Abstract: An inflatable ram has an extensible wall of flexible sheet material connecting two opposed end faces to enclose a space which is divided into a plurality of interconnected compartments by diaphragms extending between opposed regions of the inner surface of the extensible wall so as to be parallel with the end faces. Restraining means, which may comprise elastic cords, are arranged to provide increasing restraint against inflation of successive compartments so that extension of the ram takes place by sequential inflation of the compartments as the restraining means are progressively overcome.