Abstract: A linear actuator (20) including three nested telescoping sections (22, 24, 26) actuated by two internal screw drives (28, 30). First and second screw drive nuts (32, 34) are rotatably mounted in the intermediate telescoping section (24) to linearly translate respective first and second screw shafts (36, 38), which are fixed to respective distal ends (21, 27) of the outer (22) and inner (26) telescoping sections. The drive nuts may be mounted at opposite ends of the intermediate section in a housing (23, 25, 29), and may be driven by a motor (40) therein via an idler shaft (42) that spans between the two drive nuts. The motor may be designed to serve alternately as a regenerative resistance brake (R1). A mechanical brake (43) may alternately or additionally be provided. Either or both brakes may be set to engage by default on power outage.