Apparatus for tilling soil

Claim 1

IN AN APPARATUS FOR TRILLING SOIL, A HOUSING, A TRANSVERSE DRIVE SHAFT, A PAIR OF BEARING MEANS SUPPORTED FROM SAID HOUSING ADJACENT OPPOSITE ENDS OF SAID DRIVE SHAFT FOR ROTATABLY SUPPORTING SAID DRIVE SHAFT FROM SAID HOUSING, AN ANNULAR SLEEVE HAVING AN INSIDE DIAMETER SLIGHTLY GREATER THAN THE OUTSIDE DIAMETER OF SAID DRIVE SHAFT, MEANS ON SAID HOUSING SUPPORTING SAID SLEEVE INTERMEDIATE THE ENDS OF SAID DRIVE SHAFT WITH SAID DRIVE SHAFT EXTENDING THERETHROUGH IN SPACED RELATIONSHIP THERETO, A DIFFERENTIAL DRIVE MECHANISM HAVING AN INPUT SHAFT AND A PAIR OF OUTPUT SHAFTS, MEANS ATTACHED TO SAID INPUT SHAFT AND ADAPTED FOR COUPLING TO THE POWER TAKE-OFF OF A TRACTOR TO DRIVE SAID OUTPUT SHAFTS THROUGH SAID DIFFERENTIAL DRIVE MECHANISM, MEANS RESPECTIVELY COUPLING SAID PAIR OF OUTPUT SHAFTS TO OPPOSITE ENDS OF SAID DIRVE SHAFT FOR THE ROTATIONAL DRIVE THEREOF, A PLURALITY OF SOIL-ENGAGING UNITS MOUNTED ON SAID DRIVE SHAFT, EACH OF SAID UNITS INCLUDING A VERTICAL MOUNTING PLATE HAVING A CENTRAL APERTURE THROUGH WHICH SAID DRIVE SHAFT EXTENDS AND A PLURALITY OF BLADES MOUNTED ON SAID MOUNTING PLATE AND EXTENDING OUTWARDLY THEREFROM, SAID BLADES INCLUDING AN ALTERNATING PAIR OF TYPES WITH THE BLADES OF ONE OF SAID TYPES BEING TWISTED AND BEING BENT BETWEEN 45 AND 90 DEGREEES RELATIVE TO SAID PLATE IN A DIRECTION GENERALLY TOWARDS OPPOSITE ENDS OF SAID DRIVE SHAFT AND WITH THE BLADES OF THE OTHER OF SAID TYPES BEING TWISTED AND BEING BENT LESS THAN 45 DEGREES RELATIVE TO SAID PLATE IN A DIRECTION GENERALLY TOWARDS OPPOSITE OF SAID DRIVE SHAFT, SAID UNITS BEING ARRANGED IN A SPIRAL DISPOSITION AROUND SAID DRIVE SHAFT AND EACH OF SAID BLADES HAVING A MATCHING BLADE EXERTING AN EQUAL AND OPPOSITE FORCE WHEN STRIKING THE GROUND WHEREBY THE FORCES CANCEL ONE ANOTHER.