🔍 Key Concepts

• Design requirements for main propulsion reduction gear bearings on large marine diesel or turbine installations • Characteristics of Babbitt-lined bearings versus roller/ball bearings in slow-speed, heavily loaded applications • Why split-type construction and rigid mounting are used in large gear housings

💭 Think About

• Which bearing type is best suited to carry very heavy, steady loads at relatively low speed with precise gear alignment? • On a large reduction gear, is it more important for the bearing to be self-lubricating and sealed, or to be fully integrated into a forced-lubrication system? • Think about maintenance: which configuration allows inspection and renewal of bearing surfaces without removing the entire shaft?

✅ Before You Answer

• Compare which answer choices mention Babbitt lining and split type—both are strongly associated with large marine reduction gears • Eliminate options that sound like small machinery bearings (e.g., sealed, self-lubricating units) rather than large main propulsion equipment • Ask yourself: which design can be line-bored and integrated into a pressure lubrication system in a reduction gear housing?