Exam Question
With reference to stuffing box of a two stroke main engine explain following:
(a) Why stuffing box is required in two stroke diesel engines.
(b) Explain the maintenance carried out on stuffing box during piston overhaul.
Class 4 (4th Engineer)
MEP
📅 Apr 2025
Reference Answer
### (a) Requirement of Stuffing Box in Two-Stroke Diesel Engines
The stuffing box is a critical component located in the diaphragm plate that separates the scavenge air space from the crankcase in large two-stroke crosshead diesel engines. Its primary purpose is to seal the piston rod as it passes between these two distinct environments, each with different pressures and atmospheric compositions. The requirement for the stuffing box arises from the following fundamental needs:
1. **To Prevent Inter-Contamination of Lubricating Oil and Scavenge Air**:
* **Crankcase Oil Protection**: The stuffing box prevents the ingress of contaminants from the scavenge space into the crankcase. These contaminants include combustion by-products (soot, carbon), unburnt fuel, cylinder lubricating oil residues (which are high in TBN and ash), and scavenge air itself. Contamination of the system lubricating oil would degrade its properties (viscosity, TBN, detergency), leading to accelerated wear of bearings, gears, and other crankcase components.
The stuffing box is a critical component located in the diaphragm plate that separates the scavenge air space from the crankcase in large two-stroke crosshead diesel engines. Its primary purpose is to seal the piston rod as it passes between these two distinct environments, each with different pressures and atmospheric compositions. The requirement for the stuffing box arises from the following fundamental needs:
1. **To Prevent Inter-Contamination of Lubricating Oil and Scavenge Air**:
* **Crankcase Oil Protection**: The stuffing box prevents the ingress of contaminants from the scavenge space into the crankcase. These contaminants include combustion by-products (soot, carbon), unburnt fuel, cylinder lubricating oil residues (which are high in TBN and ash), and scavenge air itself. Contamination of the system lubricating oil would degrade its properties (viscosity, TBN, detergency), leading to accelerated wear of bearings, gears, and other crankcase components.
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