. Each drive wheel is coupled to the frame by a first link pivotably coupled at one end to the front portion of the frame and at an opposite end to the drive wheel, and a second link pivotably coupled at one end to the rear portion of the frame and at an opposite end to the drive wheel. The mower also includes at least one spring positioned to bias the drive wheels in a downward direction. Each of the drive wheels are movable upward and downward relative to the frame.