Exam Question
(a) What is the importance of measuring bearing clearance in a diesel engine. (4)
(b) What is Bridge gauge? Describe it's usage with diagram. (6)
(c) What are other recommended methods used onboard to check bearing clearances. (6)
Class 4 (4th Engineer)
MEKM
📅 Nov 2023
Reference Answer
### (a) Importance of Measuring Bearing Clearance (4 Marks)
The measurement of bearing clearance is a critical diagnostic and preventative maintenance task in diesel engines. Bearing clearance is the small, engineered gap between the rotating journal (of the crankshaft or camshaft) and the stationary bearing shell. Its importance is multifaceted:
1. **Formation of Hydrodynamic Lubrication Film:** The primary function of this clearance is to allow a wedge of lubricating oil to form between the moving surfaces. As the journal rotates, it pulls oil into this wedge-shaped clearance, generating a high-pressure film (hydrodynamic lubrication) that completely separates the metal surfaces, preventing friction, wear, and seizure.
2. **Prevention of Insufficient Clearance Issues:** If the clearance is too small (below manufacturer's limits), the following problems can occur:
The measurement of bearing clearance is a critical diagnostic and preventative maintenance task in diesel engines. Bearing clearance is the small, engineered gap between the rotating journal (of the crankshaft or camshaft) and the stationary bearing shell. Its importance is multifaceted:
1. **Formation of Hydrodynamic Lubrication Film:** The primary function of this clearance is to allow a wedge of lubricating oil to form between the moving surfaces. As the journal rotates, it pulls oil into this wedge-shaped clearance, generating a high-pressure film (hydrodynamic lubrication) that completely separates the metal surfaces, preventing friction, wear, and seizure.
2. **Prevention of Insufficient Clearance Issues:** If the clearance is too small (below manufacturer's limits), the following problems can occur:
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