Abstract: In a pneumatically actuated screwdriving machine having a tubular screw receiving nose which surrounds the rotatable screwdriver head and which may slide axially towards the body of the machine by being carried and guided by longitudinal rods secured to the said nose and slidably supported by the said body, one of these rods has a peripheral groove and acts as a movable slide valve member in cooperation with annular chambers provided within the body. When the nose has been pushed towards the body, the air under pressure admitted through the valve which controls the pneumatic motor of the machine is also supplied through a flexible air conduit to the selector of a screw feeding apparatus which takes a screw from the screw container of the apparatus, while when the nose is returned to its advanced position, the air conduit is depressurized and the screw is transferred towards the nose through a flexible screw conveying conduit.