USCG Exam PracticeBearings, lubrication, and care of machine parts
Journal (sleeve) bearings in propulsion shafting support the radial weight of the shaft by means of which mechanism?
- ✓ A hydrodynamic oil wedge that keeps the metal surfaces apartCorrect
- B. Direct metal-to-metal contact on a hardened bearing surface
- C. Pressurized grease injected between the shaft and the bearing shell
- D. Rolling elements interposed between the shaft journal and the bearing race
Why A is correct
NAVEDTRA 14075 §4-1 describes journal (sleeve) bearings as carrying the radial weight of a shaft on a thin film of pressurized oil forming a hydrodynamic wedge that keeps the metal surfaces apart. Rolling-element bearings are a separate category used where loads and speeds suit them.
Cited:NAVEDTRA 14075 §4-1