Abstract: A self-acting automatic clearance control apparatus for a turbine of the type which includes a turbine rotor mounted for rotation in a housing, the turbine rotor having cooperatively disposed on one side thereof a nozzle and on the other side an exhaust duct, the apparatus includes a control device positioned adjacent to the turbine rotor. The control device is coupled to the nozzle and the exhaust duct. The control device is responsive to changes in dimensions of said turbine rotor as the turbine operates over a range of temperatures to thereby change the relative position of the control device in respect of the turbine rotor whereby the clearance between the nozzle and the exhaust duct in respect to the turbine rotor is maintained automatically.