Lower pair arc stop-block overrunning clutch

An overrunning clutch, comprising:

• an outer rotating element including an annular first rotating ring;
• an inner rotating element provided in the outer rotating element, including an annular second rotating ring concentric with the first rotating ring;
• a friction block assembly including a plurality of friction blocks forming a closed ring shape by connecting end to end successively, two adjacent friction blocks overlapping partially, the friction block assembly being arranged between the first rotating ring and the second rotating ring, wherein an outer surface of each friction block is provided with an arc wedge surface and an inner surface of each friction block is a cambered-surface stop surface, and each friction block is provided with a first thruster mounting part close to a leading end thereof, which includes a first limit part close to an end surface of the leading end and a second limit part away from the end surface of the leading end;
• a wedge assembly in contact with the first rotating ring and the arc wedge surface of the friction block assembly simultaneously for allowing the outer rotating element to rotate unidirectionally relative to the friction block assembly, wherein the wedge assembly includes a plurality of circumferentially spaced wedge blocks and a holder for holding the plurality of wedge blocks, the wedge blocks changing their radial length by deflecting to achieve wedging or de-wedging between the first rotating ring and the friction block assembly;
• a first thruster assembly arranged slidably on the first thruster mounting part in a circumferential direction and limited by the first limit part and the second limit part, the first thruster assembly including a first traction element, which is driven by the inner rotating element for a non-slip-fit or a loose-fit with the second rotating ring;
• a first elastic element arranged between the two adjacent friction blocks for elastically pushing the two adjacent friction blocks in opposite directions to keep the two adjacent friction blocks away from each other;
• and
• a synchronized push-block assembly provided at an overlap of the two adjacent friction blocks for overcoming an action of the first elastic element under a thrust of the first thruster assembly to keep the two adjacent friction blocks close to each other.