Reciprocating drive means powered by a fluid such as compressed air comprising an elongate inner member with a plurality of passageways therein, an outer member slidable on the inner member and a shuttle member slidable with respect to the inner member and within the outer member, the passageways in the inner member being variously and intermittently so connected in use to each other by way of ports in the inner member and compartments provided within the outer member and the shuttle that, upon connection of a determined one of said passageways to a fluid pressure source the outer member moves with reciprocating action with respect to the inner member. The inner member has two fixed discs thereon, between which discs the shuttle member can oscillate, the discs having seals on their peripheral surfaces to seal against the inner wall of the outer member, the outer member is cylindrical with end walls having seals slidable on the inner member and cooperating with ports therein and the shuttle member has axially spaced seals on its inner peripheral surface to cooperate with ports in the inner member and to seal against the inner member and define one of the compartments therebetween. Following movement of the outer member in one direction of movement, the shuttle member is moved by pressure in an opposite direction to cause the outer member to move in said opposite direction.