An actuator comprises a screw shaft, a nut translatable along the shaft between a retracted position and an extended position, a tine component carried by the nut, the tine component including tine fingers formed with projections each being engageable with a formation provided on a housing when the nut occupies its extended position to secure the nut against axial movement, and a lock member engageable with the tine fingers to restrict radial movement of the tine fingers.