Driverless lawn mower

Claim 1

An automatically-controlled, self-powered land travelling apparatus for lawn mowing and the like, comprising a housing, rear wheel means supporting the rear of said housing for rolling motion along the ground, a pair of front wheels supported at the front of said housing for rolling motion of the front of said housing along the ground, tie rod means including a tie rod movable from side-to-side with respect to the front of said housing for steering said front wheels from one side to the other, a rotary engine secured with respect to said housing, drive means interconnecting said engine with said rear wheels for moving said apparatus along the ground, said apparatus moving drive means including a clutch having directional reverse mechanism, a pushrod reciprocably mounted with respect to said housing and movable between limit positions, resilient means normally constraining said pushrod in one of its limit positions, and automatic means including said tie rod means and said pushrod, and driven by said engine, for actuating said clutch and reversing said transmission and simultaneously turning said front wheel first in one direction and then in the other direction for sufficient lengths of time, respectively, for offsetting the reversed path of travel of said apparatus by a predetermined distance, an actuating means comprising a lead screw driven by said rear wheels drive means, a tripper member threadingly received on said lead screw and operative to be moved back and forth therealong between limit positions, and mechanism controlled by said tripper member reaching one or the other of its limit positions for moving said pushrod to the other of its limit positions, means controlled by the number of back and forth movements of said tripper member along said lead screw for automatically stopping said rotary engine, said engine stopping means comprising a second lead screw, a travelling abutment member threadingly received on said second lead screw, mechanism for incrementally and periodically turning said second lead screw in one direction every time said tripper member reaches one or the other of its limit positions, a trip lever movably supported in proximity to said second lead screw near one end thereof and operative to be contacted and moved by said travelling abutment member when in a limit position thereof along said second lead screw, and mechanism controlled by the movement of said trip lever for controlling the throttle of said engine.