Turbomachine comprising clutched turbine wheels

Solutions for clutching turbine wheels (6, 8) are disclosed. In one embodiment, an apparatus (22) includes: a turbine rotor shaft (4); a plurality of turbine wheels (6) affixed to the turbine rotor shaft (4); an independent turbine wheel (8) engagably attached to the turbine rotor shaft (4); and a clutch (10) operably connected to the turbine rotor shaft (4), the clutch (4) configured to couple and decouple the independent turbine wheel (8) from the turbine rotor shaft (4).