Variable speed and reversible dual path fan drive system

A drive system includes a planetary gear set having first and second rotatable input members connected in driven relation with respective first and second power sources, and a rotatable output member connected in driving relation with a working piece, the first and second rotatable input members being connected in differentially rotatable communication with the output member. The input members are operable to vary the rotation and direction of the output member and the connected working piece. In an aspect, the output member is rotatable about an axis for driving the working piece, and the first and second input members are also rotatable about the axis. In a further aspect, the first and second input members include coupling regions for coupling the first and second power sources on-axis with the drive system. In a further aspect, the second power source is a hydraulic input motor concentric with the first input member.