The invention discloses a planetary
roller screw which comprises a lead screw, a nut, two roller retainers, two elastic inner check rings, two inner gear rings and a plurality of rollers arranged between the lead screw and the nut; the two inner gear rings are respectively fixed at the two end parts of an inner hole of the nut, parallel annular tooth sockets are arranged at the middle part of the inner hole of the nut, the two roller retainers are respectively sleeved in the inner holes of the two inner gear rings and are respectively blocked and located by the two elastic inner check rings embedded in the inner gear rings, retaining holes, whose number is consistent with that of the rollers, are arranged on the roller retainers, parallel teeth embedded with the threads of the lead screw and the annular tooth sockets of the nut are arranged at the middle parts of the rollers, the two end parts of the rollers are plain spindle heads, and the plain spindle heads are respectively inserted in the retaining holes of the two roller retainers. The planetary
roller screw has a reasonable structure, convenience for manufacture,
high transmission efficiency, large
bearing capacity, high movement precision and low manufacturing cost, so that the planetary
roller screw can be extensively applied on such apparatuses as
numerical control machine frames and harbor machinery, etc.