There were several disadvantages that accompanied the lack of a true differential gear. This design would have been simpler than using a differential gear. Yaw is controlled by fine adjustment of a differential gear in the rotor drive transmission. The drums connected via a differential gear to twin contra-rotating propellers. The tow vehicle will still move the weight regardless of the differential gear ratio. The new transmission was joined by a 3.73&colon;1 rear differential gear ratio. The front differential gear lock was omitted because Peugeot used its own axles. The addition is done by an analogue method, using a differential gear. The drums were connected via a differential gear to twin contra-rotating propellers. They steered through an unusual wet band brake system through a differential gear system. The rear differential gear ratio was changed to 3.31&colon;1 for both transmissions. A differential gear train can be used to allow a difference between two input axles. His inventions include the differential gear and the perfection of the bicycle chain drive. It requires a differential gear, a gearing arrangement that sums or differences two angular inputs.