Abstract: A series of standardized components from which can be assembled a single stage geared turbine having any one of a large number of combinations of output power and gear rotation rate, the components including a plurality of rotor wheels having respectively different wheel pitch diameters, a plurality of steam delivery nozzle sets for each rotor wheel, a plurality of turbine casings each dimensioned to correspond to a respective wheel pitch diameter, a plurality of gear casings each dimensioned to correspond to a repectively different value for the spacing between the axis of a pinion and a gear, and a plurality of pinions having respectively different diameters, any gear casing being connectable to any turbine casing, the turbine casing employed for the turbine to be assembled being selected on the basis of the rotor wheel which has been selected, and the gear casing which is to be employed in the turbine being selected on the basis of the distance between the axes of rotation of the selected pinion and the ou