A power split transmission includes a rotatable input shaft, a rotatable output shaft, and a planetary gear assembly connected between the input shaft and the output shaft. The transmission also includes a first hydraulic unit operable as a pump or a motor, the first hydraulic unit being coupled to the output shaft via the planetary gear assembly; a second hydraulic unit operable as a pump or a motor, the second hydraulic unit being coupled to the output shaft independently of the planetary gear assembly; and a braking mechanism coupled to the input shaft that is selectively engageable to retard rotation of the input shaft in at least one direction. The braking mechanism enables the power split transmission to use both the first hydraulic unit and the second hydraulic unit to provide enhanced torque at the output shaft without damaging a prime mover coupled to the input shaft.