🔍 Key Concepts

• Difference between rotary motion and oscillating (swinging) motion in engine parts • How crankshaft journal, crankpin, wrist pin, and thrust bearings move relative to their mating surfaces • Which engine parts move through a full 360° rotation versus those that rock back and forth

💭 Think About

• For each option, ask: does this bearing surface rotate continuously, or does it only move back and forth through a limited angle? • Think about the motion of the connecting rod and piston assembly: which bearing in that system experiences a rocking or swinging action rather than full rotation? • Consider where end‑thrust (axial force) is taken in the engine and what type of motion that bearing usually sees

✅ Before You Answer

• Be clear on what swinging (oscillating) motion means: not full rotation, but back‑and‑forth movement over a small angle • Visualize the engine: crankshaft journals and crankpins – do they revolve 360°, or rock? Wrist pin – does the pin itself spin fully, or does the rod swing on it? • Confirm where thrust bearings are located and whether they mainly handle axial loads with rotation, or an oscillating swing