in a device for mounting an implement on a tractor wherein a body of the tractor is provided with an upwardly and downwardly movable hitch to which the implement is adapted to releasably mounted , a drive shaft associated to the hitch and drivingly connected to a pto shaft of the tractor is supported by the hitch and is operable to transmit a power to an input shaft of the implement through shaft coupling means . the hitch is provided with an upper engagement hook opened upwardly and a lower engagement hook opened toward the implement to be engaged with the implement . the shaft coupling means includes a self - aligning mechanism .