Class 2 (2nd Engineer) MEKG 📅 Apr 2023

Exam Question

(a) Explain why, in spite of accurate alignment under static conditions use of flexible couplings and copious supply of lubricant, main reduction gearing in still subject to pitting, scuffing and other tooth damage;

(a) Discuss the significance of viscosity in relation to the function of marine turbine oils as used in main propulsion installations, stating how the viscosity is controlled and what could cause it to change in service.

Reference Answer

### Part (a): Main Reduction Gearing Damage
Despite meticulous static alignment, the use of flexible couplings, and an ample supply of high-quality lubricant, main reduction gearing is susceptible to damage due to the severe and dynamic operating conditions encountered at sea. The protections in place are designed for ideal or static states, which are rarely maintained during a vessel's operation.
**1. Dynamic Misalignment & Hull Deflection:**
* **Static vs. Dynamic Alignment:** Alignment is typically performed in a static, 'cold' condition in port. Once at sea, dynamic factors introduce significant misalignment.

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