🔍 Key Concepts

• Location and role of a main thrust bearing in the propulsion shaft line • How propeller thrust is reacted and where that force ultimately goes • Difference between supporting radial loads (up/down) and axial loads (fore-and-aft) in shaft bearings

💭 Think About

• When a propeller pushes water aft, where does the equal and opposite force act in the ship’s structure? Think about how that force gets from the propeller into the hull. • Ask yourself: does the main thrust bearing mainly hold gears in place, or does it manage fore‑and‑aft forces along the shaft line? • Consider which component in the propulsion train is specifically designed to take axial thrust from the shaft rather than just guide or align it.

✅ Before You Answer

• Identify which option clearly involves axial (fore-and-aft) thrust rather than just alignment or lateral support. • Recall that the main thrust bearing is installed on the shaft line, not inside a reduction gear casing for gear positioning purposes. • Eliminate choices that talk about keeping things in line or preventing generic movement without mentioning the transfer of axial thrust into the ship’s structure.