Patent ID: 8261626

Claim:
A ball screw comprising: a shaft including a thread groove in an outer circumferential surface; a nut provided with a through hole to be movably mounted on the shaft, the through hole including a thread channel in an inner circumferential surface, the thread groove cooperating with the thread channel to define a loaded path, the nut being axially provided with a rolling passage which has an angular difference with respect to the shaft, the nut being further provided in an outer circumferential surface thereof with a circular groove communicating with the rolling passage; a return element disposed on the nut and provided with a return passage, which connects with the loaded path to define a circulation path; plural rolling elements provided in the circulation path; and a sleeve disposed in the circular groove of the nut and provided in an inner circumferential surface thereof with plural push grooves parallel to the shaft, there being an angular difference between the respective push grooves and the rolling passage, and the push grooves cooperating with the rolling elements that pass through the rolling passage.