A linear actuator comprises a motor for producing a bi-directional rotational output. A casing is connected to the motor at a proximal end, the casing having an inner cavity defining a joint surface. A shaft is within the inner cavity of the casing and actuated by the motor for rotation. A sliding tube is at least partially in the inner cavity of the casing for moving in translation in an axial direction relative to the casing. One or more travelling nut is connected to the sliding tube assembly for moving with the sliding tube in the axial direction, the travelling nut being operatively engaged to the shaft for converting a rotational motion of the shaft into a translation of the sliding tube. A liner is between the sliding tube and the joint surface of the inner cavity, an inner surface of the liner defining longitudinal contact surfaces separated by longitudinal grooves, the longitudinal contact surfaces contacting the sliding tube.