Overrunning clutch, gearbox and engineering machinery

The invention relates to the technical field of engineering machinery, in particular to an overrun clutch, a gearbox and engineering machinery. The overrun clutch comprises a middle input shaft, an outer ring gear, an inner ring cam, a first pin roller and a first magnet; the middle input shaft comprises a shaft body and a gear part; the outer ring gear rotationally sleeves the shaft body, and an annular groove distributed around the shaft body is formed in the end, facing the gear part, of the outer ring gear; the inner ring cam is arranged in the annular groove and connected with the gear part, a plurality of first pin roller grooves are formed in the outer circumferential face of the inner ring cam, and a first magnet groove is formed in the side, close to the wedge angle, of the groove bottom of each first pin roller groove; the first pin rollers correspond to the first pin roller grooves in a one-to-one mode, and the first pin rollers are arranged in the first pin roller grooves. The first magnets are in