Abstract: A work head (10) has a base member (12) which is connectable to carrier means (30) of a machine for lateral movement of the work head (10) parallel to an X-Y plane of a three-axes co-ordinate system, for longitudinal movement of work head (10) parallel to the Z-axis of that system and for rotating work head (10) on an A-axis parallel to the Z-axis; link means (14) connected to base member (12) so as to pivot relative thereto on a B'-axis parallel to the X-Y plane; a work member (16) connected to link means (14) so as to pivot relative thereto about a B"-axis spaced parallel to the B'-axis. Work member (16) defines a path by which a work medium is able to pass from a source to an outlet defined at a work end (52) of work member (16). Drive means (64,66) is operable to pivot each link means (14) and work member (16), on its axis, but in opposite directions and with the work member (16) pivoting through twice the angle of pivoting of link means (14) relative to base member (12).