🔍 Key Concepts

• Axial thrust vs. radial thrust in steam/reaction turbines • How a dummy piston (balance piston) uses pressure differences to reduce thrust on thrust bearings • The role of gland seals versus balance pistons in controlling leaks and thrust

💭 Think About

• Think about which direction of force the turbine rotor mainly develops as steam expands through the stages—along the shaft (axial) or around the shaft (radial)? • Ask yourself: what is a dummy or balance piston physically doing with steam pressure—does it touch the casing to control clearances, or does it create an opposing force? • Consider whether gland seal steam is primarily for thrust control or for another purpose such as minimizing steam leakage at shaft penetrations.

✅ Before You Answer

• Identify whether a dummy piston / balance piston is associated with axial or radial forces on the rotor • Clarify in your mind the primary job of gland seals (what problem are they mainly solving?) • Check which option best describes a device that uses pressure area on a piston to oppose a force along the shaft.