Rotation Structure

Abstract

A rotation structure includes a main body, two bearings mounted in the main body, a mandrel mounted between the two bearings, a rotation member having a first end connected with the mandrel, and a weight mounted on a second end of the rotation member. The rotation member is situated at a center of the mandrel and is perpendicular to the mandrel. The rotation member and the weight have a total length smaller than a radius of the main body. Thus, the weight is rotated in the main body without producing sound so that the main body is operated in a noiseless manner and will not produce noise during movement.

1 . A rotation structure comprising:
 a main body;   two bearings mounted in the main body;   a mandrel mounted between the two bearings;   a rotation member having a first end connected with the mandrel; and   a weight mounted on a second end of the rotation member;   wherein:   the main body includes two shells combined together;   the main body has an exterior provided with two finger holes and two operation portions;   the two finger holes correspond to the two operation portions respectively;   the main body has an interior provided with a receiving chamber and two mounting recesses;   the mandrel has two ends pivotally mounted on the two bearings;   the mandrel is received in the receiving chamber;   the two bearings are mounted in the two mounting recesses respectively;   the rotation member is situated at a center of the mandrel;   the rotation member is perpendicular to the mandrel; and   the rotation member and the weight have a total length smaller than a radius of the main body.   
     
     
         2 . The rotation structure as claimed in  claim 1 , wherein each of the two operation portions is a handgrip. 
     
     
         3 . The rotation structure as claimed in  claim 1 , wherein each of the two operation portions has an arcuate shape. 
     
     
         4 . The rotation structure as claimed in  claim 1 , wherein each of the two operation portions is provided with a nonslip portion. 
     
     
         5 . The rotation structure as claimed in  claim 1 , wherein the rotation member is a rod. 
     
     
         6 . The rotation structure as claimed in  claim 1 , further comprising:
 four positioning members extending through the two shells to secure the two shells;   wherein the four positioning members are situated at upper ends and lower ends of the two operation portions.   
     
     
         7 . The rotation structure as claimed in  claim 1 , wherein:
 each of the two shells has a periphery provided with at least one insertion projection and at least one insertion slot; and   the at least one insertion projection of one of the two shells is inserted into the at least one insertion slot of the other one of the two shells when the two shells are juxtaposed to each other.   
     
     
         8 . The rotation structure as claimed in  claim 1 , wherein:
 each of the two shells has an interior provided with a plurality of first connecting portions and a plurality of second connecting portions; and   the first connecting portions of one of the two shells are connected with the second connecting portions of the other one of the two shells when the two shells are juxtaposed to each other.