REVERSIBLE VARIABLE DRIVES AND SYSTEMS AND METHODS FOR CONTROL IN FORWARD AND REVERSE DIRECTIONS

A ball-planetary continuously variable transmission (CVT) capable of stable control in forward and reverse rotation over a range of speed ratios including underdrive and overdrive is provided. Imparting a skew angle (zeta) causes unbalanced forces that change the tilt angle (gamma), resulting in a change in speed ratio of the CVT. Angularly orientating a control system of the CVT with a positive offset angle (psi) configures the CVT for operation in a first direction of rotation or angularly orientating the control system with a negative offset angle (psi) configures the CVT for operation in a reverse direction of rotation. A control system for configuring the offset angle (psi) may lead or trail the planets. The control system may configure a larger offset angle for more stable control or may configure a smaller offset angle for higher sensitivity in potential rollback scenarios.