Abstract: An actuator having a load weighting mechanism is disclosed. The actuator has a screw and a nut mounted around the screw and connected with a driving shaft. The driving shaft supports a load. When moving along the screw, the nut displaces the driving shaft forward and backward. The screw has a pair of thrust bearings for bearing the load, and at least one load weighting unit installed between the pair of thrust bearings for weighting the load.

Abstract: An extension mechanism for an actuator comprises a telescopic assembly, a motor and an extension assembly. The motor and the extension assembly are respectively disposed in the telescopic assembly, and the motor is fixed at one end of the telescopic assembly. The extension assembly is connected by a plurality of X-shaped pivot members, and every two rods are pivotally connected together to form an X-shaped pivot member. The extension assembly is respectively connected to the sleeves. The motor is used to drive the extension assembly to extend and retract, thus causing the extension and retraction of the telescopic assembly.