Abstract: A fluid-powered mechanical actuator having a proximal end and a distal end and having a plurality of hollow tubular elements hingedly connected in end-to-end linked relationship to form a variable angle therebetween, each such link having one degree of freedom; provision to bias the elements in a direction to minimize the angle between them; a flexible elongated chamber enclosing a space within it, the chamber situated within the linked elements and within the link therebetween, substantially contained thereby, the chamber having a flexible but non-expansible wall; and apparatus to provide to the space within said chamber a pressurized working fluid; whereby the pressure of the working fluid causes said chamber to straighten within said elements, especially at said links, thereby moving the relative position of the elements in a manner to act against the biasing means, thereby to cause an increase of the angle between them by providing an increase in working fluid pressure.