🔍 Key Concepts

• Main thrust bearing function – how it transmits propeller thrust into the hull and controls axial movement of the shafting • Location of thrust bearing in relation to the reduction gear train (which element is on the same shaft line) • Difference between pinions and bull gear in a double‑reduction gear set (which turns faster/slower, which is on the output shaft)

💭 Think About

• Think about which gear element is on the same shaft as the main propulsion shaft that actually drives the propeller. • Ask yourself: the thrust from the propeller travels along which shaft, and which gear element is mounted on that shaft inside the reduction gear casing? • Which of these parts would need its axial (fore‑and‑aft) position controlled to protect clearances and alignment in the gear set?

✅ Before You Answer

• Identify which gear (bull gear vs pinions) is attached to the propeller (output) shaft in a main reduction gear. • Confirm which bearing in the system is specifically designed to take axial thrust, not just radial loads. • Before choosing, picture the gear train layout from turbine to propeller and trace the direction of thrust from the propeller back into the hull.