Q1
With reference to Cylinder Liner lubrication of large two stroke engines:
(16)
(a) Outline the problems associated with improper lubrication of the liner and piston assembly of a large slow speed engine
(b) Describe and state the causes of cloverleafing, and micro-seizure
(c) List out the composition of a cylinder oil suitable for an engine operating on residual fuel.
Reference Answer
### (a) Problems Associated with Improper Lubrication Improper lubrication of a large two-stroke engine's cylinder liner and piston assembly can be categorized into issues arising from under-lubrication and over-lubrication. Both conditions lead to severe operational problems, reduced efficiency, and potential catastrophic failure. **1. Under-Lubrication (Insufficient Oil Feed):** * **Adhesive Wear (Scuffing and Scoring):** This is the most immediate danger. The hydrodynamic oil film breaks down, leading to direct metal-to-metal contact between the piston rings and the cylinder liner. This causes localized welding of surface asperities, which are then torn apart, leading to severe surface damage, high frictional heat, and potential seizure.
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