Unidirectional Rotary Brake

A unidirectional rotary brake comprising:

• a body, multiple rollers, two driving rings, and at least one returning means;
• the body including an internal face and two end faces, wherein the internal face has multiple accommodation grooves separately arranged thereon and matching with the multiple rollers respectively, each of the multiple accommodation grooves has a locking segment and a unlocking segment, a first depth of the locking segment is less than a second depth of the unlocking segment, and each of the two end faces has a surrounding groove formed thereon;
• wherein the multiple rollers are accommodated in the multiple accommodation grooves of the body respectively, and each of the multiple rollers moves between the locking segment and the unlocking segment of the body, wherein each roller is columnar and has a diameter which is more than the first depth of the locking segment of each accommodation groove of the body and is less than the second depth of the unlocking segment of each accommodation groove of the body, and each roller has two limiting posts extending outwardly from two opposite ends thereof respectively;
• wherein the two driving rings are housed in two surrounding grooves of the two end faces of the body individually, and a rotatable angle produces between the two driving rings, wherein each driving ring has multiple orifices, each of the multiple orifices is more than each of the two limiting posts and is less than the diameter of each roller, and each limiting post is accommodated in each of the multiple orifices so that when each driving ring produces an angular rotation, each roller is driven synchronously;
• and
• wherein a number of the at least one returning means is less than that of the multiple rollers so as to push the two driving rings to the locking segment from the unlocking segment.