er using a period of time makes them unable of dismount and cause the puzzlement while changing relevant parts in the future.In order to solve these problems, some new structure has been designed accordingly, such as the structure disclosed in the U.S. Pat. No. 6,061,847 Please referring to FIG. 3, an actuating stem 81 and a connecting bar 82 are used to replace the afore-said lift rod, and the co