Where is the propeller supported when balancing to measure horizontal imbalance?

Where is the propeller supported when balancing to measure horizontal imbalance?

• A. On the engine crankshaft
• B. On the balance knives
• C. On the balancing stand
• D. On the propeller hub

Answer: (B)

Balancing to measure horizontal imbalance requires the propeller to rotate freely about its axis with minimal friction. The prop is placed on knife-edge supports mounted on the balancing stand. These balance knives provide stable, low-friction contact so the propeller can spin while the balancing instrument detects any tendency to lean or shift horizontally. Mounting on the engine crankshaft would tie the prop to the engine and alter the balance measurement; attaching it to the propeller hub would fix it in place and prevent the necessary rotation for a true balance; and while the balancing stand is the framework, the actual contact that allows proper measurement is the knife-edge supports.

Balancing to measure horizontal imbalance requires the propeller to rotate freely about its axis with minimal friction. The prop is placed on knife-edge supports mounted on the balancing stand. These balance knives provide stable, low-friction contact so the propeller can spin while the balancing instrument detects any tendency to lean or shift horizontally. Mounting on the engine crankshaft would tie the prop to the engine and alter the balance measurement; attaching it to the propeller hub would fix it in place and prevent the necessary rotation for a true balance; and while the balancing stand is the framework, the actual contact that allows proper measurement is the knife-edge supports.