Abstract: The present invention relates to a fluid pressure powered actuator for imparting relative angular movement between two members, connected together by a hinge, comprising an elongated inflatable flexible conduit of substantial constant surface area, connected between the two members with its longitudinal axis substantially parallel to the hinge pivot axis and with the two members substantially equispaced around the conduit whereby on inflation, the conduit exerts a pulling force between the two members to impart relative angular movement therebetween.