Rotary steam motor

A rotary steam motor comprising:

• an inlet assembly including an inlet port and an inlet housing, the inlet port being configured to allow steam to enter the inlet housing;
• a rotor assembly including a rotor, a support shaft, and a plurality of vanes, wherein the support shaft is configured to rotate with the rotor, and the rotor includes plurality of vane slots such that each vane is configured to slidably engage within a respective vane slot;
• an exhaust assembly including an exhaust port and an exhaust housing, the exhaust port being configured to allow steam to exit the exhaust housing;
• and
• a variable duration throttle assembly,
• wherein the rotor assembly is configured to receive steam from the inlet assembly, and the exhaust assembly is configured to receive steam from the rotor assembly, and
• wherein the variable duration throttle assembly is configured to regulate the flow of steam into the rotor assembly from the inlet assembly so as to provide substantially constant pressure expansion from the intake assembly through the exhaust assembly.