An occupant support includes a framework which includes a frame, an orientation adjustable deck section supported by the frame, and a lockable gas spring whose components include a piston assembly coupled to one of the frame and the deck section and a cylinder coupled to the other of the frame and the deck section. The piston assembly includes a piston and a connecting rod. The piston divides the interior of the cylinder into an isolated compartment and a non-isolated compartment. The non-isolated compartment has an inlet and an outlet. An outflow check valve resists fluid flow out of the non-isolated compartment and admits ambient fluid into the non-isolated compartment. An inflow check valve resists fluid flow into the non-isolated compartment and enables fluid flow out of the non-isolated compartment. A turbine receives fluid which flows out of the non-isolated compartment. An electrical generator is coupled to the turbine.