Linear Actuator and Pulley System
The stairs are rotated up by an actuator and pulley system. A pulley is welded to the lower stair section. A cable is attached to the pulley at one end and to the linear actuator at the other. When the actuator pulls on the cable, the bottom section of the stairs rotates up and rests on the top section.
Torsion Spring and Gravity System
The stairs are rotated down by torsion springs and the force of gravity. Torsion springs are attached by one leg to the top section of the stairs and by the other leg to the bottom section of the stairs. When the actuator releases the tension in the cable, the torsion springs push the stairs part of the way down, and the force of gravity pulls them the rest of the way.
