Aux 1 Unit 11 Q5

Correct Answer: B) By incorporating a flexible support or pivot system that allows the bearing to adjust to minor alignment changes

Explanation: Plain bearings often incorporate a flexible support or pivot system that allows them to adjust to minor alignment changes. This flexibility is crucial for accommodating the vessel's varying conditions, such as loading or hull flexing, without causing undue stress on the shaft.

Correct Answer: B) Spherical or self-aligning bearings

Explanation: Spherical or self-aligning bearings are designed to accommodate slight misalignments caused by changes in the vessel's condition. These bearings can adjust their position to maintain proper alignment of the propulsion shaft.

Correct Answer: B) It causes the shaft to lengthen, potentially leading to misalignment or excessive stress if not accommodated.

Explanation: Thermal expansion causes the shaft to lengthen, which can lead to misalignment or excessive stress on the bearings if the shaft's longitudinal movement is restricted. Allowing for this movement is essential to maintain system integrity.

Correct Answer: B) Increased risk of shaft misalignment, leading to potential damage or failure as the shaft exits the vessel

Explanation: Without a complete bush in the aftmost bearing, the shaft could become misaligned as it exits the vessel, leading to potential damage or failure. The complete bush ensures that the shaft is fully supported and aligned in this critical position.

Correct Answer: B) Because the weight of the shaft provides sufficient downward force, reducing the need for full circumferential support in intermediate positions

Explanation: Intermediate bearings may only require a bush in the lower half because the weight of the shaft provides sufficient downward force, maintaining contact with the lower bearing surface. Full circumferential support is unnecessary in these positions.

Correct Answer: B) To accommodate thermal expansion and contraction of the shaft, preventing excessive stress on the bearings and the shaft

Explanation: Allowing the shaft to move longitudinally accommodates thermal expansion and contraction. This movement prevents excessive stress on both the bearings and the shaft, which could otherwise lead to damage or misalignment

Correct Answer: B) To provide full circumferential support to the shaft, preventing any lateral movement and maintaining alignment as the shaft exits the vessel

Explanation: The aftmost bearing requires a complete bush to provide full circumferential support to the shaft. This support is crucial for preventing lateral movement and maintaining alignment, especially as the shaft exits the vessel.

Correct Answer: C) The use of axial clearances or a floating bearing design that permits the shaft to slide within the bearing

Explanation: Axial clearances or a floating bearing design allow the shaft to slide within the bearing. This design feature ensures that the shaft can move longitudinally, accommodating thermal expansion and other dynamic factors.

Correct Answer: B) By providing continuous support around the entire shaft circumference, ensuring that the shaft remains centered and aligned

Explanation: The aftmost bearing provides continuous support around the entire circumference of the shaft. This design helps keep the shaft centered and aligned, particularly important as the shaft exits the vessel and encounters external forces.

Correct Answer: B) Excessive stress could build up, leading to bearing failure or shaft damage.

Explanation: If the shaft is not allowed to move longitudinally, excessive stress can build up due to thermal expansion or other factors. This stress can lead to bearing failure or even damage the shaft itself.