Locking mechanism

A locking mechanism used in a spindle comprises:

• a first locking member insertingly disposed on the spindle;
• and
• a second locking member socketingly retained onto and jointly rotated with the spindle;
• wherein the first locking member has a pair of arc shaped notches including a first arc shaped notch and a second arc shaped notch, both of the first arc shaped notch and the second arc shaped notch of the first locking member have a front curved end and a rear curved end;
• the second locking member has a pair of arc shaped protrusions including a first arc shaped protrusion and a second arc shaped protrusion, both of the first arc shaped protrusion and the second arc shaped protrusion of the second locking member have a front curved end and a rear curved end;
• wherein front curved ends of the arc shaped notches are formed to have a first sloped surface, respectively, and rear curved ends of the arc shaped notches are formed to have a second sloped surface, respectively;
• wherein the first sloped surfaces of the arc shaped notches are an arc protrusion having an arc shape, respectively;
• wherein the second sloped surfaces of the arc shaped notches are an arc protrusion having an arc shape, respectively;
• wherein, when the second locking member is located in a single locking position, the first arc shaped protrusion is located in the first arc shaped notch and the second arc shaped protrusion is located in the second arc shaped notch;
• wherein the arc shape of the pair of arc shaped notches and the arc shape of the pair of arc shaped protrusions prevent the first arc shaped protrusion from being inserted into the second arc shaped notch and the second arc shaped protrusion from being inserted into the first arc shaped notch, the second locking member is only lockable in the single locking position.