Automatic steering mechanism for lawnmowers and the like

Claim 1

AUTOMATIC STEERING MECHANISM FOR CONTROLLING A SELF-PROPELLED LAWNMOWER TO FOLLOW A FERROMAGNETIC GUIDE LINE LAID ON OR IN THE GROUND, SAID LAWNMOWER HAVING A LEFT DRIVING WHEEL AND A RIGHT DRIVING WHEEL CONNECTED TO EACH OTHER AND TO AN ENGINE THROUGH A DIFFERENTIAL, SAID STEERING MECHANISM COMPRISING FIRST AND SECOND HOLLOW, CYLINDRICAL, HYDRAULIC BRAKE HOUSINGS NON-ROTATIVELY MOUNTED UPON THE LAWNMOWER, FIRST AND SECOND IMPELLERS ROTATIVELY MOUNTED WITHIN SAID FIRST AND SECOND HOUSINGS RESPECTIVELY, BELT-DRIVE CONNECTING MEANS FOR ROTATING SAID FIRST IMPELLER AS THE LEFT DRIVING WHEEL ROTATES, BELT-DRIVE CONNECTING MEANS FOR ROTATING SAID SECOND IMPELLER AS THE RIGHT DRIVING WHEEL ROTATES, A VISCOUS LIQUID FILLING EACH OF SAID HOUSINGS, EACH OF SAID IMPELLERS HAVING A PLURALITY OF RADIAL VANES THAT MOVE WITHIN AND ROTATE SAID LIQUID AS THE IMPELLER ROTATES, THERE BEING CLEAR SPACES BETWEEN THE ENDS OF SAID VANES AND SAID HOUSINGS, A FIRST CONTROL VANE MOVABLE SELECTIVELY INTO AND OUT OF THE CLEAR SPACE BETWEEN THE VANES OF SAID FIRST IMPELLER AND SAID FIRST HOUSING, A SECOND CONTROL VANE MOVABLE SELECTIVELY INTO AND OUT OF THE CLEAR SPACE BETWEEN THE VANES OF SAID SECOND IMPELLER AND SAID SECOND HOUSING, A FIRST SOLENOID CONNECTED TO MOVE SAID FIRST CONTROL VANE INTO THE CLEAR SPACE, A SECOND SOLENOID CONNECTED TO MOVE SAID SECOND CONTROL VANE INTO THE CLEAR SPACE, SPRING BIAS MEANS FOR MOVING SAID CONTROL VANES OUT OF SAID CLEAR SPACES WHEN SAID SOLENOIDS ARE DE-ENERGIZED, A MAGNET HAVING A PAIR OF DOWNWARD FACING POLES, A CARRIAGE SUPPORTING SAID MAGNET FOR SELFROTATION TOWARD THE GUIDE LINE ABOUT A SUBSTANTIALLY HORIZONTAL AXIS DIRECTED SUBSTANTIALLY FORE-AND AFT WITH RESPECT TO THE LAWNMOWER, CARRIAGE TRACKS SUPPORTING SAID CARRIAGE FOR MOVEMENT SIDEWISE WITH RESPECT TO THE LAWNMOWER, AN ENDLESS MOVING BELT, MEANS SUPPORTING SAID BELT IN AN ELONGATED LOOP PARALLEL TO SAID CARRIAGE TRACKS, MEANS FOR DRIVING SAID BELT TO KEEP IT IN CONSTANT MOTION AROUND THE ELONGATED LOOP SO THAT OPPOSITE DIRECTIONS SIDEWISE WITH RESPECT TO THE LAWNMOWER, A FIRST PAIR OF BELT-ENGAGING MEMBERS ATTACHED TO SAID MAGNET AND CARRIAGE AND ARRANGED TO GRIP THE LEFTWARD MOVING SIDE OF SAID BELT AND TO MOVE THE MAGNET AND CARRIAGE TOWARD THE LEFT RESPONSIVE TO SELF-ROTATION OF SAID MAGNET TOWARD THE LEFT, A SECOND PAIR OF BELT-ENGAGING MEMBERS ATTACHED TO SAID MAGNET AND CARRIAGE AND ARRANGED TO GRIP THE RIGHTWARD MOVING SIDE OF SAID BELT AND TO MOVE THE MAGNET AND CARRIAGE TOWARD THE RIGHT RESPONSIVE TO SELF-ROTATION OF SAID MAGNET TOWARD THE RIGHT, A RESISTOR BAR OF ELECTRICALLY RESISTIVE MATERIAL EXTENDING PARALLEL TO THE CARRIAGE TRACKS, AN ELECTRICAL BRUSH MOUNTED UPON SAID CARRIAGE FOR MOVEMENT THEREWITH AND IN SLIDING ELECTRICAL CONTACT WITH SAID RESISTOR BAR, AND A VOLTAGE SUPPLY CONNECTED TO SAID BRUSH, SAID FIRST SOLENOID BEING CONNECTED BETWEEN SAID SUPPLY AND THE LEFT END OF SAID RESISTOR BAR SO THAT MOVEMENT OF THE MAGNET AND CARRIAGE TOWARD THE LEFT INCREASES AND MOVEMENT TOWARD THE RIGHT DECREASES THE ELECTRIC CURRENT SUPPLIED TO THE FIRST SOLENOID, INCREASE IN SUCH CURRENT CAUSING THE SOLENOID TO MOVE THE FIRST CONTROL VANE INTO THE CLEAR SPACE OF SAID FIRST HOUSING TO BRAKE THE LEFT DRIVING WHEEL AND TURN THE LAWNMOWER TO THE LEFT, SAID SECOND SOLENOID BEING CONNECTED BETWEEN SAID SUPPLY AND THE RIGHT END OF SAID RESISTOR BAR SO THAT MOVEMENT OF THE MAGNET AND CARRIAGE TOWARD THE RIGHT INCREASES AND MOVEMENT TOWARD THE LEFT DECREASES THE ELECTRIC CURRENT SUPPLIED TO THE SECOND SOLENOID, INCREASE IN SUCH CURRENT CAUSING THE SECOND SOLENOID TO MOVE THE SECOND CONTROL VANE INTO THE CLEAR SPACE WITHIN THE SECOND HOUSING TO BRAKE THE RIGHT DRIVING WHEEL AND TURN THE LAWNMOWER TO THE RIGHT.