Patent ID: 7660657

Claim:
A method of controlling a split torque transmission having a variator input and an output to at least partially avoid drive train oscillation, the split torque transmission having a plurality of contiguous selectable operating ranges, one or more pairs of adjacent operating ranges being separated by respective synchronous points, the method comprising: operating the transmission within a first operating range; detecting that a transmission ratio defined as the transmission output speed divided by the transmission input speed has reached a value coinciding with a first synchronous point lying between the first operating range and a second operating range; causing the transmission to shift from the first operating range to the second operating range substantially at the first synchronous point; setting a lock-out timer to prevent a subsequent shift until the timer has expired; determining whether the transmission ratio is trending back toward the first synchronous point after setting the lock-out timer; and overriding the lock-out timer to allow a subsequent shift prior to expiration of the timer if the transmission ratio is trending back toward the first synchronous point and has passed a predetermined threshold value.