An automated self propelled lawn mower utilizes a pair of drive motors for independently driving left and right hand drive wheels. Each drive motor is coupled to the respective drive wheel by a double output gear reduction unit. One side of the output shaft from each gear reduction unit is provided with...http://www.google.fr/patents/US4887415?utm_source=gb-gplus-shareBrevet US4887415 - Automated lawn mower or floor polisher
