Coast Guard Exams
Question 163Motor Plants - 1st Asst/Chief70% to pass

After following the prescribed procedures to measure the thrust bearing clearance shown in the illustration, the distance "F" is determined to be 200 mm, and 'f1' is 2.3 mm. Which of the following statements describes the condition indicated by these dimensions? Illustration MO-0121

Diagram for question 163
AI Explanation
The correct answer is C. These dimensions indicate that the shaft can move axially 2.3 mm during astern operation, which relates to an excess movement of 1.3 mm, 0.3 mm beyond the maximum worn play. This is the correct interpretation because the maximum recommended axial play for a thrust bearing is typically 2.0 mm, and the measured play of 2.3 mm exceeds this limit, indicating potential issues with the thrust bearing. The other answer choices are incorrect because: A) the loading ratio is not mentioned in the problem; B) the flourishing marks are not a relevant factor in this scenario; and D) the total active thrust area is not a key measurement in determining the condition of the thrust bearing.