Abstract: A linear actuator comprises a chain having adjacent first and second links. A pivotal connection pivotally connects the first link to the second link. The first link is pivotable about a pivot axis which is non-perpendicular to a longitudinal axis of the first link. A locking mechanism releasably locks the first link and the second link to prevent the first link from pivoting about the pivot axis. A releasing mechanism releases the locking mechanism to allow the first link to pivot about the pivot axis. A drive mechanism moves the chain between an extended position and a retracted position. At least a portion of the chain is helically wound when the chain is in the retracted position.