Question 54 AEL01 - Assistant Engineer - Limited

The Correct Answer is C ### Why Option C ("12") is Correct The typical configuration for the main engine thrust bearing used in marine propulsion systems, such as the Kingsbury or Michell type bearings commonly found on large diesel or steam turbine engines (often referenced in materials like Illustration MO-0121), involves multiple segmented shoes to support the significant axial load. Standard industrial and marine practice for highly loaded thrust bearings, especially those integrated into the main engine structure, is to utilize a high number of individual shoes distributed circumferentially for optimal load distribution, cooling, and reliability. **A configuration of 12 thrust shoes is a very common standard design for high-power main propulsion thrust bearings.** Assuming Illustration MO-0121 depicts a standard, modern, high-capacity marine engine thrust bearing, the count of 12 shoes is the industry-standard choice. ### Why the Other Options are Incorrect * **A) 6:** While six shoes might be used for smaller auxiliary machinery or lower-load applications, six shoes are generally insufficient to effectively distribute the massive axial thrust generated by a large main propulsion engine, leading to excessive unit loading per shoe. * **B) 10:** Ten shoes is a plausible, though less common, arrangement than 12. However, the 12-shoe configuration is the established standard depicted in many marine engineering textbooks and manufacturer diagrams for this class of bearing (making it the most likely intended answer for a standard illustration reference). * **D) 20:** Twenty thrust shoes would provide excellent load distribution, but manufacturing and maintaining a bearing with 20 individual segments significantly increases complexity and cost compared to the highly effective 12-shoe design. Twenty shoes are generally not necessary unless the bearing diameter is extremely large or the axial load is unusually high for the engine size.