Linear actuators and methods for assembling the same are disclosed. A linear actuator according to the disclosure may include a drive unit having a drive shaft and a spindle mechanism having a spindle, which can be driven by the drive shaft. A bearing unit may be provided, which may be configured to support a connecting shaft connecting the drive shaft to the spindle and has a bearing block matched to the internal cross section of the housing.The bearing unit may have a preloading device for preloading a rotary bearing inserted into the bearing block, and the spindle may be screwed to the connecting shaft via a centering portion and a screw fastening portion.