Small Vessel Second Engineer 060-01 Exam: Marine Diesel Engineering

The four-stroke cycle consists of intake, compression, power, and exhaust strokes. In the intake stroke, the fuel-air mixture is drawn into the cylinder; during compression, the mixture is compressed; power stroke involves ignition and combustion of the mixture to produce power; and finally, the exhaust stroke releases the exhaust gases.

The pulse system in turbochargers refers to the use of pulse exhaust gases to drive the turbine. It utilizes the intermittent, pulsating flow of exhaust gases to spin the turbine wheel, providing efficient energy transfer.

The advantage of the pulse system over the constant pressure system lies in its ability to harness exhaust gas energy more effectively. The pulsating flow in the pulse system matches the engine's operation, improving overall efficiency.

A - Camshaft Sprocket, B - Crankshaft Sprocket, C - Tensioner, D - Guide Rail, E - Timing Chain

Chains may elongate or slacken due to wear and stretching over time. The chain tensioner and guide rails are common areas that may wear, affecting chain alignment and tension.

Relief valves are fitted in diesel engine crankcases to release excess pressure that may build up inside the crankcase. They operate when there is an abnormal increase in crankcase pressure, which can occur due to factors like worn piston rings, crankcase ventilation system malfunction, or blow-by from the combustion chambers.

The header tank in the main engine cooling water system serves as an expansion tank, allowing for the expansion and contraction of the coolant as temperatures change, and also maintains a positive pressure in the system. Heaters and coolers are fitted to maintain the desired operating temperature range of the coolant, with heaters warming the coolant when necessary, and coolers removing excess heat.

Baffle plates direct the flow of fluids through the heat exchanger for efficient heat transfer. The sliding tube plate allows for thermal expansion of the tubes. The tell-tale ring indicates any leakage between the two fluids. The vent cock is used to remove air from the system during commissioning. Anodes help prevent corrosion of the heat exchanger by sacrificial oxidation.

A solenoid operated, battery powered electric starting system uses a solenoid switch to engage the starter motor with the engine's flywheel ring gear when the ignition key is turned. The battery provides power to the starter motor, which then cranks the engine. A pre-engaged starter is one where the starter motor pinion gear is always engaged with the flywheel ring gear, eliminating the need for a solenoid switch.

Abnormal turbocharger vibration at steady speeds can be caused by factors like unbalanced rotating components, worn bearings, or fouling of the turbine or compressor wheels. These causes can be minimized through proper maintenance, balancing of components, timely replacement of worn parts, and ensuring clean air and exhaust gas flow.

[A sketch of a hydraulically operated, multi-plate, friction clutch should be provided, with labels for the main components such as the pressure plate, clutch discs, clutch housing, hydraulic actuator, and release bearing.]

The magnetic filter in the lubricating oil system removes ferrous particles from the oil, preventing damage to the gears. The surface finish of the gear teeth is important for smooth meshing and reducing wear. EP (Extreme Pressure) lubricating oil is preferred because it contains additives that provide better protection against high loads and shock loading conditions experienced in reduction gearing.

Blow-by refers to the leakage of combustion gases past the piston rings and into the crankcase during the combustion process. Excessive blow-by can lead to an abnormal increase in crankcase pressure, necessitating the operation of relief valves to prevent damage to the crankcase.