Patent ID: 7717816

Claim:
A transmission comprising: an input shaft; an output shaft; a mechanical transmission part interposed between the input shaft and the output shaft, the mechanical transmission part including at least one planetary gear mechanism; and a hydrostatic transmission part interposed between the input shaft and the output shaft, the hydrostatic transmission part including a plurality of pump/motors fluidly interconnected with one another through a hydraulic circuit, wherein: the plurality of pump/motors include a first pump/motor, a second pump/motor and a third pump/motor; a rotating shaft of the first pump/motor and a rotating shaft of the second pump/motor are coupled to the mechanical transmission part; the transmission further comprises a coupling mechanism for coupling a rotating shaft of the third pump/motor to at least one of the rotating shaft of the first pump/motor and the rotating shaft of the second pump/motor, and control means for controlling the coupling mechanism so as to couple the rotating shaft of the third pump/motor to both the rotating shaft of the first pump/motor and the rotating shaft of the second pump/motor such that all power input to the input shaft is transmitted to the output shaft only through the mechanical transmission part.