A minimally-invasive surgical tool, comprising: a tool shaft; an end effector; a multi-axial wrist disposed between the tool shaft and the end effector, the wrist comprising three or more sets of pulleys arranged in two orthogonal directions, comprising a first set of pulleys (340B, 350B) and a second set of pulleys (340A, 350A) arranged along an axis of rotation and a third set of pulleys (320A, 320B) arranged along a different axis of rotation, the third set of pulleys (320A, 320B) coupled to the end effector; and a drive mechanism comprising three electric motors configured to effect movement of one or both of the wrist and the end effector, the drive mechanism configured to independently control two cable loops that wind at least partially around one or more of the three or more sets of pulleys to vary relative tension between the two cable loops and between two ends of each cable loop to effect a yaw or pitch motion, wherein one of the three motors is coupled to a rocker mechanism configured to tension two sides of the same cable loop to effect a pitch motion, wherein said rocker mechanism is such that a first axis of a first pulley is coupled to a first end of the rocker mechanism and a second axis of a second pulley is coupled to a second opposite end of the rocker mechanism, and the rocker mechanism is configured to rock back and forth so that as the first end of the rocker mechanism moves proximally the first pulley moves proximally, thereby increasing tension on a side of a cable coupled to the first end, and as the second opposite end of the rocker member moves distally the second pulley moves distally, thereby relaxing tension on an opposite side of the cable coupled to the second end, to thereby effect the pitch motion of the end effector. a tool shaft; an end effector; a multi-axial wrist disposed between the tool shaft and the end effector, the wrist comprising three or more sets of pulleys arranged in two orthogonal directions, comprising a first set of pulleys (340B, 350B) and a second set of pulleys (340A, 350A) arranged along an axis of rotation and a third set of pulleys (320A, 320B) arranged along a different axis of rotation, the third set of pulleys (320A, 320B) coupled to the end effector; and a drive mechanism comprising three electric motors configured to effect movement of one or both of the wrist and the end effector, the drive mechanism configured to independently control two cable loops that wind at least partially around one or more of the three or more sets of pulleys to vary relative tension between the two cable loops and between two ends of each cable loop to effect a yaw or pitch motion, wherein one of the three motors is coupled to a rocker mechanism configured to tension two sides of the same cable loop to effect a pitch motion, wherein said rocker mechanism is such that a first axis of a first pulley is coupled to a first end of the rocker mechanism and a second axis of a second pulley is coupled to a second opposite end of the rocker mechanism, and the rocker mechanism is configured to rock back and forth so that as the first end of the rocker mechanism moves proximally the first pulley moves proximally, thereby increasing tension on a side of a cable coupled to the first end, and as the second opposite end of the rocker member moves distally the second pulley moves distally, thereby relaxing tension on an opposite side of the cable coupled to the second end, to thereby effect the pitch motion of the end effector.