Abstract: A linear actuator assembly having a flexible tether that runs along a guide track. The flexible tether has a first segment and a second segment, wherein a predetermined tension exists in the flexible tether. A restraining mechanism is coupled to the flexible tether that automatically engages the guide track when the tension in the flexible tether drops below a predetermined threshold. Accordingly, if the flexible tether were to break, the load carried by the linear actuator would lock in place and would not fall under the force of its weight.