Abstract: A turbine rotor (eg: a Pelton wheel) is described which comprises a plurality of individual radial body members (11) comprising one or more impeller elements (eg: buckets) (1). The radial body members comprises segments which have leading (13) and trailing (15) radial abutment surfaces that contact with the respective radial abutment surfaces of adjacent radial body members when assembled as a unit. Each radial body member comprises at least one further abutment (21), preferably two at opposite axial ends (17,19) thereof, and locating means (26,27) is provided which co-operates with the further abutment means, preferably directly. Wedging means which is tapered in the radial direction relative to the axis of rotation of the turbine rotor, acts between the radial body members and the locating means, and means is provided which acts via said wedging means to draw the radial body members radially inwards to hold them together as a unit.