Transaxle systems for a vehicle are disclosed where each of right and left transaxle units includes a hydraulic pump, a hydraulic motor and a casing incorporating the hydraulic pump and motor. Each hydraulic pump has a pump displacement control means operatively connected to a pump control arm pivoted on the casing, and each hydraulic motor has a motor displacement control means operatively connected to a motor control arm pivoted on the casing. A single motor controlling manipulator is operatively connected to the motor control arms to simultaneously shift the motor displacement control means of the right and left transaxle units between large displacement positions and small displacement positions.