LT3 Drive: substitution of differentials in the drivetrain

The basic principle of the LT3 drive system is a planetary gearing with a rotatable ring gear. Rolling piston cylinders enable this rotation by acting on the cam disk shaped outside of the ring gear which fix or loosen the ring gear accordingly.
By fixing the ring gear via the cylinders the gear ratio corresponds to the normal mechanical ratio of the gearing which is given by the combination of the planet gears and the ring gear. By loosening the ring gear completely there is no more power transmission to the carrier; hence, the carrier doesn’t rotate anymore. In between, the rotational speed can be adjusted continuously between 0 and the maximum speed within only a few milliseconds, “online”, as it were, depending on the compensatory need.
The technology was verified by the chair of Mobile Machines (Mobima) at Karlsruhe Institute of Technology. During the current second development process, the controlling of the system via high pressure components was elaborated. Furthermore, LT3 was designed for high torques up to 8,000 Nm. A feasibility study for heavy-duty vehicles was completed successfully in 2016.
The LT3 technology thereupon was ‘downsized’ for smaller systems. ... mehrPossible applications for LT3 are all systems where synchronisation functions or to allow a superposition of the rotation speeds are necessary, especially with the objective to substitute the differential gear in electric vehicles with central motor.
In today’s differential gears advanced driver-assistance systems normally intervene by brake action on the critical wheel. However, LT3 enables a planned control of each driven wheel. With that, active Torque Vectoring is possible which can operate foresightedly in every driving situation.
Saving potential mainly in production is the result of using the LT3 system. Viscous coupling unit or Haldex unit as well as Torsen differential are dropped. Also, the ASR assistant is no longer needed. In E-mobility application, mainly in small vehicles, space could be used in a better way or rather the packaging could be designed more favourable because the LT3 drive takes two functions at once: speed reduction of the motor and differential compensation of the driven wheels.